Abstract We propose a microwave-controlled interaction switch for driven-dissipative Rydberg ensembles. Through microwave dressing, the effective interaction is continuously reshaped from a short-range form dominated by van der Waals coupling to a longer-range form with an enhanced dipole-exchange contribution. This switch drives stationary-to-oscillatory transitions in both macroscopic thermal gases and two-dimensional (2D) lattices. In the mean-field description of thermal gases, microwave-controlled interaction tuning induces a supercritical Hopf bifurcation from a steady state to a stable limit cycle, giving rise to dissipative continuous time-crystalline behavior. In 2D lattices, where spatial correlations become important, cumulant-expansion calculations show that the same switching mechanism remains effective beyond mean-field theory. Although correlations reduce the classical oscillatory region, they sustain a correlation-modified oscillatory regime and additionally generate an oscillatory regime absent in mean-field theory. These results show that the proposed switch provides a unified route to controlling dissipative oscillatory behavior from thermal Rydberg gases to 2D lattices.
Abstract We propose a microwave-controlled interaction switch for driven-dissipative Rydberg ensembles. Through microwave dressing, the effective interaction is continuously reshaped from a short-range form dominated by van der Waals coupling to a longer-range form with an enhanced dipole-exchange contribution. This switch drives stationary-to-oscillatory transitions in both macroscopic thermal gases and two-dimensional (2D) lattices. In the mean-field description of thermal gases, microwave-controlled interaction tuning induces a supercritical Hopf bifurcation from a steady state to a stable limit cycle, giving rise to dissipative continuous time-crystalline behavior. In 2D lattices, where spatial correlations become important, cumulant-expansion calculations show that the same switching mechanism remains effective beyond mean-field theory. Although correlations reduce the classical oscillatory region, they sustain a correlation-modified oscillatory regime and additionally generate an oscillatory regime absent in mean-field theory. These results show that the proposed switch provides a unified route to controlling dissipative oscillatory behavior from thermal Rydberg gases to 2D lattices.
A dissipative time crystal is an emergent phase in driven-dissipative quantum many-body systems, characterized by sustained oscillations that break time-translation symmetry spontaneously. Here, we explore nonequilibrium phase transitions in a dissipative Rydberg system driven by a microwave (MW) field and demonstrate their critical sensitivity to high-precision MW sensing. Distinct dynamical regimes are identified, including monostable, bistable, and oscillatory phases under mean-field coupling. Unlike single-particle detection--where the beating signal decays linearly with MW field strength--the time crystalline phase exhibits high sensitivity to MW perturbations, with rapid, discontinuous frequency switching near the monostable-oscillatory boundary. The abrupt transition is rooted in spontaneous symmetry breaking in time and is fundamentally insensitive to the background noise. On this basis, a minimum detectable MW field strength on the order of 1nV/cm is achieved by leveraging this sensitivity. Our results establish a framework for controlling time crystalline phases with external fields and advance MW sensing through many-body effects.
We study steady-state phases of a one-dimensional array of Rydberg atoms coupled by a microwave (MW) field where the higher-energy Rydberg state decays to the lower-energy one via single-body and collective (superradiant) decay. Using mean-field approaches, we examine the interplay among the MW coupling, intrastate van der Waals (vdW) interaction, and single-body and collective dissipation between Rydberg states. A linear stability analysis reveals that a series of phases, including uniform, antiferromagnetic, oscillatory, and bistable and multistable phases can be obtained. Without the vdW interaction, only uniform phases are found. In the presence of the vdW interaction, multistable solutions are enhanced when increasing the strength of the superradiant decay rate. Our numerical simulations show that the bistable and multistable phases are stabilized by superradiance in a long chain. The critical point between the uniform and multistable phases and its scaling with the atom number is obtained. Through numerically solving the master equation of a finite chain, we show that the mean-field multistable phase could be characterized by expectation values of Rydberg populations and two-body correlations between Rydberg atoms in different sites.
Driven nonlinear oscillators constitute a universal paradigm for understanding synchronization, frequency pulling, and frequency comb formation in nonequilibrium systems. Here, we realize such an emergent nonlinear oscillator in strongly interacting cesium Rydberg vapor, where coherent optical excitation, dissipation, and long-range interactions give rise to a driven-dissipative time crystal phase with intrinsic oscillation frequencies. Applying a radio-frequency (RF) field allows controlled tuning of the intrinsic oscillation frequency. Under RF heterodyne conditions, we observe intermodulation, frequency pulling, and, at strong drive, the emergence of a comb-like spectrum in the atomic coherence. We quantitatively capture these observations using a four-level mean-field model and demonstrate a classical analogue with a driven Van der Pol oscillator. Our results establish interacting Rydberg ensembles as a tunable platform for exploring nonequilibrium time-crystalline order, nonlinear synchronization, and frequency comb generation in many-body atomic systems.
While dissipative Rydberg gases exhibit unique possibilities to tune dissipation and interaction properties, very little is known about the quantum many-body physics of such long-range interacting open quantum systems. We theoretically analyze the steady state of a van der Waals interacting Rydberg gas in an optical lattice based on a variational treatment that also includes long-range correlations necessary to describe the physics of the Rydberg blockade, i.e., the inhibition of neighboring Rydberg excitations by strong interactions. In contrast to the ground state phase diagram, we find that the steady state undergoes a single first order phase transition from a blockaded Rydberg gas to a facilitation phase where the blockade is lifted. The first order line terminates in a critical point when including sufficiently strong dephasing, enabling a highly promising route to study dissipative criticality in these systems. In some regimes, we also find good quantitative agreement of the phase boundaries with previously employed short-range models, however, with the actual steady states exhibiting strikingly different behavior.
We investigate the interaction between Rydberg atoms, whose electronic states are dressed by multiple microwave fields. Numerical calculations are used for an exact description of the microwave induced interactions, and employed to benchmark a perturbative treatment that yields simple insights into the involved mechanisms. Based on this theory, we demonstrate that microwave dressing provides a powerful approach to control dipolar as well as van der Waals interactions and even permits to turn them off entirely. In addition, the proposed scheme also opens up possibilities for engineering dominant three-body interactions.
We investigate the interaction between Rydberg atoms, whose electronic states are dressed by multiple microwave fields. Numerical calculations are used for an exact description of the microwave induced interactions, and employed to benchmark a perturbative treatment that yields simple insights into the involved mechanisms. Based on this theory, we demonstrate that microwave dressing provides a powerful approach to control dipolar as well as van der Waals interactions and even permits us to turn them off entirely. In addition, the proposed scheme also opens up possibilities for engineering dominant three-body interactions.