Purification and switching protocols for dissipatively stabilized entangled qubit states

TL;DR

This paper introduces a scheme to purify and stabilize entangled qubit states using auxiliary dissipative cavity modes, achieving high fidelities in superconducting qubits despite dephasing limitations.

Contribution

The authors propose a novel purification protocol that enhances entanglement fidelity by leveraging auxiliary dissipative modes in a cavity-QED setup.

Findings

Achieves up to 90% fidelity in entangled states

Effective in superconducting qubits with current technology

Purification improves robustness against dephasing

Abstract

Pure dephasing processes limit the fidelities achievable in driven-dissipative schemes for stabilization of entangled states of qubits. We propose a scheme which, combined with already existing entangling methods, purifies the desired entangled state by driving out of equilibrium auxiliary dissipative cavity modes coupled to the qubits. We lay out the specifics of our scheme and compute its efficiency in the particular context of two superconducting qubits in a cavity-QED architecture, where the strongly coupled auxiliary modes provided by collective cavity excitations can drive and sustain the qubits in maximally entangled Bell states with fidelities reaching 90% for experimentally accessible parameters.