Recurrence of optical squeezing: witness of nonclassicality in optomechanics

摘要: Witnessing nonclassicalities in the mechanical motion of mesoscopic objects is one of the important goals in optomechanics. Here, the dynamics of micro-mechanical elements can be read out by high precision measurements on the optical field. In this context, we study how nonclassicality of a mechanical movable mirror can be revealed by measuring the optical field variance alone. By developing classical and semiclassical descriptions of the system, without requiring quantization of the mirror, we recover either squeezing of the optical field or revivals in the field variance. We identify the recurrence of squeezing in the optical field as a genuine witness of nonclassicality of mechanical motion.Introduction—Cavity optomechanics studies the interaction between an electromagnetic cavity mode and a movable mechanical element. These systems are proposed as candidates to have significant impact on both foundations of physics [1] and practical applications [2]. The field has the potential to lead to understanding of a large number of deep questions, including decoherence mechanisms [3, 4] and gravitational effects in quantum mechanics [5–8]. It also promises quantum enhanced metrology with high-precision optomechanical sensing including force [9], magnetic field [10], acceleration [11], radio frequency radiation [12]. The optomechanical interaction causes the optical field to become correlated with the motion of the mechanical oscillator [13–15]. Measurement on the optical field can therefore reveal properties of the mechanical oscillator, including its nonclassicality [2, 16]. It is known that, the entanglement between two optical modes …