Efficient Phase-Encoding Quantum Key Generation with Narrow-Band Single Photons

TL;DR

This paper introduces a novel phase-encoding quantum key distribution method using heralded narrow-band single photons, significantly enhancing efficiency for fiber-based quantum communication systems.

Contribution

It presents a new phase-encoding scheme that improves key generation efficiency without passive components, applicable to existing QKD protocols and suitable for long-distance fiber communication.

Findings

Efficiency doubled in BB84 scheme

Efficiency tripled in DPS scheme

Scalable efficiency improvement for N-period DPS systems

Abstract

We propose an efficient phase-encoding quantum secret key generation scheme with heralded narrow-band single photons. The key information is carried by the phase modulation directly on the single-photon temporal waveform without using any passive beam splitters or optical switches. We show that, when the technique is applied to the conventional fiber-based phase-encoding BB84 and differential phase shift (DPS) quantum key distribution schemes, the key generation efficiencies can be improved by a factor of 2 and 3, respectively. For N(>3)-period DPS systems, the key generation efficiency can be improved by a factor of N. The technique is suitable for quantum memory-based long-distance fiber communication system.