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The Third Poznań Symposium on
"Quantum Engineering, Information, and Nonlinear Optics"
(QEINO 2013)
October 15th (Tuesday) - 17th (Thursday), 2013,
Physics Faculty, Adam Mickiewicz University, Poznań, Poland

LIST OF PARTICIPANTS AND ABSTRACTS
[PDF] 

  1. Speaker: Konrad Banaszek
    Affiliation: Institute of Theoretical Physics, Department of Quantum Optics and Atomic Physics, Faculty of Physics, University of Warsaw
    Title: Which-way experiment with an internal degree of freedom
    Abstract: We present an inequality relating visibility and which-way information for a particle equipped with an internal degree of freedom travelling through a Mach-Zehnder interferometer. The inequality paints an unexpectedly intricate picture of wave-particle duality in the general case. Strikingly, in some instances which-way information becomes erased by introducing classical uncertainty in the internal degree of freedom. Furthermore, even imperfect interference visibility measured for a suitable set of inputs can be sufficient to infer absence of which-way information.
  2. Organizer: Tadeusz Bancewicz
    Affiliation: Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, Poznań
  3. Participant: Artur Barasiński
    Affiliation: Quantum Optics and Engineering Division, Institute of Physics, University of Zielona Góra
  4. Organizer: Karol Bartkiewicz
    Poster's title: Relative entropy of entanglement for fixed nonlocality: two-qubit mixed states superior to pure states
    Authors: B. Horst1, K. Bartkiewicz1,2, and A. Miranowicz1
    1Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, Poznań, Poland
    2Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, Faculty of Science, Palacký University, Olomouc, Czech Republic
    Abstract: Amplitude and phase damping is a natural decoherence mechanism, changing entangled pure states into less-entangled mixed states. We show that even local amplitude damping of one or two qubits can result in mixed states more entangled than pure states, comparing the relative entanglement entropy (REE) for a given degree of the Bell-CHSH inequality violation (i.e., nonlocality). By applying Monte-Carlo simulations, we find maximally-entangled mixed states and show their likelihood of being optimal by checking the Karush-Kuhn-Tucker conditions, which generalize the method of Lagrange multipliers for this nonlinear optimization problem. We show that the REE for mixed states can exceed that of pure states assuming nonlocality in the (0,0.82) range and maximal REEs difference of 0.4. For comparison we normalized the nonlocality measure to equal the standard entanglement measures, including the negativity for arbitrary two-qubit pure states. We also analyze the influence of the phase-damping channels on the entanglement of initially pure states, showing that the minimum of the REE for a given nonlocality can be achieved by these two channels. Our results can stimulate further search for practical protocols of quantum information processing for which mixed states are more effective than pure states.
    [1] B. Horst, K. Bartkiewicz, and A. Miranowicz, Phys. Rev. A 87, 042108 (2013).
  5. Participant: Kacper Bocian
    Poster's title: Andreev reflection in spin-polarized transport through an interacting quantum dot in a hybrid tunneling junction
    Authors: K. Bocian and W. Rudziński
    Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań, Poland
    Abstract: By means of nonequilibrium Green function technique we calculated spin-dependent electrical conductance through a quantum dot coupled to one ferromagnetic and one superconducting electrodes in the Andreev reflection (AR) regime. Effects due to a competition between the Coulomb correlations on the dot and Zeeman splitting of the dot discrete level are analyzed in both linear and nonlinear transport regimes. It is presented that when a coherent spin rotation is present on the dot, Coulomb interactions may lead to a significant enhancement of the AR tunneling current. New conditions of matching of coupling strengths leading to the perfect AR transmission are formulated in the context of arbitrary Coulomb correlations on the dot. Origin of occurrence of a variety of the multipeak structure of the conductance in equilibrium as well as in nonequilibrium situation is also discussed in detail.
  6. Speaker: Georges Boudebs
    Affiliation: Laboratoire de photonique d'Angers (LPhiA), University d'Angers, France
    Title: Optical nonlinear characterization using imaging technique in a 4f-Z-scan system
    Abstract: We show that the direct measurement of the beam radius in Z-scan experiments using a CCD camera at the output of a 4f-imaging system allows a higher sensitivity and a better accuracy than other methods. One of the advantages is to be insensitive to pointing instability of the pulsed laser because no hard aperture is employed as in the usual Z-scan. In addition, the numerical calculations involved here and the measurement of the beam radius are simplified since we do not measure the transmittance through an aperture and it is not subject to mathematical artefacts related to a normalization process, especially when the diffracted light is very low.
    Keywords: Nonlinear optics, Z-scan, diffraction, image processing, Fourier optics
  7. Participant: Piotr Busz
    Affiliation: Institute of Molecular Physics, Polish Academy of Sciences, 60-179 Poznan, Poland
  8. Participant: Bogna Bylicka
    Poster's title: Non-Markovianity as a Resource for Quantum Technologies
    Authors: Bogna Bylicka1, Dariusz Chruąciński1, and Sabrina Maniscalco2
    1 Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland
    2 SUPA, EPS/Physics, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom and Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
    Abstract: Quantum technologies rely on the ability to coherently manipulate, process and transfer information, encoded in quantum states, along quantum channels. Decoherence induced by the environment introduces errors, thus setting limits on the efficiency of any quantum-enhanced protocol or device. A fundamental bound on the ability of a noisy quantum channel to transmit quantum (classical) information is given by its quantum (classical) capacity. Generally, the longer is a quantum channel the more are the introduced errors, and hence the worse is its capacity. In this Letter we show that for non-Markovian quantum channels this is not always true: surprisingly the capacity of a longer channel can be greater than the one of a shorter channel. We introduce a general theoretical framework linking non-Markovianity to the capacities of quantum channels, and demonstrate in full generality how harnessing non-Markovianity may improve the efficiency of quantum information processing and communication.
  9. Speaker: Antonín Černoch
    Affiliation: Institute of Physics of Academy of Science of the Czech Republic, Joint Laboratory of Optics of PU and IP AS CR, Olomouc, Czech Republic
    Title: Linear-optical qubit amplifier
    Abstract: We propose a linear-optical scheme for heralded qubit amplification. The device is able to change the ratio between probabilities of detecting vacuum or a photonic qubit in the signal transmitted via some lossy channel by using a pair of entangled ancillae. The probability of successful amplification does not asymptotically drop to zero for infinite gain and it can be optimized if (i) some a priory knowledge of input state is known or (ii) some noise in the output signal is tolerated.
    Poster's title: Quantum routing with linear optics
    Authors: A. Černoch, K. Bartkiewicz, K. Lemr, J. Soubusta
    Abstract: The poster reviews several our proposals for quantum routers using linear optics and single photon qubits. The schemes are based on two-qubit gates such as controlled-phase gate and programmable phase gate.
  10. Organizer: Grzegorz Chimczak
    Affiliation: Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, Poznań
  11. Speaker: Dariusz Chruściński
    Affiliation: Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland
    Title: Non-Markovian quantum dynamics
    Abstract: We discuss recent concepts of non-Markovianity of quantum evolution. The discussion is illustrated by simple examples (pure decoherence, amplitude damping and random unitary dynamics).
  12. Speaker: Marek Czachor
    Affiliation: Faculty of Applied Physics and Mathematics, Technical University of Gdańsk and National Quantum Information Centre in Sopot
    Title: Are EPR correlations sensitive to the form of field quantization?
    Abstract: As is widely known, the standard "one oscillator per one mode" quantization of free fields leads to the correct physical prediction <AB>=cos(a-b) for entanglement of linear polarizations, and violates the Bell inequality. This seems to suggest that the tensor product structure associated with the "oscillator per mode" quantization is indeed THE tensor structure associated with quantum fields. However, I will show that <AB>=cos(a-b) is typical also of fields quantized in a different way, where there is no relation at all between the number of modes and the number of oscillators.
  13. Speaker: Zbigniew Ficek
    Title: Role of the first-order coherence in entanglement between Gaussian modes
    Affiliation: The National Centre for Mathematics and Physics, KACST, Riyadh, Saudi Arabia
    In collaboration with: Li-hui Sun1 and Gao-xiang Li2
    1 College of Physical Science and Technology, Yangtze University, Jingzhou, P. R. China
    2 Department of Physics, Huazhong Normal University, Wuhan, P. R. China
    Abstract: The coherence and entangled properties of coupled Gaussian modes of optical systems are discussed. The systems considered are (1) an atomic ensemble located inside a ring cavity, and (2) an optical lattice trapped inside a cavity with a movable mirror. We examine separately the cases of two-mode and three-mode interactions, which are distinguished by a suitable tuning of the mode frequencies. We find that the occurrence of entanglement in the system is highly sensitive to the presence of the first-order coherence between the modes. In particular, the creation of the first-order coherence between modes is achieved at the expense of entanglement between them.
  14. Participant: Waldemar Głaz
    Title: Evolution of collisional nonlinear spectral properties of light scattered in H2-Rg mixtures. From Rg=He to Xe.
    Authors: Waldemar Głaz1, Tadeusz Bancewicz1, Jean-Luc Godet2, George Maroulis3, and Anastasios Haskopoulos3
    1 Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, 61-614 Poznań, Poland
    2 University of Angers, UFR Sciences Institute of Sciences and Molecular Technologies of Angers, 49045 Angers Cedex 01, France
    3 Department of Chemistry, University of Patras, GR-26500 Patras, Greece.
    Abstract: Intensive theoretical and numerical study of the nonlinear collisional spectra of the light hyper-Rayleigh scattered (HRS) by dihydrogen-noble gas (H2-Rg) mixtures has been recently completed by adding the heaviest elements of Kr and Xe to the previously considered set of perturbers. This allowed for studying the evolution of the roto-translational spectral features with regard to the growing mass of the supermolecules included. The influence of the spatial distribution of the first hyperpolarizability property was examined and feasibility of experimental verification of the effect indicated. The anisotropic properties of the H2-Rg interaction potential are partially taken into account for the first time in the HRS analyses.
  15. Speaker: Przemysław Głowacki
    Title: Spectroscopic investigations of the atomic structure in support of quantum engineering and metrology
    Authors: P. Głowacki1, A. Krzykowski1, A. Jarosz1, O. A. Herrera-Sancho2, M. V. Okhapkin2, E. Peik2
    1 Laboratory of Quantum Engineering and Metrology, Poznań University of Technology, Poland
    2 Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
    Abstract: The contribution is focused on spectroscopic investigations of electronic levels, in particular metastable ones, in free atoms and ions.
    A system consisting of a metastable atomic state and the ground state is very favorable for optical atomic frequency standards, since the levels are connected via a forbidden transition with possible application as a "clock" transition. The same system of levels may serve as a basis for construction of a quantum bit.
    Within the work some recent achievements in high precision spectroscopy of metastable levels in chromium atoms, obtained with ABMR-LIRF (laser - microwave double resonance on an atomic beam) method [1, 2], are presented. A brief review of experimental investigations of thorium ion structure aimed at construction of an extremely precise optical nuclear frequency standard [3], performed in cooperation in PTB, is also given.
    [1] A. Jarosz, D. Stefańska, M. Elantkowska, J. Ruczkowski, A. Buczek, B. Furmann, P. Głowacki, A. Krzykowski, Ł. Piątkowski, E. Stachowska, J. Dembczyński, High precision investigations of the hyperfine structure of metastable levels in chromium atom, J. Phys. B: At. Mol. Opt. Phys. 40: 2785-2797 (2007).
    [2] A. Krzykowski, P. Głowacki, A. Jarosz Precise measurements of the hyperfine structure of the levels belonging to the terms 3d54s 5G and 5P in Cr(I), Acta Phys. Pol. A, 122, 78-81 (2012).
    [3] O. A. Herrera-Sancho, M. V. Okhapkin, K. Zimmermann, Chr. Tamm, E. Peik, A. V. Taichenachev, V. I. Yudin, P. Głowacki, Two-photon laser excitation of trapped 232Th+ ions via the 402-nm resonance line Phys. Rev. A 85, 033402 (2012).
  16. Speaker: Jean-Luc Godet
    Affiliation: University of Angers, UFR Sciences Institute of Sciences and Molecular Technologies of Angers, France
    Title: A short historical recall about the story of the concept of refractive index: From the Antique to the 19th century.
    Abstract: The research of a refraction law played a major role in the development of the optics since the first attempts of Ptolemy until the more accomplished results of Ibn Sahl, Snel or Descartes. However, it is necessary to wait for the beginning of the XIXth century, much later than the theory of colours of Newton and thanks to the researches on the achromatic glasses, so that emerges the concept of refractive index and so that it begins to be understood well. We propose a historical reminder and an outline of the obstacles and epistemological advances which allowed to establish it.
  17. Speaker: Andrzej Grudka
    Title: Universal scheme for violation of local realism from quantum advantage in one-way communication complexity
    Authors: L. Czekaj1, A. Grudka2, M. Horodecki1, P. Horodecki3, and M. Markiewicz1
    1Faculty of Mathematics, Physics and Informatics, Gdańsk University, 80-952 Gdańsk,Poland
    2Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
    3Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, 80-952 Gdańsk, Poland
    Abstract: We consider relations between communication complexity problems and detecting correlations (violating local realism) with no local hidden variable model. We show first universal equivalence between characteristics of protocols used in that type of problems and non-signaling correlations. We construct non linear bipartite Bell type inequalities and strong nonlocality test with binary observables by providing general method of Bell inequalities construction and showing that existence of gap between quantum and classical complexity leads to violation of these inequalities. We obtain, first to our knowledge, explicit Bell inequality with binary observables and exponential violation.
  18. Organizer: Krzysztof Grygiel
    Affiliation: Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, Poznań, Poland
  19. Speaker: Keith Gubbins
    Affiliation: Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, U.S.A.
    Title: The Theory of Polar Liquids and Their Mixtures: A Historical Review
    Abstract: The primary goal of a theory of liquid mixtures is to determine, using statistical mechanics, how the structure and free energy varies with the composition, and with the chemical composition of its components. Such a theory provides the key to the determination of dielectric and spectral properties, phase transitions, critical points, solubilities, immiscible regions, metastable and unstable regions, etc.
    Theories proposed in the first half of the 20th century were, for the most part, lattice theories, and many of these are described in the books by Guggenheim [1] and Prigogine [2]. These early theories pre-dated molecular simulations and the availability of electronic computers, so that they were “tested” by direct comparison with experimental data. Since such comparisons, in the case of the lattice theories, involved adjustment of various parameters to experimental data, these tests were of dubious value. Once molecular simulation data became available in the early 1960’s these theories were shown to be in serious error, and can now be considered to be extinct.
    Modern theory of polar liquids (the last 60 years) has followed a dual path. The first has been perturbation theory, in which the free energy and other properties of the solution of interest are related to those of a simpler solution having simple intermolecular forces, for example hard spheres or Lennard-Jones mixtures. Perturbation theory has been particularly successful for thermodynamic properties. The theory of Wertheim [3], relates the free energy of a polar or associating fluid to that of a hard body (non-associating) fluid through a clever resummation of a cluster series for the free energy. It and its later extensions are finding widespread practical application [4].
    The second route to a theory of polar liquids has been integral equation theory, which yields the structure in the form of distribution functions [5]. Although less successful than the perturbation theories for thermodynamic properties, integral equation theories have been successful for other properties, in particular dielectric and spectral properties.
    References
    [1] E.A. Guggenheim, “Mixtures”, Clarendon Press, Oxford, 1952.
    [2] I. Prigogine, “The Molecular Theory of Solutions”, North-Holland Pub. Co., Amsterdam, 1957.
    [3] Wertheim, M.S. J. stat. Phys. 35, 19 (1984); ibid. 35, 35 (1984); ibid. 42, 459 (1986); ibid. 42, 477 (1986).
    [4] For reviews of the theory and its extensions, and practical applications, see: Müller, E.A. and Gubbins, K.E. Ind. Engng. Chem. Research, 40, 2193 (2001); Tan, S.P., Adidharma, H. and Radosz, M., Ind. Eng. Chem. Research, 47, 8063 (2008).
    [5] C.G. Gray and K.E. Gubbins, Theory of Molecular Fluids. I. Fundamentals, Chap. 5, Oxford University Press (1984); C.G. Gray, K.E. Gubbins and C.G. Joslin, Theory of Molecular Fluids. II. Applications, Chap. 9-11, Oxford University Press (2011).
  20. Speaker: Qiongyi He
    Title: Einstein-Podolsky-Rosen paradox and quantum steering in pulsed optomechanic
    Authors: Q. Y. He1,2, M. D. Reid2, and P. D. Drummond2
    1 State Key Laboratory of Mesoscopic Physics, School of Physics, Peking University, Beijing, China;
    2 Centre for Quantum Atom Optics, Swinburne University of Technology, Melbourne, Australia
    Abstract: We describe how to generate an Einstein-Podolsky-Rosen (EPR) paradox between a mesoscopic mechanical oscillator and an optical pulse. We find two types of paradox, defined by whether it is the oscillator or the pulse that shows the effect Schrodinger called “steering”. Only the oscillator paradox addresses the question of mesoscopic local reality for a massive system. In that case, EPR’s “elements of reality” are defined for the oscillator, and it is these elements of reality that are falsified (if quantum mechanics is complete). For this sort of paradox, we show that a thermal barrier exists, meaning that a threshold level of pulse-oscillator interaction is required for a given thermal occupation n0 of the oscillator. We find there is no equivalent thermal barrier for the entanglement of the pulse with the oscillator, nor for the EPR paradox that addresses the local reality of the optical system. Our work highlights the asymmetrical effect of thermal noise on quantum nonlocality.
  21. Speaker: Tadeusz Hilczer
    Affiliation: Division of Dielectrics Physics, Physics Faculty, Adam Mickiewicz University, Poznań
    Title: The early days of physics of dielectrics in Poznań
    Abstract: Physics of dielectrics started in Poznań when professor Arkadiusz Piekara took chair in Experimental Physics at the Poznań University in 1952. At the beginning a lot of effort was taken to prepare the measuring basis, that is to construct the measuring condensers, Schering bridges, resonance circuits, heterodyne beat apparatus (∆C/C ≈ 10−6), to purifying liquid dielectrics and to synthesize ferroelectrics. Later, professor Piekara got Stanisław Kielich interested in theoretical approach to the physics of dielectrics and his Master of Science dissertation in 1955 can be considered as the beginning of the work of young Poznań staff in theory of dielectrics.
  22. Speaker: Paweł Horodecki
    Affiliation: Faculty of Applied Physics and Mathematics, Technical University of Gdańsk and National Quantum Information Centre in Sopot, Poland
    Title: Device independent arbitrary weak randomness amplification with noise tolerance
    Abstract: Recently the protocols of randomness amplification have been introduced secure against quantum and no-signaling adversaries. Here we present the first fully constructive proof of existence of the protocol that is secure against general no-signaling adversary and amplifies arbitrary small randomness (in standard terms of Santha-Vazirani source) in a fully device independent way. The protocol tolerates some amount of noise depending among others on the initial randomness that is to be amplified.
  23. Speaker: Ryszard Horodecki
    Affiliation: Instytut Fizyki Teoretycznej i Astrofizyki, Uniwersytet Gdański, 80-952 Gdańsk oraz Krajowe Centrum Informatyki Kwantowej w Gdańsku, 81-824 Sopot, Poland
    Title: Objectivity from first principles - new role of broadcasting structure
    Abstract: Incessant run of successes of quantum mechanics suggests that quantum formalism plays decisive role in the description of physical phenomena. It leads inevitably to the problem: How does Nature create a "foot-bridge" from fragile quanta to the objective world of everyday experience? The subject of the talk will provide an answer to this fundamental issue. We will show how a crucial for quantum mechanics notion of non-disturbance due to Bohr and a natural definition of objectivity lead to a canonical spectrum broadcasting structure of a quantum system-environment state, reflecting objective information records about the system stored in the environment.
  24. Organizer: Bohdan Horst
    Affiliation: Physics Faculty, Adam Mickiewicz University, Poznań, Poland
  25. Participant: Joanna Kalaga
    Poster's title: Mean number of photons as witness of quantum chaotic dynamics of nonlinear Kerr-like oscillator
    Authors: J. K. Kalaga, W. Leoński, and V. Cao Long
    Quantum Optics and Engineering Division, Institute of Physics, University of Zielona Góra, Poland
    Abstract: We consider an anharmonic Kerr-like oscillator driven by a series of ultra-short coherent pulses. For such a model we discuss the both: quantum and classical dynamics of the system. We show that mean number of photons for quantum model can behave chaotically in classical sense, despite quantum character of the system. We believe that this parameter could be applied as indicator of its quantum-chaotic dynamics.
  26. Participant: Marcin Karczewski
    Affiliation: Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, 61-614 Poznań
  27. Speaker: Dobrosława Kasprowicz
    Title: Opportunities for Bi2ZnOB2O6 single crystals: Second and third order nonlinear optical applications
    Authors: D. Kasprowicz1, K. Iliopoulos2, A. Majchrowski3, and B. Sahraoui2
    1Faculty of Technical Physics, Poznan University of Technology, Nieszawska 13 A, 60-965 Poznan, Poland
    2LUNAM Université, Université d'Angers, CNRS UMR 6200, Laboratoire MOLTECH-Anjou, 2 Bd Lavoisier, 49045 Angers Cedex, France
    3Institute of Applied Physics, Military University of Technology, Kaliskiego 2, 00 - 908 Warszawa, Poland
    Abstract: Bi2ZnOB2O6 nonlinear optical single crystals were grown by means of the Kyropoulos method from stoichiometric melt. The SHG and THG response of the Bi2ZnOB2O6 crystal was studied by the Maker fringes techniques. Moreover SHG microscopy studies were carried out providing two-dimensional SHG images as a function of the incident laser polarization. The crystals have been shown to have high SHG and THG efficiency, comparable with those of well-known crystals such as BBO, KDP, KTP, which makes them very attractive materials for NLO applications. The high nonlinear optical efficiency combined with the possibility to grow high quality crystals make Bi2ZnOB2O6 an excellent candidate for photonic applications.
  28. Participant: Waldemar Kłobus
    Poster's title: Mutual uncertainty
    Authors: Waldemar Kłobus1, Andrzej Grudka1, Michał Horodecki2, Paweł Horodecki2, Ryszard Horodecki2, Łukasz Pankowski2
    1 Physics Faculty, Adam Mickiewicz University, Poznań, Poland
    2 National Quantum Information Centre in Sopot, Poland
    Abstract: We conjecture new uncertainty relations which restrict correlations between results of measurements performed by two parties on a shared quantum state. The uncertainty relations bounds the sum of mutual informations in scenarios when one party measures a single observable and the other party measures one of two observables, and when each party measures one of two observables. The first uncertainty relation is stronger than Hall's derived from Maassen-Uffink uncertainty relation. The uncertainty relations are proved to hold for large classes of states and observables.
  29. Participant: Jarosław W. Kłos
    Poster's title: The influence of structural changes on the spin waves spectra of periodic antidot wire
    Authors: J. W. Kłos1, M. Krawczyk1, D. Kumar2, B. Rana2, and A. Barman2
    1 Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
    2 Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 India
    Abstract: Dispersion relation of periodic wires is periodic in reciprocal space due to the Bragg reflections. Periodicity of the structure significantly alters the dispersion even when the modulation of structural or material parameters is relatively weak. The main goal of presented work is to investigate the changes in spin wave dispersion for periodic antidot wire (ADW) in dependence on the structural parameters like: lattice constant and size of antidots. We will show that precise choice of these parameters is crucial for achieving desired properties of ADW.
    We investigate numerically ADW made of permalloy (Py) with square air holes placed equidistantly along the wire, in its center. Such structure is feasible to fabricate even with a resolution in the range of few nanometers. The considered antidot wire will then operate in the frequency range of few tens of GHz. We used two different computational techniques micromagnetic simulation (OOMMF) and plane wave method to crosscheck the obtained results.
    In our calculations we assumed the ideal pinning at the Py/air interfaces. In the presence of strong pinning the row of antidots divides the system into two subwires. Depending on the period a and the size of antidots s, we have controlled the following properties of the system: (1) the width of the gap, (2) the coupling between two subwires.
    We acknowledge the financial support from FP7/2007-2013 (Grant Agreement no. 233552 for DYNAMAG), NCN of Poland project DEC-2012/07/E/ST3/00538 and a senior research fellowship from CSIR, India (D.K.).
  30. Organizer: Anna Kowalewska-Kudłaszyk
    Affiliation: Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, Poznań
  31. Speaker: Maciej Krawczyk
    Affiliation: Nanomaterials Physics Division, Physics Faculty, Adam Mickiewicz University, Poznań, Poland
    Title: Review and prospects of magnonic crystals
    Abstract: Magnonic crystals are the magnetic equivalent of photonic crystals, with spin waves as the counterpart of electromagnetic waves, playing the role of information carriers. We will present short overview of research performed on magnonic crystals offering tailored band structures for spin waves. The promising directions of magnonic crystals research and its applications will be briefly discussed.
  32. Speaker: Marek Kuś
    Affiliation: Center for Theoretical Physics, Polish Academy of Sciences, Warsaw, Poland
    Title: Engineering SU(3) models: trapped ions, quantum chaos, classical limit(s)
    Abstract: One of the current trends in quantum physics is the quest for controllable quantum many-body systems which can be used as quantum simulators. In particular, there is a growing interest in simulating spin and quantum magnetism. In recent years, the focus is moving from SU(2) spins towards SU(N)-symmetric models. The SU(3) systems, having their origin in nuclear physics, were a fruitful playground for quantum chaos investigations, in particular due to they reach possible behavior in the classical limit. Now it seems to be possible to realize such models experimentally with trapped ions providing a large degree of control from the experimental point of view.
  33. Speaker: Karel Lemr
    Affiliation: Joint Laboratory of Optics of Palacký University and Institute of Physics of Academy of Sciences of the Czech Republic, Faculty of Science, Palacký University, Olomouc, Czech Republic
    Title: Linear optical quantum routers
    Abstract: This talk summarizes our recent results in the field of quantum routing. First, we define a fully functional quantum router with emphasis on the features such router has to provide. Then we review some of the previously published schemes showing the lack for genuine linear-optical quantum router for individual photons. Subsequently we present our two proposals for linear-optical quantum routers [1,2] and discuss their advantages and disadvantages. Finally we address the experimental implementation that is currently under construction in our laboratory.
    [1] K. Lemr, A. Černoch, Linear-optical programmable quantum router, Opt. Comm. 300, 282-285 (2013).
    [2] K. Lemr, K. Bartkiewicz, A. Černoch, and J. Soubusta, Resource-efficient linear-optical quantum router, Phys. Rev. A 87, 062333 (2013).
    Poster's title: Applications of linear-optical controlled-phase gate with tunable phase shift
    Authors: K. Lemr, K. Bartkiewicz, A. Černoch, M. Dušek, J. Soubusta
    Abstract: The controlled-phase gate is a versatile quantum gate. We show that the tunable version of this gate offers even more improvement to its applications.
    Poster's title: Tunable gate for quantum amplification and nondemolition presence detection
    Authors: M. Bula, K. Bartkiewicz, A. Černoch, J. Soubusta, E. M. Scott, T. Jennewein, and K. Lemr
    Abstract: Quantum amplification is an important tool for quantum communications. We present a linear-optical scheme for amplification of an unknown qubit implemented by single photon. The scheme can be tuned to a regime of quantum presence detection where it reveals the presence of a photon without destroying it.
  34. Organizer: Wiesław Leoński
    Affiliation: Faculty of Physics and Astronomy, University of Zielona Góra
    Poster's title: Dynamics of a set of two-level subsystems in two-dimensional cavity simulated with cellular automata formalism
    Authors: Nguyen Thanh Vinh1, Bui Dinh Thuan2, Cao Long Van1, and Wiesław Leoński1
    1Quantum Optics and Engineering Division, Institute of Physics, University of Zielona Góra, Poland
    2Vinh University, 182 Le Duan str. Vinh City, Nghe An, Vietnam
    Abstract: We consider a system composed of a large number of two-level subsystems. Such models were already discussed in numerous papers not only from the point of view of contemporary physics and engineering but also biological and even social sciences. In particular, we discuss a model that is an extension of one-dimensional system, considered in previous works. We show how cellular automata formalism can be applied for investigation of such system's dynamics, and how it can be implemented in MATLAB or Octave environments.
    Poster's title: Kerr-like coupler excited by a series of ultra-short external pulses as a source of entangled states
    T.D. Nguyen1, W. Leonski1, A. Kowalewska-Kudłaszyk2, J. Perina Jr.3, and V. Cao Long1
    1Quantum Optics and Engineering Division, Institute of Physics, University of Zielona Góra, ul. Prof. Z. Szafrana 4a, 65-516 Zielona Góra, Poland
    2Faculty of Physics, Adam Mickiewicz University, ul. Umułtowska 85, 61-614 Poznań, Poland
    3Institute of Physics of AS CR, Joint Laboratory of Optics, 17 listopadu 50a, 772 07 Olomouc, Czech Republic
    Abstract: The optical coupler composed of two mutually interacting nonlinear quantum oscillators is discussed. This Kerr-like nonlinear coupler is excited by a series of ultra-short pulses of an external classical electromagnetic field. Assuming that the field was initially in the vacuum state for two oscillators' modes and week excitations we show that the system's dynamics remains closed within a set of three two-mode n-photon states. In consequence, our system can be treated as "nonlinear quantum scissors". Moreover, we show that the system is able to generate Bell states. When damping effects are taken into account, under a proper choice of parameters involved in the problem, some part of entanglement can be preserved in our model. For the system considered here, we can also observe the so-called sudden death of entanglement and its revival effects.
  35. Speaker: Tadeusz Lulek
    Affiliation: Mathematical Physics Division, Physics Faculty, Adam Mickiewicz University, Poznań, Poland
    Title: Nonlinear magnetooptics, symmetry breakings and ascents, and the magnetic translation groups
    Abstract: This commemoration intertwines between various physical ideas (as presented in the title), shared within the scientific works of Professors: Stanisław Kielich, Louis Michel, Jan Mozrzymas, Joshua Zak, Marian Surma, and others. It goes from experimental studies on Cotton-Mouton effect (heavy electromagnesses in the basements of Collegium Chemicum), through symmetry considerations in phase transitions (nematics, smectics, etc., mainly breaking of symmetry, but, somehow exceptionally, also ascent), to the magnetic translation group as a mathematical tool for the Bohm-Aharonov effect (everybody knows Landau levels of a free two-dim electron gas, and the magnetic translation group serves as an equivalent for the case of itinerant electrons, with its irreducible representations labeling the levels, and the basis functions describing degenerate cyclotronic orbits). Nowadays, these ideas can be converted to "reality" within nanotechnology, e. g. magnetic quantum dots.
  36. Speaker: Igor Lyubchanskii
    Title: Nonlinear magneto-optical ellipsometry
    Authors: Yu. S. Dadoenkova1, I. L. Lyubchanskii1,2, Y.P. Lee3, and Th. Rasing4
    1Donetsk Physical and Technical Institute of the National Academy of Sciences of Ukraine, 83114, Donetsk, Ukraine
    2Department of Physics and Technology, Donetsk National University, 83001, Donetsk, Ukraine
    3Quantum Photonic Science Research Center (q-Psi) and Hanyang University, 133-791, Seoul, Republic of Korea
    4Radboud University Nijmegen, Institute for Molecules and Materials, 6525 AJ, Nijmegen, the Netherlands
    Abstract: The ellipsometric parameters for light reflection from a dielectric film with Kerr optical nonlinearity on a bigyrotropic magneto-electric film are theoretically investigated. The combined contributions of the cubic optical nonlinearity and the magneto-electric coupling allows to control the ellipsometric parameters and thus for example the Kerr rotation with the incoming light intensity, in particular at incidence angles close to the pseudo-Brewster angle.
  37. Speaker: Małgorzata Makowska-Janusik
    Affiliation: Institute of Physics, Jan Długosz University, Częstochowa, Poland
    Title: Macroscopic optical properties of composite materials - computational approach
    Abstract: One of the possibilities to obtain efficient and stable nonlinear optical (NLO) material is to dope an amorphous polymer with organic donor-acceptor molecules forming a composite. The appropriate material for the first NLO effect as persistent second harmonic generation (SHG) requires large number of polarizable molecules embedded in polymeric matrix preventing polar orientation. The polar orientation may be induced by external electric field at the temperatures where the matrix is sufficiently mobile to allow fast alignment of the dopants. The experimental explanation of the origin of their NLO response is very difficult because optical susceptibilities are measured in condensed matter where the molecular properties are affected by the host matrix. Molecular simulations can help to explain the nature of the guest-host interaction and separate the different contribution of the material to the optical output signal. A goal of many theoretical works is to find appropriate model describing optical properties of molecules incorporated into polymeric environment.
    In the presented work linear and nonlinear optical susceptibilities of guest-host polymer systems were calculated applying the hierarchic procedure . The wild variety of chromophores characterized by different size, shape and charge distribution incorporated into different polymer matrix were studied. First of all the structures of the investigated systems have been modeled by molecular dynamic simulations applying molecular mechanics CVFF force field method. The obtained structures are amorphous. Investigations of radial distribution function prove that location of chromophores in polymeric matrix is an intrinsic property of polymer. The motion of polymer chain allows a rotation of dopants under influence of an external electric field.
    The electronic properties of the NLO chromophores were computed at the HF and DFT level using different exchange - correlation potentials. These properties were investigated for the isolated NLO molecules as well as for the ones in polymer environment. In the second case the first-order susceptibilities corresponding to SHG were calculated using discrete local field approach. The implemented method is very efficient to the molecules with high charge transfer effect and give the data approximately consistent with the experimental results. It was also proved that the optical response, especially NLO output signal of chromophores embedded into polymeric matrix, depends on their local environment.
  38. Speaker: George Maroulis
    Affiliation: Department of Chemistry, University of Patras, Greece
    Title: Quantifying the performance of quantum chemistry methods
    Abstract: We present a general method for the quantification of the performance of quantum chemical methods over an arbitrary collection of atomic/molecular properties. Our approach relies on the Minkowski metric , graph theoretic concepts and pattern recognition techniques. The method should be of interest as a rigorous approach to the introduction of order and classification in spaces of theoretical descriptions. We show how it can be used to quantify the relative merit of ab initio and DFT methods.
  39. Speaker: Jan Martinek
    Title: Cooper pair splitting as a source of entangled electrons
    Authors: Jan Martinek1, D. Tomaszewski1, M. Czechlewski1, P. Rożek1, R. Zitko2, R. Lopez3, M. Lee4, W. Kłobus5, A. Grudka5, A. Baumgartner6, and C. Schonenberger6
    1Institute of Molecular Physics, Polish Academy of Sciences, 60-179 Poznan, Poland
    2Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
    3Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain
    4Department of Physics, Kyung Hee University, Yongin 446-701, Korea
    5Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
    6Department of Physics, University of Basel, CH-4056 Basel, Switzerland
    Abstract: We study an entangled state of spatially separated electrons, in particular its spins, in a solid state electronic system. The ground state of conventional superconductors is a singlet state of electron Cooper pairs that can provide a natural source of entangled electrons. One of the proposals to obtain the nonlocal entanglement of electrons is to use the Cooper pairs split in the Double Quantum Dot (DQD) system using the Coulomb interaction between electrons [1]. We have analyzed an efficiency of the separation of Cooper pairs in systems, where the DQD is connected to the two superconducting leads, or to the superconducting and normal leads [2,3]. Addressing the idea of quantum communication with entangled electrons in a solid state, where ferromagnetic detectors allow for spin correlation detection, we provide, using quantum information theory, a lower bond on the spin polarization of detectors [4]. In ferromagnetic detectors the spin information is transformed into charge information, however, any real magnetic materials feature imperfect spin polarization due to presence of both spin component in density of states at the Fermi surface. We find that lower bond for the spin polarization is p > 58% for detection of entanglement using an optimal entanglement witness [4]. It provides the minimal spin polarization of ferromagnetic materials that can be useful in quantum communication.
    [1] L. Hofstetter, S. Csonka, J. Nygard, and C. Schönenberger, Nature 461, 960 (2009).
    [2] J. Eldridge, M. G. Pala, M. Governale, and J. König, Phys. Rev. B 82, 184507 (2010).
    [3] R. Zitko, J. Lim, R. Lopez, J. Martinek, P. Simon, Phys. Rev. Lett. 108, 166605 (2012).
    [4] W. Kłobus, A. Grudka, A. Baumgartner, D. Tomaszewski, C. Schönenberger, and J. Martinek, (in preparation).
  40. Organizer: Adam Miranowicz
    Affiliation: Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, Poznań
  41. Speaker: Jan Mostowski
    Affiliation: Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
    Title: Time crystals
    Abstract: A system of two charged particles in a harmonic trap with additional magnetic field is considered. The problem is reduced to a single-particle one in relative coordinates. The ground- and lowest excited-state energies and wave functions are found. The ground state exhibits non-zero expectation value of the velocity (kinetic momentum) and the probability current density does not vanish as well. When the ground state becomes degenerate the expectation value of velocity becomes discontinuous. The effects associated with turning on of the magnetic field are studied by solving the appropriate time-dependent Schroedinger equation. No substantial differences between abrupt (discontinuous in time) and continuous switching on have been observed. Evolution of a wave packet which is initially Gaussian is also investigated. The wave packet loses its Gaussian nature and, after sufficiently large time, a system of diffractive maxima and minima is built.
  42. Participant: Michał Mruczkiewicz
    Poster's title: Nonreciprocal dispersion of spin waves in magnonic crystals
    Authors: M. Mruczkiewicz1, M. Krawczyk1, G. Gubbiotti2, S. Tacchi2, Yu. A. Filimonov3,5, and S. A. Nikitov4,5
    1 Department of Nanomaterials Physics, Faculty of Physics, Adam Mickiewicz University, Poznań, Poland
    2 Istituto Officina dei Materiali del CNR (CNR-IOM), Unita` di Perugia, c/o Dipartimento di Fisica, Universita` di Perugia, I-06123 Perugia, Italy
    3 Kotel'nikov Institute of Radio-engineering and Electronics of RAS, Saratov Branch, Zelenaya Str. 38, Saratov, 410019, Russia
    4 Kotel'nikov Institute of Radio-engineering and Electronics of RAS, Mokhovaya Str. 11, Bld. 7, Moscow, 125009, Russia
    5 Saratov State University, Astrakhanskaya Str. 83, Saratov, 410012, Russia
    Abstract: We investigate magnonic crystals in direct contact with the perfect electric conductor. The effect of metalization on the dispersion relation has been studied with the use of finite element method. The perfect conducting overlayer has been implemented in the model as an effective boundary condition. The strong nonreciprocity of spin waves dispersion relation results in appearing of band gaps at wave vectors that do not correspond to the edge of the Brillouin zone. The analysis of the spatial distribution of dynamic magnetization amplitudes elaborates the mechanism of forming of dispersion bands in this kind of structures and explains the hybridizations between magnonic bands in magnonic crystal with nonreciprocal dispersion relation.
    We acknowledge the financial support from FP7/2007-2013 (Grant Agreement no. 247556 NoWaPhen) and NCN of Poland project DEC-2012/07/E/ST3/00538.
  43. Participant: Kamila Nowicka
    Poster's title: Nonlinear electro-optical spectroscopy of liquid crystals
    Authors: K. Nowicka, N. Bielejewska, J. Hoffmann, and W. Kuczyński
    Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17,60-179 Poznań, Poland
    Abstract: Determination of phase transition temperatures and the identification of phases in liquid crystals (LCs) are of fundamental importance for technical applications and research of liquid-crystalline properties. Experimental methods for identifying LC phases and for determining phase transitions between them involve various approaches, like switching measurements, conoscopic observations, dielectric and electro-optical spectroscopy, conventional X-ray diffraction, or differential scanning calorimetry (DSC) [1,2]. However, some of the methods are not capable of yielding reliable results, especially in cases of helical subphases (SmCα*, SmCβ* or SmCγ*).
    In this presentation, we analyzed spectra of the second, third and fourth harmonic of electro-optical response obtained using relatively weak external electric field to detect phase transitions in liquid crystals. The effectiveness of the method will be presented using the well-known prototype antiferroelectric liquid crystal materials: MHPOBC and MHPOPB in various phases.
    [1] Fukui M., Orihara H., Yamada Y., Yamamoto N. and Ishibashi Y., New Phases in the Ferroelectric Liquid Crystal MHPOBC Studied by Differential Scanning Calorimetry, Jpn. J. Appl. Phys., Part 2 28, L849 (1989).
    [2] Mandal P.K., Jaishi B. R., Haase W., Dąbrowski R., Tykarska M. and Kula P., Optical microscopy, DSC and dielectric relaxation spectroscopy studies on a partially fluorinated ferroelectric liquid crystalline compound MHPO(13F)BC, Phase Trans. 79, 223 (2006).
    Acknowledgments. This work was supported by the funds for science in the years 2010-2013 as a research project.
  44. Organizer: Małgorzata Paprzycka
    Poster's title: Two-photon blockade in a driven cavity with a qubit.
    Authors: M. Paprzycka1, A. Miranowicz1,2, Y.X. Liu2,3,4, J. Bajer5, and F. Nori2,6
    1Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland
    2RIKEN, Saitama 351-0198, Japan
    3Institute of Microelectronics, Tsinghua University, Beijing 100084, China
    4TNList, Tsinghua University, Beijing 100084, China
    5Department of Optics, Palacky University, 772 00 Olomouc, Czech Republic
    6Physics Department, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA
    Abstract: Photon blockade, in analogy to Coulomb's or phonon blockades, is a phenomenon when a single photon in a nonlinear cavity blocks the transmission of a second photon. This effect can occur in Kerr-type systems driven by a laser due to strong nonlinear photon-photon interactions. We predict the occurrence of higher-order photon blockades where the transmission of more than two photons is effectively blocked by single- and two-photon states. This photon blockade can be achieved by tuning the frequency of the laser driving field to be equal to the sum of the Kerr nonlinearity and the cavity resonance frequency. We refer to this phenomenon as two-photon blockade or two-photon state truncation via nonlinear scissors, and can also be interpreted as photon-induced tunnelling. We also show that, for a driving-field frequency fulfilling another resonance condition and for higher strengths of the driving field, even a three-photon blockade can occur but less clearly than in the case of single- and two-photon blockades. We demonstrate how various photon blockades can be identified by analyzing photon-number correlations, coherence and entropic properties, Wigner functions, and spectra of squeezing. We show that two- and three-photon blockades can, in principle, be observed in various cavity and circuit quantum electrodynamical systems for which the standard single-photon blockade was observed without the need of using two-photon driving fields or Kerr media exhibiting higher-order nonlinear susceptibility.
    [1] A. Miranowicz, M. Paprzycka, Y. Liu, J. Bajer and F. Nori, Phys. Rev. A 87, 023809 (2013).
  45. Speaker: Jan Perina Jr.
    Title: Sub-Poissonian-light generation by postselection from twin beams
    Authors: Jan Perina, Jr.1, Ondrej Haderka2, Vaclav Michalek2
    1 RCPTM, Joint Laboratory of Optics of Palacky University and Institute of Physics of AS CR, Palacky University, 17. listopadu 12, 77146 Olomouc, Czech Republic
    2 Institute of Physics of Academy of Sciences of the Czech Republic, Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Sciences of the Czech Republic, 17. listopadu 12, 772 07 Olomouc, Czech Republic
    Abstract: States with sub-Poissonian photon-number statistics obtained by post-selection from twin beams are characterized. States with Fano factors around 0.7 and mean photon numbers around 12 are experimentally reached. Their quasi-ditributions of integrated intensity attaining negative values are determined. An intensified CCD camera with quantum detection efficiency exceeding 20 % is utilized both for post-selection and characterization. Experimental results are compared with theory that provides optimum conditions for the experiment.
  46. Speaker: Tomasz Polak
    Affiliation: Solid State Theory Division, Physics Faculty, Adam Mickiewicz University, Poznań, Poland
    Title: Gauge dependent time of flight patterns in Abelian synthetic magnetic fields
    Abstract: I will show how to calculate the time-of-flight patterns of strongly interacting bosons confined in two-dimensional square lattice in the presence of an artificial magnetic field. I will discuss the cases with the artificial magnetic field being uniform, staggered or forming a checkerboard configuration. Effects of additional temporal modulation of the optical potential that results from application of Raman lasers driving particle transitions between lattice sites are also included. The presented time-of-flight patterns may serve as a verification of chosen gauge in experiments, but also provide important hints on unconventional, non-zero momentum condensates, or possibility of observing graphene-like physics resulting from occurrence of Dirac cones in artificial magnetic fields in systems of ultra-cold bosons in optical lattices. Also, I elucidate on differences between effects of magnetic field in solids and the artificial magnetic field in optical lattices, which can be controlled on much higher level leading to effects not possible in condensed matter physics.
  47. Participant: Piotr Rożek
    Poster's title: Entanglement detection of split Cooper pairs by direct current measurements using double quantum dots and ferromagnetic detectors
    Authors: Piotr Rożek1,2, M. Czechlewski2, D. Tomaszewski2, and J. Martinek2
    1Politechnika Poznańska, Wydział Fizyki Technicznej, Instytut Fizyki, Poznań, Poland
    2Instytut Fizyki Molekularnej PAN, Poznań, Poland.
    Abstract: Significant progress in nanostructures fabrication technologies opens possibility of building the quantum computer, by use of metallic/semiconducting nanostructures. The main advantage over all other possible realizations of quantum computer will be fact the nanostructures fabrication technology is highly advanced and such quantum system would be scalable. Entanglement of two qubits is essential in basics quantum communication protocols and quantum cryptography. For this applications qubits have to be moved and modified - which are called flying qubits. In solid-state systems, there are possibilities of preparing such states. We investigate the system of two quantum dots coupled with superconducting that can work as effective Cooper pair splitter. Due to the nature of superconductors charge carriers – singlet state Cooper pairs, a pair of electrons which are entangled, it is possible to have two separated but spin-entangled electrons on two quantum dots. Ferromagnetic electrodes which work as a spin detectors, gives possibility of converting information about spin of electrons to electric charge, and measuring the correlation between spins, by direct current measurement that can be easily performed in comparison to current correlation measurements. Using POVM (positive-operator valued measure) operators, we define which measurements can be used to investigate spin-correlations. Characteristics of system will be presented and results related to detection of entanglement of electrons in the system, using selected entanglement witness operators that only can be detected with current measurements.
  48. Participant: Marek Smaczyński
    Poster's title: Model quantum neuron: Construction based on nonunitary dynamics
    Abstract: Quantum neuron based on noise quantum channels are introduced. The aim of the project is to show computational capabilities of dissipative quantum systems, in which one can combine some ideas taken from quantum information theory and artificial neural network. Dynamics of quantum neuron model subjected to periodic interaction with an environment are analyzed. Learning procedures based on backward propagation of errors are developed. Under the condition of strong decoherence due to large coupling, one-qubit system with one-qubit environment, ability to conduct simple pattern recognition is shown.
  49. Speaker: Jan Soubusta
    Affiliation: Institute of Physics of Academy of Science of the Czech Republic, Joint Laboratory of Optics of PU and IP AS CR, Olomouc, Czech Republic
    Title: Recent results of the experimental-optics group in Olomouc
    Abstract: We summarize ten years of experiments dealing with quantum cloning and implementations of linear-optical quantum devices. We tried several concepts and several platforms for optimal cloning of photon qubits. We developed several linear-optical quantum information processing devices and we used them for cloning.
    Poster's title: Second harmonic generation in periodically poled KTP
    Authors: J. Soubusta, R. Machulka, J. Svozilík, J. Peřina jr., O. Haderka
    Abstract: We study influence of waveguide parameters on the second harmonic generation in periodically poled materials.
  50. Speaker: Tomasz Sowiński
    Affiliation: Institute of Physics of the Polish Academy of Sciences, Warsaw, Poland and Center for Theoretical Physics of the Polish Academy of Sciences, Warsaw, Poland
    Title: Universality of extended Bose-Hubbard models with local three-body interactions
    Abstract: Experimental progress on trapping and manipulating ultra-cold atoms confined in optical lattices has opened new perspectives for controlling many-body states of different quantum systems. In the simplest case such systems are described in the context of the Bose-Hubbard (BH) model. In my talk I will consider the class of extended BH models with additional three-body on-site interactions. After short introduction I will divide the talk into two parts: (i) Standard BH with additional three-body term: I will show that the shape of insulating lobes may crucially depend on the three-body interactions and in the case of attractive three-body term may lead to vanishing of the second insulating lobe [1,2]. (ii) Attractive BH model with soft-core three-body repulsion: I will show that the critical behavior of the system undergoing a phase transition from pair-superfluid to superfluid at integer filling depends on the value of the three-body repulsion. In particular, a critical exponent and the central charge governing the quantum phase transitions are shown to have repulsion dependent features. In consequence, the model extends the list of known systems violating the universality hypothesis [3].
    [1] T. Sowinski, Phys. Rev. A 85, 065601 (2012).
    [2] T. Sowinski, ArXiv:1307.6852 (2013).
    [3] T. Sowinski, R. W. Chhajlany, O. Dutta, L. Tagliacozzo, M. Lewenstein, ArXiv:1304.4835 (2013).
  51. Participant: Danuta Stefańska
    Affiliation: Laboratory of Quantum Engineering and Metrology, Poznań University of Technology, Poland
  52. Participant: Marian Surma
    Affiliation: Optics Division, Physics Faculty, Adam Mickiewicz University, Poznań, Poland
  53. Participant: Gustaw Szawioła
    Affiliation: Laboratory of Quantum Engineering and Metrology, Poznań University of Technology, Poland
  54. Organizer: Ryszard Tanaś
    Affiliation: Nonlinear Optics Division, Physics Faculty, Adam Mickiewicz University, Poznań, Poland
  55. Participant: Damian Tomaszewski
    Poster's title: Cooper pair splitting efficiency in double quantum dot in cotunneling regime
    Authors: Damian Tomaszewski1, R. Zitko2, R. Lopez3, M. Lee4, and J. Martinek1
    1Institute of Molecular Physics, Polish Academy of Sciences, 60-179 Poznan, Poland
    2Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
    3Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain
    4Department of Physics, Kyung Hee University, Yongin 446-701, Korea
    Abstract: Quantum communication is one of the most intensively developing areas of science. The important step is to get entangled state of electrons in solid state device. One of the solutions is the use of Cooper pairs as a source of entangled electrons and separating them in Double Quantum Dot (DQD) system. Operation of Cooper pair splitting device is based on Coulomb interactions between electrons. We considered two systems: DQD connected to two superconducting leads and DQD connected to superconducting and normal leads. In both systems we studied a flow of electrons in a cotunneling regime (simultaneous tunneling of Cooper pairs through the whole system). We calculated Cooper pair splitting (CPS) efficiency for different ground states of quantum dots. Calculations were made with use of the 4-th order perturbation theory. We were able to show several kinds of tunneling processes that are possible in these systems, where some of them lead to a split of Cooper pairs and some lead to a tunneling through a single dot only. For the first system (two superconducting leads) the CPS efficiency close to resonance is 100%. Far away from resonance the CPS efficiency is 66.6% for singlet and 50% for the DQD without electrons. For the second system close to resonance the CPS efficiency is 100% and far away from resonance is 80% and 50% for singlet and empty state, respectively.
    Poster's title: Quantum spin torque in quantum dot coupled to ferromagnetic leads
    Authors: Damian Tomaszewski1, A.-D. Crisan2, S. Datta2, J. J. Viennot2, M. R. Delbecq2, C. Feuillet-Palma3, A. Thiaville4, A. Cottet2, T.Kontos2, and J. Martinek1
  56. 1Institute of Molecular Physics, Polish Academy of Sciences, 60-179 Poznan, Poland
    2Laboratoire Pierre Aigrain, E.N.S., 24 rue Lhomond, 75231 Paris Cedex 05, France
    3Laboratoire de Physique et d'Etude des Materiaux, ESPCI, 75005, Paris, France
    4Laboratoire Physique des Solides, CNRS - Univ. Paris-Sud, 91405, Orsay, France
    Abstract: Spin manipulation requires applying a torque. This can be done with use of magnetic fields. We use, for this purpose, a single wall carbon nanotube (SWCN) quantum dot connected to leads (PdNi) with non-collinear magnetizations. We have studied an electron transport through this device, which acts like a spin-valve with a finite tunnelling magnetoresistance effect. Depending on system parameters a non-equilibrium spin accumulation on the quantum dot can be generated. We have also studied a theoretical influence of gate and bias voltage, charging energy, asymmetry of the tunnel couplings and external magnetic field. They can be determined by generalized kinetic equations within a diagrammatic real-time transport theory for the dot's density matrix. We predicted that the interplay of spin-dependent tunnelling and Coulomb interactions in quantum-dot spin valves gives rise to an interaction driven spin precession, describable in terms of an internal exchange and external magnetic field in the limit of weak dot-lead coupling. The quantities of central interest are the magnitude and direction of the spin accumulated on the quantum dot. This opens the potential of a controlled manipulation of the quantum dot spin, detectable in transport.
    Poster's title: Correlation analysis of atomic and single-molecule junction conductance
    Authors: Damian Tomaszewski1, P. Makk2, A. Halbritter2, Z. Balogh2, S. Csonka2, M. Wawrzyniak3, M. Frei4, L. Venkataraman4, and J. Martinek1
    1Institute of Molecular Physics, Polish Academy of Sciences, 60-179 Poznan, Poland
    2Department of Physics, Budapest University of Technology and Economics and Condensed Matter Research Group of the Hungarian Academy of Sciences, 1111 Budapest, Hungary
    3Faculty of Electronics and Telecommunications, Poznan University of Technology, Poland
    4Department of Applied Physics and Applied Mathematics, Columbia Univ., New York, USA
    Abstract: The break-junction technique is widely used to measure electronic properties of nanoscale junctions, including metal point-contacts and single-molecule junctions. In these measurements, conductance is measured as a function of electrode displacement yielding data that is analyzed by constructing conductance histograms to determine the most frequently observed conductance values in the nanoscale junctions. However, most of the rich physics in these measurements is lost in this simple analysis technique. Conductance histograms cannot be used to study the statistical relation of distinct junction configurations, to distinguish structurally different configurations that have similar conductance values, or to obtain information on the relation between conductance and junction elongation. We present innovative statistical methods for the study of stable atomic configurations in breaking nanowires. They are based on the 2D cross-correlation histogram analysis of conductance versus electrode separation traces, which is analogical to 2D correlation spectroscopy in magnetic resonance. This method provides new information about different junction configurations, e. g. a very regular atomic narrowing can be identified during the rupture of Ni, Fe, and V nanowires, which is absent in the majority of the metals.
  57. Participant: Jan Tuziemski
    Poster's title: Can communication power of separable correlations exceed that of entanglement resource?
    Autors: Paweł Horodecki1,3, Jan Tuziemski1,3, Paweł Mazurek2,3, and Ryszard Horodecki2,3
    1Faculty of Applied Physics and Mathematics,Technical University of Gdańsk, Poland
    2Institute of Theoretical Physics and Astrophysics, University of Gdańsk, Poland
    3National Quantum Information Centre of Gdańsk, Poland
    Abstract: The scenario of remote state preparation with shared correlated quantum state and one bit of forward communication [B. Dakic et al., Nature Physics 8, 666 (2012)] is considered. Optimisation of the transmission efficiency is extended to include general encoding and decoding strategies. The importance of use of linear fidelity is recognized. It is shown that separable states cannot exceed the efficiency of entangled states in standard "local operations plus classical communication" paradigm. It is proven however that such a surprising phenomena may naturally occur when the decoding agent has limited resources in the sense that either (i) has to use decoding which is insensitive to change of coordinate system in the plane being in question (which is the natural choice if the receive does not know the latter) or (ii) is forced to use bistochastic operations which may be imposed by physically inconvenient local thermodynamical conditions.
  58. Speaker: Werner Vogel
    Title: Unified representation of nonclassicality and entanglement
    Authors: Werner Vogel and Jan Sperling
    Arbeitsgruppe Quantenoptik, Institut für Physik, Universität Rostock, D-18051 Rostock, Germany
    Abstract: In Quantum Optics the widely used definition of nonclassicality is based on the Glauber-Sudarshan P function [1]. If the P function has the properties of a classical probability density, the state is a classical mixture of coherent states. In any other case, the quantum state clearly shows quantum interference effects. In general, the P function is strongly singular and, hence, not applicable in experiments. A universal regularization resolves this problem [2], as it was demonstrated in experiments. In view of its structure [3], entanglement can also be visualized by quasiprobabilities. This requires an optimization based on the solution of the separability eigenvalue problem [4]. Its extension to the multipartite case yields multipartite entanglement witness for complex quantum states [5]. To characterize general quantum correlations, the concept of the P function was extended to a functional [6]. Its regularized version visualizes quantum correlations, even when the state is not entangled and has zero quantum discord [7].
    [1] E. C. G. Sudarshan, Phys. Rev. Lett. 10, 277 (1963); R. J. Glauber, Phys. Rev. 131, 2766 (1963).
    [2] T. Kiesel and W. Vogel, Phys. Rev A 82, 032107 (2010).
    [3] R. F. Werner, Phys. Rev. A 40, 4277 (1989).
    [4] J. Sperling and W. Vogel, Phys. Rev. A 79, 042337 (2009).
    [5] J. Sperling and W. Vogel, Phys. Rev. Lett. 111, 110503 (2013).
    [6] W. Vogel, Phys. Rev. Lett. 100, 013605 (2008).
    [7] E. Agudelo, J. Sperling, and W. Vogel, Phys. Rev. A 87, 033811 (2013).
  59. Speaker: Jerzy Warczewski
    Title: Spin glass state and other magnetic structures with their symmetries in terms of the Fibre Bundle Approach
    Authors: Jerzy Warczewski1, Paweł Gusin2 and Daniel Wojcieszyk1
    1University of Silesia, Institute of Physics, 40-007 Katowice, Poland
    2University of Wrocław, Institute of Theoretical Physics, 50-204 Wrocław, Poland
    Abstract: The fibre bundle approach [1] has been applied to the unified description of all the eight fundamental magnetic structures and their symmetry groups [2]. On this basis the explicit formulas describing both the variety of magnetic structures and their symmetry groups have been derived. In the particular case of the spin glass state (SGS) the global magnetic coupling constant has been interpreted as a section of the corresponding fibre bundle. The fibre of this bundle makes the space of the Gaussian distributions. Thus one can say that the randomness of the distribution of both the magnetization and the individual magnetic moments in the SGS is of the Gaussian-like character. An observation was made that another kind of the fibre bundle sections make the magnetization vectors M multiplied by a certain Gaussian factor defined in R3, the last factor making the problem continuous and more physical [3, 4]. In one of the previous papers the authors have proved that an internal spontaneous magnetic field Hint is necessary for the SGS to be stable and just to exist [5]. For the angle between M and Hint equal to ϕ one can say that at ϕ=const any rotation (precession) of M around the direction of Hint makes the operation of symmetry of the SGS. Thus the magnetic symmetry group of SGS turns out to be SO(2). The role of both the Hint and the external magnetic field Hext as well as of the average kinetic energy Ekin of the separate magnetic atoms in the explanation of the experimental temperature dependencies of susceptibility is shown. Thus the fibre bundle approach equates the method of the symmetry analysis of magnetic structures with the method of the higher dimensional embeddings of the modulated structures. The symmetry groups appearing in the method of the symmetry analysis become the structural groups of the bundles. From the other side a higher dimensional space needed to the description of a modulated structure makes here the total space of the bundle. Thus these three methods, namely the symmetry analysis, the higher dimensional embeddings and the fibre bundles are equivalent. The analogous situation is with the description of the magnetic structures with the use of the spin groups, where an additional type of symmetry is introduced. Note that the Gaussian factor introduced above plays a double role: it makes the vector M to be a field and simultaneously makes the description of the magnetic structures more physical [6, 7]. It seems that the fibre bundle approach could serve also for the description of the symmetry groups of all the other aperiodic structures, like e.g. the modulated nonmagnetic structures, quasicrystals (nonmagnetic and magnetic) etc. It is worthwhile to mention here that these different magnetic structures under consideration have been found by the authors to be related with the values of the certain topological invariants [8].
    [1] Sulanke, R. Wintgen, P., Differentialgeometrie und Faserbundel, Berlin (1972)
    [2] J. Warczewski, P. Gusin, D. Wojcieszyk, Mol. Cryst. Liq. Cryst. 554 (2012), 209-220
    [3] J. Warczewski, P. Gusin et al. Central European Journal of Physics 5(3) 2007 377-384
    [4] P. Gusin and J. Warczewski, Mol. Cryst. Liq. Cryst. Vol. 521: pp. 288-292, 2010
    [5] J. Warczewski, P. Gusin et al., J. Phys.: Condens. Matter, 21 (2009) pp. 035402- 035407
    [6] J. Warczewski, J. Krok-Kowalski, P. Gusin et al., J. of Non-Linear Optics, Quantum Optics, Vol. 30, (2003) pp. 301-320
    [7] J. Warczewski, J. Krok-Kowalski, P. Gusin et al., Journal of Physics and Chemistry of Solids 66 (2005) 2044-2048
    [8] P. Gusin and J. Warczewski, J. of Magn. and Magn. Mat., 2004, 28(1/2-3), 178-187
  60. Speaker: Ireneusz Weymann
    Affiliation: Mesoscopic Physics Division, Physics Faculty, Adam Mickiewicz University, Poznań, Poland
    Title: The Kondo effect in quantum dots
    Abstract: Quantum dots are promising candidates for future quantum computing devices. They are also considered as ideal model systems to study fundamental correlations and interactions between single charges and spins. We will here present the basic transport properties of quantum dots coupled to external leads, with a special focus on the strong coupling regime where the electronic correlations can give rise to the Kondo effect. The case of the spin S=1/2 Kondo effect will be analyzed for quantum dots with both nonmagnetic and ferromagnetic leads. Moreover, we will also discuss the SU(4) Kondo effect, which can occur in double quantum dots when the system possesses both spin and orbital degeneracy.
  61. Participant: Filip Wudarski
    Poster's title: Non-Markovian random unitary qubit dynamics
    Authors: D. Chruściński and F. Wudarski
    Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland
    Abstract: We compare two approaches to non-Markovian quantum evolution: one based on the concept of divisible maps and the other one based on distinguishability of quantum states. The former concept is fully characterized in terms of local generator whereas it is in general not true for the latter one. A simple example of random unitary dynamics of a qubit shows the intricate difference between those approaches. Moreover, in this case both approaches are fully characterized in terms of local decoherence rates. As a byproduct it is shown that entropy might monotonically increase even for non-Markovian qubit dynamics.
  62. Speaker: Alexandre Zagoskin
    Affiliation: Loughborough University, UK
    Title: Quantum metamaterials: concept and applications
    Abstract: Quantum metamaterials are optical media comprised of artificial quantum scatterers (e.g., qubits), in such a way that (1) these unit blocks maintain quantum coherence for times exceeding the characteristic travel time of an electromagnetic wave through the system, and (2) their quantum state can be directly controlled. For example, a periodic arrangement of qubits in a register of an adiabatic quantum computer can be considered as a quantum metamaterial.
    The simplest case of a quantum metamaterial is a one-dimensional set of superconducting qubits in a transmission line. It was shown in experiment that a single qubit in such a line demonstrates all the expected of a pointlike quantum scatterer, with a much stronger coupling to the field than can be achieved with natural atoms in 3D space. Other implementations of quantum metamaterials (like quantum dots placed inside photonic crystals, which would operate in the optical range) are also being considered.
    In my talk I will discuss some of the unusual properties of a quantum metamaterial, which stem from its being an extended quantum object, and their possible applications.
  63. Speaker: Anna Zawadzka
    Affiliation: Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland
    Title: Nonlinear optical properties of organometallic thin films
    Abstract: This work contains investigation results of the structural and nonlinear optical properties of organometallic thin films and nanostructures. The films and nanostructures were successfully grown by Physical Vapor Deposition technique in high vacuum on transparent (quartz, glass) and semiconductor (n-type silica) substrates kept at room temperature during the deposition process. Selected films were annealed after fabrication in ambient atmosphere for 24 hours at the temperature in the range from 50oC to 250oC. Spectral properties were examined using transmission, photoluminescence, Second and Third Harmonic Generation's techniques. The experimental spectra were allowed to determine optical constant of the films. Structural properties were investigated by AFM measurements. The organometallic films and nanostructures exhibit high structural quality regardless of the annealing process, but the stability of the film can be improved by using an appropriate temperature during the annealing process. We find that the optical properties were strictly connected with the morphology and the annealing process can significantly change the structural properties of the films and lead to the formation of various nanostructures.
  64. Speaker: Marek Żukowski
    Title: Generalized Hardy correlations and quantum communication problems
    Authors: Ramij Rahaman, Marcin Wie\'sniak, and Marek \.Zukowski
    Abstract: We present multi-partite Hardy-type test against local realism. For n qubit systems, we prove the uniqueness and purity of the Hardy state (that is the one that satisfies Hardy conditions), and its genuine n-partite entanglement. We show an that Hardy correlations allow one to find solutions to some quantum communication problems. As an example we present a secure quantum scheme for the original Byzantine Generals problem. Our protocol is based on Hardy's paradox, which uses a set of conditions impossible for classical systems, but satisfied by a unique quantum two-particle state, and on entanglement swapping methods.
  65. Speaker: Karol Życzkowski
    Affiliation: Jagiellonian University, Krakow & Center for Theoretical Physics, Polish Academy of Sciences, Warsaw, Poland
    Title: Measuring the degree of quantum entanglement
    Abstract: Measures of quantum entanglement are reviewed and compared. We focus quantities characterizing entanglement which could be experimentally accessible. A quantity called 'collectibility' is proposed which can be determined in a coincidence experiment involving two copies of the state analyzed. Our approach, initially designed for the case of pure states, works also in the general case of mixed quantum states of a multi-partite system.



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