Low loss QKD optical scheme for fast polarization encoding

Abstract

Abstract: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 LiNbO 3 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 LiNbO 3 is implemented, allowing two crystals to neutralize the effect of each other. Several proofof-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.

Quantum-Secured Data Transmission in Urban Fiber-Optics Communication Lines

“…The optical scheme ( Fig. 1) realizing decoy-state BB84 QKD works as follows [15]. The laser source (L1) emits polarized optical pulses at 1550 nm.…”

Optical designs for realization of a set of schemes for quantum cryptography

“…In the absence of on-demand single photon sources, various strategies have been used to realize single photon based QKD schemes, like BB84 Bennett and Brassard (1984) and B92 Bennett (1992). Some of the experimentalists have used weak coherent pulse (WCP) as an approximate single photon source Diamanti et al (2016); Duplinskiy et al (2017); Kiktenko et al (2017); Koashi (2006); Korzh et al (2015); Lo et al (2014); Wang et al (2016); Xu et al (2015); Gleim et al (2016), while the others have used heralded single photon source Soujaeff et al (2007); Wang et al (2008). Qubits are also realized in the polarization , phase Zhao et al (2006), time-bin Gisin and Brunner (2003), and frequency Sun et al (1995) encodings of the photons (see Gisin et al (2002) for review).…”

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

“…In this context, a major effort has been made to develop robust and stable polarisation encoding and decoding unities [10], envisioning its application in QKD systems implementing mainly the BB84 or the B92 protocols [11, 12]. In this context, several polarisation modulation schemes have been proposed to generate fast and stable polarisation states [13, 14]. Active SOP generators and receivers can be implemented using Pockels cells [15], using electro‐optical polarisation modulators [16] or squeezing the fibre [17].…”

“…Besides that, polarisation modulation schemes can be obtained with optical switches, where an optical signal is split in N arms in order to define N different states of polarisation (SOP) [9, 12]. Alternatively, optoelectronic phase modulators were also employed for SOP generation without the need to split the signal [14, 18]. Nevertheless, in order to improve the stability of the SOP generation and detection stages in the QKD systems, fibre based Sagnac interferometers were proposed using phase modulators [10, 19].…”

“…Recently, a self‐compensation scheme was proposed based also in a fibre Sagnac loop [21]. Nevertheless, due to the complex experimental implementation of fibre‐based Sagnac loops, in [14] authors present a simple configuration to implement a polarisation‐encoding and ‐decoding QKD system using two in‐line phase modulators. More recently in [22], authors present a QKD polarisation‐based scheme using only a single‐phase modulator and a passive detection scheme with two single‐photon detectors.…”