A hybrid measure for detecting quantum phase transitions

Matthew Libersky, R. H. McKenzie, D. M. Silevitch +2 more

Lingchao Li, Jian‐Qi Zhang

The optomechanics shows a great potential in quantum control and precise measurement due to appropriate mechanical control. Here we theoretically study the quantum phase transition in a hybrid atom-optomechanical cavity with an external force. Our study shows, in the thermodynamic limit, the critical value of quantum phase transition between the normal phase and super-radiant phase can be controlled and modified by the external force via the tunable frequency of optomechanics, then a force dependent quantum phase transition can be achieved in our system. Moreover, this force dependent quantum phase transition can be employed to detect the external force variation. In addition, our numerical simulations illustrate the sensitivity of the external force measurement can be improved by the squeezing properties of the quantum phase transition.

Michael Kruse, H. G. Miller, Angelo Plastino +1 more

Z L Li, Hong-Yu Chen, Jiang Xue-huan +6 more

Abstract In this work, we investigate quantum phase transitions (QPTs), dynamical chaos and Loschmidt echo (LE) behaviors in a parametrically driven cavity-magnon hybrid system. The system consists of a yttrium iron garnet microsphere coupled to a microwave cavity with a squeezed cavity field generated via an optical parametric amplification process, and is described by an extended Tavis–Cummings model. Using the Holstein–Primakoff (HP) transformation and displacement transformation, we derive the ground-state energy function and obtain the phase diagram. The results show that the system undergoes a second-order QPT between the normal phase and the superradiant phase in the thermodynamic limit. Once the system enters the SP region, this design will induce a strong nonlinearity, thereby exhibiting significant chaotic dynamic behavior, verified by the Poincaré section method. Furthermore, we introduce the LE method to this hybrid system in order to characterize its QPT behaviors. With the assistance of the auxiliary atoms, the observable parameter LE exhibits consistency with the QPT laws, which can be used to effectively detect the critical behavior of this magnon-photon system. This work reveals the laws of phase transitions, dynamical chaos and LE behaviors in a parametrically driven cavity-magnon hybrid system, providing a theoretical basis for simulating and exploring quantum critical phenomena, nonlinear behaviors and quantum measurements in hybrid magnon systems.

Yanchao Li, Wing Chi Yu, Hai‐Qing Lin

Zhen Chen, Guo-Qiang Zhang, Haifeng Yu +1 more

Abstract Quantum phase transition (QPT) in the Dicke model has long attracted considerable interest due to its fundamental importance in quantum optics and many-body physics. Recent studies indicate that QPT-like behavior may also arise in the driven Tavis-Cummings (TC) model—a simplified variant of the Dicke model that neglects counter-rotating-wave coupling terms. Hybrid quantum systems, capitalizing on the advantages of different components, offer a promising platform to realize such many-body systems. Here, we experimentally observe a dissipative phase transition in the thermodynamic limit using a driven TC model, implemented by coupling an electron spin ensemble to a superconducting microwave resonator. This QPT behavior is detected via the measurements of Rabi splitting, which exhibits a unique dependence on the collective spin excitations of the system. Our findings provide a route to experimentally investigate critical phenomena in realistic many-body systems under decoherence, and promise potential applications in quantum simulation and other emerging quantum technologies.