We develop a master equation approach to study the backaction of quantum point contact (QPC) on a double quantum dot (DQD) at zero bias voltage. We reveal why electrons can pass through the zero-bias DQD only when the bias voltage across the QPC exceeds a threshold value determined by the eigenstate energy difference of the DQD. This derived excitation condition agrees well with experiments on QPC-induced inelastic electron tunneling through a DQD [S. Gustavsson et al., Phys. Rev. Lett. 99, 206804(2007)]. Moreover, we propose a new scheme to generate a pure spin current by the QPC in the absence of a charge current.
@article{arxiv.0910.5052,
title = {Backaction of a charge detector on a double quantum dot},
author = {Shi-Hua Ouyang and Chi-Hang Lam and J. Q. You},
journal= {arXiv preprint arXiv:0910.5052},
year = {2015}
}