Decoherence-induced Multiphoton Interference

TL;DR

This paper demonstrates that decoherence can be harnessed as a resource to generate and control multiphoton quantum interference on a chip, challenging the traditional view of decoherence as purely detrimental.

Contribution

It introduces a method to create coherent multiphoton states via dissipative coupling to a shared reservoir on a lithium niobate chip, utilizing loss as a resource.

Findings

Successful creation of correlations among 2, 3, and 4 photons.

Tunable multiphoton interference by adjusting pump phase.

Loss and decoherence used as resources for quantum state engineering.

Abstract

Decoherence is usually deemed detrimental to quantum information processing. Its control and minimization require significant costs and operating overheads, constituting a major hurdle to commercialize quantum technology. Yet, quantum mechanics provides for counterintuitive, sometimes surprisingly useful, phenomena and effects associated with decoherence, leading to unusual practical utilities. Here we demonstrate such an example of fundamental interest and practical potential, where genuine quantum interference is created among multiple photons through their dissipative coupling to a shared reservoir. On a thin-film lithium niobate chip, we incoherently link two spontaneous parametric down-converters through a common, highly-lossy channel to create coherent multiphoton states. Our results show that faithful correlations can be established among two, three, and four photons, and tuned by shifting the relative phase between the driving pumps for the converters. This experiment highlights an under-explored territory in quantum science and technology, where loss and decoherence serve as resources, rather than adversaries, for quantum information processing.