ABSTRACT
The global quantum internet will require long-lived, telecommunications-band photon-matter interfaces manufactured at scale1. Preliminary quantum networks based on photon-matter interfaces that meet a subset of these demands are encouraging efforts to identify new high-performance alternatives2. Silicon is an ideal host for commercial-scale solid-state quantum technologies. It is already an advanced platform within the global integrated photonics and microelectronics industries, as well as host to record-setting long-lived spin qubits3. Despite the overwhelming potential of the silicon quantum platform, the optical detection of individually addressable photon-spin interfaces in silicon has remained elusive. In this work, we integrate individually addressable 'T centre' photon-spin qubits in silicon photonic structures and characterize their spin-dependent telecommunications-band optical transitions. These results unlock immediate opportunities to construct silicon-integrated, telecommunications-band quantum information networks.
ABSTRACT
Diamond-based microelectromechanical systems (MEMS) enable direct coupling between the quantum states of nitrogen-vacancy (NV) centers and the phonon modes of a mechanical resonator. One example, a diamond high-overtone bulk acoustic resonator (HBAR), features an integrated piezoelectric transducer and supports high-quality factor resonance modes into the gigahertz frequency range. The acoustic modes allow mechanical manipulation of deeply embedded NV centers with long spin and orbital coherence times. Unfortunately, the spin-phonon coupling rate is limited by the large resonator size, >100 µm, and thus strongly coupled NV electron-phonon interactions remain out of reach in current diamond BAR devices. Here, we report the design and fabrication of a semiconfocal HBAR (SCHBAR) device on diamond (silicon carbide) with f × Q > 1012 (>1013). The semiconfocal geometry confines the phonon mode laterally below 10 µm. This drastic reduction in modal volume enhances defect center coupling to a mechanical mode by 1000 times compared to prior HBAR devices. For the native NV centers inside the diamond device, we demonstrate mechanically driven spin transitions and show a high strain-driving efficiency with a Rabi frequency of (2π)2.19(14) MHz/Vp, which is comparable to a typical microwave antenna at the same microwave power, making SCHBAR a power-efficient device useful for fast spin control, dressed state coherence protection, and quantum circuit integration.
ABSTRACT
An array of 180 nm diameter gold nanoparticles (NPs) embedded in a thin vanadium dioxide film was used as a nanoscale probe of the thermochromic semiconductor-to-metal transition (SMT) in the VO2. The observed 30% reduction in plasmon dephasing time resulted from the interaction between the localized surface plasmon resonance of the NPs with the 1.4 eV electronic transitions in VO2. The NPs act as nanoantennas probing the SMT; homogeneous broadening of the gold plasmon resonance is observed at the temperatures where electron correlations are strongest in VO2.
