A Majorana zero bound mode exists in the vortex core of a chiral $p+ip$ superconductor or superfluid, which can be driven from an $s$ -wave pairing state by two-dimensional spin-orbit coupling. We propose here a novel scheme based on realistic cold atom platforms to generate two-dimensional spin-orbit interactions in a blue-detuned square optical lattice, and predict both the quantum anomalous Hall effect and chiral topological superfluid phase in the experimentally accessible parameter regimes. This work may open a new direction with experimental feasibility to observe non-Abelian topological orders in cold atom systems.A Majorana zero bound mode exists in the vortex core of a chiral $p+ip$ superconductor or superfluid, which can be driven from an $s$-wave pairing state by two-dimensional spin-orbit coupling. We propose here a novel scheme based on realistic cold atom platforms to generate two-dimensional spin-orbit interactions in a blue-detuned square optical lattice, and predict both the quantum anomalous Hall effect and chiral topological superfluid phase in the experimentally accessible parameter regimes. This work may open a new direction with experimental feasibility to observe non-Abelian topological orders in cold atom systems.

arXiv:1304.0291Physical Review LettersFeb 24, 2014238 citations

Quantum phases of low-dimensional ultra-cold atom systems

Ludwig Mathey

Jun 1, 20070 citations

Experimental signatures of an absorbing-state phase transition in an open driven many-body quantum system

Ricardo Gutiérrez, Cristiano Simonelli, Matteo Archimi +6 more

Understanding and probing phase transitions in nonequilibrium systems is an ongoing challenge in physics. A particular instance are phase transitions that occur between a nonfluctuating absorbing phase, e.g., an extinct population, and one in which the relevant order parameter, such as the population density, assumes a finite value. Here, we report the observation of signatures of such a nonequilibrium phase transition in an open driven quantum system. In our experiment, rubidium atoms in a quasi-one-dimensional cold disordered gas are laser excited to Rydberg states under so-called facilitation conditions. This conditional excitation process competes with spontaneous decay and leads to a crossover between a stationary state with no excitations and one with a finite number of excitations. We relate the underlying physics to that of an absorbing-state phase transition in the presence of a field (i.e., off-resonant excitation processes) which slightly offsets the system from criticality. We observe a characteristic power-law scaling of the Rydberg excitation density as well as increased fluctuations close to the transition point. Furthermore, we argue that the observed transition relies on the presence of atomic motion which introduces annealed disorder into the system and enables the formation of long-ranged correlations. Our study paves the road for future investigations into the largely unexplored physics of nonequilibrium phase transitions in open many-body quantum systems.Understanding and probing phase transitions in nonequilibrium systems is an ongoing challenge in physics. A particular instance are phase transitions that occur between a nonfluctuating absorbing phase, e.g., an extinct population, and one in which the relevant order parameter, such as the population density, assumes a finite value. Here, we report the observation of signatures of such a nonequilibrium phase transition in an open driven quantum system. In our experiment, rubidium atoms in a quasi-one-dimensional cold disordered gas are laser excited to Rydberg states under so-called facilitation conditions. This conditional excitation process competes with spontaneous decay and leads to a crossover between a stationary state with no excitations and one with a finite number of excitations. We relate the underlying physics to that of an absorbing-state phase transition in the presence of a field (i.e., off-resonant excitation processes) which slightly offsets the system from criticality. We observe a characteristic power-law scaling of the Rydberg excitation density as well as increased fluctuations close to the transition point. Furthermore, we argue that the observed transition relies on the presence of atomic motion which introduces annealed disorder into the system and enables the formation of long-ranged correlations. Our study paves the road for future investigations into the largely unexplored physics of nonequilibrium phase transitions in open many-body quantum systems.

arXiv:1611.03288Physical Review AOct 9, 201765 citations

Dynamics of quantum control in cold-atom systems

Analabha Roy

May 1, 20090 citations

Moiré superradiance in cavity quantum electrodynamics with quantum atom gas

Lu Zhou, Zheng-Chun Li, Keye Zhang +3 more

As a novel platform for exploring exotic quantum phenomena, the moir\'e lattice has garnered significant interest in solid-state physics, photonics, and cold-atom physics. While moir\'e lattices in two- and three-dimensional systems have been proposed for neutral cold atoms, the simpler one-dimensional moir\'e effect remains largely unexplored. We present a scheme demonstrating moir\'e effects in a one-dimensional cold-atom--cavity coupling system, which resembles a generalized open Dicke model exhibiting superradiant phase transitions. We reveal a strong link between the phase transition critical point and the one-dimensional moir\'e parameter. Evidence of the one-dimensional moir\'e effect is explicitly explored, including the cavity field spectrum, phase transition dynamics, and anomalous atomic diffusion. This work provides a new route for testing one-dimensional moir\'e effects with cold atoms and opens new possibilities in moir\'e metrology.As a novel platform for exploring exotic quantum phenomena, the moir\'e lattice has garnered significant interest in solid-state physics, photonics, and cold-atom physics. While moir\'e lattices in two- and three-dimensional systems have been proposed for neutral cold atoms, the simpler one-dimensional moir\'e effect remains largely unexplored. We present a scheme demonstrating moir\'e effects in a one-dimensional cold-atom--cavity coupling system, which resembles a generalized open Dicke model exhibiting superradiant phase transitions. We reveal a strong link between the phase transition critical point and the one-dimensional moir\'e parameter. Evidence of the one-dimensional moir\'e effect is explicitly explored, including the cavity field spectrum, phase transition dynamics, and anomalous atomic diffusion. This work provides a new route for testing one-dimensional moir\'e effects with cold atoms and opens new possibilities in moir\'e metrology.

arXiv:2503.17696Physical Review ASep 15, 20252 citations

A Majorana zero bound mode exists in the vortex core of a chiral

p+ip

superconductor or superfluid, which can be driven from an

s

-wave pairing state by two-dimensional spin-orbit coupling. We propose here a novel scheme based on realistic cold atom platforms to generate two-dimensional spin-orbit interactions in a blue-detuned square optical lattice, and predict both the quantum anomalous Hall effect and chiral topological superfluid phase in the experimentally accessible parameter regimes. This work may open a new direction with experimental feasibility to observe non-Abelian topological orders in cold atom systems.