National University of Singapore

Christian Kurtsiefer

Lijiong Shen

Peng Kian Tan

Brenda Mei Yuen Chng

Yicheng Shi

Jianwei Lee

Mei Yuen Brenda Chng

A method of identifying occurrence of a blinding attack in a quantum cryptography system, and a receiver for a quantum cryptography. The method comprises the steps of providing a light emitter at a receiver of the quantum cryptography system, wherein at least a portion of light emitted from the light emitter is detectable by a single photon detector of the receiver; switching the light emitter off during a normal operation mode of the single photon detector; measuring a first number of detection events registered in the single photon detector in a first time period, T1, with the light emitter switched on; and identifying the occurrence of the blinding attack based on the first number of detection invents.

Method for detecting blinding attacks on photodetectors in a quantum cryptography system

A method of clock synchronization between first and second clocks on first and second ends, respectively, of an optical channel; and a system for clock synchronization between first and second clocks on first and second ends, respectively, of an optical channel. The method comprises the steps of generating light exhibiting thermal photon statistics, as opposed to a Poissonian timing statistic of coherent laser light; transmitting a portion of the light though the optical channel; determining timing information of single photon detection events of photons of the light at the first side of the optical channel using the first clock and at the second side of the optical channel using the second clock; using a temporal signature imprinted on the light as a result of the thermal photon statistics to identify temporal correlations between the single photon detection events at the first side of the optical channel and the single photon detection events at the second side of the optical channel; and determining an offset between the first and second clocks based on the identified temporal correlations.

Clock synchronization based on temporal photon bunching effect

A method and system for random number generation. The method comprises the steps of exposing first and second photodetectors to the same mode of a first electromagnetic field in the presence of a mode in a vacuum state of a second electromagnetic field, such that an illumination of the first and second photodetectors is at least substantially balanced; and generating a random noise signal based on a photocurrent difference between the first and second photodetectors.

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Singapore, Singapore

Christian Kurtsiefer