Sebastian Kleis

Continuous variable quantum key distribution with a real local oscillator using simultaneous pilot signals

In this Letter, we propose a novel implementation of continuous variable quantum key distribution that operates with a real local oscillator placed at the receiver site. In addition, pulsing of the continuous wave laser sources is not required, leading to an extraordinary practical and secure setup. It is suitable for arbitrary schemes based on modulated coherent states and heterodyne detection. The shown results include transmission experiments, as well as an excess noise analysis applying a discrete 8-state phase modulation. Achievable key rates under collective attacks are estimated. The results demonstrate the high potential of the approach to achieve high secret key rates at relatively low effort and cost.

Simple and efficient detection scheme for continuous variable quantum key distribution with m-ary phase-shift-keying

A detection scheme for discriminating coherent states in quantum key distribution systems employing PSK is proposed. It is simple and uses only standard components. Its applicability at extremely low power levels of as low as 0.045 photons per symbol is experimentally verified.

Coherent receiver architectures for secure key distribution using faint optical multilevel signals

Optical multilevel signals for QKD are evaluated in terms of security and key generation rate when they are used with post-selection. Potential receiver architectures are analyzed from a quantum-mechanical point of view and compared regarding these parameters as well as implementation complexity. Based on that, a coherent state QKD system is proposed.