# Reservoir Engineering using Quantum Optimal Control for Qubit Reset

## TL;DR

This paper presents a method to optimize the reset of superconducting qubits by employing quantum optimal control to engineer reservoir interactions, significantly improving reset efficiency in terms of speed and error reduction.

## Contribution

It introduces a novel approach combining quantum optimal control with reservoir engineering to enhance qubit reset protocols.

## Key findings

- Optimized reset protocols achieve faster qubit initialization.
- Time-dependent control shapes improve reset fidelity.
- Maximizing decay rates enhances population transfer efficiency.

## Abstract

We determine how to optimally reset a superconducting qubit which interacts with a thermal environment in such a way that the coupling strength is tunable. Describing the system in terms of a time-local master equation with time-dependent decay rates and using quantum optimal control theory, we identify temporal shapes of tunable level splittings which maximize the efficiency of the reset protocol in terms of duration and error. Time-dependent level splittings imply a modification of the system-environment coupling, varying the decay rates as well as the Lindblad operators. Our approach thus demonstrates efficient reservoir engineering employing quantum optimal control. We find the optimized reset strategy to consist in maximizing the decay rate from one state and driving non-adiabatic population transfer into this strongly decaying state.