Quantum State Preparation by Controlled Dissipation in Finite Time: From Classical to Quantum Controllers

TL;DR

This paper introduces a versatile method for preparing arbitrary pure quantum states in finite time using controlled dissipation, leveraging classical feedback concepts adapted for quantum systems.

Contribution

It presents a general, scalable scheme for dissipative quantum state preparation employing a 'splitting-subspace' approach with practical control resources.

Findings

Applicable to multipartite qubit registers

Connections to experimental stabilization protocols

Flexible engineering of conditional quantum operations

Abstract

We propose a general scheme for dissipatively preparing arbitrary pure quantum states on a multipartite qubit register in a finite number of basic control blocks. Our "splitting-subspace" approach relies on control resources that are available in a number of scalable quantum technologies (complete unitary control on the target system, an ancillary resettable qubit and controlled-not gates between the target and the ancilla), and can be seen as a "quantum-controller" implementation of a sequence of classical feedback loops. We show how a large degree of flexibility exists in engineering the required conditional operations, and make explicit contact with a stabilization protocol used for dissipative quantum state preparation and entanglement generation in recent experiments with trapped ions.