Floquet Diamond Sensor with Optimal Precision

Abstract

The diamond sensor has emerged as a promising platform for quantum sensing, enabling the estimation of physical quantities -- such as microwave~(MW) field -- with precision unattainable by classical counterpart. However, traditional diamond sensors suffer severe precision degradation when the signal MW is not resonant with the sensor transition frequency. Here, we propose and demonstrate a Floquet diamond sensor~(FDS) for high-precision off-resonant MW amplitude sensing without attenuating the strength of the signal MW. The periodic driven field effectively induces an quasi-energy shift that matches the off-resonant MW frequency. The measurement precision of FDS is characterized by quantum Fisher information, which approaches the ultimate precision -- Heisenberg limit -- within the coherent time. Furthermore, the FDS exhibits robust tolerance to practical control errors and is compatible with dynamical coupling protocol, enabling a robust and high-sensitivity magnetic sensing. Our results confirm the quantum advantage of quantum sensing and provide a practical technology for high-precision off-resonant MW sensing.

Figures (7)

• Figure 1: The illustration of Floquet diamond sensor (FDS). The original diamond sensor (ODS) is periodically driven by a control field, which introduces a quasi-energy shift that matches the frequency of off-resonant signal MW.
• Figure 2: Experimental results of MW sensing. (a) The Rabi oscillations of ODS when sensing the resonant MW signal (green circles) and the off-resonate MW signal (red circles). The purple circles are the results of Rabi oscillation of FDS with $k=1, 3$ and 5 when sensing the off-resonant MW signal. (b) The insets shows the $\phi$ and $\theta$ as functions of $\Omega_\text{s}$. Red line is Heisenberg scaling and purple circles are experiment results for QFI of FDS. Red line (circles) is simulation (experiment) results for QFI of ODS. The error bars are calculated by Monte Carlo simulation with Poisson noise.
• Figure 3: Robustness of Floquet diamond sensor. (a) and (b) respectively illustrate QFI when the parameters $\Omega_\text{F}$ and $\omega_\text{F}$ in the control Hamiltonian do not match the theoretical optimal values. Purple line is numerically simulation results for $\mathcal{H}_\text{F}^\prime$ and points are experimental results. Red line is QFI of ODS. (c) The Rabi oscillation of the NV center driven by the off-resonant signal for FDS without (top) and with (bottom) DD sequence, the decoherence time is approximately $17.9\mu s$ and $162.5\mu s$ respectively.
• Figure 4: (a) The atomic structure of the nitrogen vacancy (NV) center in diamond lattice. (b) Energy-level configuration of the NV defect center.
• Figure 5: (a) Schematic drawing of the home-built optical confocal microscope setup. (b) The fluorescence intensity map of a $18~\mu\text{m}\times 9~\mu\text{m}$ from a two-dimensional laterally scanning.