The impact of microwave phase noise on diamond quantum sensing

Precision measurements of the electron-spin precession of nitrogen-vacancy (NV) centers in diamond form the basis of numerous applications. The ultimate limits in precision are fundamental and cannot be avoided (e.g., due to spin-projection shot noise), but some sources of noise are due to experimental imperfections that could in principle be eliminated or at least mitigated. One example is microwave phase noise [1]. From the perspective of pulsed electron-spin measurements, noise due to random fluctuations of the phase of the waveform rotate the spins away from the desired axis and, left unmitigated, are indistinguishable from magnetic field noise. Phase noise is always present at some level because of the limited clock precision in microwave signal generators. It is particularly a challenge for applications that require large magnetic fields, such as nuclear magnetic resonance spectroscopy [2] because a higher microwave frequency translates timing errors into larger phase fluctuations and could significantly lower the achievable sensitivity. We will present research that confirms the effect of phase noise in pulsed electron-spin measurements, quantifies the phase noise as a function of frequency for several commonly-used commercial microwave signal generators, and presents solutions to mitigate the phase noise effects.

[1] Harrison Ball, William D Oliver & Michael J Biercuk, “The role of master clock stability in quantum information processing”, npj Quantum Information volume 2, Article number: 16033 (2016), DOI:10.1038/npjqi.2016.33;

[2] J. Smits*, J. Damron*, P. Kehayias, A. F. McDowell, N. Mosavian, N. Ristoff, I. Fescenko. A. Laraoui, A. Jarmola, V. M. Acosta, "Two-dimensional nuclear magnetic resonance spectroscopy with a microfluidic diamond quantum sensor" Science Advances Vol 5, Issue 7 (2019), DOI: 10.1126/sciadv.aaw789.