Speeding up thermalization and quantum state preparation through engineered quantum collisions

TL;DR

This paper introduces a collision model approach with engineered ancilla interactions, significantly accelerating thermalization and quantum state preparation in cavity fields without time-dependent Hamiltonian control.

Contribution

It presents a novel collision-based method optimized via genetic algorithms for fast quantum state preparation, bridging the gap between control and reservoir engineering.

Findings

Significant speed-up in thermalization process.

Efficient preparation of coherent, squeezed, and non-Gaussian states.

Diagonal qubit ancilla states are sufficient for thermalization.

Abstract

We realize fast thermalization and state preparation of a single mode cavity field using a collision model-like approach, where a sequence of qubits or three level system ancillae, sequentially interacting with the field, is engineered with a genetic algorithm approach. In contrast to optimal control techniques, there is no time-dependent system Hamiltonian control deployed and, in contrast to reservoir engineering, the engineered full system-environment dynamics is optimized, and the target is not a steady state. We prove a significant speed up in thermalization - for which we show that diagonal qubit ancilla states are sufficient - and in the preparation of coherent states. We demonstrate the preparation of squeezed states and of highly non-Gaussian states. Our work offers a new alternative for fast preparation of cavity states that lays in between optimal Hamiltonian control and reservoir engineering, and gives further insights on the resources needed to realize or speed up the preparation of such states.