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

Abstract

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 $10^{10}$ cm${}^{-2}$, visible correlations between noises in spin splitting and in energy of electron's ground state in the quantum dot, are expected.

6 pages, 4 figures, added repository: https://doi.org/10.24435/materialscloud:91-mj

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• Decoherence induced by a sparse bath of two-level fluctuators: peculiar features of $1/f$ noise in high-quality qubits
• Industrially fabricated single-electron quantum dots in Si/Si-Ge heterostructures
• Interacting Two-Level Systems as a Source of 1/f Charge Noise in Quantum Dot Qubits
• Decoherence of electron spin qubit during transfer between two semiconductor quantum dots at low magnetic fields
• Heavy-hole spin relaxation in quantum dots: Isotropic versus anisotropic effects
• Decoherence and fidelity enhancement during shuttling of entangled spin qubits