Temperature shifts of the resonances of theNV−center in diamond

Abstract

Significant attention has been recently focussed on the realization of high precision nanothermometry using the spin-resonance temperature shift of the negatively charged nitrogen-vacancy (NV − ) center in diamond. However, the precise physical origins of the temperature shift is yet to be understood. Here, the shifts of the center's optical and spin resonances are observed and a model is developed that identifies the origin of each shift to be a combination of thermal expansion and electron-phonon interactions. Our results provide new insight into the center's vibronic properties and reveal implications for NV − thermometry.PACS numbers: 63.20.kp, 61.72.jn, 76.70.hb The negatively charged nitrogen-vacancy (NV − ) center in diamond [1] is an important quantum technology platform for a range of new applications exploiting quantum coherence. Beyond quantum information processing, the prospect of employing the NV − center as a room temperature nanoscale electric and magnetic field sensor has attracted considerable interest [2][3][4][5][6][7]. Recently, the effects of temperature on the center's ground state spin resonance have been investigated [9], which enabled the influence of temperature on existing NV − metrology applications to be characterized and new thermometry applications to be proposed [8][9][10][11] and demonstrated [12][13][14]. However, the temperature shift of the center's spin resonance is not well understood and previous attempts at modelling the shift have been largely unsuccessful [9][10][11]. It is evident that the implementation of the NV − center as a nano-thermometer, magnetometer or electrometer requires a thorough understanding of the temperature shifts of its resonances, particularly if these implementations are designed for ambient conditions [15]. Here, the temperature shifts of the center's visible, infrared and spin resonances are observed and a model is developed that identifies the origin of each shift to be a combination of thermal expansion and electron-phonon interactions. This new insight reveals implications for NV − metrology.The NV − center is a C 3v point defect in diamond consisting of a substitutional nitrogen atom adjacent to a carbon vacancy that has trapped an additional electron (refer to Fig. 1a). As depicted in Fig. 1b, the oneelectron orbital level structure of the NV − center contains three defect orbital levels (a 1 , e x and e y ) deep within the diamond bandgap. Electron paramagnetic resonance (EPR) observations and ab initio calculations indicate that these defect orbitals are highly localized to the center [16][17][18][19][20]. Figure 1c shows the center's manyelectron electronic structure generated by the occupation of the three defect orbitals by four electrons [21,22], including the low-temperature zero phonon line (ZPL) energies of the visible (E V ∼1.946 eV) [23] and infrared (E IR ∼1.19 eV) [24][25][26] transitions. The energy separations of the spin triplet and singlet levels ( 3 A 2 ↔ 1 E and 1 A 1 ↔ 3 E) are unknown. As depicted in the inset of Fig...

All-Optical Thermometry and Thermal Properties of the Optically Detected Spin Resonances of the NV– Center in Nanodiamond

“…14,[23][24][25][26] Consequently, the center's excited state spin resonances represent additional quantum resources for the center's exciting applications that are yet to be precisely examined. 27 To rectify this situation, we report comprehensive observations of the effects of temperature on all of the optically detected spin resonances of NV − centers in nano-diamond.…”

“…of centers in bulk diamond. 14,[23][24][25][26]53 Acosta et al have also studied the temperature dependence of the 3 A 2 strain splitting E g.s. in bulk diamond NV − ensembles, but since it was much smaller than D g.s.…”

“…, did not observe a variation above experimental uncertainty over the range 5-400 K. 23,24 The pressure and temperature dependence of interactions. 26 Since thermal expansion and hydrostatic pressure are intimately related, the contribution of thermal expansion to the temperature shifts may be alternatively expressed in terms of the hydrostatic pressure shifts and the pressure of thermal expansion in diamond. 53 …”

Diamond-nitrogen-vacancy electronic and nuclear spin-state anticrossings under weak transverse magnetic fields

“…where hD gs is the NV ground-state crystal field splitting energy (which is temperature-dependent [14]), d ⊥ and d || are the components of the ground-state electric dipole moment, the total effective electric field = E + σ encompasses both static electric fields E and strain σ , g e and g n are the electric and nuclear Landé g factors, μ B and μ n are the Bohr and nuclear magneton constants, B is the applied magnetic field, A || and A ⊥ describe the axial and transverse magnetic hyperfine interactions with the 14 N nucleus, P gs is the nuclear electric quadrupole parameter, S is the electron spin operator, and I is the spin operator of the 14 N nucleus. Figure 1 shows the numerically calculated electronic ground-state triplet and 14 interaction driven level anticrossings scales quadratically with respect to the applied transverse magnetic field as described in [25].…”

“…DOI: 10.1103/PhysRevA.94.021401 Nitrogen-vacancy (NV) defect centers in diamond are optically polarizable quantum systems with spin-dependent fluorescence. Using electron spin resonance (ESR) under ambient conditions, sensitivity to electric fields [1][2][3][4], transverse and axial magnetic fields [5][6][7][8][9][10], temperature [11][12][13][14], strain [15], and pressure [16] have been observed via resonance frequency shifts of the NV ground-state manifold. Nonseparable sensitivity to multiple environmental factors is problematic when it comes to using the NV as a sensor.…”