Optics Seminar
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2022-03-24 (Thursday)
join us at 10:15 
dr Piotr Kolenderski (Wydział Fizyki UMK Toru)Optical satellite links
Seminarium z użyciem łącza internetowegohttps://zoom.us/j/97696726563(meeting ID: 97696726563, password: 314297)
2022-03-17 (Thursday)
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dr Tomasz Stefaniuk (Instytut Geofizyki WF UW)Nanostructured optical components: new opportunities and functionalities
The concept of nanostructuring is based on the idea that the introduction of subwavelength elementscan significantly alter the macroscopic optical properties of the system. During the presentation, Iwill discuss how the nanostructured materials which exhibit epsilon-near-zero property or nonlocaleffects can be efficiently used to control dispersion [1], electron temporal dynamics [2], lightmodulation or nonlinear effects [3].[1] T. Stefaniuk, L. H. Nicholls, R. M. Córdova-Castro, M. E. Nasir, A. V. Zayats, Nonlocality-Enabled Pulse Management in Epsilon-Near-Zero Metamaterials. Adv. Mater. 2107023, (2022).[2] L.H., Nicholls, T. Stefaniuk, M.E. Nasir, F.J. Rodríguez-Fortuño, G.A. Wurtz, A.V Zayats,Designer photonic dynamics by using non-uniform electron temperature distribution for on-demandall-optical switching Times, Nat. Comm., 10 (1), art. no. 2967, (2019).[3] T. Stefaniuk, N. Olivier, A. Belardini, C. P. T. McPolin, C. Sibilia, A. A. Wronkowska, A.Wronkowski, T. Szoplik, A. V. Zayats, Self-Assembled Silver–Germanium NanolayerMetamaterial with the Enhanced Nonlinear Response, Adv. Opt. Mater., 5, 22, (2017).
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: 97696726563, password: 314297)
2022-03-10 (Thursday)
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dr hab. Michał Tomza (IFT UW)Accurate ab initio molecular calculations for ultracold scattering experiments
I will present how molecular electronic structure and quantum scattering calculationscan support and explain ultracold quantum physics experiments. Quantum-chemicalcalculations of potential energy curves, permanent and transition electric dipolemoments, fine and hyperfine coupling constants provide parameters for effectiveHamiltonians describing nuclear dynamics. Multichannel quantum scatteringcalculations give scattering lengths, elastic, inelastic, and reactive rate constants. Iwill discuss the capabilities and limits of state-of-the-art methods applied to neutraland ionic systems based on alkali-metal and alkaline-earth-metal atoms, and presentour recent results for ongoing experimental efforts
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: 97696726563, password: 314297)
2022-03-03 (Thursday)
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dr hab. Jan Masajada (Wydział Podstawowych Problemów Techniki Politechniki Wrocławskiej)Optical vortices in microscopy
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563 (meeting ID: 97696726563, password: 314297)
In this presentation the question of optical vortices (OVs) application in vortex microscopy isdiscussed, starting from a short historical background. Next the Optical Vortex ScanningMicroscope (OVSM) developed by Singular Optics Group (SOG) is presented. All microscopicsystems based on OVs are still under development with no guarantee of final success. Thus, thepresentation is a short report on an ongoing project, but not a final solution.The OVSM is based on the Mach-Zender interferometer with carrier frequency. The conventionalGaussian beam (from He-Ne laser) passes through the spiral phase plate and is focused on thesample plane, where it interacts with the investigated object. The sample plane is magnified andimaged to the CCD camera. The interferometer’s reference arm enables detection of the interferencefringes, from which the internal structure of the object beam can be recovered.The crucial steps in the OVSM development are presented. The new scanning technique namedinternal scanning method (ISM) is also discussed. The ISM enables scanning the sample just byvortex point, while the whole focused beam stays in place. The method is sensitive and resistant tomechanical vibration. The first images taken with resolution exceeding the classical diffraction limitare shown. At this stage the simple phase structures can be imaged. The possible directions of theOVSM development are discussed in brief.
2022-01-27 (Thursday)
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Dr. Goulven Quéméner (Laboratoire Aimé Cotton, CNRS, Université Paris-Saclay, Orsay, Francja)Ultracold molecules: Control with fields and applications
Ultracold dipolar molecules are excellent candidates for engineering quantum applications andcontrolled chemistry [1]. Therefore a lot of effort is devoted nowadays to produce ground stateultracold molecules in high densities as well as to understand their properties and ways of control[2]. The tools of control available in experiments are for example electric, magnetic andelectromagnetic fields. In this talk, I will present recent theoretical and experimental results usingthese tools of control for different applications such as shielding molecules against destructivecollisions and evaporative cooling [3], chemical reactions of ultracold molecules [4] and proposalsfor new states of matter [5].[1] L. Carr, D. DeMille, R. V. Krems, J. Ye, New J. Phys. 11, 055049 (2009); J. L. Bohn, A.-M.Rey, J. Ye, Science 357, 1002 (2017)[2] G. Quéméner, P. Julienne, Chem. Rev. 112, 4949 (2012)[3] K. Matsuda, L. De Marco, J.-R. Li, W. G. Tobias, G. Valtolina, G. Quéméner, J. Ye, Science370, 1324 (2020); J.-R. Li, W. G. Tobias, K. Matsuda, C. Miller, G. Valtolina, L. De Marco, R. R.W. Wang, L. Lassablière, G. Quéméner, J. L. Bohn, J. Ye, Nat. Phys. 17, 1144 (2021)[4] M.-G. Hu, Y. Liu, M. A. Nichols, L. Zhu, G. Quéméner, O. Dulieu, K.-K. Ni, Nat. Chem. 13,435 (2021); G. Quéméner, M.-G. Hu, Y. Liu, M. A. Nichols, L. Zhu, K.-K. Ni, Phys. Rev. A 104,052817 (2021)[5] M. Schmidt, L. Lassablière, G. Quéméner, T. Langen, arXiv:2111.06187
Seminarium użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2022-01-20 (Thursday)
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prof. Bolesław Kozankiewicz (Instytut Fizyki PAN)Spectroscopy of single organic dye molecules in electric field
Narrow, zero-phonon lines of single fluorescent molecules embedded in crystalline organic matrices at cryogenic temperatures provide a sensitive nanoprobe of electric fields and charges. Broad tunability of the molecular transitions will be demonstrated for dibenzoterrylene molecules in anthracene and in 2,3-dibromonaphthalene crystals, where a quadratic and a linear Stark shifts have been respectively observed. Recently, it has been demonstrated that the spectral tuning can be also induced optically. The presented systems show promise for photonic quantum technologies.
2022-01-13 (Thursday)
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Anna Dawid-Łękowska (IFT UW)Unsupervised machine learning of topological phase transitions from experimental data
Identifying phase transitions is one of the key challenges in quantum many-body physics. Recently, machine learning methods have been shown to be an alternative way of localising phase boundaries also from noisy and imperfect data and without the knowledge of the order parameter. Here we apply various unsupervised machine learning techniques including anomaly detection and influence functions to experimental data from ultracold atoms. In this way we obtain the topological phase diagram of the Haldane model in a completely unbiased fashion. We show that the methods can successfully be applied to experimental data at finite temperature and to data of Floquet systems, when postprocessing the data to a single micromotion phase. Our work provides a benchmark for unsupervised detection of new exotic phases in complex many-body systems.
Seminarium z użyciem połączenia internetowego https://zoom.us/j/97696726563 (meeting ID: ID 97696726563, password: 314297)
2021-12-16 (Thursday)
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prof. Michał Matuszewski (Instytut Fizyki PAN)Efficient optical computing with exciton-polaritons
Recent years have witnessed remarkable developments in big data, artificial intelligence and neural networks. Machine learning has found wide applications in both research and the industry. This comes at the cost of high levels of energy consumption that are necessary to process large amounts of data. It is expected that over 20% of global electricity use by 2030 will be used for information processing. The performance of complementary metal-oxide semiconductors (CMOS) no longer follows Moore's law [1]. In result, much research has been aimed at finding an alternative platform for information processing, characterized by high performance and energy efficiency. In this talk I will review recent progress in machine learning with photons [2,3]. Photonic information processing benefits from high speed, parallelization, low communication losses, and high bandwidth. Fully functional photonic neurons, including spiking neurons, as well as neural networks, have been already realized in laboratories. Several networks achieved high performance in challenging machine learning tasks, such as image and video recognition. We recently demonstrated hardware neural network systems where strong optical nonlinearity results solely from interactions of exciton-polaritons, quantum superpositions of light and matter [4,5,6]. Such superpositions, in the form of mixed quasiparticles of photons and excitons, are characterized by excellent photon-mediated transport properties and strong exciton-mediated interactions. These semiconductor microcavity systems can be used to construct fully all-optical neural networks characterized by extremely high energy efficiency [7]. We show why using polaritonics in place of standard nonlinear optical phenomena, is the key to achieving such a performance. [1] M. M. Waldrop, Nature News 530, 144 (2016) [2] G. Wetzstein, A. Ozcan, S. Gigan, S. Fan, D. Englund, M. Soljacic, C. Denz, D. A. Miller, and D. Psaltis, Nature 588 , 39 (2020) [3] B. J. Shastri, A. N. Tait, T. F. de Lima, W. H. Pernice, H. Bhaskaran, C. D. Wright, and P. R. Prucnal, Nature Photonics 15, 102 (2021) [4] A. Opala, S. Ghosh, T. C. Liew, and M. Matuszewski, Physical Review Applied 11 , 064029 (2019) [5] D. Ballarini, A. Gianfrate, R. Panico, A. Opala, S. Ghosh, L. Dominici, V. Ardizzone, M. De Giorgi, G. Lerario, G. Gigli, Timothy C. H. Liew, Michal Matuszewski, and Daniele Sanvitto, Nano Letters 20, 3506 (2020) [6] R. Mirek, A. Opala, P. Comaron, M. Furman, M. Król, K. Tyszka, B. Seredynski, D. Ballarini, D. Sanvitto, Timothy C. H. Liew, Wojciech Pacuski, Jan Suffczyński, Jacek Szczytko, Michał Matuszewski, and Barbara Piętka, Nano Letters (2021) [7] M. Matuszewski, A. Opala, R. Mirek, M. Furman, M. Król, K. Tyszka, T.C.H. Liew, D. Ballarini, D. Sanvitto, J. Szczytko, B. Piętka, arXiv:2108.12648
Seminarium z użyciem połączenia internetowego https://zoom.us/j/97696726563 (meeting ID: ID 97696726563, password: 314297)
2021-12-09 (Thursday)
join us at 10:15
Hue Thi Nguyen (Instytut Geofizyki WF)Optical properties and development of flat-surface nano-structured gradient index micro-optical vortex phase components
An optical vortex (OV) refers to an optical donut-like beam which exhibits phase singularity surrounded by a helicoidal spatial wave-front and, associated with it, orbital angular momentum. Due to such unique properties OVs have been extensively exploited in the context of their fundamental properties as well as practical applications, particularly, optical tweezing, super-resolution imaging, quantum entanglements, and nano-structured surface machining. These promising applications require efficient approaches to generate reliable, high-quality optical vortices. In addition, from practical points of view, it is desirable to minimize the sizes of generated vortex beams as well as optimize vortex generators. The presentation focuses on flat-surface nano-structured gradient index micro-optical vortex phase mask (nVPM) components and their developments based on nanostructurization technique and effective medium theory. The mask was fabricated utilizing a cost-effective modified stack-and-draw technique. In the first part, I will introduce the concept, design and fabrication of the nanostructured vortex phase masks. Verification of its optical performance in air, water, and ethanol will be also analyzed both numerically and experimentally. Moreover, numerical studies also show that the problem of the undesirable light waveguide effect inside the gradient phase components, which accounts to the non-uniformity of the beam intensity profile, can be mitigated. In addition, possibilities to use nanostructured phase masks to generate vortices with high topological charge will be analyzed. In the next part, I will present the design and fabrication of the fiber-based vortex converter microprobe based on the aforementioned nVPM. The probe comprises a single-mode fiber, coreless fiber spacer, and nGRIN VPM integrated manually using active alignment technique. Both experimental and theoretical verifications will be discussed in this section. The results confirm that the probe efficiently converts fiber guided fundamental ode into an optical OV beam with single topological charge. The research results also confirm that the proposed nanostructurization method for the fabrication of a flat parallel surface nanostructured gradient index element is compatible with the optical fiber technique.
Seminarium z użyciem połączenia internetowego https://zoom.us/j/97696726563 (meeting ID: ID 97696726563, password: 314297)
2021-12-02 (Thursday)
room B2.38, Pasteura 5 at 10:00
(IFD UW)