Correlations of spin splitting and orbital fluctuations due to 1/f charge noise in the Si/SiGe Quantum Dot

Fluctuations of electric fields can change the position of a gate-defined quantum dot in a semiconductor heterostructure. In the presence of magnetic field gradient, these stochastic shifts of electron's wavefunction lead to fluctuations of electron's spin splitting. The resulting spin dephasing due to charge noise limits the coherence times of spin qubits in isotopically purified Si/SiGe quantum dots. We investigate the spin splitting noise caused by such process caused by microscopic motion of charges at the semiconductor-oxide interface. We compare effects of isotropic and planar displacement of the charges, and estimate their densities and typical displacement magnitudes that can reproduce experimentally observed spin splitting noise spectra. We predict that for defect density of 10¹⁰ cm⁻², visible correlations between noises in spin splitting and in energy of electron's ground state in the quantum dot, are expected.

电场波动可导致半导体异质结构中由栅极定义的量子点位置发生变化。在磁场梯度存在的情况下，这些电子波函数的随机偏移会导致电子自旋分裂的波动。由电荷噪声引起的由此产生的自旋去相位限制了同位素纯化硅/锗量子点中自旋量子比特的相干时间。我们研究了由半导体-氧化物界面处电荷微观运动引起的自旋分裂噪声。我们比较了电荷各向同性和平面位移的影响，并估计了其密度和典型位移量，这些量能够再现实验观察到的自旋分裂噪声光谱。我们预测，对于缺陷密度为10¹⁰ cm⁻²，预期在自旋分裂噪声和量子点中电子基态能量噪声之间将出现可见的相关性。