Radiation pressure backaction on a hexagonal boron nitride nanomechanical resonator

Abstract

Hexagonal boron nitride (hBN) is a 2D material with excellent mechanical properties hosting quantum emitters and optically active spin defects, several of them being sensitive to strain. Establishing optomechanical control of hBN will enable hybrid quantum devices that combine the spin degree of freedom with the cavity optomechanical toolbox. In this letter, we report the first observation of radiation pressure backaction at telecom wavelengths with a hBN drum-head mechanical resonator. The thermomechanical motion of the resonator is coupled to the optical mode of a high finesse fiber-based Fabry-Pérot microcavity in a membrane-in-the-middle configuration.We are able to resolve the optical spring effect and optomechanical damping with a single photon coupling strength of g 0 = 710 Hz. Our results pave the way for tailoring the mechanical properties of hBN resonators with light. Main TextPart of the current research efforts in the field of cavity optomechanics 1 focuses on implementing nanomechanical resonators based on low dimensional materials, such as carbon nanotubes, 2-5 nanowires 6 or two-dimensional (2D) materials. 7-10 Their low mass makes them very sensitive and responsive to external stimuli, and their large zero-point fluctuations x zpf provide large optomechanical single-photon couplings g 0 , necessary to manipulate the mechanical or optical states in the quantum regime. [11][12][13] Hexagonal boron nitride (hBN) has recently caught the attention of the optomechanics community. Its large in-plane Young's modulus of 392 GPa 14 and breaking strain of 12.5 %, 15 together with the recent development of patterning methods 16,17 have opened the door to the engineering of mechanical resonators with high quality factors and tunable frequencies. This layered crystal is transparent in the visible and infrared part of the optical spectrum due to its wide bandgap of 6 eV, 18 and therefore is less prone to photothermal heating than other 2D materials like graphene. So far, photothermal forces, rather than radiation pressure, were