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Journal of Physics Conference Series

QKD using polarization encoding with active measurement basis selection

Alexander Duplinskiy, Vasily E. Ustimchik, A. A. Kanapin, Yury Kurochkin

Published Nov 1, 2017• 3 citations
Publisher

Abstract

We report a proof-of-principle quantum key distribution experiment using a one-way optical scheme with polarization encoding implementing the BB84 protocol. LiNbO 3 phase modulators are used for generating polarization states for Alice and active basis selection for Bob. This allows the former to use a single laser source, while the latter needs only two single-photon detectors. The presented optical scheme is simple and consists of standard fiber components. Calibration algorithm for three polarization controllers used in the scheme has been developed. The experiment was carried with 10 MHz repetition frequency laser pulses over a distance of 50 km of standard telecom optical fiber.

DOI
10.1088/1742-6596/917/6/062058

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We report a proof-of-principle quantum key distribution experiment using a one-way optical scheme with polarization encoding implementing the BB84 protocol. LiNbO 3 phase modulators are used for generating polarization states for Alice and active basis selection for Bob. This allows the former to use a single laser source, while the latter needs only two single-photon detectors. The presented optical scheme is simple and consists of standard fiber components. Calibration algorithm for three polarization controllers used in the scheme has been developed. The experiment was carried with 10 MHz repetition frequency laser pulses over a distance of 50 km of standard telecom optical fiber.
We present a new optical scheme for BB84 protocol quantum key distribution (QKD). The proposed setup consists of a compact all-fiber polarization encoding optical scheme based on LiNbO3 phase modulators, single laser source and two single-photon detectors. Optical scheme consists of standard telecommunication components and is suitable for both fiber and free-space quantum communication channels. Low losses (~2dB) in Bob's device increase both the key generation rate and distance limit. A new technique for solving polarization mode dispersion (PMD) issue in LiNbO3 is implemented, allowing two crystals to neutralize the effect of each other. Several proof-of-concept experiments have been conducted at 10 MHz repetition frequency over 50 km of standard optical fiber under laboratory conditions and over 30 km of urban fiber with high losses (13dB), which is a link within a QKD network. To achieve this, calibration algorithms have been developed, allowing the system to work autonomously and making it promising for practical applications.
An optical scheme for polarization encoding BB84 protocol is described. Fiber electro-optical LiNbO3 phase modulators based on Pockels cells provide both polarization states generation for Alice and basis choosing for Bob at high frequency, requiring low operation voltages (Vπ < 5V). Proposed scheme uses only one laser source, which guarantee the indistinguishability of the pulses and active basis choosing allows the system to have two single photon detectors in contrast to the four in the standard polarization encoding schemes. Two phase modulators compensate each others’ polarization mode dispersion, caused by the natural birefringence of the lithium niobate crystal. The system consists of standard components and has simple configuration. The principle of operation is experimentally demonstrated.
Abstract The BB84 quantum key distribution (QKD) protocol sets the foundation for achieving secure communication against quantum threats. Since its inception, significant advancements have aimed towards frugal experimental implementations with enhanced security. In this paper, we report a passive polarization encoded BB84 protocol. By passively and randomly encoding the polarization states, the setup avoids active modulation and simplifies design with security standards analogous to entanglement-based QKD. The heralding of a probabilistic single-photon source ensures an extremely low probability of multi-photon emissions evading photon number-splitting attacks. The quality of the single-photon source and thus, the QKD setup is certified by the second-order correlation function, g (2) (0) = 0.006 ± 0.0002. Our protocol provides an optimisation trade-off between the conventional BB84 and the BBM92 protocol. The advantage relies on using fewer detectors (compared to the BBM92 protocol) and no reliance on active quantum random number generators (compared to the standard BB84) to drive Alice’s encoding scheme. Our implementation achieves a quantum bit error rate of 7% and a secure key rate of 5 kbps.
Quantum Key Distribution (QKD) is a potential defense against future quantum attacks that can break traditional encryption algorithms, such as RSA and ECC. The current work is based on the development of the BB84 protocol with the features of utilizing quantum mechanics and eavesdropping detection through signal disturbance. A simulation of the BB84 protocol was built using polarization encoding over a 10 km single-mode optical fiber using OptiSystem software. The system consists of standard telecom equipment, such as a continuous wave laser at a frequency of 193.1 THz, polarization controllers, and single-photon detectors. Both secure and insecure cases were simulated, where an attacker (Eve) had used an intercept-resend attack. The outcome showed significant Bit Error Rate (BER) and Quantum Bit Error Rate (QBER) increases during attacks, thus proving the protocol's vulnerability to interference. In addition, a special intrusion detection system based on BER was used to identify such anomalies in real-time. The simulation illustrates the feasibility of using QKD in today's optical networks to secure communications.