Generic eigenstate preparation via measurement-based purification
Jia‐shun Yan, Jun Jing · Physical Review A · 2023
It is not a general opinion 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. Projective measurement on the ancillary qubit gives rise to positive operator-valued measures on the system that can filter out the unwanted states except the target one. In application, we discuss measurement-based entanglement purification by which maximally entangled states (Bell states and Greenberger-Horne-Zeilinger states) can be distilled from 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.