Two-level system damping in a quasi-one-dimensional optomechanical resonator

Article

关键词: TEMPERATURE MECHANICAL-PROPERTIES;    SINGLE-CRYSTAL SILICON;    THERMAL-CONDUCTIVITY;    MICROWAVE;    MOTION;    OSCILLATOR;    PHONONS;    GLASSES;    ENTANGLEMENT;    ATTENUATION;   

DOI  :  10.1103/PhysRevB.98.214303

来源: SCIE

【 摘 要 】

Nanomechanical resonators have demonstrated great potential for use as versatile tools in a number of emerging quantum technologies. For such applications, the performance of these systems is restricted by the decoherence of their fragile quantum states, necessitating a thorough understanding of their dissipative coupling to the surrounding environment. In bulk amorphous solids, these dissipation channels are dominated at low temperatures by parasitic coupling to intrinsic two-level system (TLS) defects; however, there remains a disconnect between theory and experiment on how this damping manifests in dimensionally reduced nanomechanical resonators. Here, we present an optomechanically mediated thermal ringdown technique, which we use to perform simultaneous measurements of the dissipation in four mechanical modes of a cryogenically cooled silicon nanoresonator, with resonant frequencies ranging from 3-19 MHz. Analyzing the device's mechanical damping rate at fridge temperatures between 10 mK and 10 K, we demonstrate quantitative agreement with the standard tunneling model for TLS ensembles confined to one dimension. From these fits, we extract the defect density of states (P-0 similar to 1-4 x 10(44) J(-1) m(-3)) and deformation potentials (gamma similar to 1-2 eV), showing that each mechanical mode couples on average to less than a single thermally active defect at 10 mK.

【 授权许可】

Free