Charge Relaxation in a Single Electron Si/SiGe Double Quantum Dot

TL;DR

This study measures and analyzes the charge relaxation time in a Si/SiGe double quantum dot, revealing tunability and phonon-mediated relaxation, with implications for silicon spin qubit development.

Contribution

It provides the first systematic measurement of charge relaxation times in a Si/SiGe double quantum dot, demonstrating tunability over four orders of magnitude.

Findings

Maximum T_1 of 45 microseconds observed.

T_1 is tunable via detuning and tunnel coupling.

Relaxation is consistent with phonon-mediated processes.

Abstract

We measure the interdot charge relaxation time T_1 of a single electron trapped in an accumulation mode Si/SiGe double quantum dot. The energy level structure of the charge qubit is determined using photon assisted tunneling, which reveals the presence of a low lying excited state. We systematically measure T_1 as a function of detuning and interdot tunnel coupling and show that it is tunable over four orders of magnitude, with a maximum of 45 microseconds for our device configuration. Measured relaxation times are consistent with a phonon mediated energy relaxation process and indicate that low lying excited states may have important implications in the development of silicon spin qubits.