Salle de conference de l’INSP – Barre 22-23, 3e étage, pièce 317
Orazio Scarlatella (Theory of Condensed Matter Group, Université de Cambridge, UK)
Abstract
There has been impressive recent progress in controlling many-particle quantum systems in non-equilibrium regimes, ranging from superconducting qubits to atomic systems and driven quantum materials, motivating the exploration of interesting quantum phases of matter that might arise in those regimes. In this talk, I will discuss some examples of such phases, occurring as a result of both external driving and dissipation.
I will first consider the unconventional preparation, via the coupling to an engineered reservoir, of a conventional quantum phase, a bosonic Mott insulator, inspired by a superconducting-circuit experiment. I will show that this scheme can lead to a non-equilibrium phase transition, determining an intrinsic fragility of this phase [1]. Then, I will introduce a Dynamical Mean-Field Theory (DMFT) for lattice problems described by Markovian master equations [2], for which few theoretical methods are available, inspired by its success for correlated fermions in condensed matter physics. Using this method, I will study driven arrays of ultracold atoms in free space, a platform at the forefront of research on quantum optics, metamaterials and quantum information. I will discuss how the Mollow triplet spectrum of the light scattered by the atoms gets modified by strong dipolar interactions [3], and how entangled subradiant states, interesting for photon storage and metrology, can be prepared by a non-linear driving of a two-particle process [4].
[1] OS, A. A. Clerk, and M. Schirò, Stability of dissipatively-prepared Mott insulators of photons, Phys. Rev. Res. 6, 013033 (2024).
[2] OS, A. A. Clerk, R. Fazio, and M. Schiró, Dynamical Mean-Field Theory for Markovian Open Quantum Many-Body Systems, Phys. Rev. X 11, 031018 (2021).
[3] OS and N. R. Cooper, Fate of the Mollow triplet in strongly coupled atomic arrays, Phys. Rev. A 110, L041305 (2024).
[4] OS and N. R. Cooper, Non-Linear Steady States of Subwavelength Atomic Arrays at Low Light Intensities and beyond Mean Field, arXiv:2409.01386.
