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Bulk acoustic resonators can be fabricated on the same substrate as other components and can operate at various frequencies with high quality factors. Mechanical dynamic metrology of these devices is challenging as the surface information available through laser Doppler vibrometry lacks information about the acoustic energy stored in the bulk of the resonator. Here we report the spin-acoustic control of naturally occurring negatively charged silicon monovacancies in a lateral overtone bulk acoustic resonator that is based on 4H silicon carbide. We show that acoustic driving can be used at room temperature to induce coherent population oscillations. Spin-acoustic resonance is shown to be useful as a frequency-tunable probe of bulk acoustic wave resonances, highlighting the dynamical strain distribution inside a bulk acoustic wave resonator at ambient operating conditions. Our approach could be applied to the characterization of other high-quality-factor microelectromechanical systems and has the potential to be used in mechanically addressable quantum memory.

 

The recently discovered spin defects in hexagonal boron nitride (hBN), a layered van der Waals material, have great potential in quantum sensing. However, the photoluminescence and the contrast of the optically detected magnetic resonance (ODMR) of hBN spin defects are relatively low so far, which limits their sensitivity. Here we report a record-high ODMR contrast of 46% at room temperature and simultaneous enhancement of the photoluminescence of hBN spin defects by up to 17-fold by the surface plasmon of a gold film microwave waveguide. Our results are obtained with shallow boron vacancy spin defects in hBN nanosheets created by low-energy He+ ion implantation and a gold film microwave waveguide fabricated by photolithography. We also explore the effects of microwave and laser powers on the ODMR and improve the sensitivity of hBN spin defects for magnetic field detection. Our results support the promising potential of hBN spin defects for nanoscale quantum sensing. 

ilicon Nitride integrated photonic circuits have drawn much attention owing to its ultra-low loss and large Kerr nonlinearity. However, the lack of Pockels effect makes it difficult to be modulated electro-optically, which posts a major challenge for the further development of Si3N4 circuits with advanced functions. The widely adopted thermo-optical tuning suffers from large power consumption and restricted speed (~1 kHz). In this study, microwave frequency modulation (up to 9 GHz) of Si3N4 ring resonator is achieved by exciting bulk acoustic waves piezoelectrically, which modulates the microring via stress-optical effect. The acoustic waves are confined tightly in a released SiO2 thin film which enhances the acoustic energy density and thus modulation efficiency. 

We propose a novel implementation of a trapped- atom Sagnac gyroscope based on the interference between matter- wave solitons confined around an optical microring resonator. Our integrated nanophotonic approach to trapped atom interferometry combines the long-term stability and quantum-limited sensitivity of ultracold matter-wave interferometers with the robustness, scalability and low power operation of nanophotonic architectures. The use of optical microresonators for atomic confinement ensures disorder-free symmetric waveguides for the confined atoms, a high degree of vibration insensitivity owing to the reciprocal structure of the waveguide, and enhanced bias and scale-factor stability via concurrent feedback stabilization of the microresonator. We have performed detailed quantum simulations based on demonstrated experimental parameters to confirm stable dispersion-free propagation of matter-wave solitons around the microresonator and the appearance of high contrast interference fringes due to the accrued Sagnac phase shift. We estimate the shot-noise limited rotation sensitivity of this gyroscope to be 0.8urad/s/rt.Hz for single-loop propagation of the solitons around a microring of radius 1 mm, with the possibility of substantial improvements via multiloop propagation of the solitons, fabrication of microring resonators of larger diameter, and the use of quantum-correlated states such as spin- squeezed quantum states. The proposed device illustrates the benefits of harnessing quantum many-body states such as matter- wave solitons for quantum-enhanced inertial sensing applications.