Energy efficient coherent quantum control of nitrogen vacancy (NV) spin with nanoscale magnets

TL;DR

This paper demonstrates energy-efficient, nanoscale magnetic control of NV center spins in diamond using surface acoustic wave-driven nanomagnets, enabling scalable quantum computing and sensing.

Contribution

It introduces a novel method of controlling NV spins with nanoscale magnets driven by surface acoustic waves, significantly reducing energy consumption compared to traditional microwave antennas.

Findings

High-contrast Rabi oscillations achieved with nanoscale nanomagnets.

Surface acoustic wave excitation is 400 to 10,000 times more energy efficient than antennas.

Measured spin relaxation times T1, T2, and T2* demonstrate effective quantum control.

Abstract

We investigate coherent quantum control of a nitrogen vacancy (NV) center in diamond with microwave fields generated from a nanoscale magnet that is proximal to the NV center. Our results show remarkable coherent control with high contrast Rabi oscillations using nearfield microwaves from shape anisotropic nanomagnets of lateral dimensions down to 200 nm x 180 nm, driven remotely by surface acoustic wave (SAW) excitation that is at least 400 times and potentially 4 orders of magnitude more energy efficient than generating microwaves with an antenna. Furthermore, we show that varying the acoustic power driving such nanomagnets can achieve control over Rabi frequency. We also report spin-lattice relaxation time T1 is 103 +/-0.5 micro-seconds, the spin-spin relaxation time T2 is 1.23+/-0.29 micro-seconds, and the Ramsey coherence time T2* is 218+/-27 nanoseconds measured using microwave pulses generated by such nanomagnets. The use of the nanoscale magnets to implement highly localized and energy efficient coherent quantum control can replace thermally noisy microwave circuits and demonstrate a path to scalable quantum computing and sensing with NV-defects in diamond and other spin qubits.