Generic eigenstate preparation via measurement-based purification

TL;DR

This paper introduces a measurement-based scheme for preparing arbitrary eigenstates and purifying quantum states, demonstrating its effectiveness in entanglement distillation and accelerated state transfer, thus enriching quantum control techniques.

Contribution

It proposes a novel, measurement-driven approach for eigenstate preparation and purification applicable to multipartite systems, expanding quantum control capabilities.

Findings

Effective purification of entangled states from mixed or separable states.

Significant acceleration of Raman adiabatic passage using measurements.

Versatile scheme for arbitrary eigenstate preparation in quantum systems.

Abstract

It is not a general opinion that that a quantum system could be purified into a target eigenstate via repeated measurements on a coupled qubit rather than direct transitions in the Hamiltonian. The projective measurement on the ancillary qubit gives rise to the positive operator-valued measures on the system that can filter out the unwanted states except the target one. In application, we discuss the measurement-based entanglement purification by which maximally entangled states (Bell states and Greenberger-Horne-Zeilinger states) can be distilled from the maximally mixed states or separable states. We also demonstrate the significant acceleration of a stimulated Raman adiabatic passage assisted by similar measurements. Our scheme allows arbitrary eigenstate preparation and reveals efficiency in multipartite systems for subspace purification. It offers a promising and generic quantum-control framework enriching the functionalities of quantum measurement.