Reversal operator to compensate polarization random drifts in quantum communications

Abstract

A quantum bit error rate (QBER) based algorithm for polarization random drift compensation is proposed. For a transmission window of 8 ms, for instance in aerial fiber installations, the algorithm overhead is below 1%. In an extreme turbulent situation, where the transmission window is as shorter as 0.8 ms, the overhead is still below 10%. Besides being able to operate smoothly, even in a very extreme situation, the algorithm overhead is also insensitive to the length of the communication system. It is upper layer protocol agnostic, and it is based on the mapping of the QBER on the Poincaré sphere. The algorithm finds the polarization reversal operator, which results in much lower overhead contrary to the blind methods currently used. The algorithm reverts the polarization random drift performing two QBER estimations and applying three rotations, at most. The uncertainty on the two QBER estimations defines an area over the sphere surface that is related with upper-layer protocols QBER threshold.

Cost-Effective ML-Powered Polarization-Encoded Quantum Key Distribution

“…Let us denote |p(t)〉 = <θp(t), φp(t)> as the real polarization of the received photon. We adopt the QRx hardware architecture proposed in [13] and [14], where the QRx is equipped with a Beam Splitter (BS), two Electronic Polarization Controllers (EPC) followed by Polarization Beam Splitters (PBS) and Single-Photon Detectors (SPD). The photon first reaches the EPCs, which are in charge of polarization alignment.…”

“…For illustrative purposes, Fig. 1a shows the operation of the quantum channel with time based on the approach proposed in [13]. At regular time intervals of size m, the QTx sends a number of qubits with a predefined polarization that are used to monitor the current SOP, denoted |o(t)〉, at the QRx.…”

“…The authors in [12] proposed reactive methods to compensate random SOP drift by performing multiple rotations based on QBER estimation. Finally, authors in [13] proposed a procedure based also in multiple rotations to estimate the polarization state and compensate measured polarization random drift, which resulted in QBER reduction. Authors in [15] used 10 6 qubits/s for QBER estimation.…”

Generation and Distribution of Quantum Oblivious Keys for Secure Multiparty Computation

“…Note that these states can be physically instantiated using, for instance, a polarization encoding fiber optic quantum communication system, provided that a fast polarization encoding/decoding process and an algorithm to control random polarization drifts in optical fibers are available [30,31]. 1.…”

FPGA‐assisted state‐of‐polarisation generation for polarisation‐encoded optical communications

“…In practice, such loss of symmetry may result either from a non‐circular geometry of the fibre core or from other mechanisms associated with the material anisotropy, likewise asymmetric stresses [5]. In turn, those extrinsic mechanisms make fibre birefringence to change randomly over time, reflecting the environmental conditions, which may request for polarisation rotation compensation schemes [6, 7].…”