Diamond nanomechanical resonators protected by a phononic band gap

We report the design, fabrication, and characterization of diamond cantilevers attached to a phononic square lattice. We show that the robust protection of mechanical modes by phononic band gaps leads to a three-orders-of-magnitude increase in mechanical Q-factors, with the Q-factors exceeding 10^6 at frequencies as high as 100 MHz. Temperature dependent studies indicate that the Q-factors obtained at a few K are still limited by the materials loss. The high-Q diamond nanomechanical resonators provide a promising hybrid quantum system for spin-mechanics studies

Hybrid Quantum Systems with Solid State Spins in Diamond

As work progresses towards a useful quantum computer using various physical implementations, it seems likely that no single physical system can fully realize all necessary requirements for a large scale, interfaced, stable quantum computer. Instead, it seems various systems are more predisposed for use as computational qubits while others to acting as “flying” qubits. The nitrogen vacancy center in diamond is a physical system of numerous applications, of which significant interest has been towards the NV’s role in quantum computation. The center’s impressive spin coherence as well as its coupling to magnetic fields, strain fields and nuclear spins suggests the role of the NV in hybrid quantum systems will be critical. In this dissertation, I will report on progress made towards the use of the NV in various hybrid quantum systems, including the coupling of the NV between optical, microwave and strain fields

Coupling a Surface Acoustic Wave to an Electron Spin in Diamond via a Dark State

The emerging field of quantum acoustics explores interactions between acoustic waves and artificial atoms and their applications in quantum information processing. In this experimental study, we demonstrate the coupling between a surface acoustic wave (SAW) and an electron spin in diamond by taking advantage of the strong strain coupling of the excited states of a nitrogen vacancy center while avoiding the short lifetime of these states. The SAW-spin coupling takes place through a Λ-type three-level system where two ground spin states couple to a common excited state through a phonon-assisted as well as a direct dipole optical transition. Both coherent population trapping and optically driven spin transitions have been realized. The coherent population trapping demonstrates the coupling between a SAW and an electron spin coherence through a dark state. The optically driven spin transitions, which resemble the sideband transitions in a trapped-ion system, can enable the quantum control of both spin and mechanical degrees of freedom and potentially a trapped-ion-like solid-state system for applications in quantum computing. These results establish an experimental platform for spin-based quantum acoustics, bridging the gap between spintronics and quantum acoustics