1-Mbps Twin-Field Quantum Key Distribution over 200 km Using Independent Dissipative Kerr Solitons

TL;DR

This paper demonstrates a scalable, high-rate twin-field quantum key distribution over 200 km using independent dissipative Kerr soliton microcombs to multiplex 16 channels, achieving over 1 Mbps secure key rate.

Contribution

It introduces a novel architecture employing independent integrated microcombs for multi-wavelength TF-QKD, overcoming scalability challenges of traditional methods.

Findings

Achieved 1.57 Mbps SKR over 201 km with 16 channels.

Implemented stabilization of all comb lines with only pump wavelength and repetition rate control.

Demonstrated over an order-of-magnitude improvement over single-wavelength TF-QKD.

Abstract

Twin-field quantum key distribution (TF-QKD) dramatically enhances the secure key rate (SKR) over inter-city distances through its square-root scaling. Further improvements in aggregate SKR can be achieved by wavelength-division multiplexing (WDM) of parallel QKD channels. However, direct implementation in TF-QKD poses significant challenges, as each wavelength channel requires an independent ultra-stable seed laser, narrow-linewidth transmitters, and optical phase-locked loops (OPLLs), which are not easily scalable. Here, we circumvent these limitations by employing two independent, integrated dissipative Kerr soliton (DKS) microcombs at Alice and Bob as multi-wavelength sources. High-visibility single-photon interference across all wavelength channels is achieved by stabilizing the frequencies of every comb line - requiring only the stabilization of the pump wavelength and repetition rates of the two microcombs. Based on this architecture, we perform a full TF-QKD experiment using the sending-or-not-sending protocol, achieving a total SKR of 1.57 Mbps over 201.1 km of fiber using 16 DWDM channels. This result represents more than an order-of-magnitude enhancement compared with single-wavelength TF-QKD at the same distance. Given that a single DKS comb can support over 100 coherent lines across the C-band, this approach offers a scalable pathway toward high-rate quantum key distribution over inter-city distances.