Polarization-basis tracking scheme for quantum key distribution using revealed sifted key bits

Abstract

Calibration of the polarization basis between the transmitter and receiver is an important task in quantum key distribution (QKD). An effective polarization-basis tracking scheme will decrease the quantum bit error rate (QBER) and improve the efficiency of a polarization encoding QKD system. In this paper, we proposed a polarization-basis tracking scheme using only unveiled sifted key bits while performing error correction by legitimate users, rather than introducing additional reference light or interrupting the transmission of quantum signals. A polarization-encoding fiber BB84 QKD prototype was developed to examine the validity of this scheme. An average QBER of 2.32% and a standard derivation of 0.87% have been obtained during 24 hours of continuous operation.

Simple quantum key distribution with qubit-based synchronization and a self-compensating polarization encoder

“…Compared to the approach of Ding et al [30], our approach has the advantage that only the reconciliation step is required to obtain sufficient information to run the polarization compensation algorithm. This allows for a greater tracking speed which is necessary to stabilize links with polarization drift of few Hz bandwidth.…”

“…Several approaches have been conceived to counteract these random polarization drifts, most of them requiring auxiliary laser pulses and complex time or wavelength multiplexing schemes [29], which add unwanted complexity to the QKD setups. A different approach was introduced by Ding et al that used the revealed portion of the sifted key [30], produced during the error correction and privacy amplification procedures, to detect and compensate the polarization drifts of the fiber link.…”

“…The temporal synchronization is performed using the Qubit4Sync method, with no need for auxiliary time reference, by sending a public qubit sequence at preestablished times [31]. Predetermined qubit sequences are also exploited to monitor and compensate the polarization drift introduced by the 26 km of optical fiber, with an approach somewhat similar to the work of Ding et al [30]. The reduced complexity of both the transmitter and the receiver, as well as the robustness and stability demonstrated by our implementation, represent an important technological step towards mature QKD systems.…”

Fibre polarization state compensation in entanglement-based quantum key distribution

“…A different compensation scheme was proposed more recently that does not require any reference light signals [23,24]. In this scheme, one utilizes the number of erroneous bits in the revealed portion of the sifted keys during error correction process, which has to be monitored in a QKD protocol anyways to assess potential information leakage to an eavesdropper.…”

Polarization Calibration Scheme for a Practical Handheld Free Space Quantum Key Distribution Link

“…Polarization calibration is required in most QKD systems [7]- [11]. Considering an optical fiber channel, [8] used piezoelectric actuators to compensate the change of polarization, and [9] proposed a polarization-basis tracking scheme using sifted key bits revealed in the error correction step. Real-time continuous control was demonstrated based on a wavelengthdivision multiplexing method in [10].…”