Quantum Orbital-State Control of a Neutral Nitrogen-Vacancy Center at Millikelvin Temperatures

TL;DR

This study demonstrates that cooling a neutral nitrogen-vacancy center to millikelvin temperatures significantly enhances its orbital coherence, enabling strong coupling with microwave photons for quantum electrodynamics applications.

Contribution

It shows that at millikelvin temperatures, NV$^0$ centers achieve extended orbital coherence times, facilitating strong coupling with microwave resonators, a novel step for quantum technologies.

Findings

Orbital relaxation time increases tenfold at 15 mK compared to 5 K.

Dynamical decoupling pulses extend orbital coherence to 1.8 μs.

Potential for strong coupling with microwave resonators established.

Abstract

A neutral nitrogen-vacancy center (NV$^0$) is promising for realizing strong coupling with a single microwave photon due to its large electric field sensitivity, although it is susceptible to environmental phonon noise at 5 K. Decreasing the temperature to 15 mK results in a tenfold increase in orbital relaxation time compared to that at 5 K. Dynamical decoupling pulses significantly increase the orbital coherence time to around 1.8 $\mu$s, representing a 30-fold improvement compared to that without decoupling pulses. Based on these results, a single NV$^0$ can reach the strong coupling regime when coupled with a high-impedance microwave resonator, thus opening up the possibility of microwave quantum electrodynamics using a single optically-active defect center in diamond.