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

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 neighbouring 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 thermometry 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 signal 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 temperature 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 processing and multicenter entanglement under ambient conditions.

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“…The four dangling sp 3 orbitals at the V Si site contribute four electrons. If V Si captures an additional electron, it becomes a negatively charged silicon vacancy (V − Si ) [16,[22][23][24] whose spin state was shown to be S = 3/2 by a radiofrequency-optical double resonance technique [23,25]. The site symmetry of V − Si is C 3v , as shown in Fig.…”

On accuracy estimation of ultrasonic thermometry technique with heated wire method

“…High-Intensity Focused Ultrasound (HIFU) [16][17] or a heated wire [15,18] and are used for heating the tissue-equivalent material of test objects. There are some other methods [23,24,25] of thermometry technique which could not be used in our task.…”

Diamond quantum thermometry: From foundations to applications

“…The transverse magnetic field can affect both spin and optical properties via spin mixing because it affects the ODMR shift, linewidth, and fluorescence brightness, as observed in colour centres in diamonds and silicon carbide [173][174][175][176][177][178]. SiV, GeV, and SnV are not substantially affected by the magnetic field at room temperature.…”