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arXiv · 1604.02884

Quantum and Tunnelling Capacitance in Charge and Spin Qubits

R. Mizuta·R. M. Otxoa·A. C. Betz·M. F. Gonzalez-Zalba
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Abstract

We present a theoretical analysis of the capacitance of a double quantum dot in the charge and spin qubit configurations probed at high-frequencies. We find that in general the total capacitance of the system consists of two state-dependent terms: The quantum capacitance arising from adiabatic charge motion and the tunnelling capacitance that appears when repopulation occurs at a rate comparable or faster than the probing frequency. The analysis of the capacitance lineshape as a function of externally controllable variables offers a way to characterize the qubits' charge and spin state as well as relevant system parameters such as charge and spin relaxation times, tunnel coupling, electron temperature and electron g-factor. Overall, our analysis provides a formalism to understand dispersive qubit-resonator interactions which can be applied to high-sensitivity and non-invasive quantum-state readout.

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R. Mizuta, R. M. Otxoa, A. C. Betz, M. F. Gonzalez-Zalba. 2016-04-11. Quantum and Tunnelling Capacitance in Charge and Spin Qubits. https://doi.org/10.1103/physrevb.95.045414

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