Demonstration of a Quantum Controlled-NOT Gate in the Telecom Band

TL;DR

This paper demonstrates a fiber-based quantum CNOT gate operating in the telecom band, capable of producing and characterizing Bell states with high fidelity, advancing quantum communication and optical quantum computing.

Contribution

It presents the first realization of a telecom-band fiber-based quantum CNOT gate with full Bell state characterization and high entangling fidelity.

Findings

Successfully produced all four Bell states

Achieved high-fidelity entanglement

Validated the gate's suitability for quantum communication

Abstract

We present the first quantum controlled-NOT (CNOT) gate realized using a fiber-based indistinguishable photon-pair source in the 1.55 $\mu$m telecommunications band. Using this free-space CNOT gate, all four Bell states are produced and fully characterized by performing quantum state tomography, demonstrating the gate's unambiguous entangling capability and high fidelity. Telecom-band operation makes this CNOT gate particularly suitable for quantum information processing tasks that are at the interface of quantum communication and linear optical quantum computing.