Sagnac secret sharing over telecom fiber networks

Abstract

We report the first Sagnac quantum secret sharing (in three-and four-party implementations) over 1550 nm single mode fiber (SMF) networks, using a single qubit protocol with phase encoding. Our secret sharing experiment has been based on a single qubit protocol, which has opened the door to practical secret sharing implementation over fiber telecom channels and in free-space. The previous quantum secret sharing proposals were based on multiparticle entangled states, difficult in the practical implementation and not scalable. Our experimental data in the three-party implementation show stable (in regards to birefringence drift) quantum secret sharing transmissions at the total Sagnac transmission loop distances of 55-75 km with the quantum bit error rates (QBER) of 2.3-2.4% for the mean photon number micro?= 0.1 and 1.7-2.1% for micro= 0.3. In the four-party case we have achieved quantum secret sharing transmissions at the total Sagnac transmission loop distances of 45-55 km with the quantum bit error rates (QBER) of 3.0-3.7% for the mean photon number micro= 0.1 and 1.8-3.0% for micro?= 0.3. The stability of quantum transmission has been achieved thanks to our new concept for compensation of SMF birefringence effects in Sagnac, based on a polarization control system and a polarization insensitive phase modulator. The measurement results have showed feasibility of quantum secret sharing over telecom fiber networks in Sagnac configuration, using standard fiber telecom components.

Experimental circular quantum secret sharing over telecom fiber network

“…Moreover, our scheme provides autocompensation of birefringence with just a commercial polarization-sensitive phase modulator connected to a Faraday mirror, which has been shown to provide full compensation of the birefringence [17]. Thanks to this design, our setup can also automatically provide completely polarization-insensitive phase modulation; to the best of our knowledge, there is no commercially available polarization-insensitive phase modulator, and our method is simpler than other previously reported ways to realize polarization-insensitive phase modulation [12,18].…”

“…Moreover, since commercial single-mode fiber has birefringence, polarization encoding is impractical in applications over commercial networks. Recently, Bogdanski et al [12,13] reported using a single qubit protocol [14] with phase encoding in a 1550 nm fiber network, thus solving the above mentioned problems. However, the stability of their systems was based on a complicated polarization control system [15] with a polarization insensitive phase modulator, and the bit generation efficiency was just 50%.…”

Experimental single qubit quantum secret sharing in a fiber network configuration

“…Additional parties can be added depending upon the application. In comparison with entangled states schemes [8,9], the use of a single qubit guarantees practical experimental realization and scalability [10,11]. Furthermore, this scheme perfectly compensates for birefringence.…”

“…The proposed experimental system not only automatically provides perfect birefringence compensation, but also realizes a polarization-insensitive phase modulator. It is easier than other ways to realize a polarization-insensitive phase modulator [10,14].…”