Experimental circular quantum secret sharing over telecom fiber network.

We present a robust single photon circular quantum secret sharing (QSS) scheme with phase encoding over 50 km single mode fiber network using a circular QSS protocol. Our scheme can automatically provide a perfect compensation of birefringence and remain stable for a long time. A high visibility of 99.3% is obtained. Furthermore, our scheme realizes a polarization insensitive phase modulators. The visibility of this system can be maintained perpetually without any adjustment to the system every time we test the system.

Experimental single qubit quantum secret sharing in a fiber network configuration.

We present a robust single-photon quantum secret sharing (QSS) scheme with phase encoding in three-party implementations and a design way of more parties over a 50 km single-mode fiber network using a single QSS protocol. This scheme automatically provides perfect compensation for birefringence. A high visibility of 99.4% is obtained over three hours in visibility and stability measurements without any system adjustments, showing good potential for practical systems. Furthermore, polarization-insensitive phase modulators are realized using this system.

True random number generator based on discretized encoding of the time interval between photons.

We propose an approach to generate true random number sequences based on the discretized encoding of the time interval between photons. The method is simple and efficient, and can produce a highly random sequence several times longer than that of other methods based on threshold or parity selection, without the need for hashing. A proof-of-principle experiment has been performed, showing that the system could be easily integrated and applied to quantum cryptography and other fields.

Quantum key distribution based on phase encoding in long-distance communication fiber.

A robust two-way quantum key distribution system based on phase encoding is demonstrated in 50 km and 100 km commercial communication fiber. The system can automatically compensate for birefringence effects and remain stable over 23 h. A low quantum bit error rate and high visibility are obtained. Furthermore, the storage fiber is unnecessary and train of pulses is only needed in the test with 100 km fiber.

Quantum key distribution based on phase encoding and polarization measurement.

A one-way quantum key distribution scheme based on intrinsically stable Faraday-mirror-type Michelson interferometers with four-port polarizing beam splitters has been demonstrated that can compensate for birefringence effects automatically. The encoding is performed with phase modulators, but decoding is accomplished through measurement of the polarization state of Bob's photons. An extinction ratio of about 30 dB was maintained for several hours over 50 km of fiber at 1310 nm without any adjustment to the setup, which shows its good potential for practical systems.

Random number generation based on the time of arrival of single photons.

We report the demonstration of a new type of true random number generator based on the random distribution of the time interval between photons from a single-photon-like source. The experimental setup is simple and robust against mechanical and temperature disturbances. With improved detector resolution and efficiency, the random number bit rate could be increased by more than an order of magnitude to satisfy practical requirements.