Optomechanics: Exploring the quantum nature of mechanical systems

Max Ludwig

Michael Ross Vanner, Igor Pikovski, Garrett D. Cole +5 more

Studying mechanical resonators via radiation pressure offers a rich avenue for the exploration of quantum mechanical behavior in a macroscopic regime. However, quantum state preparation and especially quantum state reconstruction of mechanical oscillators remains a significant challenge. Here we propose a scheme to realize quantum state tomography, squeezing, and state purification of a mechanical resonator using short optical pulses. The scheme presented allows observation of mechanical quantum features despite preparation from a thermal state and is shown to be experimentally feasible using optical microcavities. Our framework thus provides a promising means to explore the quantum nature of massive mechanical oscillators and can be applied to other systems such as trapped ions.

Dan Mei Hu

In this dissertation, I theoretically investigate the open system dynamics of cavity optomechanical systems in the quantum limit, where a mechanical resonator couples to a cavity mode via radiation pressure force. Recent developments in nano-fabrication and cooling techniques make it possible to optically control and manipulate the motion of micro- and nano-mechanical resonator. Several experiments have demonstrated the possibility of preparing macroscopic mechanical resonators into their quantum ground state, which makes optomechanical systems an ideal candidate for studying the quantum behavior of macroscopic objects. One important direction in quantum optomechanics is the study of the decoherence of optomechanical system due to the interaction with their external environments. This dissertation explores the decoherence effects by considering the influence of the radiation pressure coupling on the interaction between optomechanical system and its environments. Because the effects of the nonlinear interaction vary with the optomechanical coupling strength, three different interaction regimes are fully studied here: the weak coupling, the intermediate coupling and the strong coupling.

Shabir Barzanjeh, André Xuereb, Simon Gröblacher +3 more

Ramon Moghadas Nia

Quantum entanglement is an essential feature of quantum physics and an important resource for applications in quantum information processing and quantum communication, including prominent examples such as quantum teleportation and quantum cryptography, as well as for fundamental tests of quantum theory. This thesis explores the generation and verification of continuous wave optomechanical entanglement between a light mode and a multimode mechanical oscillator. The optomechanical system consists of a thin silicon nitride membrane placed within a high finesse Fabry-Pérot cavity. It is successively improved and verified to operate in the strong cooperativity regime, a necessary condition for the generation of entanglement. A pulsed-continuous verification protocol is applied to correlation measurements with strong cooperativity. The results demonstrate that the naive approach of filtering a single high-Q mode to obtain a witness for entanglement is not viable. The multimode nature of the mechanics has to be, and is, explicitly considered in the evaluations as well as spectral features of the detection scheme, thereby paving the way towards multimode optomechanical entanglement.

Baijun Li, Tianxiang Lu, Jie Wang +1 more

Cavity optomechanics represents a frontier research direction in quantum science and technology, centered on the control and exploration of interactions between electromagnetic fields and mechanical motion. Rooted in quantum mechanics, this field realizes efficient coupling and precise manipulation of optical fields and mechanical vibrations through the structural design and precise regulation of optical microcavities and mechanical oscillators, thereby revealing and harnessing novel quantum phenomena. In recent years, cavity optomechanics has evolved into an interdisciplinary frontier integrating quantum optics, condensed matter physics, and quantum precision measurement, exhibiting profound application in both fundamental physics research and quantum information science. With advancements in technologies such as nanomanufacturing and laser cooling, optomechanical interactions have been successfully demonstrated in various experimental systems. Among these platforms, cavity cold-atom systems stand out as one of the ideal platforms for implementing quantum optomechanics. Featuring exceptional environmental isolation, long quantum coherence times, and strong light-matter interaction, these systems provide a crucial testbed for exploring strong and even ultrastrong optomechanical coupling effects as well as rich nonlinear quantum phenomena. This paper reviews the recent progress in optomechanical control and manipulation based on cavity cold-atom systems. We first outline the fundamental principles of standard cavity optomechanical systems. Then, we describe the experimental realization of linear and nonlinear optomechanical couplings in cold-atom systems. After that, we focus on the representative applications of this platform in high-precision quantum sensing, quantum memory, and the preparation of macroscopic nonclassical states. Finally, we give an outlook and challenges in this field.