A spin-optomechanical quantum interface enabled by an ultrasmall mechanical and optical mode volume cavity

Abstract

We propose a coherent mechanical interface between defect centers in diamond and telecom optical modes. Combining recent developments in spin-mechanical devices and optomechanical crystals, we introduce a 1D diamond nanobeam with embedded mechanical and electric field concentrator with mechanical and optical mode volumes V mech /Λ 3 p ∼ 10 −5 and Vopt/λ 3 ∼ 10 −3 , respectively. By placing a Group IV vacancy in the concentrator we demonstrate exquisitely high spin-mechanical coupling rates approaching 40 MHz, while retaining high acousto-optical couplings. We theoretically show that such a device, used in an entanglement heralding scheme, can provide high-fidelity Bell pairs between quantum repeaters. Using the mechanical interface as an intermediary between the optical and spin subsystems, we are able to directly use telecom optics, bypassing the native wavelength requirements of the spin. As the spin is never optically excited or addressed, we do not suffer from spectral diffusion and can operate at higher temperatures (up to 40 K), limited only by thermal losses. We estimate that based on these metrics, optomechanical devices with high spin-mechanical coupling will be a useful architecture for near-term quantum repeaters.

Spin-Acoustic Control of Silicon Vacancies in 4H Silicon Carbide

“…Thinning devices to smaller thickness could help increase acoustic coupling and enhance the rate of optical read-out significantly [22,33]. This experimental work also reinforces recent theoretical proposals suggesting V − Si as a potential candidate for hybrid quantum memories and a means of microwave to optical qubit transduction schemes in a future quantum network [34].…”

Diamond Integrated Quantum Nanophotonics: Spins, Photons and Phonons

“…Quantum frequency down-conversion provides a method for interfering photons from spectrally distinguishable emitters, by detuning the pump laser to compensate for the spectral difference [498]. Alternatively, coherent photon-phonon and spin-phonon coupling in an optomechanical cavity provide a way to realize a spin-photon interface operating directly at telecom wavelengths [75], [84], [388].…”

“…These mechanical resonators have the potential to be universal quantum transducers [79], [80], capable of coupling a myriad of different quantum systems, including connecting superconducting qubit resonators and optical photons [81], [82]. Photon-phonon and subsequent spin-phonon coupling in a mechanical resonator constitute a promising route to realize a spin-photon interface natively operating at telecom wavelengths [75], [83], [84]. Furthermore, the high mechanical frequencies of these diamond resonators suppress the population of thermal phonons, facilitating preparing of the mechanical resonator to the quantum ground state.…”

Nanoelectromechanical Control of Spin–Photon Interfaces in a Hybrid Quantum System on Chip

“…An important metric for acoustic manipulation of CC spins is the spin-phonon coupling rate, g sm , dictating the efficiency of acoustic spin manipulation and potential for coherent coupling between spin states and single phonons. − For SnVs g sm depends on the degree of spin–orbit mixing as well as the prestrain present in the sample (Supplemental Figure 12); prestrain can counteract the effects of transverse magnetic field, quenching g sm . Using a model taking into account magnetic field, prestrain, and Jahn–Teller effects, we fit the peak locations in the PLE spectra for the SnV shown in Figure d (Supplemental Figure 11a) and estimate a transverse magnetic field of 0.022 ∓ 0.005 T at the sample, with a ground state prestrain of 865 GHz.…”