Self-heterodyne Technique for measuring Linewidth of Laser for applications in Continuous Variable Quantum Key Distribution

Geli Lv, Dazu Huang, Ying Guo

Max Rückmann, Sebastian Kleis, Christian Schaeffer

We experimentally investigate the impact of laser frequency noise on the achievable key rate and distance of a heterodyne continuous variable quantum key distribution system using different lasers at the transmitter site.

Julian König, Daniel Pereira, Martin Achleitner +5 more

We demonstrate the first fully integrated continuous-variable quantum key distribution (CV-QKD) transmitter, combining a narrow-linewidth laser, high-speed IQ modulator, and variable optical attenuator on a single indium phosphide (InP) chip. The transmitter occupies a compact footprint of 2 mm by 4.6 mm. Component characterization confirms single-mode laser operation with 120 kHz linewidth, >8 GHz modulator bandwidths, and 58 dB attenuation range. Deployed in a complete heterodyne CV-QKD system with probabilistically shaped 64-QAM, the system achieves an average excess noise of 0.1 shot noise units (SNU) and a secret key rate of 8.4 Mbit/s over a 14.3 km fiber link in the asymptotic regime. These results establish a practical and scalable route toward fully integrated quantum-secure communication systems.

Михаил Арсеньевич Фадеев, P. A. Morozova, Semyon V. Smirnov +3 more

Julian Konig, Daniel Pereira, Martin Achleitner +5 more

We demonstrate the first fully integrated continuous-variable quantum key distribution (CV-QKD) transmitter, combining a narrow-linewidth laser, high-speed IQ modulator, and variable optical attenuator on a single indium phosphide (InP) chip. The transmitter occupies a compact footprint of 2 mm by 4.6 mm. Component characterization confirms single-mode laser operation with 120 kHz linewidth, >8 GHz modulator bandwidths, and 58 dB attenuation range. Deployed in a complete heterodyne CV-QKD system with probabilistically shaped 64-QAM, the system achieves an average excess noise of 0.1 shot noise units (SNU) and a secret key rate of 8.4 Mbit/s over a 14.3 km fiber link in the asymptotic regime. These results establish a practical and scalable route toward fully integrated quantum-secure communication systems.

Михаил Арсеньевич Фадеев, P. A. Morozova, Semyon V. Smirnov +3 more