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Register a new userLocking of electron spin coherence over fifty milliseconds in natural silicon carbide
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We demonstrate that silicon carbide (SiC) with natural isotope abundance can preserve a coherent spin superposition in silicon vacancies over unexpectedly long time approaching 0.1 seconds. The spin-locked subspace with drastically reduced decoherence rate is attained through the suppression of heteronuclear spin cross-talking by applying a moderate magnetic field in combination with dynamic decoupling from the nuclear spin baths. We identify several phonon-assisted mechanisms of spin-lattice relaxation, ultimately limiting quantum coherence, and find that it can be extremely long at cryogenic temperature, equal or even longer than 8 seconds. Our approach may be extended to other polyatomic compounds and open a path towards improved qubit memory for wafer-scale quantum techmologies.
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Irradiation-induced lattice defects in silicon carbide (SiC) have already exceeded their previous reputation as purely performance-inhibiting. With their remarkable quantum properties, such as long room-temperature spin coherence and the possibility of downscaling to single-photon source level, they have proven to be promising candidates for a multitude of quantum information applications. One of the most crucial parameters of any quantum system is how long its quantum coherence can be preserved. By using the pulsed optically detected magnetic resonance (ODMR) technique, we investigate the spin-lattice relaxation time ($T_1$) and spin coherence time ($T_2$) of silicon vacancies in 4H-SiC created by neutron, electron and proton irradiation in a broad range of fluences. We also examine the effect of irradiation energy and sample annealing. We establish a robustness of the $T_1$ time against all types of irradiation and reveal a universal scaling of the $T_2$ time with the emitter density. Our results can be used to optimize the coherence properties of silicon vacancy qubits in SiC for specific tasks.
The elimination of defects from SiC has facilitated its move to the forefront of the optoelectronics and power-electronics industries. Nonetheless, because the electronic states of SiC defects can have sharp optical and spin transitions, they are increasingly recognized as a valuable resource for quantum-information and nanoscale-sensing applications. Here, we show that individual electron spin states in highly purified monocrystalline 4H-SiC can be isolated and coherently controlled. Bound to neutral divacancy defects, these states exhibit exceptionally long ensemble Hahn-echo spin coherence, exceeding 1 ms. Coherent control of single spins in a material amenable to advanced growth and microfabrication techniques is an exciting route to wafer-scale quantum technologies.
In this paper, we study the electron spin decoherence of single defects in silicon carbide (SiC) nuclear spin bath. We find that, although the natural abundance of $^{29}rm{Si}$ ($p_{rm{Si}}=4.7%$) is about 4 times larger than that of $^{13}{rm C}$ ($p_{rm{C}}=1.1%$), the electron spin coherence time of defect centers in SiC nuclear spin bath in strong magnetic field ($B>300~rm{Gauss}$) is longer than that of nitrogen-vacancy (NV) centers in $^{13}{rm C}$ nuclear spin bath in diamond. The reason for this counter-intuitive result is the suppression of heteronuclear-spin flip-flop process in finite magnetic field. Our results show that electron spin of defect centers in SiC are excellent candidates for solid state spin qubit in quantum information processing.
Spin defects in silicon carbide (SiC) have attracted increasing interests due to their excellent optical and spin properties, which are useful in quantum information processing. In this work, we systematically investigate the temperature dependence of spin properties of divacancy defects in implanted 4H-SiC. The zero-field splitting parameter D, the inhomogeneous dephasing time $T_2^{*}$, the coherence time $T_2$, and the depolarization time $T_1$ are extensively explored in a temperature range from 5 K to 300 K. Two samples implanted with different nitrogen molecule ion fluences ($N_2^{+}$, $10^{14}/rm cm^{2}$ and $10^{13}/rm cm^{2}$) are investigated, whose spin properties are shown to have similar temperature-dependent behaviors. Still, the sample implanted with a lower ion fluence has longer $T_2$ and $T_1$. We provide possible theoretical explanations for the observed temperature-dependent dynamics. Our work promotes the understanding of the temperature dependence of spin properties in solid-state systems, which can be helpful for constructing wide temperature-range thermometers based on the mature semiconductor material.
We report the influence of static mechanical deformation on the zero-field splitting of silicon vacancies in silicon carbide at room temperature. We use AlN/6H-SiC heterostructures deformed by growth conditions and monitor the stress distribution as a function of distance from the heterointerface with spatially-resolved confocal Raman spectroscopy. The zero-field splitting of the V1/V3 and V2 centers in 6H-SiC, measured by optically-detected magnetic resonance, reveal significant changes at the heterointerface compared to the bulk value. This approach allows unambiguous determination of the spin-deformation interaction constant, which turns out to be $0.75 , mathrm{GHz}$ for the V1/V3 centers and $0.5 , mathrm{GHz}$ for the V2 centers. Provided piezoelectricity of AlN, our results offer a strategy to realize the on-demand fine tuning of spin transition energies in SiC by deformation.
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