Correlation-induced suppression of decoherence in capacitively coupled Cooper-pair boxes

TL;DR

This paper demonstrates that Coulomb correlation between two capacitively coupled Cooper-pair boxes can significantly suppress charge-induced decoherence, enhancing the potential of these systems as logical qubits.

Contribution

The study introduces an experimentally feasible method to reduce decoherence in charge qubits by leveraging Coulomb correlation in coupled CPBs.

Findings

Decoherence is suppressed by Coulomb correlation in coupled CPBs.

A low-decoherence subspace of two states is identified.

Coupled CPBs show promise as logical qubits with improved coherence.

Abstract

Charge fluctuations from gate bias and background traps severely limit the performance of a charge qubit in a Cooper-pair box (CPB). Here we present an experimentally realizable method to control the decoherence effects of these charge fluctuations using two strongly capacitively coupled CPBs. This coupled-box system has a low-decoherence subspace of two states. Our results show that the inter-box Coulomb correlation can help significantly suppress decoherence of this two-level system, making it a promising candidate as a logical qubit, encoded using two CPBs.