Proposal for Inverting the Quantum Cloning of Photons

TL;DR

This paper proposes an experiment to invert quantum cloning of photons, aiming to demonstrate quantum information preservation, prove micro-macro entanglement, and develop sensitive quantum detection methods.

Contribution

It introduces a novel experimental approach to invert photon cloning, enabling tests of entanglement preservation and micro-macro entanglement in multiphoton states.

Findings

Potential to demonstrate quantum information preservation in cloning

Proof of micro-macro entanglement in multiphoton states

Enhanced sensitivity in quantum detection techniques

Abstract

We propose an experiment where a photon is first cloned by stimulated parametric down-conversion, making many (imperfect) copies, and then the cloning transformation is inverted, regenerating the original photon while destroying the copies. Focusing on the case where the initial photon is entangled with another photon, we study the conditions under which entanglement can be proven in the final state. The proposed experiment would provide a clear demonstration that quantum information is preserved in quantum cloning. It would furthermore allow a definitive experimental proof for micro-macro entanglement in the intermediate multiphoton state, which is still an outstanding challenge. Finally, it might provide a quantum detection technique for small differences in transmission (e.g., in biological samples), whose sensitivity scales better with the number of photons used than a classical transmission measurement.