A heralded quantum amplifier of multi-photon states

TL;DR

This paper demonstrates a high-fidelity, post-selection-free heralded amplifier for multi-photon quantum states, achieving significant intensity gain and coherence preservation, advancing quantum networking and information processing capabilities.

Contribution

The authors experimentally realize a scalable, noiseless heralded amplifier for multi-photon states, overcoming previous limitations in multi-photon quantum state amplification.

Findings

Achieved over a hundredfold intensity gain for two-photon states

Demonstrated coherence-preserving amplification operation

Scalable approach applicable to higher photon numbers

Abstract

Large-scale quantum networking systems will inevitably require methods to overcome photon loss. While the no-cloning theorem forbids perfect and deterministic amplification of unknown quantum states, probabilistic heralded amplification schemes offer a viable path forward. Yet, for over a decade, successful multi-photon state amplification has remained out of reach, despite the fundamental importance of such states in achieving quantum advantage in optical applications. Here, we experimentally demonstrate a high-fidelity and post-selection-free amplifier for multi-photon states. We achieve heralded amplification of states with up to two photons in a single optical mode, with over a hundredfold intensity gain, and verify the coherence-preserving operation of our scheme. Our approach is scalable to higher photon numbers and enables noiseless amplification of complex multi-photon quantum states, with applications in large-scale quantum communication systems, distributed quantum metrology, and information processing.