Nonlocality test of energy-time entanglement via nonlocal dispersion cancellation with nonlocal detection

TL;DR

This paper demonstrates a successful nonlocality test of energy-time entanglement over 62 km of optical fiber using nonlocal dispersion cancellation and nonlocal detection, advancing quantum communication and fundamental tests.

Contribution

It provides the first experimental violation of a Bell-like inequality for energy-time entanglement over long-distance fiber channels using nonlocal detection.

Findings

Violation of Bell-like inequality after 62 km fiber transmission

First experimental demonstration of nonlocality test with single-photon detectors at long distances

Feasibility of nonlocality tests in fiber and free-space quantum communication

Abstract

Energy-time entangled biphoton source plays a great role in quantum communication, quantum metrology and quantum cryptography due to its strong temporal correlation and capability of nonlocal dispersion cancellation. As a quantum effect, nonlocal dispersion cancellation is further proposed as an alternative way for nonlocality test of continuous variable entanglement via the violation of Bell-like inequality proposed by Wasak et al. [Phys. Rev. A, 82, 052120 (2010)]. However, to date there is no experimental report either on the inequality violation or on a nonlocal detection with single-photon detectors at long-distance transmission channel, which is key for a true nonlocality test. In this paper, we report an experimental realization of a violation of the inequality after 62km optical fiber transmission at telecom wavelength with a nonlocal detection based on event timers and cross-correlation algorithm, which indicates a successful nonlocal test of energy-time entanglement. This work provides a new feasibility for the strict test of the nonlocality for continuous variables in both long-distance communication fiber channel and free space.