Optimizing Decoy‐State Protocols for Practical Quantum Key Distribution Systems

Abstract

The decoy-state protocol enables quantum key distribution (QKD) systems to achieve high performance without using the single-photon source. In the dozen years since the decoy-state protocol has been proposed, a series of advances in scheme design, finite-size analysis, system modelling, and parameter estimation has developed. Unfortunately, most advances are based on different starting points and lack a synthesis to figure out the optimal protocol of decoy-state method. Here, the advances in decoy-state method are reviewed and they are synthesized to compare the key-rate performance of 38 decoy-state protocols using the particle swarm optimization (PSO) algorithm. To form a guideline for practical QKD systems, the optimal decoy-state protocols are found with the change of five system parameters (the transmission loss, the block size of postprocessing, the misalignment-error probability, the dark-count probability, and the afterpulse rate). It is expected that this work can answer the questions of what the actual performance is for different decoy-state protocol in various scenarios and which decoy-state protocol is the optimal choice for various QKD systems.

High-Efficient Syndrome-Based LDPC Reconciliation for Quantum Key Distribution

“…To further improve the efficiency, the symmetric-blind protocol was proposed by introducing symmetry in operations of two parties and consideration on unsuccessful decoding results [22]. Though f could also be calculated by Equation (6), this protocol used a quite different approach to obtain the desired efficiency f desire , that is, only shortened or punctured bits were used. For each code among the code set, the number of shortened or punctured bits was calculated as follows.…”

“…Then, some syndrome bits of these syndromes are used to initialize the punctured bits of the frames in L 2 , and the others are transmitted together with the syndromes of L 2 to Bob. Let T represent the set of punctured bits in L 2 that are initialized by the syndrome bits from L 1 (e.g., T = {x 3,1 , x 3,u , x 3,v , x 3,v+1 } in Figure 2), the efficiency of our protocol can be calculated according to Equation (6) as…”

“…Unlike conventional cryptography, QKD is based on quantum mechanical principles and is guaranteed to be secure without assumptions of adversary's (i.e., Eve's) computing power or technological capability [2,3]. For this reason, QKD has been developing rapidly in both theory and experiment during the last few decades [4][5][6][7][8][9][10][11][12][13]. In fact, QKD has become one of the most mature branches of quantum information technology [14][15][16].…”

Measurement-device-independent quantum key distribution for nonstandalone networks

“…IM2 and an electronic variable optical attenuator (EVOA) of Alice and Bob modulate the intensity of pulses for decoy-state technology [60][61][62][63][64]. In our system, the three-intensity decoy-state method is used and these three intensities are denoted by µ, ν, ω, respectively.…”

Asymmetric tridirectional quantum teleportation using seven-qubit cluster states

“…Entanglement is a critical concept employed in a variety of applications, including quantum teleportation (QT) [1][2][3], quantum secret sharing (QSS) [4][5][6], quantum key distribution (QKD) [7][8][9][10], and quantum information theory [11,12].…”