Name: OpenQMBP2023: New perspectives in the out-of-equilibrium dynamics of open many-body quantum systems
Start: 2023-06-12T09:00:00+02:00
End: 2023-06-30T17:00:00+02:00
Location: Institut Pascal

lundi 12 juin 2023
11:00 Assembling and probing strongly correlated fluids of light - Andrei Vrajitoarea (University of Chicago)
Assembling and probing strongly correlated fluids of light
- Andrei Vrajitoarea (University of Chicago)
11:00 - 11:40
Learning how to create and manipulate highly-entangled many-body systems is a central challenge of modern quantum science, with promising applications from quantum computation to many-body physics and quantum-enhanced metrology. Analog quantum simulators provide a rich playground for exploring the emergent collective phenomena in synthetic quantum systems, and how to harness these many-body effects for future quantum technologies. In this talk, I will describe various approaches for assembling quantum matter from strongly interacting microwave photons. Our quantum circuit platform consists of an array of capacitively coupled transmon qubits acting as a Hubbard lattice for photons. I will highlight a novel approach to constructing low-entropy quantum fluids of light by employing particle-resolved assembly combined with adiabatic control of lattice disorder. Studying these fluids with site-resolved microscopy of entanglement and two-body correlations reveals how the photons delocalize and avoid one another, behaving as noninteracting fermions. The precise time- and space-resolved control of the lattice potential landscape presents another unique capability in our platform for investigating out-of-equilibrium quantum dynamics. Using controlled perturbations in the lattice potential, we can spectroscopically probe quasiparticle excitations, prepare superpositions of many-body eigenstates and observe the propagation of sound modes of light in the lattice. Towards developing practical tools for quantum computers, I will show how we can leverage many-body dynamics in these fluids for preparing highly-entangled states useful for quantum information processing and metrology.
11:50 Novel Non-equilibrium Phenomena in Quantum Fluids of Light - Marzena Szymanska (University College London)
Novel Non-equilibrium Phenomena in Quantum Fluids of Light
- Marzena Szymanska (University College London)
11:50 - 12:30
15:00 An open quantum safari: Criticality, Computing, and Chaos - Fabrizio Minganti (EPFL)
An open quantum safari: Criticality, Computing, and Chaos
- Fabrizio Minganti (EPFL)
15:00 - 16:30
mardi 13 juin 2023
10:00
10:00 - 16:10
Contributions

10:00 Negative tripartite information after quantum quenches in integrable systems - Vincenzo ALBA (University of Pisa)

10:25 Inelastic Cooper pair tunneling in the strongly interacting regime - Jérôme ESTEVE (Laboratoire de Physique des Solides)

11:00 Neural-Network Quantum States for Entanglement Phase Transitions - Filippo Vicentini (Ecole Polytechnique)

11:25 Adiabatic atom losses in nearly integrable quantum gases - Jérôme Dubail (CNRS)

11:50 Phase transitions in finite-component systems: Superradiance beyond the Dicke paradigm - Alexandre LE BOITE (Laboratoire MPQ, CNRS, Université de Paris Cité)

14:00 Comparing bipartite entropy growth in open-system matrix product simulation methods - Johannes SCHACHENMAYER (CESQ/ISIS, CNRS & University of Strasbourg)

14:25 Effect of slow losses in quantum gases with short range interactions: UV divergence in higher dimensions and breakdown of Tan's relation in 1D gases - Isabelle Bouchoule

15:00 Quantum-Darwinism-encoding transitions - Xiangyu CAO (CNRS/LPENS)

15:25 Continuous superradiance sustained by a stream of excited atoms - Martin ROBERT DE SAINT VINCENT (Laboratoire de Physique des Lasers, CNRS, USPN)

15:50 Sensing dynamical phase transitions - Katarzyna Macieszczak (University of Warwick)
mercredi 14 juin 2023
10:30 Presentation of Institut Pascal - Yves BALKANSKI (Institut Pascal - UPSaclay)
Presentation of Institut Pascal
- Yves BALKANSKI (Institut Pascal - UPSaclay)
10:30 - 11:00
11:00 Gaussian quantum trajectories for open and closed systems - Michiel Wouters
Gaussian quantum trajectories for open and closed systems
- Michiel Wouters
11:00 - 11:40
I will discuss the use of Gaussian states for the modeling of open quantum systems within the quantum trajectory framework, with applications to bosonic systems and spin systems: the to two-photon driven cavities and the dissipative XYZ model. Thanks to the dissipation, the quantum fluctuations typically remain small at all times, therefore improving the validity of the Gaussian states as compared to their use for the dynamics of closed systems. It is therefore suggested to introduce some fictitious dissipation to closed systems in order to improve their simulability.
15:15 Laser-driven superradiant ensembles - Igor Ferrier-Barbut (CNRS, Institut d'Optique Graduate School, Université Paris Saclay)
Laser-driven superradiant ensembles
- Igor Ferrier-Barbut (CNRS, Institut d'Optique Graduate School, Université Paris Saclay)
15:15 - 15:55
I will present our recent studies on superradiance in dense clouds of ultracold atoms, that are indistinguishably coupled to a mode of the electromagnetic field, akin to cavity or waveguide QED systems, but here in free space. We are in particular interested in the case where the atomic ensemble is continuously driven by a resonant laser that leads to a competition between laser driving and collective spontaneous emission. We observed that this competition induces a transition to a steady-state superradiant phase. Beyond measuring the field intensity, we measure photon-photon correlations. This precious tool of quantum optics allows us to question wether atomic correlations can impart non-trivial photonic correlations. I will show that indeed photonic correlations emerge, and despite the system’s simplicity, their description poses a challenge to many-body theories.
16:00

16:00 - 19:00
jeudi 15 juin 2023
11:00 Search as (quantum) selforganized process - Giovanna Morigi (University of Saarland)
Search as (quantum) selforganized process
- Giovanna Morigi (University of Saarland)
11:00 - 11:40
Efficient retrieval of information is a core operation in the world wide web, it is essential for the sustainance fof living organism. Search dynamics, moreover, is a paradigm for optimization algorithms: Searches permeate our everyday life. Inspired by the food search dynamics of a living organism, the Physarum polycephalum, we analyse the role of noise in finding the optimal path on a graph with multiple constraints and where the weight of the edges connecting the nodes is a dynamical variable. The network dynamics results from the interplay between a nonlinear function of the flow, dissipation, and Gaussian, additive noise. At a finite value the noise amplitude, the network selforganizes in the most robust topology with a resonant-like behavior. This specific topology maximizes the transport efficiency, it is reached with the maximal convergence rate, and it is not found by the noiseless dynamics. We argue that this dynamics is a manifestation of noise-induced resonances in network self-organization. Drawing from this knowledge, we then discuss the perspectives of designing quantum search algorithms that are assisted by stochastic dnamics.
11:50 Density wave ordering in a unitary gas with photon-mediated interactions - Jean-Philippe Brantut (EPFL)
Density wave ordering in a unitary gas with photon-mediated interactions
- Jean-Philippe Brantut (EPFL)
11:50 - 12:30
I will present the realization of a quantum degenerate Fermi gas interacting simultaneously via unitary-limited contact interaction and long-range, photon mediated interaction induced by an optical cavity. We observe the onset of density-wave order above a critical strength of the photon-mediated interaction, and characterize the phase diagram as a function of both interactions type. This system is very promising for the investigation of the interplay of charge-density wave order with superfluidity with a fully controlled microscopic Hamiltonian. I will then present briefly the perspectives open in the mid-term for the realization of the SYK interactions in quantum gases.
14:30 Phantom relaxation in local many-body Floquet systems - Marko Znidaric (University of Ljubljana)
Phantom relaxation in local many-body Floquet systems
- Marko Znidaric (University of Ljubljana)
14:30 - 15:10
We would like to understand relaxation towards a long-time steady state under unitary pure-state evolution. Focusing on a bipartite entanglement or out-of-time-ordered correlations, one sometimes finds that relaxation is not a simple exponential with a fixed rate, but that the rate exhibits a jump at an extensive time. Studying some solvable cases of random circuits one finds that this two-step relaxation can be traced back to interesting non-Hermitian physics. Despite relaxation being described by a gapped Markovian matrix the rate is in the thermodynamic limit not given by the 2nd largest eigenvalue, but rather by a phantom eigenvalue -- an "eigenvalue" that is not in the spectrum. Resolution of this puzzle will lead to a pseudospectrum, Jacobi theta functions, and realization that when dealing with non-Hermitian matrices being exact can actually be wrong, while being slightly wrong is correct.
vendredi 16 juin 2023
11:00 Driven-Dissipative Systems: two messy experiments and one developing theory - Mohammad Hafezi
Driven-Dissipative Systems: two messy experiments and one developing theory
- Mohammad Hafezi
11:00 - 11:40
As an example of driven-dissipative systems, I discuss two recent experiments: (1) strongly interacting excitons in moire heterostructures, (2) orbital angular pumping of quantum Hall states of graphene with vortex light. In the end, I briefly discuss our recent progress in verifying measurement-induced phases by avoiding the post-selection barrier. https://arxiv.org/abs/2304.09731 https://arxiv.org/abs/2306.03417
11:50 Phase transitions at a many-body exceptional point - Sebastian Diehl
Phase transitions at a many-body exceptional point
- Sebastian Diehl
11:50 - 12:30
samedi 17 juin 2023
dimanche 18 juin 2023

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