Resonator-Assisted Quantum Bath Engineering of a Flux Qubit

TL;DR

This paper presents a method for preparing arbitrary quantum states of a superconducting flux qubit using resonator-assisted bath engineering, achieving high fidelity and fast state preparation in a dissipative environment.

Contribution

It introduces a novel approach to quantum bath engineering for flux qubits, enabling controllable state preparation with high fidelity using resonator photon loss.

Findings

State-preparation fidelities >99% achievable

Preparation time on the order of microseconds

Effective polarization control via resonator-assisted dissipation

Abstract

We demonstrate quantum bath engineering for preparation of any orbital state with controllable phase factor of a superconducting flux qubit assisted by a microwave coplanar waveguide resonator. We investigate the polarization efficiency of the arbitrary direction rotating on the Bloch sphere, and obtain an effective Rabi frequency by using the convergence condition of Markovian master equation. The processes of polarization can be implemented effectively in a dissipative environment created by resonator photon loss when the spectrum of the microwave resonator matches with the specially tailored Rabi and resonant frequencies of the drive. Our calculations indicate that state-preparation fidelities in excess of 99\% and the required time on the order of magnitude of microsecond are in principle possible for experimentally reasonable sample parameters. Furthermore, our proposal could be applied to other systems with spin-based qubits.