Versatile nanoscale sensors that are susceptible to changes in a variety of physical quantities often exhibit limited selectivity. We propose a novel scheme based on microwave-dressed spin states for optically probed nanoscale temperature detection using diamond quantum sensors, which provides selective sensitivity to temperature changes. By combining this scheme with a continuous pump-probe scheme using ensemble nitrogen-vacancy centers in nanodiamonds, we demonstrate a sub-100-nanosecond temporal resolution with thermal sensitivity of 3.7 K$\cdot$Hz$^{-1/2}$ that is insensitive to variations in external magnetic fields on the order of 2 G. The presented results are favorable for the practical application of time-resolved nanoscale quantum sensing, where temperature imaging is required under fluctuating magnetic fields.
Versatile nanoscale sensors that are susceptible to changes in a variety of physical quantities often exhibit limited selectivity. We propose a novel scheme based on microwave-dressed spin states for optically probed nanoscale temperature detection using diamond quantum sensors, which provides selective sensitivity to temperature changes. By combining this scheme with a continuous pump-probe scheme using ensemble nitrogen-vacancy centers in nanodiamonds, we demonstrate a sub-100-nanosecond temporal resolution with thermal sensitivity of 3.7 K⋅Hz−1/2 that is insensitive to variations in external magnetic fields on the order of 2 G. The presented results are favorable for the practical application of time-resolved nanoscale quantum sensing, where temperature imaging is required under fluctuating magnetic fields.
Abstract Versatile nanoscale sensors that are susceptible to changes in a variety of physical quantities often exhibit limited selectivity. This paper reports a novel scheme based on microwave‐dressed spin states for optically probed nanoscale temperature detection using diamond quantum sensors, which provides selective sensitivity to temperature changes. By combining this scheme with a continuous pump–probe scheme using ensemble nitrogen‐vacancy centers in nanodiamonds, a sub‐microsecond temporal resolution with thermal sensitivity of 3.7 that is insensitive to variations in external magnetic fields on the order of 2 G is demonstrated. The presented results are favorable for the practical application of time‐resolved nanoscale quantum sensing, where temperature imaging is required under fluctuating magnetic fields.
Accurate temperature readings of transient events at the nanometer scale are challenging due to the low sensitivity of available sensors. Nanodiamonds containing nitrogen-vacancy (NV) centers have been used for nanoscale thermometry in complex environments, including inside living cells. However, their performance has been limited by short coherence times and low photon counts. In this work, we use isotopically-purified dual-NV nanodiamonds and a bespoke quantum sensing chip to showcase an order of magnitude improvement in temperature measurement sensitivity compared with previous reports. We demonstrate robust temperature measurements with an error of 682 μK, experimental sensitivities below 50 mK/√Hz and a shot-noise limited sensitivity of 9.6 mK/√Hz. To confirm the utility of these high-performance nanothermometers, we quantify the temperature change induced by the thermometry measurement itself, specifically the optical excitation laser used to probe the NV spin state. In addition, we observe directly at the nanometre scale the transient heating caused by the exothermic mixing of dimethyl sulfoxide in water. Sub-millikelvin resolution and millikelvin sensitivity thermometry unlock the possibility of monitoring minute thermal fluctuations in living systems and assessing catalyst performance at the nanometre scale.
Abstract Temperature sensing at the nanoscale is a significant experimental challenge. Here, an approach using dressed states is reported to make a leading quantum sensor – the nitrogen‐vacancy (NV) center in diamond – selectively sensitive to temperature, even in the presence of normally confounding magnetic fields. Using an experimentally straightforward approach, the magnetic sensitivity of the NV center is suppressed by a factor of seven, while retaining full temperature sensitivity and narrowing the NV center linewidth. These results demonstrate the power of engineering the sensor Hamiltonian using external control fields to enable sensing with improved specificity to target signals.
Magnetic field fluctuations on nanometer length scales manifest in a diverse range of phenomena -- electron and spin dynamics in materials and devices, quantum many-body systems, and molecular chemistry. Measuring these phenomena requires sensors with a challenging combination of broad spectral bandwidth, high sensitivity, and nanoscale spatial resolution. Nitrogen-vacancy (NV) centers, atom-like quantum sensors in diamond, possess the requisite sensitivity and nanoscale sensing volume, but are typically limited in bandwidth by the practical speed of the applied quantum control sequence. Here, we overcome this limitation by exposing the NV qubit to a microwave dressing field during a dynamical decoupling sequence, which both amplifies and frequency-mixes target signals at arbitrary frequencies into the detection band of the dynamical decoupling protocol. We demonstrate this approach by using NV centers to detect both coherent and noisy nanoscale spin wave dynamics in a magnetic yttrium-iron-garnet (YIG) thin film over a broad frequency range. Our technique generalizes to other qubit platforms, providing a versatile framework for nanoscale spectroscopy across diverse physical and chemical systems.
Nitrogen-vacancy (N-V) centers in diamond are promising quantum sensors due to their ultralong coherence time under ambient conditions and multimodal sensing capability. N-V centers are strongly coupled to magnetic fields, leading to unprecedented sensitivity in magnetic field sensing. However, the coupling strengths between N-V centers and other crucial parameters, such as temperature and pressure, are not as strong as that of the magnetic field, resulting in a relative low sensitivity. A previous study showed that the temperature sensitivity of a diamond quantum sensor could be largely improved by magnetic criticality enhancement. Here, we propose and demonstrate a hybrid quantum thermometer composed of bulk diamond with ensemble N-V centers and a gadolinium magnetic flux concentrator. In addition to the magnetic criticality enhancement of gadolinium, our scheme leverages the magnetic flux concentration and ensemble N-V centers, achieving a temperature sensitivity of about 251.5nK/Hz. Near the critical point, the spin resonance to temperature $(\mathrm{\ensuremath{\partial}}{f}_{\ifmmode\pm\else\textpm\fi{}}/\mathrm{\ensuremath{\partial}}T)$ reached 57.3MHz/K under an external magnetic field of 1.213 G, which is about 774 times enhanced compared with that of bare N-V centers. The submicrokelvin temperature resolution of our hybrid thermometer can be used in the calibration of a reference point of temperature, integrated marine environmental surveys, laser-frequency stabilization, aerospace high-stability temperature-control systems, and many other practical applications on a macroscopic scale.
Abstract Nitrogen-vacancy centers have demonstrated significant potential as quantum magnetometers for nanoscale phenomena and sensitive field detection, attributed to their exceptional spin coherence at room temperature. However, it is challenging to achieve solid-state magnetometers that can simultaneously possess high spatial resolution and high field sensitivity. Here we demonstrate nanoscale quantum sensing with high field sensitivity by using on-chip diamond micro-ring resonators. The ring resonator enables the efficient use of photons by confining them in a nanoscale region, enabling the magnetic sensitivity of 1.0 μT/√Hz on a photonic chip with a measurement contrast of theoretical limit. We also show that the proposed on-chip approach can improve the sensitivity via efficient light extraction with photonic waveguide coupling. Our work provides a pathway toward the development of chip-scale packaged sensing devices that can detect various nanoscale physical quantities for fundamental science, chemistry, and medical applications.