The six-state protocol is a discrete-variable protocol for quantum key distribution, that permits to tolerate a noisier channel than the BB84 protocol. In this work we provide a lower bound on the maximum achievable key rate of a practical implementation of the entanglement-based version of the six-state protocol. Regarding the experimental set-up we consider that the source is untrusted and the photon-number statistics is measured using photon-number-resolving detectors. We provide the formula for the key rate for a finite initial number of resources. As an illustration of the considered formalism, we calculate the key rate for the setting where the source produces entangled photon pairs via parametric down-conversion and the losses in the channel depend on the distance. As a result we find that the finite-key corrections for the considered scenario are not negligible and they should be considered in any practical analysis.
Quantum key agreement requires all participants to recover the shared key together, so it is crucial to resist the participant attack. In this paper, we propose a verifiable multi-party quantum key agreement protocol based on the six-qubit cluster states. A verifiable distributor who preserves some subsequences of the six-qubit cluster states is introduced into this protocol, thus the participants can not obtain the shared key in advance. Besides, the correctness and simultaneity of the shared key are guaranteed by the trusted design combiner and homomorphic hash function. Furthermore, the sec…
The first device-independent quantum private query protocol (MRT17) which is proposed by Maitra \emph{et al.} [Phys. Rev. A 95, 042344 (2017)] to enhance the security through the certification of the states and measurements. However, the MRT17 protocol works under an assumption of perfect detectors, which increases difficulty in the implementations. Therefore, it is crucial to investigate what would affect the security of this protocol if the detectors were imperfect. Meanwhile, Maitra \emph{et al.} also pointed out that this problem remains open. In this paper, we analyze the security of MRT1…
Comment on "Deterministic six states protocol for quantum communication" [Phys. Lett. A 358 (2006) 85]
在[J.S. Shaari，M. Lucamarini，M.R.B. Wahiddin，Phys. Lett. A 358（2006）85-90]已经开发了用于量子通信的确定性六态协议（6DP）。该协议是基于三个相互无偏基地和四个编码算子。信息通过来自不同基地的两个量子比特在用户之间传输。研究了三种攻击：拦截重发攻击（IRA），双重CNOT攻击（2 hocTA）和量子中间人攻击。在这封信中，我们表明IRA和2 hocTA没有得到适当的解决。例如，我们发现，在IRA的控制模式下检测到夏娃的概率是70%，而不是以前的研究中的50%。此外，在2 hocTA中，Eve只能获得50%的数据，而不是前面所说的全部数据。
Bidirectional quantum teleportation is a fundamental protocol for exchanging quantum information between two quantum nodes. All bidirectional quantum teleportation protocols till now have achieved a maximum efficiency of $40\%$. Here, we propose a new scheme for symmetric bidirectional quantum teleportation using a six-qubit cluster state as the quantum channel, for symmetric ($3\leftrightarrow3$) qubit bidirectional quantum teleportation of a special three-qubit entangled state. The novelty of our scheme lies in its generalization for ($N\leftrightarrow N$) qubit bidirectional quantum telepor…
We study a novel protocol for reference frame independent (RFI) quantum key distribution (QKD) using six states for Alice and four states for Bob, while previous RFI protocols require a six state analyzer for Bob. Our protocol can generate a secure key for any possible phase of the entangled state, provided the variation is small compared to the measurement rate, shown by our numerical key rate analysis. We perform a proof-of-principle experiment using polarization entangled photon pairs. In the presence of a varying rotational phase, we obtain a consistently low error rate of less than $4\%$ …
Trustworthiness of detectors in quantum key distribution with untrusted detectors
与测量设备无关的量子密钥分发（MDI-QKD）协议是一种有效的解决检测器侧信道攻击的方案。MDI-QKD的主要优点之一是可以证明安全性，而无需对测量设备如何工作进行任何假设。与传统的量子密钥分发（QKD）协议（如诱饵态BB84协议）相比，代价是相对较低的安全密钥速率。最近，一个新的QKD协议，旨在弥补MDI-QKD的强安全性和传统QKD的高效率，已经被提出。在该协议中，合法接收方采用可信线性光学网络对从不安全量子信道接收到的光子信息进行编码，然后使用不可信检测器进行贝尔态测量（Bell state measurement，BSM）。在大多数这些研究中，一个关键的假设是，位于接收者实验室内的不可信BSM不能向外部发送任何不需要的信息。在这里，我们表明，如果BSM是完全不可信的，一个简单的计划将允许BSM发送信息到外部。结合特洛伊木马攻击，该方案可以让Eve在不被发现的情况下获得量子密钥的信息。为了防止上述攻击，需要针对特洛伊木马攻击的对策或对“不可信”BSM设备的某种可信度。
There is considerable interest in predicting the efficiency of Quantum Key Distribution (QKD) protocols when one of their implementation quantities is modified. One significant imperfection that affects the efficiency of the setup is the afterpulse phenomenon which consists in the spontaneous detections triggered by trapped carriers after previous avalanches at the detectors. While it is widely studied in bibliography for various QKD protocols, it has been reported much more scarcely for the well-known decoy-state QKD protocols and for dual detectors only. We develop a theoretical analysis of …
Security of high speed quantum key distribution with finite detector dead time
分析了有限检测器死时间τ下高速量子密钥分发系统的安全性。当传输速率变得高于各个检测器的最大计数速率（1/τ）时，安全问题影响用于筛选比特的算法。分析计算和数值模拟的Bennett-Bullard BB84协议进行。我们研究罗杰斯等人。的协议（在“Detector dead-time effects and paralyzability in high-speed量子密钥分发，”New J.Phys.9（2007）319中介绍），其中存在具有执行拦截-重发攻击的能力的主动窃听者Eve。它表明，罗杰斯等人。的协议不再安全更具体地说，Eve可以在接收器端引起依赖于基底的检测效率。然后介绍了在存在死区时间和主动窃听者的情况下安全的修改的密钥筛选方案。我们分析和比较这些安全的筛选方案，这个活跃的Eve场景，并计算和模拟他们的密钥生成率。结果表明，被动基选择的最大密钥生成速率为1/（2τ），主动基选择的最大密钥生成速率为1/τ。有限检测器死时间的安全性分析也扩展到诱饵状态BB84协议。
We consider six-photon entangled state emitted from a single third-order parametric down-conversion process. In the regime of weak nonlinearities, we present a symmetry detector which is capable of analyzing the twin-beam six-photon symmetric states. By cascading the symmetry detectors, as an application, it is shown that one can purify the desired six-photon entangled state from an arbitrary twin-beam six-photon symmetric state. With linear optics we propose a fruitful scheme for exploring a class of multimode-photon entangled states from third-order parametric down-conversion process. Furthe…
Mode-pairing quantum key distribution (MP-QKD) is a potential protocol that is not only immune to all possible detector side channel attacks, but also breaks the repeaterless rate-transmittance bound without needing global phase locking. Here we analyze the finite-key effect for the MP-QKD protocol with rigorous security proof against general attacks. Moreover, we propose a six-state MP-QKD protocol and analyze its finite-key effect. The results show that the original protocol can break the repeaterless rate-transmittance bound with a typical finite number of pulses in practice. And our six-st…
The decoy-state method has been developed rapidly in quantum key distribution (QKD) since it is immune to photon-number splitting attacks. However, two basis detector efficiency asymmetry, which exists in realistic scenarios, has been ignored in the prior results. By using the recent 4-intensity decoy-state optimization protocol, we report the first implementation of high-rate QKD with asymmetric basis detector efficiency, demonstrating 1.9 to 33.2 times higher key rate than previous protocols in the situation of large basis detector efficiency asymmetry. The results ruled out an implicitly as…
Noise Resilience of Quantum Key Distribution Protocols Secured Against Independent Attacks With One-Way Communication
VSB–Technical University of Ostrava（俄斯特拉发理工大学）；IT4Innovations, VSB–Technical University of Ostrava（俄斯特拉发理工大学 IT4创新研究院）；Institute of Theoretical and Applied Informatics, Polish Academy of Sciences（波兰科学院理论与应用信息学研究所）
In the original round-robin differential-phase-shift (RRDPS) quantum key distribution and its improved method, the photon-number-resolving detectors are must for the security. We present a RRDPS protocol with yes-no detectors only. We get the upper bounds of mutual information of Alice and Eve, and Bob and Eve, and the formula of key rate. Our main idea is to divide all counts into two classes, the counts due to the odd number photons of incident detectors and the counts due to the even number photons of incident detectors. The fact that the bit-flip error rate of the later class is certainly …
Randomness, mainly in the form of random numbers, is the fundamental prerequisite for the security of many cryptographic tasks. Quantum randomness can be extracted even if adversaries are fully aware of the protocol and even control the randomness source. However, an adversary can further manipulate the randomness via tailored detector blinding attacks, which are hacking attacks suffered by protocols with trusted detectors. Here, by treating no-click events as valid events, we propose a quantum random number generation protocol that can simultaneously address source vulnerability and ferocious…
We calculate the key sharing rate of Lu et al.'s Quantum Key Recycling (QKR) protocol. The key sharing rate is another version of the key rate, but it can be calculated for both the Quantum Key Distribution (QKD) protocols and the QKR protocols. We define the key sharing rate in this study and compare the key sharing rate of the QKR protocol to the rate of the QKD protocols. We found Lu et al.'s QKR protocol can be used to share keys more efficiently than BB84 in some situations. We also compare the six-state version of Lu et al.'s QKR protocol to the six-state QKD protocol. The results of thi…
We analyze the security of two multipartite quantum key distribution (QKD) protocols, specifically we introduce an $N$-partite version of the BB84 protocol and we discuss the $N$-partite six-state protocol proposed in arXiv:1612.05585v2. The security analysis proceeds from the generalization of known results in bipartite QKD to the multipartite scenario, and takes into account finite resources. In this context we derive a computable expression for the achievable key rate of both protocols by employing the best-known strategies: the uncertainty relation and the postselection technique. We compa…
We put forward a hybrid quantum key distribution protocol based on coherent states, Gaussian modulation, and photon-number-resolving (PNR) detectors, and show that it may enhance the secret key generation rate (KGR) compared to homodyne-based schemes. Improvement in the KGR may be traced back to the dependence of the two-dimensional discrete output variable on both the input quadratures, thus overcoming the limitations of the original protocol. When reverse reconciliation is considered, the scheme based on PNR detectors outperforms the homodyne one both for individual and collective attacks. I…
We propose a multi-parameter quantum metrological protocol based on a Mach-Zehnder interferometer with a squeezed vacuum input state and an anti-squeezing operation at one of its output channels. A simple and intuitive geometrical picture of the state evolution is provided by the marginal Wigner functions of the state at each interferometer output channel. The protocol allows to detect the value of the sum $β=\frac{1}{2}(φ_1+φ_2)+θ_\mathrm{in}-θ_\mathrm{out}$, of the relative phase $θ_\mathrm{in}-θ_\mathrm{out}$ between the two squeezers, and the average of the phase delays $φ_1,φ_2$ in the tw…
