Tight finite-key security for twin-field quantum key distribution

Lorenzo, Guillermo Curras; Navarrete, Alvaro; Azuma, Koji; Kato, Go; Curty, Marcos; Razavi, Mohsen

doi:10.48550/arxiv.1910.11407

Cited by 10 publications

(14 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One can directly substitute the experimental statistics into our framework and obtain secure finite-size key rates, without knowing any techniques of security analysis. To show how to apply our framework, we give an example of the recent Twin-Field QKD or Phase-Matching QKD [28,29], which are proved to surpass the linear key-rate bound [30,31] in finite-size cases [32,33]. Our result shows such a result can still be achieved even with simplified protocol designs.…”

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

Numerical Method for Finite-size Security Analysis of Quantum Key Distribution

Zhou¹,

Sasaki²,

Koashi³

2021

Preprint

View full text Add to dashboard Cite

Quantum key distribution (QKD) establishes secure links between remote communication parties. As a key problem for various QKD protocols, security analysis gives the amount of secure keys regardless of the eavesdropper's computational power, which can be done both analytically and numerically. Compared to analytical methods which tend to require techniques specific to each QKD protocol, numerical ones are more general since they can be directly applied to many QKD protocols without additional techniques. However, current numerical methods are carried out based on some assumptions such as working in asymptotic limit and collective attacks from eavesdroppers. In this work, we remove these assumptions and develop a numerical finite-size security analysis against general attacks for general QKD protocols. We also give an example of applying the method to the recent Phase-Matching QKD protocol with a simple protocol design. Our result shows that the finite-size key rate can surpass the linear key-rate bound in a realistic communication time.

show abstract

Section: Introductionmentioning

confidence: 95%

“…where ǫ is the given failure probability satisfying 0 < ǫ ≤ 1. The optimization problem can be solved analytically [33],…”

Section: Example: Phase-matching Qkdmentioning

confidence: 99%

Numerical Method for Finite-size Security Analysis of Quantum Key Distribution

Zhou¹,

Sasaki²,

Koashi³

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…36(2y+1) z0(y) = 0, i.e. the second condition (7), and the concavity of the function G(x, y, z) with respect to x, i.e. the third condition (8).…”

Section: Proof Of Theoremmentioning

confidence: 99%

“…Many relations [1,2,3,4] are known to be martingale concentration inequalities. However, we will use the former interpretation, because there are situations where the conditional expectation itself has physical meaning [5,6,7], and the natural premises in the former case are not always natural in the latter case. Note that the condition on the expected values is necessary because we can easily define correlated random values such that the sum of the observed values is far from that of the expected values with high probability.…”

Section: Introductionmentioning

confidence: 99%

Concentration inequality using unconfirmed knowledge

Kato¹

2020

Preprint

Self Cite

View full text Add to dashboard Cite

We give a concentration inequality based on the premise that random variables take values within a particular region. The concentration inequality guarantees that, for any sequence of correlated random variables, the difference between the sum of conditional expectations and that of the observed values takes a small value with high probability when the expected values are evaluated under the condition that the past values are known. Our inequality outperforms other wellknown inequalities, e.g. the Azuma-Hoeffding inequality, especially in terms of the convergence speed when the random variables are highly biased. This high performance of our inequality is provided by the key idea in which we predict some parameters and adopt the predicted values in the inequality.

show abstract

“…This idea, sketched in Fig. 1a, was proved secure against general attacks [20][21][22][23][24] also in the finite-size scenario [25][26][27] and with the aid of two-way communication [28], but it is based on the critical assumptions that the optical pulses are phase-coherent in Alice and Bob and preserve coherence throughout the path to Charlie. While the first requirement can be fulfilled by phase-locking the two QKD lasers in Alice and Bob to a common reference laser transmitted through a service channel, the uncorrelated fluctuations of the length and refractive index of the connecting paths (i.e.…”

mentioning

confidence: 99%

Coherent phase transfer for real-world twin-field quantum key distribution

Clivati,

Meda,

Donadello

et al. 2020

Preprint

View full text Add to dashboard Cite

Quantum mechanics allows the distribution of intrinsically secure encryption keys by optical means. Twin-field quantum key distribution is the most promising technique for its implementation on long-distance fibers, but requires stabilizing the optical length of the communication channels between parties. In proof-of-principle experiments based on spooled fibers, this was achieved by interleaving the quantum communication with periodical adjustment frames. In this approach, longer duty cycles for the key streaming come at the cost of a looser control of channel length, and a successful key-transfer using this technique in a real world remains a significant challenge. Using interferometry techniques derived from frequency metrology, we developed a solution for the simultaneous key streaming and channel length control, and demonstrate it on a 206 km field-deployed fiber with 65 dB loss. Our technique reduces the quantum-bit-error-rate contributed by channel length variations to <1%, representing an effective solution for real-world quantum communications.Quantum key distribution (QKD) enables to share secret cryptographic keys between distant parties, whose intrinsic security is guaranteed by the laws of quantum mechanics [1][2][3]. Besides pioneering experiments involving satellite transmission [4,5], the challenge is now to integrate this technology on the long-distance fiber networks already used for telecommunications [6][7][8][9][10][11][12][13][14][15]. The maximum secure key rate for QKD decreases exponentially with the channel losses. Although the reach could be extended using quantum repeaters, the related research is still at a rudimentary level and these devices are far from operational [16][17][18]. Nowadays, intercity distances could only be covered using trusted nodes [13], whose security represents however a significant technical issue. A fundamental resource for next-generation long-distance secure communications is represented by the recently proposed twin-field QKD (TF-QKD) protocol [19], because of its weaker dependence on channel loss. In TF-QKD, the information is encoded as discrete phase states on dim laser pulses generated at distant Alice and Bob terminals and sent through optical fiber to a central node, Charlie, where they interfere. This idea, sketched in Fig. 1a, was proved secure against general attacks [20][21][22][23][24] also in the finite-size scenario [25][26][27] and with the aid of two-way communication [28], but it is based on the critical assumptions that the optical pulses are phase-coherent in Alice and Bob and preserve coherence throughout the path to Charlie. While the first requirement can be fulfilled by phase-locking the two QKD lasers in Alice and Bob to a common reference laser transmitted through a service channel, the uncorrelated fluctuations of the length and refractive index of the connecting paths (i.e. the optical length) introduce phase noise to the system and reduce the visibility of the interference measurement. In proof-of-principle experiments

show abstract

Tight finite-key security for twin-field quantum key distribution

Cited by 10 publications

References 55 publications

Numerical Method for Finite-size Security Analysis of Quantum Key Distribution

Numerical Method for Finite-size Security Analysis of Quantum Key Distribution

Concentration inequality using unconfirmed knowledge

Coherent phase transfer for real-world twin-field quantum key distribution

Contact Info

Product

Resources

About