Phase readout of a charge qubit capacitively coupled to an open double quantum dot

TL;DR

This paper investigates how the state of a charge qubit influences the transient current in a coupled double quantum dot system, enabling both charge and phase readout of the qubit.

Contribution

It introduces a method to read out the charge and phase of a qubit via transient current measurements in a capacitively coupled quantum dot system.

Findings

Transient current peaks correlate with initial qubit states.

The method allows phase information extraction from current dynamics.

Charge readout is achieved through resonant and off-resonant transport analysis.

Abstract

We study the dynamics of a charge qubit that is capacitively coupled to an open double quantum dot. Depending on the qubit state, the transport through the open quantum dot may be resonant or off-resonant, such that the qubit affects the current through the open double dot. We relate the initial qubit state to the magnitude of an emerging transient current peak. The relation between these quantities enables the readout of not only the charge but also the phase of the qubit.