Abstract
Divacancy spins implement qubits with outstanding characteristics and capabilities in an industrial semiconductor host. On the other hand, there are still numerous open questions about the physics of these important defects, for instance, spin relaxation has not been thoroughly studied yet. Here, we carry out a theoretical study on environmental spin-induced spin relaxation processes of divacancy qubits in the 4H polytype of silicon carbide (4H-SiC). We reveal all the relevant magnetic field values where the longitudinal spin relaxation time T1 drops resonantly due to the coupling to either nuclear spins or electron spins. We quantitatively analyze the dependence of the T1 time on the concentration of point defect spins and the applied magnetic field and provide an analytical expression. We demonstrate that dipolar spin relaxation plays a significant role both in as-grown and ion-implanted samples and it often limits the coherence time of divacancy qubits in 4H-SiC.
Highlights
We study the longitudinal spin relaxation of divacancy qubits in 4H polytype of silicon carbide (4H-silicon carbide (SiC)) due to various environmental spins, such as spin-1/2, spin-1, and spin-3/2 point defects and 13C and 29Si nuclear spins
At the magnetic field value of the ground state level anticrossing (GSLAC), BGSLAC ðD; EÞ 1⁄4 ðD À EÞ=geμB, the Zeeman shift of the mS = −1 divacancy spin states compensates for the zero-field-splitting
Note that for different divacancy configurations the GSLAC resonance appears at different magnetic field values due to the different D
Summary
Through the example of the nitrogen-vacancy center in diamond[1,2,3,4](NV center), point defects in wide-bandgap semiconductors have demonstrated their potential for quantum-enhanced technologies.In particular, NV center-based devices are about to revolutionize sensing at the nanometer scale[5,6,7,8,9,10,11,12], while NV centers coupled to adjacent nuclear spins can serve as nodes for quantum internet[13,14,15] and quantum computing[16,17,18]. (NV center), point defects in wide-bandgap semiconductors have demonstrated their potential for quantum-enhanced technologies. Recent reports on the neutral divacancy have demonstrated 64 ms coherence time[24], implementation of spin-to-photon interface[25], nuclear spin operations for quantum memory applications[26,27], dynamic nuclear polarization[26,28,29], and a room temperature spin contrast as high as 30%30. In addition to the coherent properties of the qubits, longitudinal spin relaxation, with the corresponding decay time T1, is of great importance as it sets the fundamental limit for several applications, e.g., for dynamical decoupling techniques and sensing[34,35,36,37]. Even less is known about environmental resonances that may give rise to T1 spectroscopy and dynamic nuclear polarization in SiC
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