Modulator-free coherent-one-way quantum key distribution

Abstract

Time-bin encoding is an attractive method for transmitting photonic qubits over long distances with minimal decoherence. It allows a simple receiver for quantum key distribution (QKD) that extracts a key by measuring time of arrival of photons and detects eavesdropping by measuring interference of pulses in different time bins. In the past, coherent pulses have been generated using a CW laser and an intensity modulator. A greatly simplified transmitter is proposed and demonstrated here that works by directly modulating the laser diode. Coherence between pulses is maintained by a weak seed laser. The modulator-free source creates time-bin encoded pulses with a high extinction ratio (29.4 dB) and an interference visibility above 97 %. The resulting QKD transmitter gives estimated secure key rates up to 4.57 Mbit/s, the highest yet reported for coherent-one-way QKD, and can be programmed for all protocols using weak coherent pulses.

4 pages, 3 figures

References in corpus (4)

• Provably Secure and Practical Quantum Key Distribution over 307 km of Optical Fibre
• Long-distance quantum key distribution secure against coherent attacks
• Continuous operation of high bit rate quantum key distribution
• Amplification of nanosecond laser pulse chain via dynamic injection locking of laser diode

Cited by in corpus (1)

• Manipulating photon coherence to enhance the security of practical quantum key distribution