Single-crystal diamond is a promising material for MEMs devices because of its low mechanical loss, compatibility with extreme environments, and built-in interface to high-quality spin centers. But its use has largely been limited by challenges in processing and growth. We demonstrate a wafer bonding-based technique to form diamond on insulator, from which we make single-crystal diamond micromechanical resonators with mechanical quality factors as high as 338,000 at room temperature. Variable temperature measurements down to 10 K reveal a nonmonotonic dependence of quality factor on temperature. These resonators enable integration of single-crystal diamond into MEMs technology for classical and quantum applications.Comment: 15 pages total, 4 figures, 1 tabl

We discuss the heat transfer by photons between two metals coupled by a circuit containing linear reactive impedances. Using a simple circuit approach, we calculate the spectral power transmitted from one metal to the other and find that it is determined by a photon transmission coefficient, which depends on the impedances of the metals and of the coupling circuit. We study the total photonic power flow for different coupling impedances, both in the linear regime, where the temperature difference between the metals is small, and in the non-linear regime of large temperature differences.

Thermal hysteresis in a micron-size Superconducting Quantum Interference Device (µ-SQUID), with weak links as Josephson junctions, is an obstacle for improving its performance for magnetometery. Following the "hot-spot" model of Skocpol et al. [J. Appl. Phys. 45, 4054 (1974)] and by incorporating the temperature dependence of thermal conductivity of superconductor using a linear approximation, we find a much better agreement with the observed temperature dependence of the retrapping current in short superconducting Nb-based weak links and µ-SQUIDs. In addition, using the temperature dependence of the critical current, we find that above a certain temperature hysteresis disappears. We analyze the current-voltage characteristics and the weak link temperature variation in both the hysteretic and non-hysteretic regimes. We also discuss the effect of the weak link geometry in order to widen the temperature range of hysteresis-free operation.