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All-optical quantum thermometry based on spin-level cross-relaxation and multicenter entanglement under ambient conditions in SiC

Anisimov, A. N.; Soltamov, V. A.; Breev, I. D.; Babunts, R. A.; Mokhov, E. N.; Astakhov, G.; Dyakonov, V.; Yakovlev, D. R.; Suter, D.; Baranov, P. G.

Abstract

All-optical thermometry technique based on the energy level cross-relaxation in atomic-scale spin centers in SiC is demonstrated. This technique exploits a giant thermal shift of the zero-field splitting for centers in the triplet ground state, S=1, undetected by photoluminescence (so called “dark” centers) coupling to neighbour- ing spin-3/2 centers which can be optically polarized and read out (“bright” centers), and does not require radiofrequency fields. EPR was used to identify defects. The width of the cross-relaxation line is almost an order of magnitude smaller than the width of the excited state level-anticrossing line, which was used in all-optical ther- mometry and which can not be significantly reduced since determined by the lifetime of the excited state. With approximately the same temperature shift and the same sig- nal intensities as for excited state level-anticrossing, cross-relaxation signal makes it possible to increase the sensitivity of the temperature measurement by more than an order of magnitude. Temperature sensitivity is estimated to be approximately 10 mK/Hz1/2 within a volume about 1 μ3, allocated by focused laser excitation in a scanning confocal microscope. Using cross-relaxation in the ground states of “bright” spin-3/2 centers and “dark” S=1 centers for temperature sensing and ground state level anti-crossing of “bright” spin-3/2 centers an integrated magnetic field and tempera- ture sensor with submicron space resolution can be implemented using the same spin system. The coupling of individually addressable “bright” spin-3/2 centers connected by a chain of “dark” S=1 spins, could be considered in quantum information pro- cessing and multicenter entanglement under ambient conditions.

Keywords: Defects; Quantum Technology; Thermometry; Silicon Carbide

Permalink: https://www.hzdr.de/publications/Publ-27798