Bose-Einstein Condensates

Abstrakt wykład (w języku angielskim)

Bose-Einstein condensation is a low-temperature phenomenon. However, when  bosonic particles are characterized by low effective mass, it can occur even at room temperature. This opens up the way for interesting practical applications. In this talk will present results on exciton-polariton systems and condensates and their application for computing. Polaritons are bosonic quasiparticles of mixed light and matter nature, which inherit the properties of both worlds, including the very low mass and strong interparticle interactions. This makes them ideal candidates for integrated photonic and quantum technologies.

Wykładowca: 

Michał Matuszewski (Center for Theoretical Physics, Polish Academy of Sciences)

Biogram wykładowcy

Michal Matuszewski obtained his PhD in theoretical physics in 2007 at the University of Warsaw, which was followed by a three-year postdoc at the Australian National University. In 2010 he moved to the Institute of Physics of the Polish Academy of Sciences, where he established a group focusing on the interactions between light and matter in the strong coupling regime. He is now a Professor at the Center for Theoretical Physics, Polish Academy of Science.

Abstrakt wykład (w języku angielskim)

The exploration of superfluidity has fascinated scientists for decades, spanning a wide range of systems—from solids and liquids to gases, and even light. Traditionally, the study of superfluid order has been confined to spatially homogeneous systems, where uniform conditions provide a simpler framework for understanding this extraordinary quantum state. But what happens when superfluidity arises in systems with periodic density modulations? Can the inherent localization of periodic structures coexist with the fluid-like properties of a superfluid? Could a solid, with its rigid crystalline structure, exhibit superfluid behavior? Or conversely, might a superfluid reveal a crystalline order? These questions have long intrigued the scientific community, pushing the boundaries of our understanding. Recent breakthroughs have provided compelling answers with the discovery of “supersolid” quantum states—phases that uniquely combine superfluid and crystalline properties.

This talk will delve into the experimental realization of supersolidity in magnetic quantum gases, enabled by the momentum-dependent, long-range, and anisotropic dipole-dipole interactions. Key topics include the softening of roton excitations as a precursor to the supersolid phase transition, the dynamics of symmetry breakings, and the observation of quantized vortices in rotating supersolid states. These advancements open new avenues for understanding many-body quantum physics and the interplay of order and coherence in complex quantum systems.

Wykładowca: 

Francesca Ferlaino ( Institut für Experimentalphysik, Universität Innsbruck, Austria & IQOQI- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria)

Biogram wykładowcy

Francesca Ferlaino is an experimental AMO physicist. She received her PhD at the University of Florence in 2004, and she is currently professor at the University of Innsbruck, and one of the Research Director at the Institute for Quantum Optics and Quantum Information (IQOQI, ÖAW), and in the Board of Directors of the Cluster of Excellence “Quantum Science Austria”. Her research explores few- and many-body quantum physics using ultracold atoms and molecules, interacting via long-range forces. Recently, she focused on creating quantum gases with multielectron atoms possessing large magnetic dipole moments to access novel dipolar phenomena. Ferlaino awards includes the Grand Prix de Physique „Cécile-DeWitt Morette” from the French Academy of Science, the Erwin Schrödinger Prize, the Junior BEC Award, and three ERC grants.

Abstrakt wykład (w języku angielskim)

Quantum simulation has emerged as a new and interdisciplinary research field that enables a microscopic view of quantum matter both in and out of equilibrium across different physical platforms. Recent applications of quantum simulations involving strongly correlated electronic systems using ultracold atoms in optical lattices and tweezers will be outlined. The lecture gives an introduction into quantum simulation with fermionic atoms. It also outlines how by comparing with state-of-the-art numerical methods, quantum simulations with fermionic atoms can provide highly valuable and novel insights into the understanding of strongly correlated matter. As an example, we present an analysis of the emergence of the pseudogap phase in the fermionic Hubbard model. We identify a novel universal behavior of magnetic correlations upon entering the pseudogap phase, observed in both spin-spin and higher-order spin-charge correlations. We also show a novel route for realizing p-wave superfluids using ultracold dipolar fermionic molecules.

In addition to analog methods, gate-based fermionic quantum computing offers distinct advantages in quantum computations. We demonstrate the elementary operations required to manipulate the orbital degrees of freedom, which form the basis of a fermionic quantum computer.

Wykładowca

Immanuel Bloch (Max-Planck-Institute of Quantum Optics & LMU Munich)

Biogram wykładowcy

IMMANUEL BLOCH is scientific director at the Max Planck Institute of Quantum Optics in Garching and holds a chair for experimental physics at the Ludwig Maximilians University of Munich. His scientific work is among the most frequently cited in the field of quantum physics and has helped to open a new interdisciplinary research field at the interface of atomic physics, quantum optics, quantum information science and solid state physics. For his research, he has received numerous international awards, including the Körber European Science Prize, the Harvey Prize, the Zeiss Research Award, the Stern Gerlach Medal of the German Physical Society and was named Clarivate Citation Laureate in 2022 for work on quantum simulations.

Abstrakt wykład (w języku angielskim)

Bose-Einstein condensation has been observed in several physical systems, including cold atomic gases, exciton-polaritons, and magnons. However, the most common Bose gas, photons in blackbody radiation does now show this phase transition, because the particle number is not conserved and photons at low temperatures vanish in the system walls. Here I describe experimental work with dye-filled optical microresonators where Bose-Einstein condensation of photons is observed experimentally. Thermalization is achieved in a number conserving way by repeated absorption re-emission cycles on the dye molecules, and the cavity mirrors provide both an effective photon mass and a confining potential.

More recent work with photon Bose-Einstein condensates includes the observation of a non-Hermitian phase transition between an oscillating and a bi-exponential phase of the second order coherence of the photon condensate. In other works, the compressibility of the optical quantum gas has been determined, moreover photon Bose-Einstein condensates have also been observed in semiconductor-based systems. In this lecture, I will begin with a general introduction and give an account of current work and future ideas on such photon quantum gas experiments.

Wykładowca

Martin Weitz (University of Bonn)

Biogram wykładowcy

Martin Weitz is a Professor for Experimental Physics at the University of Bonn in Germany. He studied physics and electrical engineering at the University of Kaiserslautern and the Technical University of Munich. He received his PhD from the University of Munich for work on precision spectroscopy of atomic hydrogen under supervision of Prof. T. W. Hänsch. After a postdoctoral stay at Stanford University and joining the Max Planck Institute of Quantum Optics in Garching he became Professor at the University of Tübingen in 2001. Since 2006 he is Professor at the University of Bonn. In 2012 he received an Advanced Grant of the European Research Council for research on Bose-Einstein condensation of photons in optical microcavities.

Abstrakt wykład (w języku angielskim)

Quantum gases of atoms and molecules serve to realize paradigmatic models of many-body physics, enabling us to search for novel states of matter.
In this lecture, I will focus on strongly interacting gases of fermionic atoms. These systems display pairing and superfluidity in the crossover from Bose-Einstein condensation of tightly bound molecules to the Bardeen-Cooper-Schrieffer state of long-range Cooper pairs. The thermodynamics of such resonant Fermi gases constrain the equation of state of nuclear matter. Studies of transport of spin, sound and heat have revealed low, quantum-limited damping, the property of a „perfect liquid”. Direct measurements of heat transport show second sound in the superfluid Fermi gas, the wave-like propagation of heat.

Recent experiments exploit single-atom resolved imaging of these continuum quantum gases, revealing bosonic bunching in a Bose gas, fermionic anti-bunching and the formation of fermion pairs in a 2D Fermi gas. Trapped in optical lattices, fermionic atoms realize the Hubbard model of strongly interacting electrons. For attractive interactions, one observes pairing to occur even above the superfluid transition, in the “pseudo-gap” regime of preformed pairs. Extensions of these atom-resolved studies are promising for the exploration of bosonic and fermionic quantum Hall states in rotating gases, as well as molecular gases with long-range dipolar interactions.

Wykładowca

Martin Zwierlein (MIT)

Biogram wykładowcy

Martin Zwierlein is Thomas A. Frank Professor of Physics at MIT. He studied physics in Bonn and at the ENS Paris. His PhD at MIT focused on the observation of superfluidity in ultracold Fermi gases, a novel form of quantum matter. After a postdoc in Mainz he joined the MIT faculty in 2007. Zwierlein studies quantum gases of atoms and molecules as model matter for superconductors, quantum magnets and topological materials. His awards include the I.I. Rabi Prize from the APS, the Vannevar Bush Faculty Fellowship, and the Humboldt Research Prize.

Abstrakt wykład (w języku angielskim)

Ultracold polar molecules are an exciting new platform for quantum science and technology. The combination of rich internal structure of vibration and rotation, controllable long-range dipole-dipole interactions and strong coupling to applied electric and microwave fields has inspired many applications. These include quantum simulation of strongly interacting many-body systems, the study of quantum magnetism, quantum metrology and molecular clocks, quantum computation, precision tests of fundamental physics and the exploration of ultracold chemistry. Many of these applications require full quantum control of both the internal and motional degrees of freedom of the molecule – a major challenge owing to the additional complexity of molecules. However, the recent reports of Fermi degenerate gases and Bose-Einstein condensates of diatomic molecules demonstrate that this control is now within reach.

In this talk, I will outline the new opportunities offered by molecules and describe the techniques developed over the last decade to bring the molecules under full experimental control, using our work on ultracold RbCs molecules to illustrate the key advances. In so doing I will demonstrate that two atoms are indeed better than one.

Wykładowca 

Simon L. Cornish (Department of Physics, Durham University, UK)

Biogram wykładowcy

Simon L. Cornish is a Professor in the Department of Physics at Durham University working in the Quantum Light and Matter research group. He was educated at Oxford University where he received his PhD in experimental atomic physics in 1998. He developed an interest in ultracold gases at the University of Colorado, where he undertook pioneering experiments on Bose-Einstein condensation with tunable interactions. His current research focusses on the study of ultracold polar molecules formed by associating pairs of ultracold atoms, inspired by the prospect of using molecules as a platform for quantum simulation and quantum computation.  He leads a national research program in the UK focused on the study of quantum science with ultracold molecules and was awarded the 2019 Institute of Physics Joseph Thomson medal and prize for outstanding contributions to experiments on ultracold atoms and molecules.

Abstrakt wykład (w języku angielskim)

Strong coupling of the photons with semiconductors’ excitons in the high-quality optical cavities can create new quasiparticles called exciton-polaritons and many exotic phenomena, such as Bose-Einstein Condensates and superfluidity. Traditionally exciton-polariton experiments were mainly performed in quantum-well microcavities grown with molecular beam epitaxy (MBE), where liquid helium temperatures must be maintained to prevent exciton autoionization. 

Recently, semiconducting lead halide perovskites with a composition of ABX3 (where A is commonly CH3NH3+ (MA+) or Cs+; B is Pb2+; X is Cl−, and Br−) have emerged as contenders to MBE-grown quantum-well microcavities like GaAs for polaritonic but at room temperature, due to their large exciton binding energy, high photoluminescence (PL) quantum yield, tunable bandgap and high room-temperature nonlinear interaction strength.

In this talk, will first highlight recent researchers’ efforts with emergent excitonic materials on room-temperature polaritonic. Then, I will introduce our approaches to obtain various large halide perovskite single crystals inside optical nanocavities. Due to the uniform confined environment, the solution growth approach shows uniformity, comparable to the MBE-grown GaAs quantum well, enabling submillimeter-large single crystals with superb excitonic quality. These crystals with Wannier-Mott excitons allowed us to demonstrate a polaritonic XY spin Hamiltonian with arrary of Bose-Einstein Condensates at room temperature successfully. Further, we will also our recent two works using halide perovskite on topological valley Hall polariton condensation and polariton superfluidity, critical steps towards the ultimate goal of realizing a room-temperature polaritonic platform on par with other systems at low temperatures.

Wykładowca 

Wei Bao (Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA)

Biogram wykładowcy

Wei Bao is an assistant professor in the Department of Materials Science and Engineering at the Rensselaer Polytechnic Institute, where his lab focuses on optical physics and nanophotonic. Prior to this, he was an assistant professor at the University of Nebraska-Lincoln and a postdoc at the University of California, Berkeley. He received his B.S. in physics (minor in chemistry) at Peking University and his Ph.D. in materials science and engineering at the University of California, Berkeley. He received the US Army Research Office Early Career Program Award in 2024, the US National Science Foundation CAREER Award in 2022, and the Light Science & Application Rising Star of Light in 2022.

Abstrakt wykład (w języku angielskim)

Photons confined in optical cavities or propagating in paraxial geometries acquire an effective mass and behave like matter particles. Moreover, an effective photon-photon interaction can be engineered when the photons propagate in a nonlinear medium, resulting in collective fluid-like behaviors of light, such as superfluidity [1].

The characterization of the elementary excitations in such quantum fluids of light is essential to study their collective effects. 

In this lecture, I will present a novel coherent probe spectroscopy technique allowing to measure the Bogoliubov dispersion of the collective excitations [2] and I will show how the properties of quantum fluids of light can be used to study driven-dissipative phase transitions and to simulate astrophysical objects like Black Holes.

In the last part of the talk, I will introduce a new kind quantum fluid of light, obtained on a nonlinear hot Rb vapor, in paraxial geometry and briefly discuss our recent results on such a system. 

[1] I. Carusotto and C. Ciuti, Quantum Fluids of Light, Rev. Mod. Phys. 85, 299 (2013)
[2] F. Claude, M. Jacquet, R. Usciati, I. Carusotto, E. Giacobino, A. Bramati, Q. Glorieux, Phys. Rev. Lett. 129, 103601 (2022)

Wykładowca 

Alberto Bramati (Laboratoire Kastler Brossel, Sorbonne Université, CNRS, Ecole Normale Supérieure PSL, Collège de France)

Biogram wykładowcy

Alberto Bramati received his PhD in physics in 1998 at the Laboratoire Kastler Brossel of the Sorbonne University and Ecole Normale Supérieure, on the generation of squeezed states of light. His main research topics are in the framework of Quantum Optics, Quantum Information and Nano-Photonics. In the last years he focussed on the study of polariton systems and semiconductor nanocrystals obtaining several pioneering results: among them are the first demonstration of polariton superfluidity, hydrodynamic dark solitons and polarized single photon sources. He has co-authored more than 130 papers in international journals and gave several invited talks in international conferences and various tutorials in international schools.

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Tak.

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Wykłady odbywają się w środy (pierwszy 5 marca 2025, a ostatni 23 kwietnia 2025 roku) o godz. 14:15 (czasu warszawskiego).

Nagrania z wykładów zostaną opublikowane po zakończeniu serii wykładów w serwisie YouTube.. Planujemy opublikować je w czerwcu 2025 roku.