光力腔中超冷原子的超辐射相塌缩

Collapse of the Superradiant Phase in a Optomechanical Cavity

基于Dicke量子相变实验,我们通过调控双腔耦合强度和机械振子声子-光子相互作用研究了双腔光力系统中玻色爱因斯坦凝聚体的多重稳定宏观量子态。本文用自旋相干态变分法从理论上给出双腔光力系统的基态能量泛函,并通过调节双腔耦合强度和机械振子声子-光子相互作用给出了宏观多粒子量子态的丰富结构。在共振情形下,系统不仅存在正常相到超辐射相的量子相变,而且双腔耦合强度和机械振子声子-光子相互作用都能诱导超辐射相的塌缩,而且当机械振子声子-光子相互作用增大到一定值时系统还会出现正常相到原子布局数反转态的正常相的新的量子相变。

Based on the experimental realization of quantum phase transition,the multiple stable macroscopic quantum states of a Bose-Einstein condensates in an optomechanical cavity have been investigated with double-cavity coupling strength and mechanical oscillator photon-phonon coupling strength.In this paper,the spin-coherent-state variation method is used to theoretically calculate the ground state energy functional,and the rich structures of the macroscopic multi-particle quantum state are given by adjusting double-cavity coupling strength and mechanical oscillator photon-phonon coupling strength.In resonance case,the usual transition from normal phase to superradiant phase still exists.However,with the increasing of the atom-field coupling strength,the superradiant phase collapses in a certain coupling value for the mechanical oscillator’s resonant damping or double-cavity coupling strength.As a result,the system occurs an additional phase transition from the normal phase of the atomic population to the inverted atomic population.