Hybridized solid-state qubit in the charge-flux regime

TL;DR

This paper introduces a hybrid charge-flux superconducting qubit with a third Josephson junction, enabling optimized low-decoherence operation and efficient quantum measurement of charge or current.

Contribution

It presents a novel hybridized qubit design that combines charge and flux regimes with a third Josephson junction for improved performance.

Findings

Reduced decoherence through optimal junction design

Efficient measurement of charge or current achieved

Consideration of charge and flux noise effects

Abstract

Most superconducting qubits operate in a regime dominated by either the electrical charge or the magnetic flux. Here we study an intermediate case: a hybridized charge-flux qubit with a third Josephson junction (JJ) added into the SQUID loop of the Cooper-pair box. This additional JJ allows the optimal design of a low-decoherence qubit. Both charge and flux $1/f$ noises are considered. Moreover, we show that an efficient quantum measurement of either the current or the charge can be achieved by using different area sizes for the third JJ.