Tunable Spin Loading and T-1 of a Silicon Spin Qubit Measured by Single-Shot Readout

Simmons, C. B. and Prance, J. R. and Van Bael, B. J. and Koh, Teck Seng and Shi, Zhan and Savage, D. E. and Lagally, M. G. and Joynt, R. and Friesen, Mark and Coppersmith, S. N. and Eriksson, M. A. (2011) Tunable Spin Loading and T-1 of a Silicon Spin Qubit Measured by Single-Shot Readout. Physical review letters, 106 (15): 156804. -. ISSN 0031-9007

Abstract

We demonstrate single-shot readout of a silicon quantum dot spin qubit, and we measure the spin relaxation time T-1. We show that the rate of spin loading can be tuned by an order of magnitude by changing the amplitude of a pulsed-gate voltage, and the fraction of spin-up electrons loaded can also be controlled. This tunability arises because electron spins can be loaded through an orbital excited state. Using a theory that includes excited states of the dot and energy-dependent tunneling, we find that a global fit to the loading rate and spin-up fraction is in good agreement with the data.