The negatively charged silicon monovacancy
The energy damping time in a mechanical resonator is critical to many precision metrology applications, such as timekeeping and force measurements. We present measurements of the phonon lifetime of a microwave-frequency, nanoscale silicon acoustic cavity incorporating a phononic bandgap acoustic shield. Using pulsed laser light to excite a colocalized optical mode of the cavity, we measured the internal acoustic modes with single-phonon sensitivity down to millikelvin temperatures, yielding a phonon lifetime of up to
- Publication Date:
- NSF-PAR ID:
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- Page Range or eLocation-ID:
- p. 840-843
- American Association for the Advancement of Science (AAAS)
- Sponsoring Org:
- National Science Foundation
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Enhanced cavity coupling to silicon vacancies in 4H silicon carbide using laser irradiation and thermal annealing
The negatively charged silicon monovacancy
in 4H silicon carbide (SiC) is a spin-active point defect that has the potential to act as a qubit in solid-state quantum information applications. Photonic crystal cavities (PCCs) can augment the optical emission of the , yet fine-tuning the defect–cavity interaction remains challenging. We report on two postfabrication processes that result in enhancement of the optical emission from our PCCs, an indication of improved coupling between the cavity and ensemble of silicon vacancies. Below-bandgap irradiation at 785-nm and 532-nm wavelengths carried out at times ranging from a few minutes to several hours results in stable enhancement of emission, believed to result from changing the relative ratio of (“dark state”) to (“bright state”). The much faster change effected by 532-nm irradiation may result from cooperative charge-state conversion due to proximal defects. Thermal annealing at 100 °C, carried out over 20 min, also results in emission enhancements and may be explained by the relatively low-activation energy diffusion of carbon interstitials , subsequently recombining with other defects to create additional s. These PCC-enabled experiments reveal insights into defect modifications and interactions within a controlled, designated volume and indicate pathways tomore »
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