Magnetic Criticality Enhanced Hybrid Nanodiamond Thermometer under Ambient Conditions

Abstract

Nitrogen vacancy (NV) centres in diamond are attractive as quantum sensors owing to their superb coherence under ambient conditions. However, the NV centre spin resonances are relatively insensitive to some important parameters such as temperature. Here we design and experimentally demonstrate a hybrid nano-thermometer composed of NV centres and a magnetic nanoparticle (MNP), in which the temperature sensitivity is enhanced by the critical magnetization of the MNP near the ferromagnetic-paramagnetic transition temperature. The temperature susceptibility of the NV center spin resonance reached 14 MHz/K, enhanced from the value without the MNP by two orders of magnitude. The sensitivity of a hybrid nano-thermometer composed of a Cu1-xNix MNP and a nanodiamond was measured to be 11 mK/Hz 1/2 under ambient conditions. With such high-sensitivity, we monitored nanometer-scale temperature variation of 0.3 degree with a time resolution of 60 msec. This hybrid nano-thermometer 2 provides a novel approach to studying a broad range of thermal processes at nanoscales such as nano-plasmonics, sub-cellular heat-stimulated processes, thermodynamics of nanostructures, and thermal remanent magnetization of nanoparticles. MAIN TEXT:Nanoscale temperature sensing is important for studying a broad range of phenomena in physics, biology, and chemistry, such as the temperature heterogeneities 1-3 in living cells, heat dissipation in nano circuits 4 , nano-plasmonics, and nano-magnetism (like thermal remanent magnetism of nanoparticles). There have been a number of nanoscale temperature detection schemes 5, 6 , such as scanning thermal microscopy (SThM) 7-9 , SQUID based nano-thermometer 10 , and fluorescence thermometers 11 based on rare-

Robust and efficient quantum optimal control of spin probes in a complex (biological) environment. Towards sensing of fast temperature fluctuations

“…However, the Coop-D-Ramsey converges at the end of each segment to the desired superposition state. To calculate the optimal set of u k (t) for the Coop-D-Ramsey, we used the projectors, which are described in equations (6). We labeled the projectors between 'seg1' and 'seg2' with ( ) figure B1).…”

“…To introduce cooperativity, we use the projector sets ( ) ( ) / P P xy xy (6) in two sub-ensembles. All P xy project into a two-dimensional subspace of the Liouville space of density matrices, with the difference, that projectors with the superscript (b) introduce an additional p 2 phase shift.…”

“…To demonstrate that it is mandatory to use both projector sets, we compiled in appendix B one sequence with ( ) P xy 1 and ( ) P xy 2 only, and one including all projectors defined in equations (6). Only in the latter case the correct response of the D-Ramsey can be resampled.…”

“…One representative of such quantum sensors, is the negatively charged nitrogen-vacancy center (NV) in diamond. Several applications as a magnetic [1] and electric field [2], pressure [3] and temperature [4][5][6][7][8][9][10][11][12] probe have been demonstrated. In addition, one can also extract chemical information about samples by nuclear magnetic resonance with ∼Hz spectral and nanometer-scale spatial resolution [13,14].…”

Optimal architecture for diamond-based wide-field thermal imaging

“…Besides building on the temperature dependance of the spin resonance, temperature sensing with NV centers in diamond, can utilize the temperature dependance of their optical response (Debye-Waller factor, zero-phonon line or Anti-Stokes photoluminescence wavelength) 21,22 ; such all-optical schemes have also been extended to other point defects in diamond, including SiV, GeV or SnV colored centers 23-25 . Last but not least, the temperature sensitivities of NV centers can be pushed down to few tens µK/ √ Hz, by relying on a transduction of temperature gradients on magnetic fields probed by their electronic spins 26,27 .These thermal sensing modalities can be exploited for thermal imaging. A first strategy consists in grafting a NV-doped nanodiamond at the apex of either an optical fiber or an AFM tip, which is scanned above the surface of the sample to be probed 28-30 .…”