Experimental observation of a dissipative phase transition in a multi-mode many-body quantum system

Abstract

Dissipative phase transitions are a characteristic feature of open systems. One of the paradigmatic examples for a first order dissipative phase transition is the driven nonlinear single mode optical resonator. In this work, we study a realization with an ultracold bosonic quantum gas, which generalizes the single mode system to many modes and stronger interactions. We measure the effective Liouvillian gap of the system and find evidence for a first order dissipative phase transition. Due to the multi-mode nature of the system, the microscopic dynamics is much richer and allows us to identify a non-equilibrium condensation process.

Nonequilibrium steady states and critical slowing down in the dissipative Bose-Hubbard model

“…At intermediate times, however, the modes surrounding the central site will act as a reservoir, making the lossy site effectively a driven-dissipative system. Competition between the losses and the Bose-Hubbard dynamics, which tends to level the particle number in all sites, drives the system in a good approximation to a NESS [18][19][20]. In the following, we will call the quasisteady state at intermediate times simply the steady state of the system, with the timescale over which this state exists becoming longer with increasing system size L and tending to infinity in the thermodynamic limit.…”

“…Additional losses can therefore be introduced by externally engineering dissipation, giving good control over the relative importance of dissipative and Hamiltonian dynamics. One particular experimental implementation of a lossy atomic system was realized on a cigar-shaped Bose-Einstein condensate (BEC), tightly confined along the x and y axes and having a periodic potential along the z direction [17][18][19]. Particle losses around one potential minimum in the center were induced by ionizing atoms with a focused electron beam.…”

“…This system is simple enough to allow for a full numerical study within the truncated Wigner approximation (TWA) and therefore constitutes a good starting point for the development of models that truncate the number of lattice sites. The aim of this work is the construction of a minimal effective description that captures not only the same steady-state physics but also the dynamics and quantum-fluctuation-induced switches between the branches of the bistability [19].…”

Noise-resilient phase transitions and limit-cycles in coupled Kerr oscillators

“…However, in recent years, the investigation of phase transitions and critical phenomena in driven-dissipative many-body quantum systems has emerged as a significant area of study. Various experimental platforms, such as cavity arrays, superconducting circuits, and exciton-polaritons, have provided versatile setups to analyze the interplay between (in)coherent drive, dissipation, and interaction within the non-equilibrium steady state (NESS) of open quantum systems [1][2][3][4][5][6][7][8][9][10]. These include phenomena like multi-stability and crystallization in driven-dissipative nonlinear resonator arrays [11][12][13][14], spins [15], and synchronized switching in arrays of coupled Josephson junctions [16].…”

Quantum metrology with critical driven-dissipative collective spin system

“…Dissipative phase transitions can also be characterized by the vanishing of the Liouvillian gap, in which the second largest eigenvalue of the Liouvillian superoperator, often called asymptotic decay rate, tends to zero at the critical point. Moreover, the experimental observation of dissipative phase transition has been realized in various quantum-optical platforms including for example onedimensional circuit QED lattice [24], semiconductor microcavity [25,26], and ultracold bosonic quantum gas [27]. Such a critical driven-dissipative interaction may drive the system into an entangled many-body stationary state and thus it can be used as a resource for high-precision quantum metrology [28][29][30][31][32][33][34].…”