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ABSTRACTS

ABSTRACTS

of The Fifth Poznań Symposium on
"Quantum Technologies, Nonlinear Optics,
Magnonics, and Metamaterials"
QuTecNOMM 2019 

    Session on Plasmonics & Photonics

  1. Date: Tuesday 2019.10.15 at 9:00-9:10
    Speaker: Prof. Adam Miranowicz
    Title: Symposium Opening and Welcome Note
  2. Date: Tuesday 2019.10.15 at 9:10-9:30
    Speaker: Prof. Igor L. Lyubchanskii (invited speaker)
    Title: One-dimensional multiperiodic photonic structures: a new route in photonics (four-component media)
    Authors: I. S. Panyaev (1), L. R. Yafarova (1), D. G. Sannikov (1), N. N. Dadoenkova (1), Y. S. Dadoenkova (2,1), and I. L. Lyubchanskii (3,4)
    Addresses:
    (1) Ulyanovsk State University, Ulyanovsk, Russia
    (2) Lab-STICC (UMR 6285), CNRS, ENIB, 29238 Brest Cedex 3, France
    (3) Donetsk Institute for Physics and Engineering of the National Academy of Sciences of Ukraine
    (4) V. N. Karazin Kharkiv National University, 61022 Kharkiv, Ukraine
    Abstract: We study the transmittivity spectra of one-dimensional finite three-periodic photonic crystals of the structure [(ab)N(cd)M]K composed of four different layers a, b, c, d being dielectric oxides Al2O3, SiO2, TiO2, and ZrO2. We analyze modification of the transmittivity spectra of near-infrared electromagnetic waves of the TE and TM polarizations in the vicinity of the photonic band gaps with variations of the sub-cell numbers N and M and super-cell number K, the incidence angle, and the order of the layers in the structure. We propose classification of three-periodic photonic crystals by the magnitude and sign of the optical contrast between the layers in pairs (ab) and (cd) forming the sub-cells and discuss common spectral properties as well as their differences in these structures [1].
     
    [1] I. S. Panyaev, L. R. Yafarova, D. G. Sannikov, N. N. Dadoenkova, Y. S. Dadoenkova, and I. L. Lyubchanskii. J. Appl. Phys. 126 , 103102 (2019).
    Chair: Prof. Jarosław Kłos
    Seminar language: English
  3. Date: Tuesday 2019.10.15 at 9:30-9:45
    Speaker: M.Sc. Vishal Vashistha
    Affiliation: Faculty of Physics, Adam Mickiewicz University in Poznań, Poznań
    Title: 4f system design and performing spatial filtering using independent amplitude and phase control metasurfaces
    Abstract: Metasurfaces based devices are widely in fashion and metasurface become one of the promising platforms for photonics devices. It has been explored for various photonics applications such as light guiding, color filter design [1, 3]. Current research based on metasurfaces is mostly dependent upon either independent amplitude control or independent phase control mechanism. To explore the further capability of metasurfaces, it is important to have independent and simultaneous control on amplitude, phase, polarisation, and, the optical impedance of the wave [2]. In this talk, I am going to explain about independent amplitude and independent phase control of metasurfaces based on Pancharatnam-Berry (PB) phase mechanism. The technique is used to design the complete 4f system based on metasurface for parallel computing especially, spatial filtering purposes. It has high potential to design the neural network front-end to performed fast and parallel convolution operation which is difficult and time-consuming in the electronic domain platform.
     
    [1] Patrice Genevet, Federico Capasso, Francesco Aieta, Mohammadreza Khorasaninejad, and Robert Devlin. Recent advances in planar optics: from plasmonic to dielectric metasurfaces. Optica, 4(1):139–152, 2017.
    [2] Adam C Overvig, Sajan Shrestha, Stephanie C Malek, Ming Lu, Aarton Stein, Changxi Zheng, and Nanfang Yu. Dielectric metasurfaces for complete and independent control of optical amplitude and phase. arXiv preprint arXiv:1903.00578, 2019.
    [3] Vishal Vashistha, Gayatri Vaidya, Ravi S Hegde, Andriy E Serebryannikov, Nicolas Bonod, and Maciej Krawczyk. All-dielectric metasurfaces based on cross-shaped resonators for color pixels with extended gamut. ACS photonics, 4(5):1076–1082, 2017.
    Seminar language: English

    Session I on Quantum Technologies

  4. Date: Tuesday 2019.10.15 at 9:45-10:05
    Speaker: Prof. Karel Lemr (invited speaker)
    Affiliation: RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, Olomouc, Czech Republic
    Title: Experimental implementation of a programmable controlled-phase gate (work in progress)
    Abstract: The talk presents the concept of a programmable controlled-phase gate and its linear-optical scheme. Usefulness of this gate is discussed in the context of quantum machine learning and quantum communications. Finally, the talk briefly outlines the currently ongoing experimental implementation of this gate on the platform of linear optics.
    Chair: Prof. Ryszard Tanaś
    Seminar language: English
  5. Date: Tuesday 2019.10.15 at 10:05-10:25
    Speaker: Dr. Grzegorz Chimczak
    Affiliation: Nonlinear Optics Division, Physics Faculty, AMU, Poznań
    Title: Two-photon blockade via interaction with a nonlinear reservoir
    Abstract: Recently, the group led by Gerhard Rempe has demonstrated experimentally two-photon blockade in a driven nonlinear system (composed of a harmonic cavity with a driven atom). Inspired by this experiment, we show that two-photon blockade can be generated in a driven harmonic cavity without an atom or any other kind of nonlinearity, but instead coupled to a nonlinear reservoir. We also investigate the possibility of generating other nonstandard types of photon-blockade and photon-induced tunneling.
    Chair: Prof. Ryszard Tanaś
    Seminar language: English
  6. Date: Tuesday 2019.10.15 at 10:25-10:45
    Speaker: Prof. Jan Soubusta (invited speaker)
    Affiliation: RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, Olomouc, Czech Republic
    Title: New experimental tests of three-qubit nonlocality
    Abstract: We use our experimental setup, which is capable to generate three-qubit GHZ states with high repetition rate. With this setup we decided to test Hardy's paradox and to measure nonlocal volume of the generated GHZ states.
    Chair: Prof. Ryszard Tanaś
    Seminar language: English
  7. Date: Tuesday 2019.10.15 at 10:45-11:00
    Speaker: M.Sc. Vojtěch Trávníček
    Affiliation: RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, Olomouc, Czech Republic
    Title: Experimental measurement of Hilbert-Schmidt distance
    Abstract: The talk touches on the definition of Hilbert-Schmidt distance and its translation to measurable observables. Further it discusses the experimental implementation on the platform of linear optics. The reasons and benefits of measuring the Hilbert-Schmidt distance.
    Chair: Prof. Ryszard Tanaś
    Seminar language: English

    Session II on Quantum Technologies

  8. Date: Tuesday 2019.10.15 at 11:20-11:35
    Speaker: M.Sc. Zakarya Lasmar
    Affiliation: Quantum Electronics Division, Physics Faculty, AMU
    Title: When can many fermions exhibit bosonic behaviour?
    Abstract: A many-body system made of an even number of fermionic constituents can collectively behave in a bosonic way. The simplest example of such systems is the one made of two fermions. In fact, this is example was heavily studied so far, and it is unanimously accepted that entanglement plays a crucial role behind the bosonic quality of its collective behaviour. However, if we consider four fermions, they can behave like two bipartite bosons or further assemble into a single four-partite bosonic molecule. In general, 2N fermions can take many possible arrangements which might be treated as composite bosons. In this talk, I will aim to answer the question: what determines which fermionic arrangement is going to be realized in a given situation and can such arrangement be considered truly bosonic? I will discuss an entanglement-based method to assess bosonic quality of fermionic arrangements and apply it to study how the ground state of the extended one-dimensional Hubbard model changes as the strength of intra-particle interactions increases.
     
    Ässembly of 2N entangled fermions into multipartite composite bosons" Zakarya Lasmar, P. Alexander Bouvrie, Adam S. Sajna, Malte C. Tichy, and Paweł Kurzyński Phys. Rev. A 100, 032105 (2019)
    Chair: Prof. Karel Lemr
    Seminar language: English
  9. Date: Tuesday 2019.10.15 at 11:35-11:50
    Speaker: M.Sc. Marcin Karczewski
    Affiliation: Quantum Electronics Division, Physics Faculty, AMU
    Title: Generating entanglement with single-photon subtractions
    Abstract: The states of a system of identical particles are required to be symmetric for bosons and antisymmetric for fermions. Are these inherent correlations just a mathematical artifact or can they be treated as a resource? In the talk I will support the latter point of view by showing how operationally accessible entanglement can be extracted form the indistinguishability of particles. I will focus on a recently proposed method [1] based on tailored single-photon subtractions from multiboson states.
     
      [1] M. Karczewski et al., "Sculpting out quantum correlations with bosonic subtraction." Phys. Rev. A 100, 033828 (2019).
    Chair: Prof. Karel Lemr
    Seminar language: English
  10. Date: Tuesday 2019.10.15 at 11:50-12:10
    Speaker: Prof. Paweł Kurzyński
    Affiliation: Quantum Electronics Division, Physics Faculty, AMU
    Title: Contextuality of identical particles
    Abstract: Contextuality is a more general notion than nonlocality, since it also applies to measurements done in a single laboratory on a local system. In majority of scenarios one considers measurements done on a single particle and there are many proofs showing that these measurements do not admit a classical description in terms of noncontextual hidden-variable theories. However, the situation might be different if one performs collective measurements on many particles. In particular, what happens if one considers many indistinguishable particles? I am going to show that indistinguishability affects our ability to observe contextuality. Moreover, I will show that this approach allows one to resolve the problem of Bell inequality violations with classical light.
     
    [1] "Contextuality of identical particles", P. Kurzyński, Phys. Rev. A 95, 012133 (2017)
    [2] "From contextuality of a single photon to realism of an electromagnetic wave", M. Markiewicz, D. Kaszlikowski, P. Kurzyński, A. Wójcik, npj Quantum Information 5, 5 (2019).
    Chair: Prof. Karel Lemr
    Seminar language: English
  11. Date: Tuesday 2019.10.15 at 12:10-12:30
    Speaker: Prof. Rafał Demkowicz-Dobrzański (invited speaker)
    Affiliation: Faculty of Physics, University of Warsaw
    Title: The great unified theory of quantum metrology
    Abstract: A general model of unitary parameter estimation in presence of Markovian noise is considered, where the parameter to be estimated is associated with the Hamiltonian part of the dynamics. In absence of noise, unitary parameter can be estimated with precision scaling as 1/T, where T is the total probing time. A simple algebraic condition involving solely the operators appearing in the quantum Master equation, decides whether 1/T or 1/√T scaling of precision is achievable using the most general adaptive quantum estimation strategies including quantum error-correction protocols.
    Chair: Prof. Karel Lemr
    Seminar language: English
  12. Date: Tuesday 2019.10.15 at 14:30-14:50
    Speaker: Prof. Karol Bartkiewicz
    Affiliations: (1) Nonlinear Optics Division, Physics Faculty, AMU, Poznań and (2) RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, Faculty of Science, Palacký University, Czech Republic
    Title: Kernel based quantum machine learning with photons
    Abstract: Is it possible to implement practical quantum machine learning? Here we answer this question by implementing first all-optical setup that implements a kernel-based supervised quantum machine learning for three standard two-dimensional classification problems. In contrast to distance-based quantum machine learning, we need only to perform projective measurements on specially designed quantum states that efficiently encode the training data set. Our experiment is a two-photon implementation of a recent proposal of Schuld and Killoran [Phys. Rev. Lett. 122 040504 (2019)], where instead of continuous variables we implement variable spread kernels by varying the number of photons used in feature mapping circuit.
    Chair: Prof. Jan Soubusta
    Seminar language: English
  13. Date: Tuesday 2019.10.15 at 14:50-15:05
    Speaker: M.Sc. Jan Roik
    Affiliation: RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, Olomouc, Czech Republic
    Title: Comparison of three experimental approaches to weak value estimation
    Abstract: Weak values are traditionally obtained using a weak interaction between the measured system and a pointer state. It has, however, been pointed out that weak coupling can be replaced by a carefully tailored strong interaction. This talk is about a direct comparison of two strong interaction-based approaches (strong interaction accompanied by either a suitably prepared pointer state or quantum erasure) and the traditional weak interaction-based method on the platform of linear optics.
    Chair: Prof. Jan Soubusta
    Seminar language: English
  14. Date: Tuesday 2019.10.15 at 15:05-15:20
    Speaker: M.Sc. Kateřina Jiráková
    Affiliation: RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, Olomouc, Czech Republic
    Title: Experimental implementation of a machine-learned quantum gate
    Abstract: The talk will focus on experimental implementation of a machine-learned quantum gate. The goal was to learn the gate to perform optimal phase-covariant cloning by means of reinforcement learning. This experiment demonstrates present-day feasibility and practical applicability of the hybrid machine learning approach.
    Chair: Prof. Jan Soubusta
    Seminar language: English
  15. Date: Tuesday 2019.10.15 at 15:20-15:40
    Speaker: Dr. Antonin Černoch (invited speaker)
    Affiliation: RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, Olomouc, Czech Republic
    Title: Interferometers in the service of quantum information processing
    Abstract: Interferometer is a complex device frequently used in experimental proof-of-principle setups for research using optical methods. In this talk several constructions will be presented and basic parameters discussed in the context of our recent research.
    Chair: Prof. Jan Soubusta
    Seminar language: English

    Session IV on Quantum Technologies

  16. Date: Friday 2019.10.18 at 13:00-13:30
    Speaker: Prof. Jan Peřina Jr. (invited speaker)
    Affiliation: Joint Laboratory of Optics of Palacký University and Institute of Physics of the Czech Academy of Sciences, Faculty of Science, Palacký University, Olomouc, Czech Republic
    Title: Waves in spatio-spectral and -temporal coherence of evolving ultra-intense twin beams
    Abstract: Waves in the spatio-spectral and -temporal coherence of evolving ultra-intense twin beams are predicted [1]: Twin beams with low intensities attain maximal coherence in the beam center until certain threshold intensity is reached. Then the area of maximal coherence moves with increasing intensity from the beam center towards its edges leaving the beam center with low coherence (the first coherence wave). For even larger intensities, a new coherence maximum is gradually built in the beam center with the increasing intensity [2] and, later, it again moves towards the beam edges forming the second coherence wave. Rotationally-symmetric twin beams are analyzed within a three-dimensional model that couples spectral and spatial degrees of freedom. Relation between the twin-beam coherence and its local density of modes during the nonlinear evolution is discussed.
     
    [1] J. Perina Jr.: Waves in spatio-spectral and -temporal coherence of evolving ultra-intense twin beams, Sci. Rep. 9, 4256 (2019).
    [2] J. Perina Jr.: Spatial, spectral and temporal coherence of ultra-intense twin beams, Phys. Rev. A 93, 013852 (2016).
    Chair: Prof. Adam Miranowicz
    Seminar language: English
  17. Date: Tuesday 2019.10.15 at 13:30-13:45
    Speaker: M.Sc. Shilan Ismael Abo
    Affiliation: Nonlinear Optics Division, Physics Faculty, AMU, Poznań
    Title: Unconventional multiphoton blockade
    Chair: Prof. Adam Miranowicz
    Seminar language: English

    Session V on Quantum Technologies

  18. Date: Wednesday 2019.10.23 at 11:00-11:20
    Speaker: Prof. Ryszard Tanaś (invited talk)
    Affiliation: Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, Poznań, Poland
    Title: Collective nonclassical effects in a three-atom system
    Abstract: Multi-qubits systems can exhibit various correlations, classical and quantum, which are subject of intensive studies. Quantum correlations in multi-qubit systems are subject of intensive studies. Probably the most popular measure of quantum correlations is entanglement, but there are other measures that have been introduced and studied, such as quantum discord, geometric quantum discord, measurement induced disturbance and others. The simplest bipartite system in which the correlations can be studied is a system of two qubits, or two two-level atoms. In case of two-level atoms interacting with the reservoir of electromagnetic field modes in the vacuum, the evolution of the system can be described by the well known Lehmberg-Agarwal master equations. The collective evolution of the two-atom system depends on two collective parameters: collective damping 12 and dipole-dipole interaction 12, which both depend on the interatomic distance. Such a system is a good testing ground for studying evolution of quantum correlations. In my talk, I want to give some results dealing with collective effects in a system of three- atoms. Such a system is more difficult to describe because, for mixed states, we deal with 8×8 matrix which leads to 63 equations, and, what is even worse, there are no formulas to calculate concurrence, even if we know all the matrix elements. However, if we forget about damping, The Hamiltonian of the system can be diagonalized leading to pure eigenstates of the system including the dipole-dipole interaction. It is possible to calculate concurrence and negativity for such states, which gives some information on collective effects in the system. When the collective damping is included, evolution of the system is governed by the ma- ster equation which can be solved numerically for the matrix elements of the density matrix (analytical solution is possible but it is too complicated to be useful). It allows to calculate evolution of the negativity for different initial states. We have found, in particular, the so called monogamy relations for negativity, for chosen initial states of the system. It was shown that for some initial states the monogamy relations are violated.
    Chair: Prof. Wiesław Leoński
  19. Date: Wednesday 2019.10.23 at 11:20-11:40
    Speaker: Prof. Yueh-Nan Chen (invited talk)
    Affiliation: Department of Physics and National Center for Theoretical Sciences, National Cheng-Kung University, Tainan 701, Taiwan
    Title: Temporal quantum steering
    Abstract: Quantum steering is the ability to remotely prepare different quantum states by using entangled pairs as a resource. In this talk, I will introduce a natural temporal analog of the EPR steering when considering measurements on a single object at different times. I will also give nontrivial operational meaning to violations of the temporal steering inequality by showing that it is connected to the security bound in the Bennett-Brassard 1984 protocol. Moreover, I will show that the temporal steering can be measured, via semidefinite programing, with a temporal steerable weight, in direct analogy to the proposed EPR steerable weight. Finally, I will demonstrate that the temporal steering can be experimentally verified on IBM Q.
    Chair: Prof. Wiesław Leoński
    Seminar language: English
  20. Date: Wednesday 2019.10.23 at 11:40-12:00
    Speaker: Prof. dr. Zbigniew Ficek (invited talk)
    Affiliation: Quantum Optics and Engineering Division, Institute of Physics, University of Zielona Góra, Zielona Góra
    Title: Phase control of entanglement and quantum steering in a three-mode optomechanical system
    Abstract: The phase control of coherence, entanglement and quantum steering will be discussed for an optomechanical system composed of a single mode cavity containing a partially transmitting dielectric membrane and driven by short laser pulses. The membrane divides the cavity into two mutually coupled optomechanical cavities resulting in an effective three-mode closed loop system, two field modes of the two cavities and a mechanical mode representing the oscillating membrane. The closed loop in the coupling creates interfering channels which depend on the relative phase of the coupling strengths of the field modes to the mechanical mode. For example, populations and correlations of the output modes show several interesting phase dependent effects such as reversible population transfer from one field mode to the other, creation of collective modes, and induced coherence without induced emission. The inseparability criterion for the output modes will be also investigated and we will show that entanglement may occur only between the field modes and the mechanical mode. We find that depending on the phase, the field modes can act on the mechanical mode collectively or individually resulting, respectively, in tripartite or bipartite entanglement. In addition, we will examine the phase sensitivity of quantum steering of the mechanical mode by the field modes. Deterministic phase transfer of the steering from bipartite to collective is predicted and optimum steering corresponding to perfect EPR state can be achieved.
    Chair: Prof. Wiesław Leoński
    Seminar language: English

    Session VI on Quantum Technologies

  21. Date: Wednesday 2019.10.23 at 13:00-13:20
    Speaker: Prof. Wiesław Leoński (invited speaker)
    Affiliation: Quantum Optics and Engineering Division, Institute of Physics, University of Zielona Góra, Zielona Góra, Poland
    Title: Quantum steering and its transfer along the chains of nonlinear oscillators
    Chair: Prof. Yueh-Nan Chen
    Seminar language: English
  22. Date: Wednesday 2019.10.23 at 13:20-13:35
    Speaker: Dr. Jhen-Dong Lin (invited speaker)
    Affiliation: Department of Physics and National Center for Theoretical Sciences, National Cheng-Kung University, Tainan 701, Taiwan
    Title: Quantifying quantum scrambling with temporal quantum steering
    Abstract: Quantum information scrambling describes the delocalization of local information to entanglement throughout all possible degrees of freedom. A well-known scrambling witness is the so-called out-of-time-ordered correllator (OTOC). The important insight of OTOC is that it is closely related to the incompatibility of two separate operators at two different times. In this work, we show that quantum scrambling can be witnessed in the context of temporal quantum steering. The essential point relies on the connection between Choi-Jamiolkowski isomorphism and the pseudo-density matrix formalism used in temporal quantum correlations. Based on this relation, we propose a scrambling quantifier, −T3, according to an extended temporal steering scenario. We prove that −T3 is monogamous, and when the channel is non-interacting (non-scrambled), −T3=0.
    Chair: Prof. Yueh-Nan Chen
    Seminar language: English
  23. Date: Wednesday 2019.10.23 at 13:35-13:50
    Speaker: Dr. Huan-Yu Ku (invited speaker)
    Affiliation: Department of Physics and National Center for Theoretical Sciences, National Cheng-Kung University, Tainan 701, Taiwan
    Title: Quantum computations on IBM Q: Experimental test of non-macrorealistic cat states in the cloud
    A quantum witness attempts to classify observations or experimental outcomes as arising from one of two possible classes of physical theories: those described by macrorealism, and those that are not (e.g., quantum theory). While many notions of what makes something macroscopic exist, here we take a practical approach of increasing the number of qubits contributing to the witness, and maximizing the `disconnectivity' (in the form of the entanglement) between said qubits. In this regard we experimentally implement a quantum witness on a set of small cat states (two-qubit entangled states) and large cat states (GHZ states with qubit number n = 4 and 6) using the IBM quantum experience.Our results show that the small cat states and four-qubit GHZ state are non-macrorealistic. In contrast, a six-qubit GHZ state does not violate the witness beyond a so called measurement invasiveness test, and thus might be understood in macrorealistic terms. As a comparison, we also consider un-entangled superposition states with n = 2, 3, 4, and 6 qubits, in which the disconnectivity is low.
  24. Chair: Prof. Yueh-Nan Chen
    Seminar language: English

    Session VII on Quantum Technologies

  25. Date: Wednesday 2019.10.23 at 13:50-14:10
    Speaker: Dr. Joanna Kalaga (invited speaker)
    Affiliation: Quantum Optics and Engineering Division, Institute of Physics, University of Zielona Góra, Zielona Góra, Poland
    Title: Entanglement generation in system of two coupled nonlinear oscillators
    Abstract: The system ability to produce maximally or almost maximally entangled states is important for the development of quantum information theory and its applications. Such states are necessary for quantum communication, quantum cryptography or quantum calculations. As a source of maximally entangled states will be considered the system consisting of two coupled nonlinear oscillators excited by a series of ultra-short coherent pulses. For such a system the influence of various excitation methods on the efficiency of generation maximally entangled states will be discussed.
    Chair: Prof. Zbigniew Ficek
    Seminar language: English
  26. Date: Wednesday 2019.10.23 at 14:10-14:25
    Speaker: M.Sc. Izabela Domagalska
    Title: Thermodynamic properties of superconductivity - the numerical and semi-analytical approaches
    Authors: I. A. Domagalska (1), E. A. Drzazga–Szczęśniak (2), M. W. Jarosik (2), R. Szczęśniak (2), J. K. Kalaga (1)
    Addresses:
    (1) Quantum Optics and Engineering Division, Institute of Physics, University of Zielona Góra, Zielona Góra, Poland
    (2) Institute of Physics, Częstochowa University of Technology, Częstochowa, Poland
    Abstract: Despite the relatively large electron-phonon coupling constant for vanadium, the quantities such as the order parameter, the specific heat, and the thermodynamic critical field determine the values of the dimensionless ratios not deviating much from the predictions of the BCS theory. This result is associated with the reduction of the strong-coupling and the retardation effects by the high value of the Coulomb pseudopotential. It has been shown that the results of the Eliashberg formalism can be relatively precisely reproduced with the help of the semi-analytical formulas, if the value of μ is determined on the basis of the Tc-Allen-Dynes expression. The attention should be paid to the fact that in the numerical and in the semi-analytical approach the comparable values of the thermodynamic parameters for the same μ have been obtained only in the vicinity of the point.
    Chair: Prof. Zbigniew Ficek
    Seminar language: English
  27. Date: Wednesday 2019.10.23 at 14:25-14:40
    Speaker: M.Sc. Mateusz Nowotarski
    Affiliation: Quantum Optics and Engineering Division, Institute of Physics, University of Zielona Góra, Zielona Góra, Poland
    Title: Frequency of violation of Bell-type inequalities as a quantifier of nonlocality
    Authors: Artur Barasiński (1,2), Antonín Černoch (2), Karel Lemr (2), and Jan Soubusta (2)
    Addresses:
    (1) Institute of Physics, University of Zielona Góra, Poland
    (2) Joint Laboratory of Optics of Palacky University and Institute of Physics of Czech Academy of Sciences, 771 46 Olomouc, Czech Republic
    Abstract: Motivated by the proposal for quantification of Bell nonlocality [2], we present our results of the analysis of this concept, namely, the volume of violation. This new measure of nonlocality has been proposed to prove that the anomaly between maximally entangled states and states that maximally violate Bell inequality is caused by the method of quantifying nonlocality itself, and such anomaly disappears when the volume of violation is applied. We prove that this is not the case for all bipartite quantum systems with dimension d×d [1].
     
    [1] Artur Barasiński, Mateusz Nowotarski Phys.Rev. A 98, 022132 (2018)
    [2] E. A. Fonseca, Fernando Parisio Phys.Rev. A 92, 030101 (2015)
    Chair: Prof. Zbigniew Ficek
    Seminar language: English

    Day I on Magnonics and Metamaterials of QuTecNOMM 2019

  28. Date: Thursday, 14 Nov 2019 at 9:40-10:00
    Speaker: Dr. Bartłomiej Graczykowski
    Authors: M. Kasprzak, M. Śledzińska, K. Zaleski, I. Iatsunskyi, S. Volz, F. Alzina, C. M. Sotomayor Torres, and B. Graczykowski.
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Nanoscale silicon thermal diode and switch
    Abstract: The recent research has pointed to nanostructuring as a highly efficient approach to reducing thermal conductivity. One example of nanostructured materials are porous/holey phononic crystals (PnCs), which thermal conductivity can be engineered by means of the surface-to-volume ratio and surface roughness. Tuneable thermal properties make these structures good candidates for integrated heat management devices, for instance for waste heat recovery or heat rectification. In particular, the thermal rectification means that the magnitude of heat flux changes when the temperature gradient is reversed in direction. As a step towards heat rectification using silicon porous membranes in this work, we studied both thermal conductivity and its temperature dependence on a geometric parameter, i.e. the surface-to-volume ratio.
    Chair: prof. Sławomir Mielcarek
    Seminar language: English
  29. Date: Thursday, 14 Nov 2019 at 10:05-10:20
    Speaker: M.Sc. N.K.P. Babu
    Authors: N. K. P. Babu, A. Trzaskowska, S. Mielcarek, H. Glowiński, P. Kuświk, F. Stobiecki, M. Zdunek, P. Graczyk, J. W. Kłos, G. Centala, and M. Krawczyk
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Detection of magnon-phonon Interactions using BLS spectroscopy in CoFeB/Au multilayer structure
    Abstract: The investigations about the phenomena involving interactions between thermal magnons and phonons have grate interest in modern emerging field of spintronics. In our studies, we determine the dispersion relation of thermal magnons and phonons in the CoFeB/Au multilayer deposited on a silicon substrate with Ti and Au buffer layers using Brillouin light scattering spectroscopy. We choose two geometries oblique geometry, (where the angle between magnetic field and wave vector is 45°) and Backward volume geometry (where the magnetic field and wave vector are perpendicular to each other). We found three different types of spin waves (Backward volume mode (BV-SW), perpendicular standing mode (PS-SW) and Damon-Eshbach mode (DE-MSW) and two phonon modes (Rayleigh (R-SAW) and Sezawa (S-SAW).
    Chair: prof. Sławomir Mielcarek
    Seminar language: English
  30. Date: Thursday, 14 Nov 2019 at 10:25-10:40
    Speaker: M.Sc. Miłosz Zdunek
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Interaction between thermal magnons and phonons in [Ni80Fe20Co/Au]10 multilayer
    Abstract: We have investigated surface acoustic waves’ and spin waves’ dispersion relations in [Ni80Fe20Co/Au]10 multilayers. The method we used in our investigations was high resolution Brillouin spectroscopy. The thickness of 0.8 nm has been chosen for cobalt (Co) layer as it exhibits in-plane effective anisotropy. It allowed us to gather spectra of spin waves for two canonical geometries. In both cases spin wave’s wave vector lies in the plane of our sample, the difference occurs with the orientation of wave vector vs. static magnetization: in one geometry those vectors are perpendicular (Damon-Eschbach spin wave), while in the other they are parallel to each other (Backward Volume spin wave). The main goal of our experiment was to investigate the crossing regions of phononic ang magnonic dispersion relations.
    Chair: prof. Sławomir Mielcarek
    Seminar language: English
  31. Date: Thursday, 14 Nov 2019 at 10:45-11:00
    Speaker: Dr. O. M. Chumak
    Affiliation of the presenting author: Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
    Title: Strain Modulated Ferromagnetic Resonance technique and it’s application for Co2YZ Heusler thin films investigation
    Abstract: The unique Strain Modulated Ferromagnetic Resonance (SMFMR) technique will be presented, which allows determination of the magnetoelastic properties of thin magnetic films or ribbons, viz. magnetoelastic constants of the material. The SMFMR technique is successfully applied for investigation of thin layers of Co2FexMn1−xSi (CFxM1−xS), Co2Fe0.4Mn0.6Si (CFMS) and Co2FeGa0.5Ge0.5 (CFGG) Heusler alloys. The alloys mentioned above are characterized by high spin polarization and are good candidates for technical applications, among others in spintronics and magnonics; the magnetoelastic properties, magnetic anisotropy and dissipative properties play an important role in these materials. Several effects are investigated: the effect of the magnetic layer composition changing (CFxM1−xS), the finite thickness of the magnetic layer and the use of various buffer and surface layers (CFMS and CFGG). This work is partially supported by the National Science Centre of Poland – project number 2018B04006.
    Chair: prof. Sławomir Mielcarek
    Seminar language: English
  32. Date: Thursday, 14 Nov 2019 at 11:20-11:40
    Speaker: Dr. Radosław Strzałka
    Authors: Radosław Strzałka, Ireneusz Bugański, Janusz Wolny.
    Affiliation of the presenting author: Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland
    Title: New approach to structural disorder in aperiodic systems – example of decagonal AlCuRh quasicrystal
    Abstract: An intriguing feature observed in modern refinements’ results of quasicrystals in the log-log plot of calculated vs. observed intensities is a characteristic bias in the low-peaks regime [e.g. 1,2]. The underestimation of the calculated diffraction intensities is of an unknown origin so far. The two possible reasons are most likely: (i) improper phasonic correction conventionally used in the form of the exponential Debye-Waller factor [3], and/or (ii) multiple scattering effect [4]. In our previous studies based on the model calculations we showed that the new correction for phasons developed within the statistical approach is potentially useful to solve the problem of a bias [3]. The correction for phasons (understood as flips/rearrangement of tiles in the quasiperiodic tiling) is made at the stage of the structure factor calculation, and it assumes the fragmentation of the probability distributions of atomic positions (called also the average unit cell, AUC, which is a real-space equivalent of the atomic surface/occupation domain in the hyperspace description, more on the AUC method in [5]). The Fourier transform of the “fragmented” (influenced by phason flips) AUC gives a diffraction pattern affected by a phasonic disorder. The only parameter to fit is a flip ratio (a probability of a single tile rearrangement in the structure). We assume only two types of flips (in regions of two thin and one thick, or two thick and one thin rhombuses, which build a hexagon), the phason-phonon coupling and the secondary phason flip effects are neglected. Recently we developed also a phenomenological way of diffraction data treatment in terms of the multiple scattering effect [6]. It is based on the Rossmanith theory [7 and later works] and considers a redistribution of intensities among all diffraction peaks with a given probability (the probability parameter is to be fitted). The two corrections are included in our refinement procedure developed within the statistical method. In the presentation we will show the application of new corrections to the diffraction data (with different refinement strategies) for decagonal AlCuRh quasicrystal, originally studied by Kuczera et al. [1]. The final results are: the value of R-factor is  6in the original refinement) with phasonic ADP of 1.35A2, phason flip probability of 1.34probability of 4.2×10-7. The results were published in [6].
     
    [1] P. Kuczera, J. Wolny, W. Steurer, Acta Cryst. B 68, 578 (2012).
    [2] H. Takakura, C.P Gomez, A. Yamamoto, M. de Boissieu, A.P. Tsai, Nature Mater. 6, 58 (2007).
    [3] J. Wolny, I. Bugański, P. Kuczera, R. Strzałka, J. Appl. Cryst. 49, 2106 (2016).
    [4] H. Takakura, R. Mizuno, Mater. Struct. 22, 281 (2015).
    [5] R. Strzałka, I. Bugański, J. Wolny, Crystals 6, 104 (2016).
    [6] I. Bugański, R. Strzałka, J. Wolny, Acta Cryst. A 75, 352 (2019).
    [7] E. Rossmanith, J. Appl. Cryst. 32, 355 (1999).
    Chair: prof. Jarosław W. Kłos
    Seminar language: English
  33. Date: Thursday, 14 Nov 2019 at 11:45-12:00
    Speaker: M.Sc. Szymon Mieszczak
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Spin wave localization on phasonic defects in magnonic quasicrystal
    Abstract: Phasons are the structural defects that are specific for quasicrystal. They are local rearrangements of the constituent elements in the quasiperiodic structure. We investigated the perturbed Fibonacci sequences of stripes with lower concentrations of phasonic defects. The goal of this study is to find the impact of the phasonic-like disorder on the spectrum and the localization of spin wave eigenmodes in magnonic quasicrystals.
     
    The authors acknowledge the financial support of the National Science Centre Poland for Grant No. 2016B00452 and UMO-2017T00173.
    Chair: prof. Jarosław W. Kłos
    Seminar language: English
  34. Date: Thursday, 14 Nov 2019 at 13:35-13:55
    Speaker: Dr. Gabriel Chaves-O’Flynn
    Authors: Daniel L Stein, Andrew D Kent, and Gabriel Chaves-O’Flynn.
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Activation Barriers for Creation and Annihilation of Magnetic Droplet Solitons
    Abstract: Droplet solitons are magnetization fluctuations that preserve their shape as they precess with uniform frequency. We introduce an effective energy ξ that quantifies the work done (against damping and spin torque) to create a fluctuation of arbitrary shape θ(ρ). We show that, for specific values of σ, some soliton solutions are saddles of ξ. This allows us to calculate thermal activation barriers ∆ξ between uniform precession at the ferromagnetic resonance and stable solitons. We present results of ∆ξ as a function of σ for a variety of nanocontact radii ρ*.
    Chair: prof. Piotr Zieliński
    Seminar language: English
  35. Date: Thursday, 14 Nov 2019 at 14:00-14:15
    Speaker: M.Sc. Mateusz Zelent
    Authors: S. Saha, M. Zelent, J. Feilhauer, J. Tobik, S. Finizio, M. Mruczkiewicz, S. Tacchi, A. K. Suszka, S. Wintz, N. S. Bingham, J. Raabe, M. Krawczyk, And L. J. Heyderman.
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Formation and driving by electric current of Neel-type skyrmion in antidot lattices
    Abstract: Magnetic skyrmions are topologically protected nano-meter sized chiral spin textures. Due to their various unique features, such as stability given by their topology, they are considered as potential candidates for information carriers in next generation data storage devices, like racetrack memory. Therefore, it is crucial to be able to manipulate their current-induced motion. We extend the idea to control motion of skyrmion in 2D plane with the in plane electric current pulses. This goal we have achieved through the use of magnetic antidot arrays. We have demonstrated experimentally that magnetic skyrmions can stabilize in a magnetic antidot array based on TaPt multilayers. Moreover with micromagnetic simulations we show that in such an antidot array the skyrmions can be guided in different directions. Depending on both, the size of the antidots and the current density, different types of skyrmion motion on the film plane were found, also the one shown in figure. Thus, magnetic antidot arrays can be used as a controller for skyrmion motion by using properly designed sequences of electrical current pulses, which makes them a promising candidate for current driven skyrmion motion control.
    Chair: prof. Piotr Zieliński
    Seminar language: English
  36. Date: Thursday, 14 Nov 2019 at 14:20-14:35
    Speaker: M.Sc. Krzysztof Szulc
    Authors: K. Szulc, M. Mruczkiewicz, P. Graczyk, G. Gubbiotti, and M. Krawczyk.
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Spin-wave diode and circulator
    Abstract: We propose a model of spin-wave diode which is based on the effect of unidirectional coupling of spin waves in wide frequency range in bilayered ferromagnetic system. This effect bases on Dzyaloshinskii-Moriya interaction and dipolar coupling. Our spin-wave diode consists of ferromagnetic stripe lying above the ferromagnetic layer. Unidirectional coupling permits spin waves to transfer to the stripe when propagating in coupling direction, while in non-coupling direction the spin-wave transfer is very weak. Structure with additional layer coupled with the stripe can be proposed as a spin-wave circulator.
    Chair: Prof. Piotr Zieliński
    Seminar language: English
  37. Date: Thursday, 14 Nov 2019 at 14:40-15:00
    Speaker: Prof. Maciej Krawczyk
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Spin wave dynamics in complex magnetization textures
    Abstract: We study spin wave dynamics in thin films with perpendicular magnetic anisotropy patterned with a square lattice of antidots. We show reach spin-wave spectra at remanence which indicates the non-collinear magnetization states around the antidots. The obtained results of spin-wave dynamics in these thin films with complex, but periodic magnetization textures, allow as to point out features promising for new phenomena in magnonics and their potential usefulness for applications.
    Chair: Prof. Piotr Zieliński
    Seminar language: English
  38. Date: Thursday, 14 Nov 2019 at 15:20-15:40
    Speaker: Prof. Piotr Tomczak
    Authors: Piotr Tomczak and Henryk Puszkarski.
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Spin wave dynamics in complex magnetization textures
    Abstract: One of the main goals of performing FMR experiments is to find how the magnetic energy of a sample under investigation depends on magnetic field direction with respect to a sample crystallographic axes. This information is usually obtained by examining the experimental dependence of the resonance field value on its direction in space. The traditional analysis of experimental data is carried out using the well-known Kittel or Smit-Beljers equations describing the precessional motion of the sample magnetization.
    We propose [1] a new FMR data analysis method by referring to the geometric meaning of the Smit-Beljers equation: the resonance frequency of the magnetic moment precessional motion is equal to the Gaussian curvature of the spatial distribution of the magnetic free energy. This approach allows finding all the values of relevant physical quantities with high accuracy (the saturation magnetization M, g-factor, demagnetizing tensor Nαβ and magnetocrystalline anisotropy constants Kα) and consequently the spatial distribution of the free energy from a single set of FMR experimental data.
    We tested successfully [1] this approach using the cross-validation procedure [2] for bulk magnetite, (Ga,Mn)As thin film, YIG ultrathin film, Co ultrathin film and Fe thin film. Note, that it was necessary while doing the cross-validation, to use a proper form of the free energy dependence on all above mentioned magnetic parameters characterizing the sample of each ferromagnet under investigation. Therefore, the criterion of the correctness of the free energy formulas given in [2] was also applied in this work. Let us emphasize that none of the known methods of analysis of FMR experiments does give such universal opportunities.
    Acknowledgments
    Supported by NCN grant No. DEC-2013M00967.
    References
    [1] P. Tomczak and H. Puszkarski, arXiv:1901.01207.
    [2] P. Tomczak and H. Puszkarski, Phys. Rev. B 98, 144415 (2018).
    Chair: Dr. Andrzej Janutka
    Seminar language: English
  39. Date: Thursday, 14 Nov 2019 at 15:45-16:05
    Speaker: Prof. Sławomir Mamica
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Nonuniform softening of spin waves in 2D magnonic crystals
    Abstract: In thin-film bicomponent magnonic crystals (MCs) an in-plane magnetization causes the demagnetizing field to occur around interfaces between constituent materials. The field has a great impact on the spin-wave spectrum, e.g. in cobalt-permalloy MCs at the low external magnetic field the lowest-frequency spin waves are excited in Co much more likely than in Py regardless the matrix or rods are made from Co. As a consequence the nonuniform softening of spin waves takes place. We show it could be very useful mechanism to design complete magnonic gaps with different sensitivity for the tiny change of the external field.
     
    [1] S. Mamica, M. Krawczyk, and D. Grundler, Non-uniform spin wave softening in 2D magnonic crystals as a tool for opening omnidirectional magnonic band gaps, Phys. Rev. Applied 11, 054011 (2019). arXiv: 1810.04005
    [2] S. Mamica and M. Krawczyk, Reversible tuning of omnidirectional band gaps in two-dimensional magnonic crystals by the low magnetic field, (2019), arXiv:1906.07469
    Chair: Dr. Andrzej Janutka
    Seminar language: English
  40. Date: Thursday, 14 Nov 2019 at 16:10-16:30
    Speaker: Prof. Piotr Zieliński
    Authors: D. Kuzma, J. Kłos, J. Rychły, S. Mieszczak, P. Sobieszczyk, and P. Zieliński.
    Affiliation of the presenting author: Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Kraków, Poland
    Title: Static configurations and spin wave dynamics in finite magnetic chains: from simplified models to micromagnetic calculations
    Abstract: Any defect of periodicity is a potential localization of one or several bound modes. They differ from the bulk modes in that their wave functions decay exponentially with the distance from the defect in contrast with bulk mode showing a Bloch oscillatory behavior typical of propagative waves. In this note we study possibilities of existence of end bound (edge) modes in 1d systems of macrospins of selected shapes and test validity of some simplified models in the description of the lowest frequency range dynamics in such systems. The simplest possible model by Stoner and Wohlfarth assumes the whole magnetic moment of the macrospin concentrated in one point. The dipolar interactions are, thus, very strong. The configurations of finite magnetic chains obtained with this model are very interesting in that they show a number of tilted structures as a function of a magnetic field perpendicular to the chain. More developed model involves long 1D thin threads or wires. We have found a simple analytic expression for the dipolar interactions in such threads. The latter model reproduces fairly well the lowest excitations in the finite chains of macrospins with, however, selected geometries. We will discuss the validity of the models and the best physical realization of bound states in the finite chains.
    Chair: Dr. Andrzej Janutka
    Seminar language: English
  41. Date: Thursday, 14 Nov 2019 at 16:35-16:55
    Speaker: Prof. Tadeusz Lulek
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Algebraic Bethe Ansatz as a tool for quantum information processing
    Abstract: Algebraic Bethe Ansatz (ABA), known as the way of expressing a unique exact result of a quantum onedimensional N-body problem – the eigenproblem of the Heisenberg Hamiltonian for the chain of N spins 1/2 , can be also seen as a tool for various operations with systems of qubits, prepared in highly correlated multiparticle states with precisely prescribed properties. As a rule, one uses ABA in its off-diagonal version, in order to create single-magnon states with rapidities resulting from Bethe Ansatz equations – a system of r highly nonlinear algebraic equations which yields exact eigenstates of an integrable model. Here, we advocate for the diagonal version of ABA, namely for an immediate solution of (roughly) N spectral problems for constants of motion, generated from the transfer matrix – the trace of the monodromy matrix. The resulting system of constants of motion provides a realisation of a positive operator-valued measure (POVM), that is, a complete set of commuting operators along the prescripyion of Dirac. The program can be computationally realised only for a small number N of qubits, but it might be pretty practical for typical procedures carried by Alice and Bob.
    Chair: Dr. Andrzej Janutka
    Seminar language: English

    Day II on Magnonics and Metamaterials of QuTecNOMM 2019

  42. Date: Friday, 15 Nov 2019 at 9:00-9:20
    Speaker: Dr. Jakób Walowski
    Authors: Maria Mansurova, Jakób Walowski, Henning Ulrichs, and Markus Münzenberg.
    Affiliation of the presenting author: Universität Greifswald, Germany
    Title: Spin-wave packets triggered by ultrashort laser pulses
    Abstract: We investigate Broadband excitations of spin-wave packets by ultrashort laser pulses at different magnonic antidot crystals and continuous magnetic film interfaces exhibit surface spin-wave modes that propagate out of the crystal into the continuous film. The propagation distance depends on the direction of the applied magnetic field as well as the surface geometry of the crystal. Additionally, Spatially resolved measurements of the magnetization dynamics on thin CoFeB films reveal that the frequencies of resulting spin-wave modes depend strongly on the distance to the pump center. This can be attributed to a laser generated temperature profile. We determine a shift of 0.5 GHz in the spin-wave frequency due to the spatial thermal profile induced by the femtosecond pump pulse that persists for up to one nanosecond.
    Chair: Dr. Paweł Gruszecki
    Seminar language: English
  43. Date: Friday, 15 Nov 2019 at 9:25-9:45
    Speaker: Dr. Joachim Gräfe
    Affiliation of the presenting author: Max Planck Institute for Intelligent Systems, Stuttgart, Germany
    Title: Imaging nanoscale spin dynamics using x-ray microscopies
    Abstract: State of the art x-ray microscopy allows an unprecedented insight into dynamic magnetic systems, featuring a spatial resolution of 20 nm and a temporal resolution of 20 ps. This technique uniquely allows us real space observation of artificial spin systems that have been created using contemporary nanolithography methods. To this end we have developed sophisticated measurement and evaluation techniques that allow the fast acquisition of full spin wave dispersion relations and the quantitative measurement of minute spin angles. We showcase this technique with three examples: magnetic droplets, magnetic skyrmions, and short wavelength spin waves.
    Chair: Dr. Paweł Gruszecki
    Seminar language: English
  44. Date: Friday, 15 Nov 2019 at 9:50-10:10
    Speaker: Dr. Justyna Rychły
    Authors: F. Lisiecki, J. Rychły, P. Kuswik, H.Glowiński, J. W. Kłos, F. Gross, N. Trager, I. Bykova, M. Weigand, M. Zelent, E. J. Goering, G. Schutz, G. Gubbiotti, M. Krawczyk, F. Stobiecki, J. Dubowik, and J. Grafe.
    Affiliation of the presenting author: Institute of Molecular Physics, Polish Academy of Sciences, Poznań, Poland
    Title: 1D Fibonacci magnonic quasicrystals –self-similarity of spin wave spectra, spin waves localization, andreprogrammability
    Abstract: Quasicrystals are structures that exhibit long-range order, lack translational periodicity, but possess another noteworthy symmetry property, which is self-similarity by scaling [1]. Therefore, magnonic quasicrystals surpass regular magnonic crystals regarding provided by them possibilities of spin waves control: they offer complex, self-similar spin wave spectra, localization of spin waves inside the structure, and on the surfaces of the structure [2]. The results of joint collaborative research with the experimental groups will be shown, demonstrating the possibility of spin wave propagation through magnonic quasicrystal, the opening of additional mini-bandgaps [3], and the reprogrammability of the resonance frequencies, dependent on the magnetization order in magnonic quasicrystals [4]. The measurements of SWs propagating in a 1D Fibonacci sequence of dipolarly coupled permalloy nanowires are done with the help of a combined X-ray microscopic and Brillouin Light Scattering. The experimental results are interpreted using numerical calculations. Additionally, a simple model estimating frequencies of magnonic gaps in the spin wave spectra of the Fibonacci quasiperiodic structure matches the frequency mini-band gaps calculated numerically and measured experimentally. The demonstrated features of one-dimensional magnonic quasicrystals allow utilizing this class of metamaterials for magnonics and make them an ideal basis for future applications. We would like to acknowledge the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie GA Grant No. 644348 (MagIC) and NCN Poland Grant No. UMO2017T00173, No. UMO-2012E00538, and No. UMO-2016B00452, Helmholtz Zentrum Berlin/BESSY II is gratefully acknowledged for allocating beam time at the MAXYMUS end station. J.R. would like to additionally acknowledge the financial support from the Adam Mickiewicz University Foundation.
     

    [1] C. Janot, Quasicrystals: A Primer 2nd edition, Oxford University Press, 2012
    [2] J. Rychły, J. W. Kłos, M. Mruczkiewicz, M. Krawczyk, Spin waves in one-dimensional bicomponent magnonic quasicrystals, Physical Review B 92, 054414 (2015)
    [3] Filip Lisiecki, Justyna Rychły, Piotr Kuświk, Hubert Głowiński, Jarosław W. Kłos, Felix Groß, Nick Trager, Iuliia Bykova, Markus Weigand, Mateusz Zelent, Eberhard J. Goering, Gislea Schutz, Maciej Krawczyk, Feliks Stobiecki, Janusz Dubowik, and Joachim Gräfe, Magnons in a Quasicrystal: Propagation, Extinction, and Localization of Spin Waves in Fibonacci Structures, Phys. Rev. Applied 11, 054061 (2019)
    [4] F. Lisiecki, J. Rychły, P. Kuswik, H. Glowiński, J. W. Kłos, F. Groß, I. Bykova, M. Weigand, M. Zelent, G. Schutz, G. Gubbiotti, M. Krawczyk, F. Stobiecki, J. Dubowik, and J. Grafe, Reprogrammability and scalability of Fibonacci magnonic quasicrystal, Physical Review Applied 11, 054003 (2019)
    Chair: Dr. Paweł Gruszecki
    Seminar language: English
  45. Date: Friday, 15 Nov 2019 at 10:30-10:50
    Speaker: Dr. Andrzej Janutka
    Affiliation of the presenting author: Department of Theoretical Physics, Wrocław University of Science and Technology, 50-370 Wrocław, Poland
    Title: Magnetoreactance at the nanoscale
    Abstract: Magnetoreactance is a magnetic-field dependence of the imaginary part of the electrical impedance. While giant magnetoimpedance (GMI) of ferromagnetic microwires or sandwiched multilayers is being widely applied for sensing magnetic field with a superior field sensitivity, it is suppressed at the nanoscale in the accessible (microwave) range of the current frequency, which limits the spatial resolution of the sensors. A giant magnetoreactance (GMX), that is assisted by driven oscillations of the ferromagnetic domain walls, is an alternative to GMI when miniaturizing the field sensor. Efficiency of GMX is studied for several nanomagnetic systems by means of micromagnetic simulations.
     
    [1] A. Janutka, K. Brzuszek, JMMM 465 (2018) 437.
    [2] A. Janutka, K. Brzuszek, J. Phys. D 52 (2019) 035003.
    [3] A. Janutka, K. Brzuszek, IEEE Magn. Lett. 10 (2019) 6103105.
    Chair: Dr. Joachim Gräfe
    Seminar language: English
  46. Date: Friday, 15 Nov 2019 at 10:55-11:15
    Speaker: Dr. Emerson Coy
    Affiliation of the presenting author: NanoBioMedical Centre, Adam Mickiewicz University, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland
    Title: Nanoindentation Applications for Oxide Electronics
    Abstract: Nanoindentation is a well-established characterization technique for the extraction of mechanical information of nanomaterials. Nevertheless, much of the potential of the technique is still overlooked by the functional oxides and the electronics community, due to traditional preconceptions about their applicability and use. In this talk, some of the unique capabilities of the technique will be discussed. Followed by specific applications on different materials such as flexoelectric, ferroelectric and ferromagnetic. Finally, the potential of nanoindentation as a powerful tool for information technology, energy, and communications, will be presented.
    Chair: Dr. Joachim Grafe
    Seminar language: English
  47. Date: Friday, 15 Nov 2019 at 11:20-11:40
    Speaker: Prof. Andrzej Wawro
    Authors: A. Wawro, Z. Kurant, M. Tekielak, M. Jakubowski, E. Milińska, I. Sveklo, P. Mazalski, R. Böttger, A. Maziewski.
    Affiliation of the presenting author: Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
    Title: Spatial ion beam modifications of Co layered structures – a recipe for magnonic crystals
    Abstract: Magnetic properties of a single Co layer depend on its thickness and a type of buffer and capping film [1]. In multilayered systems magnetic configurations are more complex due to interlayer coupling depending on the nonmagnetic spacer thickness [2]. Irradiation of such structures with an ion beam substantially affects anisotropy, the coupling strength or type and even suppresses their ferromagnetic nature [3,4]. Application of a focus ion beam enables local magnetic modifications in the nanometre scale leading to 3D magnonic crystals (MC) creation. Several types of MCs are proposed for various stacks of the sample and applied fluence of the ion beam.
     
    Acknowledgements: This work was supported by the National Science Centre in Poland under the projects: 2014B01834 and the EU European Regional Development Fund (REINTEGRATION 2017 OPIE 14-20).
     
    [1] A. Wawro et al., J. Phys. D 50, 215004 (2017)
    [2] Z. Kurant et al., J. Magn. Magn. Mat. 475, 683 (2019)
    [3] A. Maziewski et al., Phys. Rev. B 85, 054427(2012)
    [4] A. Wawro et al., Phys. Rev. Appl. 9, 014029 (2018)
    Chair: prof. Joachim Grafe
    Seminar language: English
  48. Date: Friday, 15 Nov 2019 at 11:45-12:05
    Speaker: Dr. Ewelina Milińska
    Authors: Ewelina Milińska, Sukanta Kumar Jena, Marcin Jakubowski, Aleksiej Pietruczik, Roman Minikayev, Sabina Lewińska, Artem Lynnyk, Pavlo Aleshkevych, Anuj Dhiman, Zbigniew Kurant, Iosif Sveklo, Andrzej Maziewski, Andrzej Wawro .
    Affiliation of the presenting author: Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
    Title: Magnetization reversal, domain structure and ferromagnetic resonance of heavy metal/ferromagnetic heterostructures
    Abstract: Inversion-Asymmetric heterostructures have been fabricated by molecular beam epitaxy (MBE) technique, in which Co magnetic layer is surrounded by Pt and W material. The WPt and PtW systems exhibit the high spin-orbit coupling (SOC) and iDMI (interfacial Dzyaloshinskii Moriya interaction). The labyrinth-like magnetic domains observed in as-deposited the WPt multilayers evolve into parallel stripe domain structure (forming 1D magnonic crystals) after saturation in the magnetic field applied in the sample plane, followed by an inplane ac demagnetization with decreasing amplitude. The average width of the labyrinth and parallel strip domains decrease with the repetition number of multilayers. Additionally, FMR and VNA-FMR spectra reveal resonance lines originating from uniform ferromagnetic precession (above saturation field) and from stripe labyrinth domain structure below the saturation field. Obtained results give insight into the dynamics properties of the samples which can be considered as MCs.
     
    Acknowledgements: This work was supported by the EU European Regional Development Fund (REINTEGRATION 2017 OPIE 14-20).
    Chair: Joachim Grafe
    Seminar language: English
  49. Date: Friday, 15 Nov 2019 at 13:40-14:00
    Speaker: Prof. Ryszard Gieniusz
    Authors: Ryszard Gieniusz, Michał Matczak, Anuj K. Dhiman, Iosif Sveklo, Zbigniew Kurant, Urszula Guzowska, Feliks Stobiecki, Andrzej Maziewski
    Affiliation of the presenting author: Faculty of Physics, University of Bialystok, Bialystok, Poland
    Title: Magnetooptical and Brillouin Light Scattering studies of ultrathin Co wedges with Pt and Ir covers
    Abstract: IrPt and PtIr trilayers with a wedged Co layer (Co thickness d=0±3.6nm) were deposited by magnetron sputtering on naturally oxidized Si substrates with a Ta/Au buffer. Their magnetic properties have been investigated using magneto-optical polar Kerr effect and Brillouin light scattering (BLS) technique in the Damon-Eshbach geometry. We have employed Brillouin Light Scattering spectroscopy in backscattering geometry for DMI constant DS and spectral linewidths studies. DS was nearly two times larger for the IrPt trilayer than for the PtIr with opposite chirality. The effective uniaxial magnetic anisotropy and DS depend non-monotonically on d with a maximum at d ≈ 1.2 nm. The asymmetry in linewidth for Stokes and anti-Stokes peaks is observed for both IrPt and PtIr trilayers for d < 1.6 nm, and it is increasing with decrease of Co thickness. Acknowledgements: Supported by Polish National Science Center projects: DEC-2016G04196 Beethoven and UMO-2018C00308 SONATINA.
    Chair: Dr. Hubert Głowiński
    Seminar language: English
  50. Date: Friday, 15 Nov 2019 at 14:05-14:20
    Speaker: M.Sc. A.K. Dhiman
    Authors: A.K. Dhiman, R. Gieniusz, H.Głowiński, Z. Kurant, M. Matczak, F. Stobiecki, I.Sveklo, M.Tekielak, A.Maziewski.
    Affiliation of the presenting author: Faculty of Physics, University of Białystok, Białystok, Poland
    Title: Magnetic properties of IrPt and PtIr multilayers with Dzyaloshinskii- Moriya interaction
    Abstract: [Co(dCo)Ir(dIr)]N and [Co(dCo)Pt(dPt)]N multilayers were deposited by magnetron sputtering. Different dCo was chosen to approach spin reorientation transition SRT from perpendicular to in-plane magnetization state. Different coupling between layers was obtained changing spacer layers thicknesses dIr and dPt. Investigation of magnetic characterization was done using longitudinal and polar magneto-optical Kerr effect MOKE, vibrating sample magnetometer VSM, Brillouin light scattering BLS spectroscopy, magnetic force microscopy MFM, VNA-FMR and FMR spectroscopy. The following magnetization distribution was deduced from magnetization curves and magnetic domain imaging: large macrodomain (micrometer size) differentiated by inplane “core” magnetization modulated by small nano-domain differentiated by out-of-plane magnetization. Hysteresis of BLS signal (measured also without magnetic field) was found. The in-plane “core” magnetization in domains seems to be responsible for BLS signal. Work supported by Polish National Science Center projects: DEC-2016G04196 Beethoven and UMO- 2018C00308 SONATINA.
    Chair: Dr. Hubert Głowiński
    Seminar language: English
  51. Date: Friday, 15 Nov 2019 at 14:25-14:45
    Speaker: Dr. Jan Kisielewski
    Authors: J. Kisielewski, P. Gruszecki, M. Krawczyk, and A.Maziewski .
    Affiliation of the presenting author: Faculty of Physics, University of Bialystok, Bialystok, Poland
    Title: Mapping magnetic textures in films with Dzyaloshinskii-Moriya interaction.
    Abstract: Exploiting the results of micromagnetic simulations, I will demonstrate the effect of Dzyaloshinskii-Moriya interaction (DMI) on static and dynamic magnetic properties of ultrathin single films and multilayer systems. Beside a DMI magnitude, other parameters were also adjusted, like the perpendicular magnetic anisotropy (characterized by the quality factor Q) and external magnetic field. Playing with the parameters, several types of magnetic textures were observed: domains with narrow wall of either Bloch or Neel type, spin spirals, skyrmions, conical spin spirals, or in-plane magnetization configuration. Multilayer systems were also modeled with different types of nonmagnetic spacers, and different coupling between magnetic films, what led to even more interesting variety of possible magnetization states. The structures were also characterized by their magnetic susceptibility and resonant oscillations of magnetization. Acknowledgements: Work supported by Polish National Science Center project DEC-2016G04196 Beethoven.
    Chair: Dr. Hubert Głowiński
    Seminar language: English
  52. Date: Friday, 15 Nov 2019 at 15:05-15:25
    Speaker: Dr. Mirosław Werwiński
    Affiliation of the presenting author: Institute of Molecular Physics, Polish Academy of Sciences, Poznań, Poland
    Title: Magnetocrystalline anisotropy of L10FeNi from DFT
    Abstract: This contribution presents the results of ab initio calculations of selected magnetic parameters of the L10 FeNi phase, which are the magnetocrystalline anisotropy energies (MAEs), the full potential calculations of the anisotropy constant K3, spin and orbital magnetic moments, and the magnetostrictive coefficient λ001 [1]. Furthermore, the calculated 3D k-resolved map of the MAE combined with the Fermi surface analysis gives a complete picture of the MAE contributions in the Brillouin zone. To increase the certainty of the result, the MAEs were calculated by using three different ab initio codes. All three codes employ the full potential and generalized gradient approximation (GGA) and give the MAEs below 0.5 MJ m−3. It is expected that due to the limitations of the GGA this values are underestimated. The more reliable model including orbital polarization corrections doubles this value [2], whereas the experimental values of the anisotropy constant K1 from the literature oscillate around 1.0 MJ m−3 [3]. The L10 FeNi has further potential to improve its MAE by modifications, like for example tetragonal strain or alloying.
     
    [1] M. Werwiński and W. Marciniak 2017 J. Phys. D: Appl. Phys. 50 495008
    [2] Y. Miura, S. Ozaki, Y. Kuwahara, M. Tsujikawa, K. Abe, M. Shirai, 2013 J. Phys.: Condens. Matter 25 106005
    [3] L.H. Lewis, F.E. Pinkerton, N. Bordeaux, A. Mubarok, E. Poirier, J.I. Goldstein, R. Skomski, K. Barmak 2014 IEEE MAGNETICS LETTERS 5 5500104.
    Chair: Dr. Emerson Coy
    Seminar language: English
  53. Date: Friday, 15 Nov 2019 at 15:30-15:45
    Speaker: M.Sc. Piotr Rzeszut
    Authors: Piotr Rzeszut, Witold Skowroński, Sławomir Zietek, Jakub Checiński, Jerzy Wrona and Tomasz Stobiecki .
    Affiliation of the presenting author: AGH University of Science and Technology, Department of Electronics, 30-059 Kraków, Poland
    Title: Serially connected perpendicular magnetic tunnel junctions for multi-bit STTMRAM storage cells and neuromorphic computing
    Abstract: One of the main limitation of the storage density of a contemporary MRAM cell is the size of the transistor capable of driving sufficiently high current density needed to switch magnetic tunnel junction (MTJ). This limitation can be overcome by using so-called multi-bit MRAM cell. We present a method of manufacturing such multi-bit cells [1] with use of serially connected standard MTJs. The device may also be used as a memristor in neuromorphic computing [2-3]. Such design is very simple to manufacture, but due to spread of parameters of MTJ some limitations are observed. Mainly an ability to distinguish adjacent resistance states is reduced as well as define voltages for writing reduces as more non-equal elements are connected. To address this issue a way to determine maximum capacity of such multi-bit cell is needed. Therefore we also propose a behavioural simulation of such multi-bit cells. We also present complete analysis of limitations of the design. Scientific work funded from budgetary funds for science in 2017-2018, as a research project under the “Diamond Grant” program (Polish Ministry of Science and Higher Education Diamond Grant No. 00482017/46).
     
    This work is supported by the Polish National Center for Research and Development grant No. LIDERL- 6NCBR/2015. T.S. acknowledges the SPINORBITRONICS grant No. 2016B01430.
     
    [1] Rzeszut, P. et al. J. Appl. Phys. 125 (2019): 223907
    [2] Torrejon, J. et. al. Nature 547 (2017): 428-431 [3] Raymenants, E. et. al. J. Appl. Phys. 124 (2018): 152116
    Chair: Dr. Emerson Coy
    Seminar language: English
  54. Date: Friday, 15 Nov 2019 at 15:50-16:10
    Speaker: Dr. Piotr Graczyk
    Authors: Piotr Graczyk and Maciej Krawczyk
    Affiliation of the presenting author: Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland
    Title: Nonresonant amplification of coherent spin waves through voltage-induced interface magnetoelectric effect and spin-transfer torque
    Abstract: Spin waves are a promising candidates as a carriers for the next-generation low-energy signal processing devices. Here, we present the operation and we analyze the performance of the device which amplifies and modulates the spin wave by the ac electric field through the spin-transfer torque. Although the spin-transfer torque is regarded as a non-selective effect, i.e., it affects all the spin-wave modes together with noise, in our work we investigate the mechanism of this torque which is related to the specific spin wave symmetry and group velocity. As a consequence, it affects only coherent spin-wave modes but not noise. The system consists of two high-κ dielectric thin-film capacitors separated by ferromagnetic bilayer. The magnetization dynamics is affected non-resonantly with an ac voltage applied to such heterostructure by the spin accumulation. The spin accumulation is generated by the charge-mediated magnetoelectric effect (i.e., spin-dependent surface screening) and interacts with magnetization through the so-called field-like and anti-damping spin transfer torques. The spin transfer torques lead to the periodic spin wave amplification and attenuation with the frequency of the applied ac voltage. We show the criteria for the effective amplification and dependences of the obtained gain on the applied voltage amplitude and spin wave frequency. The generation of non-equilibrium spin density through dynamic spin-dependent surface screening in the proposed magnetoelectric heterostructure allows to reduce the thickness of fixed magnetization layer used in conventional spin valve to a few nanometers, thus the proposed effect can significantly contribute to miniaturization of the spintronic devices. The study has received financial support from the National Science Centre of Poland under grant 2018C00052.
    [1] P. Graczyk, M. Krawczyk, Spin-polarized currents driven by spin-dependent surface screening, arXiv:1902.06481
    Chair: Dr. Emerson Coy
    Seminar language: English
  55. Date: Friday, 15 Nov 2019 at 16:15-16:35
    Speaker: Dr. Hubert Głowiński
    Authors: Hubert Głowiński, Piotr Kuświk, Filip Lisiecki, and Błażej Anastaziak
    Affiliation of the presenting author: Institute of Molecular Physics, Polish Academy of Sciences, Poznań, Poland
    Title: Ion bombardment influence on magnetization damping
    Abstract: Both anisotropy and damping is a function of spin-orbit coupling (SOC). It is commonly observed that the damping increases with increasing perpendicular magnetic anisotropy (PMA). It is believed that this is due to their relation to SOC. We have studied AuAu samples after ion bombardment, which is a known method to modify PMA. We have found that although PMA changes significantly nonmonotonically with ion fluence, the damping changes monotonically. In summary, we believe that the connection between damping and PMA is not a simple relation to SOC. This work was supported by DAAD within the program PPP Polen 2018 under Grant No. 57392264
    Chair: Dr. Emerson Coy
    Seminar language: English
  56. Date: Friday, 15 Nov 2019 at 16:40-17:00
    Speaker: Dr. Piotr Kuświk
    Authors: Piotr Kuświk, Błażej Anastaziak, Łukasz Frąckowiak, Michał Matczak, Gabriel David Chaves-O’Flynn, Maciej Urbaniak, Paweł Piotr Michałowski, Arno Ehresmann, and Feliks Stobiecki .
    Affiliation of the presenting author: Institute of Molecular Physics, Polish Academy of Sciences, Poznań, Poland
    Title: Local modification of magnetic properties for potential applications in magnonics
    Abstract: The development of new methods to modify magnetic properties is important in many areas. In particular, this applies to magnonics, where artificial modulation of magnetic parameters can be used to control and manipulate spin waves. Here, we present two methods for achieving such modulation. The first uses ion bombardment of ferrimagnetic layered systems; and the second, plasma oxidation of ferromagnetic layers. Both methods allow to obtain layers with periodically varied properties without topographical changes. This opens new ways to generate magnonic crystals.
     
    This work was supported by the National Science Centre in Poland Sonata-Bis (DEC- 2015E00557) project. B. A. acknowledges support from project No. POWR.03.02.00-00-I032/16 under the European Social Fund – Operational Programme Knowledge Education Development, Axis III Higher Education for Economy and Development, Action 3.2 PhD Programme.
    Chair: Dr. Emerson Coy
    Seminar language: English

    Day III on Magnonics and Metamaterials of QuTecNOMM 2019

    ------------
  57. Date: Monday, 18 Nov 2019 at 9:00-9:20
    Speaker: Dr. Kacper Wrześniewski
    Authors: Kacper Wrześniewski and Ireneusz Weymann.
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Quench dynamics of spin in magnetic impurity systems
    Abstract: We theoretically investigate the quench dynamics in quantum impurity systems coupled to a spinpolarized reservoir. In particular, we consider a single quantum dot system and a large-spin magnetic molecule coupled to external ferromagnetic lead. We examine the response to a quench in the spin-dependent coupling strength to ferromagnetic lead as well as in the position of the orbital level. The dynamics is analyzed by studying the timedependent expectation values of the magnetization and spin-quadrupole moment. We predict the time-dependence of a ferromagneticcontact-induced dipolar exchange field and its nonmonotonic build-up, as well as the development of local quadrupolar exchange field. The relevant time scales describing the dynamics are identified.
    Chair: Prof. Maciej Krawczyk
    Seminar language: English
  58. Date: Monday, 18 Nov 2019 at 9:25-9:45
    Speaker: Dr. Karol Zaleski
    Authors: Karol Zaleski, Emerson Coy, Mateusz Kempiński, Hans-Peter Schönherr, Joao Marcelo Lopes, Jens Herfort, and Feliks Stobiecki
    Affiliation of the presenting author: NanoBioMedical Centre, Adam Mickiewicz University, Poznań, Poland
    Title: Thin films of Heusler alloy Co2FeSi on graphene and HOPG –the candidate for highly spin-polarized injector for graphene spintronics
    Abstract: Graphene is a promising material for a spin channel in spintronic devices because of the large electron mobility and the long spin diffusion length [1]. Half-metallic Heusler alloys are the best materials for spin injectors and detectors due to the 100% spin-polarization of electrons at the Fermi level [2]. Combination of these materials can lead to the improvement of performance of the spintronic devices [3]. However, the growth of the Heusler alloys on the graphene was not studied before. Herein, we present the influence of the growth temperature on structural and magnetic properties of Co2FeSi Heusler alloys thin films deposited on: CVD graphene transferred on Si/SiO2, epitaxial graphene on SiC and HOPG (highly oriented pyrolytic graphite – whose surface is similar to graphene). The films were grown by molecular beam epitaxy (on graphene) and by magnetron sputtering (on HOPG). In particular, the films deposited on transferred and epitaxial graphene are polycrystalline, while Co2FeSi films deposited on HOPG grow with the (001) texture. Structural and magnetic properties, and in particular the differences in the growth between the graphene and HOPG substrates will be discussed.
     
    This work is supported by the National Science Centre – Poland under the contract 2016D02121.
     
    [1] W. Han et al., Nat. Nanotechnol. 2014, 9, 794.
    [2] T. Kimura et al., NPG Asia Mater. 2012, 4, e9.
    [3] T. Yamaguchi et al., Appl. Phys. Express 2016, 9, 063006.
    Chair: prof. Maciej Krawczyk
    Seminar language: English
  59. Date: Monday, 18 Nov 2019 at 10:05-10:25
    Speaker: Dr. Liubov Ivzhenko
    Authors: Liubov Ivzhenko, Sergey Polevoy, Vladimir Yachin, Boris Chichkov, and Sergey Tarapov.
    Affiliation of the presenting author: Radiospectroscopy Dept., IRE NAS of Ukraine, Kharkiv, Ukraine
    Title: Experimental and numerical identification of Faraday effect enhancement by allferrodielectric metasurface
    Abstract: We demonstrate a design of all-ferrodielectric metasurface which exhibit sufficient enhancement of the Faraday rotation induced by particular grating mode excitation [1,2]. The metasurface is presented as periodic arrangement of cylinders (open dielectric resonators) which located on the substrate and both made of ferrodielectric. The conditions of the grating mode excitation are revealed for different geometrical parameters of the resonators forming the array. It was established that the Faraday rotation [3,4] is increased in several times versus uniform ferrodielectric layer with the same thickness at the corresponding resonant frequency. The effect is confirmed in the microwave measurements.
     
    [1] V. I. Belotelov, I. A. Akimov, M. Pohl, V. A. Kotov, S. Kasture, A. S. Vengurlekar, A. V. Gopal, D. R. Yakovlev, A. K. Zvezdin, and M. Bayer, “Enhanced magneto-optical effects in magnetoplasmonic crystals,” Nature Nanotechnology 6, 370-376 (2011).
    [2] A. V. Chetvertukhin, A. A. Grunin, A. V. Baryshev, T. V. Dolgova, H. Uchida, M. Inoue, and A. A. Fedyanin, “Magneto-optical Kerr effect enhancement at the Wood’s anomaly in magnetoplasmonic crystals,” J. Magn. Magn. Mater. 324, 21, 3516–3518 (2012).
    [3] M. Inoue, M. Levy, and A. V. Baryshev, (Eds.). Magnetophotonics: From Theory to Applications (Springer Science Business Media, 2013).
    [4] A. A. Girich, S. Y. Polevoy, S. I. Tarapov, A. M. Merzlikin, A. B. Granovsky, and D. P. Belozorov, “Experimental Study of the Faraday Effect in 1D-Photonic Crystal in Millimeter Waveband,” Solid State Phenomena 190, 365-368 (2012).
    Chair: prof. Sławomir Mamica
    Seminar language: English
  60. Date: Monday, 18 Nov 2019 at 10:30-10:45
    Speaker: B.Sc. Mateusz Gołębiewski
    Authors: Mateusz Gołębiewski, Paweł Gruszecki, Andriy Serebryannikov, and Maciej Krawczyk.
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Spin-wave Talbot effect in thin ferromagnetic film
    Abstract: Demonstration, in micromagnetic simulation, the self-imaging phenomenon (called the Talbot effect) for spin waves propagation in thin ferromagnetic film magnetized out-of-plane. We show that the diffraction grating created by the holes in thin permalloy film allows obtaining Talbot’s carpets formed by the transmitted spin waves at high frequencies, where the exchange interactions dominate, and at low frequencies where the magnetostatic interactions influence the shape of the dispersion relation. The analyzed effect is particularly interesting due to the potential application in magnonic devices, e.g. logic circuits.
    Chair: Prof. Sławomir Mamica
    Seminar language: English
  61. Date: Monday, 18 Nov 2019 at 10:50-11:05
    Speaker: B.Sc. Krzysztof Sobucki
    Authors: Krzysztof Sobucki, Pawel Gruszecki, and Maciej Krawczyk.
    Affiliation of the presenting author: Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
    Title: Subwavelength control of the phase of spin waves by ferromagnetic resonators
    Abstract: Phase and amplitude are the fundamental characteristics of spin waves that can be used to carry information. We propose here a method of the modulation of the phase of reflected spin waves from the edge of a thin ferromagnetic film. Utilizing micromagnetic simulations, we demonstrate that the application of narrow resonators on top of the edges can be used to mold the phase of the reflected waves. We show that near the Fano resonances, even small change of the resonator’s geometry significantly influences the phase of the reflected waves. Noteworthy, this resonator can be treated as a magnonic counterpart of metasurface since it enables spin waves modulation, i.e., manipulation of the phase at subwavelength distances.
    Chair: Prof. Sławomir Mamica
    Seminar language: English

    Satellite Sessions on Quantum Technologies QuTecNOMM'19

  62. Date: Wednesday 2019.10.09 at 13:00
    Speaker: Dr. Thomas B. Bahder (invited speaker)
    Affiliation: Program Manager, Army Research Office 7-23-17 Roppongi, Minato-ku Tokyo 106-0032 Japan
    Title: Topological Quantum Sensors?
    Abstract: I will review the theory of "conventional" quantum sensors as quantum channels of information between the quantity (classical field) to be sensed and the measurement outcomes. The Shannon mutual information and the Fisher information may be used as metrics for the quality of a quantum sensor [1]. Next, I will briefly describe non-ideal quantum sensors, which perform non-unitary transformations on the input quantum state. The theory of non-ideal quantum sensors is relevant to experiments because the input quantum state may have errors, there may be scattering (decoherence and dispersion) in the quantum channel, and the output state detectors may not be ideal [2,3]. Next, I will introduce simple 1-qubit and 2-qubit models of a quantum sensor that have an analogy with topological energy band theory [4]. In preparation, I review some topological concepts such as Berry curvature and the Quantum Geometric Tensor. I will suggest that a new class of quantum sensors called "topological quantum sensors" may be realizable. Finally, I will give a detailed example of a topological quantum sensor of magnetic fields based on the dynamical quantum Hall effect [5].
     
    1. T. B. Bahder and P. A. Lopata, "Fidelity of quantum interferometers", Rev. A 74, 051801(R) (2006).
    2. D. S. Simon, A. V. Sergienko, and T. B. Bahder, “Dispersion and fidelity in quantum interferometry”, Phys. Rev. A 78, 053829 (2008).
    3. T. B. Bahder, “Phase estimation with nonunitary interferometers: Information as a metric’’, Phys. Rev. A 83, 053601 (2011).
    4. A. Bansil, H. Lin, and T. Das, "Colloquium: Topological Band Theory", Rev. Mod. Phys. 88, 021004 (2016).
    5. V. Gritsev and A. Polkovnikov, PNAS (Proceedings of the National Academy of Sciences U. S.) 109, 6457 (2012).
    Chair: Prof. Adam Miranowicz
    Seminar language: English
  63. Date: Thursday 2019.11.21 at 14:20
    Speaker: Prof. Karol Życzkowski (invited speaker)
    Affiliation: Institute of Physics, Jagiellonian University, Cracow; Center for Theoretical Physics, Polish Academy of Sciences, Warsaw
    Title: Decoherence in the space of quantum operations: How to coherify a classical map?
    Abstract: [PDF]  The theory of quantum information processing meets experiment: in view of the emerging field of quantum technologies future theoretical studies will be closer linked to the physical world by considering more realistic systems and putting even more emphasis on interaction of the system in question with environment and the effect of quantum decoherence. In this talk I will shortly review the standard notion of decoherence and its formal inverse: coherification of a classical probability vector denotes the search of all its preimages with respect to the coarse graining channel, which induces the decoherence. A similar problem can also be posed for channels: For a given classical map corresponding to a stochastic transition matrix T we look for quantum channel Φ, which induces the same classical transition matrix T, but is "more coherent". To quantify the coherence of a channel Φ we measure the coherence of the corresponding Jamio kowski state JΦ. We show that a classical transition matrix T can be coherified to a reversible unitary dynamics if and only if T is unistochastic. Otherwise the Jamio kowski state JΦ of the optimally coherified channel is mixed, and the dynamics must necessarily be irreversible.
     
    [1] K. Korzekwa, S. Czachórski, Z. Pucha a and K. Życzkowski, New J. Phys. 20, 043028 (2018).
    [2] K. Korzekwa, S. Czachórski, Z. Pucha a and K. Życzkowski, J. Phys. A 52, 475303 (2019).
    Chair: Prof. Adam Miranowicz
    Seminar language: English



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