Vibronic States and Their Effect on the Temperature and Strain Dependence of Silicon-Vacancy Qubits in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mn>4</mml:mn><mml:mi>H</mml:mi></mml:math>-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mrow><mml:mi>Si</mml:mi><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>
Péter Udvarhelyi, Gergő Thiering, Naoya Morioka, Charles Babin, Florian Kaiser, Daniil Lukin, Takeshi Ohshima, Jawad Ul-Hassan, Nguyen Tien Son, Jelena Vučković, Jörg Wrachtrup, Adam Gali
Abstract
Silicon-vacancy qubits in silicon carbide ($\mathrm{Si}\mathrm{C}$) are emerging tools in quantum-technology applications due to their excellent optical and spin properties. In this paper, we explore the effect of temperature and strain on these properties by focusing on the two silicon-vacancy qubits, V1 and V2, in $4H$-$\mathrm{Si}\mathrm{C}$. We apply density-functional theory beyond the Born-Oppenheimer approximation to describe the temperature-dependent mixing of electronic excited states assisted by phonons. We obtain a polaronic gap of around 5 and 22 meV for the V1 and V2 centers, respectively, which results in a significant difference in the temperature-dependent dephasing and zero-field splitting of the excited states, which explains recent experimental findings. We also compute how crystal deformations affect the zero-phonon line of these emitters. Our predictions are important ingredients in any quantum applications of these qubits sensitive to these effects.