Quantum control of the environment in open quantum systems enables rapid qubit reset

TL;DR

This paper demonstrates how controlling the environment in open quantum systems enables rapid and high-fidelity qubit reset by reversing polaron formation through time-dependent coupling protocols, advancing quantum reset techniques.

Contribution

It introduces a method to control the environment in open quantum systems using time-dependent coupling, achieving fast and high-fidelity qubit reset by reversing polaron states.

Findings

Achieved qubit reset with $10^{-6}$ excited-state population in 10 ns.

Identified coupling protocols to control environment dynamics effectively.

Showed environment control can improve quantum process efficiency.

Abstract

Qubit reset is crucial in quantum technology and is typically achieved by coupling the qubit to a dissipative environment. However, the achievable speed and fidelity are limited by qubit-environment entanglement. We use exact tensor-network simulations and a time-dependent variational approach to investigate these effects for transmon qubits with a time-dependent system-environment coupling. We show that they are due to the formation of a polaron state and how this can be reversed using a time-dependent coupling. Coupling protocols are identified which achieve reset with an excited-state population of $10^{-6}$ in $10$ ns. A related paper [C. Ortega-Taberner, E. O'Neill and P. R. Eastham, arXiv:XXXX.XXXX] addresses the complementary case of control via a time-dependent Hamiltonian. Our work shows how the dynamics of the environment of an open quantum system can be controlled to design effective quantum processes in non-Markovian systems.