Resonant Tunneling Charge Detection and Dephasing

We analyze the properties of charge detection and dephasing of a charge qubit through a resonant tunneling detector. The resonant tunneling detector is modeled as a one-dimensional double barrier delta-function potential with its barrier height being sensitive to the charge state of the qubit. The dephasing and the measurement rates show quasi-periodic oscillations as a function of the energy of the incident electron. We show that there exists a phase-sensitive contribution to dephasing, even for a detector with perfect mirror symmetry, which is not observed in a non-resonant detector. We demonstrate that this behavior originates from the abrupt phase change in the reflection amplitude, which is not sensitive to the transmission probability, but retains the charge state information. KCI Citation Count: 4