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.
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.
We present the first Sagnac quantum secret sharing (in three- and four-party implementations) as well as Sagnac two-user quantum key distribution (QKD) over 1550 nm single mode fiber (SMF) networks, using the BB84- protocol with phase encoding. The secret sharing experiment has implemented a single qubit protocol, which allows for a practical secret sharing implementation over fiber telecom channels and in free-space. The previous quantum secret sharing proposals were based on multiparticle entangled states, not scalable and diffcult in the experimental implementations. Our experimental data show stable, in regards to birefringence drift, 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 μ = 0.1. In the QKD experiment we have achieved the total Sagnac transmission loop distances of 100-150 km with quantum bit error rates (QBER) of 5.84-9.79 % for μ = 0.1. The distances were much longer and rates much higher than in any other published Sagnac QKD experiments. The stability of quantum transmission in both secret sharing and QKD experiments 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 and QKD over telecom fiber networks in Sagnac confi;guration, using standard fiber telecom components. Our birefringence compensation in SMF Sagnac open the door to other Sagnac-based applications over SMF links such as precise optical sensing, dispersion characteristics of optical fibers, acoustic and strain sensing, and generally sensing of any time varying phenomenon.
The paper reports on the first fiber quantum secret sharing experiment in three, four, and five-party implementations in the plug & play and Sagnac interferometer setups using single photons with phase encoding. A plug & play setup a secure secret sharing transmission distance of 66:1 km has been achieved for three-party with quantum bit error rate (QBER) of 7.1%; 40:5 km for four-party with QBER of 6:6%; and 6:7 km with QBER of 2:7%, suitable for local area network (LAN) applications, for five-party. In Sagnac interferometric setup, 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 mu = 0.1 and 1.7-2.1% for mu = 0.3. In the four-party case a quantum secret sharing transmissions at the total Sagnac transmission loop distances of 45-55 km has been achieved with the quantum bit error rates (QBER) of 3.0-3.7% for the mean photon number mu = 0.1 and 1.8- 3.0% for mu = 0.3. The stability of quantum transmission has been achieved due to the new concept for compensation of SMF birefringence effects in Sagnac, based on a polarization control system and a polarization insensitive phase modulator.
We report quantum secret sharing experiment in telecommunication fiber in five-party implementation. The quantum secret sharing experiment has been based on a single qubit protocol, which has opened the door to practical secret sharing implementation over fiber 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. The secret sharing protocol has been implemented in an interferometric fiber optics setup with phase encoding and demonstrated for three, four, and five parties. The experimental setup measurements have shown feasibility and scalability of secure multiparty quantum communication over commercial telecom fiber networks.
We are currently experiencing a rapid development of quantum information, a new branch of science, being an interdisciplinary of quantum physics, information theory, telecommunications, computer science, and many others. This new science branch was born in the middle of the eighties, developed rapidly during the nineties, and in the current decade has brought a technological breakthrough in creating secure quantum key distribution (QKD), quantum secret sharing, and exciting promises in diverse technological fields. Recent QKD experiments have achieved high rate QKD at 200 km distance in optical fiber. Significant QKD results have also been achieved in free-space. Due to the rapid broadband access deployment in many industrialized countries and the standing increasing transmission security treats, the natural development awaiting quantum communications, being a part of quantum information, is its migration into commercial switched telecom networks. Such a migration concerns both multiuser quantum key distribution and multiparty quantum secret sharing that have been the main goal of my PhD studies. They are also the main concern of the thesis. Our research efforts in multiuser QKD has led to a development of the five-user setup for transmissions over switched fiber networks in a star and in a tree configuration. We have achieved longer secure quantum information distances and implemented more nodes than other multi-user QKD experiments. The measurements have shown feasibility of multiuser QKD over switched fiber networks, using standard fiber telecom components. Since circular architecture networks are important parts of both intranets and the Internet, Sagnac QKD has also been a subject of our research efforts. The published experiments in this area have been very few and results were not encouraging, mainly due to the single mode fiber (SMF) birefringence. Our research has led to a development of a computer controlled birefringence compensation in Sagnac that open the door to both classical and quantum Sagnac applications. On the quantum secret sharing side, we have achieved the first quantum secret sharing experiment over telecom fiber in a five-party implementation using the "plug & play" setup and in a four-party implementation using Sagnac configuration. The setup measurements have shown feasibility and scalability of multiparty quantum communication over commercial telecom fiber networks.
We present a new concept for birefringence compensation in Sagnac single mode fiber (SMF) interferometer, which has opened the door to secure multiuser quantum communications. The concept has been tested in both quantum key distribution (QKD) and secret sharing applications at total fiber loop lengths up to 150 km. Now, we present a Jones matrix based model of the concept as well as the visibility measurements confirming its practical validity. Sagnac based circular SMF network architecture is an attractive solution for both commercial telecom Intranets and backbone networks as well as for secure quantum information channels exploring QKD and secret sharing applications. Due to the difference in birefringence between the clockwise and counterclockwise transmission directions, Sagnac has not been so much explored by the quantum information community as other network architectures, especially the "plug & play". Our SMF Sagnac birefringence compensation uses polarization maintaining, horizontally aligned components only, except for the SMF fiber link. It converts the arbitrary elliptically polarized clockwise and counterclockwise light signals, transmitted over the SMF fiber, into the horizontal polarization. Thus, both the sent and received light signals have the same horizontal polarization. In order to avoid unnecessary power losses in the birefringence compensator, we have included a simple proportional-integral-derivative controller into our setup. The compensator provides a perfect birefringence compensation for the destructive interference, which leads to a high system visibility. The presented SMF Sagnac birefringence compensation could also be use in Sagnac metrology, for instance in very low power level sensing, requiring high measurement accuracy.
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.