Metastability and avalanche dynamics in strongly correlated gases with long-range interactions

Abstract

We experimentally study the stability of a bosonic Mott insulator against the formation of a density wave induced by long-range interactions and characterize the intrinsic dynamics between these two states. The Mott insulator is created in a quantum degenerate gas of 87-Rubidium atoms, trapped in a 3D optical lattice. The gas is located inside and globally coupled to an optical cavity. This causes interactions of global range, mediated by photons dispersively scattered between a transverse lattice and the cavity. The scattering comes with an atomic density modulation, which is measured by the photon flux leaking from the cavity. We initialize the system in a Mott-insulating state and then rapidly increase the global coupling strength. We observe that the system falls into either of two distinct final states. One is characterized by a low photon flux, signaling a Mott insulator, and the other is characterized by a high photon flux, which we associate with a density wave. Ramping the global coupling slowly, we observe a hysteresis loop between the two states-a further signature of metastability. A comparison with a theoretical model confirms that the metastability originates in the competition between short- and global-range interactions. From the increasing photon flux monitored during the switching process, we find that several thousand atoms tunnel to a neighboring site on the timescale of the single-particle dynamics. We argue that a density modulation, initially forming in the compressible surface of the trapped gas, triggers an avalanche tunneling process in the Mott-insulating region.

Symmetries and conservation laws in quantum trajectories: Dissipative freezing

“…[13][14][15][16][17][18][19][20][21][22]. Due to their fundamental interest and practical applications, such as enhanced metrological properties [23,24], DPTs have attracted a significant amount of attention, with much work being devoted to study the associated phenomena of bistability [3-5, 22, 25-28], hysteresis [2,29], intermittency [6,26,[29][30][31][32], multimodality [25,31], metastability [33] and symmetry breaking [34][35][36]. All these effects are understood as different manifestations of the coexistence of several non-equilibrium phases.…”

Dissipation-Induced Instabilities of a Spinor Bose-Einstein Condensate Inside an Optical Cavity

“…This was also discussed in several theoretical works [13][14][15][16][17]. Further advances have led to the study of competition between shortand long-ranged interactions using optical lattices [18][19][20], the simulation of continuous symmetry breaking with multiple cavities [21,22], and the observation of complex manybody phenomena in multi-mode cavities [23][24][25].…”

P -Band Induced Self-Organization and Dynamics with Repulsively Driven Ultracold Atoms in an Optical Cavity

“…The self-organization process is a second order phase transition at which the atoms reduce their potential energy in the modified potential landscape by a larger amount than the kinetic energy of the additional crystalline structure costs. This self-consistent ordering of atoms and light has become an experimental model system for driven-dissipative quantum phases [12][13][14][15][16][17][18][19][20][21].…”