Self-Adapted Floquet Dynamics of Ultracold Bosons in a Cavity

Abstract

Floquet dynamics of a quantum system subject to periodic modulations of system parameters provides a powerful tool for engineering new quantum matter with exotic properties. While system dynamics is significantly altered, the periodic modulation itself is usually induced externally and independent of Floquet dynamics. Here we propose a new type of Floquet physics for a Bose-Einstein condensate (BEC) subject to a shaken lattice generated inside a cavity, where the shaken lattice and atomic Floquet bands are mutually dependent, resulting in self-adapted Floquet dynamics. In particular, the shaken lattice induces Floquet quasienergy bands for the BEC, whose backaction leads to a self-adapted dynamical normal-superradiant phase transition for the shaken lattice. Such self-adapted Floquet dynamics shows two surprising and unique features: (i) The normal-superradiant phase transition possesses a hysteresis even without atom interactions. (ii) The dynamical atom-cavity steady state could exist at free energy maxima. The atom interactions strongly affect the phase transition of the BEC from zero to finite momenta. Our results provide a powerful platform for exploring self-adapted Floquet physics, which may open an avenue for engineering novel quantum materials.

Cavity QED with Quantum Gases: New Paradigms in Many-Body Physics

“…Periodic phase modulation of the cavity-induced optical lattice can also modify the properties of the superradiant phase transition. For instance, periodic phase modulation of a cavity field has been predicted to yield a first-order superradiant phase transition with a hysteresis loop, provided the modulation frequency is chosen appropriately and the bosonic gas is sufficiently-weakly interacting [319]. The periodic phase modulation of a cavity field can also result in cavity-assisted long-range hoppings for fermionic atoms in an external lattice inside the cavity, leading to topological superradiant states [320].…”

Time crystals in a shaken atom-cavity system

“…which can be experimentally realized by using two optical modulators [51]. This produces a standing-wave potential cos(ky + ϕ(t)), where k = 2π/λ p and λ p is the pump wavelength, that is shaking at a period of T = 2π/ω d .…”

Phase separation and multistability of two-component Bose-Einstein condensate in an optical cavity

“…In recent years, BECs loaded in optical cavities have been studied extensively [11][12][13][14][15][16][17][18][19][20][21][22]. Atom-photon interactions in a cavity-BEC system generate highly nonlocal nonlinearity, which gives rise to many interesting phenomena, such as selforganization of atoms inside the optical cavity [23][24][25], Dicke quantum phase transitions [26][27][28][29][30], optical bistability [31][32][33][34][35][36][37][38], instability and chiral dynamics [39], and Floquet dynamics [40,41].…”