Optics Seminar
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2021-03-18 (Thursday)
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Nicolas Fabre (Centrum Nowych Technologii UW)Quantum information in time-frequency continuous variables of single photon
This talk tackles the time-frequency continuous variables degree of freedom encoding of single photons andtheir application in quantum information. In the first part of the talk, we examine the formal mathematicalanalogy between the quadrature continuous variables of the electromagnetic field and the time-frequencyvariables of a single photon. This analogy inspires to define a new qubit, a time-frequency grid state, whichis robust against time-frequency displacement errors, which can be implemented with an optical integratedwaveguide. In a second part of the talk, we explore how to simulate the statistics of quantum particles bytuning the initial entanglement of a photon pair.
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2021-03-11 (Thursday)
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Prof. Tobias Schaetz (Albert Ludwigs University Freiburg)The Onset of Sympathetic Cooling and the control of quantum effects
Isolating ions and atoms from the environment is essential for experiments, especially if we aim to study quantumeffects. For decades, this has been achieved by trapping ions with radiofrequency (rf) fields and neutral particles withoptical fields. We are trapping ions by the interaction with light and electrostatic fields, in absence of any rf-fields. Wetake our results as starting point for studying how to combine the advantages of optical trapping and ions.In the first part of the talk, we will focus on the basics of optically trapping ions. In the second talk we aim todemonstrate the prospects of our approach in the context of interaction and reaction at ultralow temperatures as ashowcase. Following the seminal work in other groups in hybrid traps, we embed optically trapped ions into quantumgases to reach lowest temperatures, circumventing the currently inevitable excess kinetic energy in hybrid traps, whereions are kept but also driven by rf-fields. It might permit to enter the temperature regime where quantum effects arepredicted to dominate.
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2021-03-04 (Thursday)
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dr Piotr Hańczyc (IFD UW)Laser spectroscopy methods for detection of aggregated proteins and peptides doped with fluorescent markers
There is currently no definitive test for early detection of neurodegeneration which is linked withprotein aggregation. Finding methods capable of detecting the intermediate states of proteinaggregates, named oligomers, is critical for the early-stage diagnosis of over 30 neurodegenerativediseases including Alzheimer’s or Parkinson’s.Improved understanding of amyloid structures and functions is crucial for the diagnosis andtreatment of these diseases. Fluorescence-based spectroscopy provides indispensable tools inamyloid research.Currently, fluorescence-based imaging using intrinsic protein chromophores or organic dyes isthe gold standard for detecting protein aggregation. It is used to detect aggregation in vitro and invarious tissues including the cerebrospinal fluid (CSF), whereby the disease-related proteinrecombinant is seeded with the patient’s fluid. The major drawback is the lack of technology thatwould be sensitive to the oligomeric forms of protein aggregates.It is possible to overcome this limitation by amplifying the signal in organic dyes in theprocess of stimulated emission. By monitoring the amplified spontaneous emission (ASE) it ispossible to achieve better recognition sensitivity to pre-fibrillar amyloid oligomeric forms than instandard fluorescence test.ASE can detect and differentiate amyloid oligomers and by that means it could be possible toevaluate the risk levels of neurodegenerative diseases to potential patients before the clinicalsymptoms occur.
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2021-01-28 (Thursday)
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mgr Filip Sośnicki (IFD UW)Electro-optic shaping of single photon pulses
One of the most important tasks in the field of quantum optics is the ability to fully control singlephotons, meaning controlling them in all degrees of freedom (DoF). While many experimentsdemonstrated control of single photons in polarization or transverse-spatial mode, one still requiresmethods for unitary, phase-only manipulation in the time-frequency DoF. In my presentation, I willshow a method for shaping single photons in time and spectrum by employing electro-optic phasemodulation combined with dispersive propagation. I will show our recent results on tuning singlephoton’scenter wavelength and bandwidth. Especially I will focus on using photonically generatedRF signals achieving very high stability of the modulation in the course of 24h. I will show alsoemploying complex phase modulation patterns for spectrally compressing single photons by morethan 2 orders of magnitude down to hundreds of MHz of spectral width.
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2021-01-21 (Thursday)
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mgr Mateusz Narożnik (UMK Toruń)Ultra-stable cavity system as a potential gravitational wave detector
The existing gravitational wave observatories, i.e. LIGO, Virgo and KAGRA, are sensitive togravitational signal in the range from over a dozen Hz to roughly 2 kHz and cannot observe anysignificant signal below several Hz. In LIGO-like ground-based detectors the low frequency regionis fundamentally limited by seismic noises. During my presentation I will present the idea of usingexisting and future planned high-quality-factor cavities to cover lacking range of gravitational wavefrequency. The table-top ultra-stable cavities system will fill lacking range from several mHz tosingle Hz. In that range optical cavity is the most sensitive and because of its construction andisolation from ground it’s not so susceptible to seismic noises as LIGO-like detectors. Moreover, Iwill present new limit on relic gravitational-wave background in the millihertz range using existingdata from two ultra-stable cavities comparison
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2021-01-14 (Thursday)
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dr Jacek Szczepkowski (IF PAN)Electronic structure of polar dimers - spectroscopic research
Over the last decade a significant increase of interest in polar molecules having a permanentelectric/magnetic dipole moment can be observed from researchers interested in ultracold matterphysics. The long-range nature of dipole interactions and the possibility to control them usingexternal electric or magnetic fields can be used to control chemical reactions in ultracold gas, toprocess quantum information, to study fundamental properties of matter. In order to carry out thatkind of research it is necessary to product a trapped ultracold (~uK/nK) or quantitativelydegenerated gas of polar molecules in the ground rovibrational state. It is usually realised byassociating the molecules from the trapped ultracold atomic gas or by using a method of direct lasercooling of hot molecules. Such methods of production of ultra-cold molecules, as well as furthertransfer to the desired energy state, require a very precise knowledge of their energy structure. Thisknowledge includes information on the energy of certain rovibrational levels of particular states,transition probabilities, i.e. Franck-Condon factors, and transition dipole moments. Thepresentation will discuss the results of spectroscopic studies of the electronic structure of selectedpolar molecules.
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2021-01-07 (Thursday)
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mgr Marcin Kalinowski (Harvard University)Quantum Computing with Rydberg Atoms
An array of highly-excited (Rydberg) atoms is an emerging platform for quantum many-bodysimulation and computation. In the talk, I will introduce this modern approach and review its recentsuccesses: e.g. discovery of many-body quantum scars, generation of large entangled states, andimplementation of efficient quantum gates. I believe the topic should be interesting for a broadaudience interested in condensed matter, quantum information, or AMO.
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2020-12-17 (Thursday)
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Dr. Alexandre Dauphin (ICFO – The Institute of Photonic Sciences, Barcelona)Self-trapped polarons and topological defects in a topological Mott insulator
In the last decades, topological insulators have attracted great interest and also have promising applicationsin topics such as metrology or quantum computation. These exotic materials go beyond the standardclassification of phases of matter: they are insulating in their bulk, conducting on their edges, andcharacterized by a global topological invariant, in contrast to a local order parameter as in the conventionalGinzburg-Landau theory of phases of matter. Such topological phases have been experimentally observed incondensed matter systems and more recently in quantum simulators. The latter are very versatile platformsthat allow one to simulate a material with another quantum system in a very controllable environment. In thecase of topological insulators, this degree of control is particularly promising to unveil the mechanismsleading to these phases. The quantum simulation of these exotic materials typically relies on the generationof artificial gauge fields. However, recent studies have shown that topological phases can also emerge fromparticle interactions. The latter mechanism leads to the concept of interaction-induced topological phases, inwhich topology is acquired through a spontaneous symmetry breaking process. The interplay of thespontaneous symmetry breaking with the global topological properties can lead to very interesting effects.In this talk, I will discuss how such interplay can lead to new strongly-correlated topological effects ina 2D material. In particular, I will show how interactions can localize particles in the insulating bulk atincommensurate fillings, leading to self-trapped polarons. Furthermore at higher filling, the interactingnature of the topological insulator gives rise to domains in the bulk. Interestingly, the nontrivial topologyassociated to each domain leads to the appearance of protected conducting states in the bulk, localized at thedomain boundaries. Finally, I will discuss the possibility of quantum simulating such phases with cold laserexcitedRydberg atoms in an optical lattice.
seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2020-12-10 (Thursday)
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mgr Anna Dawid - Łękowska (IFT UW)Two interacting ultracold molecules in a trap: magnetic properties and quench dynamics
Ultracold polar molecules possess a significantly richer internal structure than atoms and offerstrong dipolar interactions due to their permanent electric dipole moment. These two qualities makethem a highly promising platform for quantum simulations. Numerous applications of ultracoldmolecules have been introduced, but particular interest can be noticed in the field of quantummagnetism. Their rotational states (in which pseudo-spins can be encoded) combined with dipolarinteraction and the possibility of control with microwave fields inspired many proposals realizingvarious quantum magnetism models with polar molecules in optical lattices. We follow anotherapproach, focusing on the bound states of two ultracold polar and paramagnetic molecules in aharmonic trap. We show that various magnetization states arise from the interplay of the molecularinteractions, electronic spins, dipole moments, rotational structures, external fields, and spinrotationcoupling. The rich magnetization diagrams depend primarily on the anisotropy of theintermolecular interaction and the spin-rotation coupling. These specific molecular properties arechallenging to calculate or measure. Therefore, we propose the quench dynamics experiments forextracting them from observing the time evolution of the analyzed system. Results provide newinsight into the rich magnetic properties of ultracold molecules and indicate the possibility tocontrol the molecular few-body magnetization with the external electric field. The chosensimplified system is also the first step towards research on the controlled magnetization of manybodymolecular systems in optical tweezers or optical lattices and their application in quantumsimulation of molecular multichannel many-body Hamiltonians and quantum information storing.Instrukcja obsługi połączenia internetowego znajduje się na stronie:https://support.zoom.us/hc/en-us/articles/201362193-Joining-a-Meetinglub w
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)
2020-12-03 (Thursday)
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Stefan Willitsch (Department of Chemistry, University of Basel)Quantum-Non-Demolition State Detection of Single Molecules for Precise Molecular Spectroscopy
Inspired by methods established within the realms of quantum optics and atomic-ion quantumtechnologies, we demonstrate a quantum-non-demolition technique for the non-destructivedetection of the internal quantum state of a single trapped molecular ion. The method is based onthe state-dependent coherent excitation of the motion of the trapped molecular ion and subsequentdetection of the motional quantum state using a co-trapped atomic ion. This new approach offersnew perspectives not only for the detection, but also for the preparation and the manipulation ofmolecular quantum states on the single-particle level with a greatly improved sensitivity comparedto previously used destructive schemes. We present a characterization of our technique using thehomonuclear diatomic species N2+ as an example, show how it can be used for non-invasivespectroscopic measurements on single molecules and discuss prospective applications in the realmof precision molecular spectroscopy.
Seminarium z użyciem połączenia internetowegohttps://zoom.us/j/97696726563(meeting ID: ID 97696726563, password: 314297)