Sources of light for quantum communications

Karlsson, Goobar, Björk

Bing Qi

A method and a system for pilot-aided feedforward data recovery are provided. The method and system include a receiver including a strong local oscillator operating in a free running mode independent of a signal light source. The phase relation between the signal light source and the local oscillator source is determined based on quadrature measurements on pilot pulses from the signal light source. Using the above phase relation, information encoded in an incoming signal can be recovered, optionally for use in communication with classical coherent communication protocols and quantum communication protocols.

S. V. Sorokin, N. A. Maleev, M. M. Kulagina +13 more

Yuan, ZL, Fröhlich, B, Lucamarini, M +4 more

The art of imparting information onto a light wave by optical signal modulation is fundamental to all forms of optical communication. Among many schemes, direct modulation of laser diodes stands out as a simple, robust, and cost-effective method. However, the simultaneous changes in intensity, frequency, and phase have prevented its application in the field of secure quantum communication. Here, we propose and experimentally demonstrate a directly phase-modulated light source which overcomes the main disadvantages associated with direct modulation and is suitable for diverse applications such as coherent communications and quantum cryptography. The source separates the tasks of phase preparation and pulse generation between a pair of semiconductor lasers leading to very pure phase states. Moreover, the cavity-enhanced electro-optic effect enables the first example of subvolt half-wave phase modulation at high signal rates. The source is compact, stable, and versatile, and we show its potential to become the standard transmitter for future quantum communication networks based on attenuated laser pulses.

Z. L. Yuan, B. Fröhlich, M. Lucamarini +3 more

The art of imparting information onto a light wave by optical signal modulation is fundamental to all forms of optical communication.Among many schemes, direct modulation of laser diodes stands out as a simple, robust, and cost-effective method.However, the simultaneous changes in intensity, frequency, and phase have prevented its application in the field of secure quantum communication.Here, we propose and experimentally demonstrate a directly phase-modulated light source which overcomes the main disadvantages associated with direct modulation and is suitable for diverse applications such as coherent communications and quantum cryptography.The source separates the tasks of phase preparation and pulse generation between a pair of semiconductor lasers leading to very pure phase states.Moreover, the cavity-enhanced electro-optic effect enables the first example of subvolt half-wave phase modulation at high signal rates.The source is compact, stable, and versatile, and we show its potential to become the standard transmitter for future quantum communication networks based on attenuated laser pulses.

Jonny Roberts, Robert James Young