Temperature Sensitivity of $^{14}\mathrm{NV}$ and $^{15}\mathrm{NV}$ Ground State Manifolds

TL;DR

This study measures how the ground state spin transition frequencies of $^{14}$NV and $^{15}$NV centers in diamond vary with temperature, providing key parameters for improving nuclear-spin-based quantum sensors.

Contribution

It provides the first detailed temperature dependence of spin transition parameters for both isotopes, enhancing understanding for quantum sensing applications.

Findings

Temperature dependence of nuclear spin transitions: +0.52 ppm/K for $^{14}$NV, -1.1 ppm/K for $^{15}$NV.

Isotopic shift in zero-field splitting parameter D: approximately 120 kHz.

Residual transverse magnetic fields affect nuclear spin transition frequencies, especially in $^{15}$NV.

Abstract

We measure electron and nuclear spin transition frequencies in the ground state of nitrogen-vacancy (NV) centers in diamond for two nitrogen isotopes ($^{14}\mathrm{NV}$ and $^{15}\mathrm{NV}$) over temperatures ranging from 77 K to 400 K. Measurements are performed using Ramsey interferometry and direct optical readout of the nuclear and electron spins. We extract coupling parameters $Q$ (for $^{14}\mathrm{NV}$), $D$, $A_{||}$, $A_{\perp}$, $\gamma_e/\gamma_n$, and their temperature dependences for both isotopes. The temperature dependences of the nuclear-spin transitions within the $m_s = 0$ spin manifold near room temperature are found to be +0.52(1) ppm/K for $^{14}\mathrm{NV}$ ($|m_I=-1> \leftrightarrow |m_I=+1>$) and -1.1(1) ppm/K for $^{15}\mathrm{NV}$ ($|m_I=-1/2> \leftrightarrow |m_I=+1/2>$). An isotopic shift in the zero-field splitting parameter $D$ between $^{14}\mathrm{NV}$ and $^{15}\mathrm{NV}$ is measured to be $\sim$ 120 kHz. Residual transverse magnetic fields are observed to shift the nuclear spin transition frequencies, especially for $^{15}\mathrm{NV}$. We have precisely determined the set of parameters relevant for the development of nuclear-spin-based diamond quantum sensors with greatly reduced sensitivity to environmental factors.