Optomechanical cooling in a continuous system

Radiation-pressure-induced optomechanical coupling permits exquisite control of micro- and mesoscopic mechanical oscillators. This ability to manipulate and even damp mechanical motion with light---a process known as dynamical backaction cooling---has become the basis for a range of novel phenomena within the burgeoning field of cavity optomechanics, spanning from dissipation engineering to quantum state preparation. As this field moves toward more complex systems and dynamics, there has been growing interest in the prospect of cooling traveling-wave phonons in continuous optomechanical waveguides. Here, we demonstrate optomechanical cooling in a continuous system for the first time. By leveraging the dispersive symmetry breaking produced by inter-modal Brillouin scattering, we achieve continuous mode optomechanical cooling in an extended 2.3-cm silicon waveguide, reducing the temperature of a band of traveling-wave phonons by more than 30 K from room temperature. This work reveals that optomechanical cooling is possible in macroscopic linear waveguide systems without an optical cavity or discrete acoustic modes. Moreover, through an intriguing type of wavevector-resolved phonon spectroscopy, we show that this system permits optomechanical control over continuously accessible groups of phonons and produces a new form of nonreciprocal reservoir engineering. Beyond this study, this work represents a first step towards a range of novel classical and quantum traveling-wave operations in continuous optomechanical systems.Comment: Manuscript with supplementary information. 17 pages, 4 Figures. Minor correction in Fig.

Quantum optomechanics in tripartite systems

Owing to their long-lifetimes at cryogenic temperatures, mechanical oscillators are recognized as an attractive resource for quantum information science and as a testbed for fundamental physics. Key to these applications is the ability to prepare, manipulate and measure quantum states of mechanical motion. Through an exact formal solution to the Schrodinger equation, we show how tripartite optomechanical interactions, involving the mutual coupling between two distinct optical modes and an acoustic resonance enables quantum states of mechanical oscillators to be synthesized and interrogated.Comment: 8 pages, 4 figure