The performance degradation of reference-frame-independent measurement-device-independent quantum key distribution (RFI-MDI-QKD) protocol caused by the finite key size effect impedes its practical ...implementation. The protocol utilizes the double-scanning method, which makes it possible to precisely estimate both the counts of single-photon pairs and the phase-flip error. This method effectively counteracts the statistical fluctuation brought on by the finite key size effect. Based on this method, we propose a scheme in this work that substitutes heralded single-photon sources (HSPS) for weak coherent sources (WCS), and we compare the performance of the two schemes by calculating the key rate. The RFI-MDI-QKD using HSPS, according to the results of the simulation, has a lower key rate than the RFI-MDI-QKD using WCS, but it also has a longer transmission distance and a more noticeable improvement in transmission distance at larger rotation angles. Thus, we demonstrate that the RFI-MDI-QKD protocol, based on the double-scanning method and using HSPS, has promising future application potential.
Quantum key distribution (QKD) generates information-theoretical secure keys between two parties based on the physical laws of quantum mechanics. The phase-matching (PM) QKD protocol allows the key ...rate to break the quantum channel secret key capacity limit without quantum repeaters, and the security of the protocol is demonstrated by using equivalent entanglement. In this paper, the wavelength division multiplexing (WDM) technique is applied to the PM-QKD protocol considering the effect of crosstalk noise on the secret key rate. The performance of PM-QKD protocol based on WDM with the influence of adjacent classical channels and Raman scattering is analyzed by numerical simulations to maximize the total secret key rate of the QKD, providing a reference for future implementations of QKD based on WDM techniques.
A novel structure aluminosilicate molecular sieve, named BUCT-3, was prepared by dynamic hydrothermal synthesis, and the critical factor to obtain the new structure is using an active silicon and ...aluminum source, aluminosilica perhydrate hydrogel. Meanwhile, only high content of O-O bonds can ensure the pure phase of BUCT-3. Through the characterization of x-ray powder diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), and so on, some structure and morphology information of BUCT-3 molecular sieves as well as the special silicon and aluminum source was obtained. It’s worth noticing that the O-O bonds of reactants can be reserved in the products, and thus, help us to get a new structure with cell parameters a = 8.9645 Å, b = 15.2727 Å, c = 11.3907 Å, α = 90°, β = 93.858°, γ = 90°. The crystal system is monoclinic. Though the thermostability of BUCT-3 is not satisfactory, its potential application derived from O-O bonds cannot be neglected.
Nowadays, the O?-sialon ceramics are synthesized by the reaction of Si3N4,
SiO2 and Al2O3. However, it is difficult to achieve the single phase
materials. Here, we have successfully developed porous ...single phase
O?-sialon ceramics by pre-oxidation combined with gas-pressure sintering
method. The effects of ?-Si3N4 powder on the microstructure, phase
evolution, mechanical property were investigated. The result illustrated
that the main crystal phase of the porous ceramics was composed of the
single O?-sialon phase. The pores were well distributed and generated from
the decomposition of Si2N2O. The elongated O?-sialon grains were found and
formed around pore walls. Additionally, the addition of ?-Si3N4 powder was
beneficial for improving the bending strength because of the reduction of
porosity and pore size. The porous O?-sialon ceramics with uniform pores
obtained the excellent bending strength when the ?-Si3N4 powder was 6 wt%.
Quantum light generated through spontaneous four-wave mixing (SFWM) process in nonlinear materials, such as entangled photon pairs and single photons, is an important resource for various emerging ...quantum applications. Integrated quantum photonics has enabled the generation, manipulation, and detection of quantum states of light with steadily increasing scale and complexity levels. Importantly, the exploration of on-chip integration has accumulated substantial progresses in recent years toward the realization of low-cost, large-scale quantum photonic circuits. Here, we review the underlying mechanism and discuss state-of-the-art SFWM on-chip quantum light sources fabricated with various structures and materials on chip. Furthermore, we enumerate the most appealing applications of on-chip SFWM such as heralding single-photon source, entangled photon source, and system-level integration.
Recently, to bridge the gap between security of Measurement-device-independent quantum key distribution (MDI-QKD) and a high key rate, a novel protocol, the so-called detector-device-independent QKD ...(DDI-QKD), has been independently proposed by several groups and has attracted great interest. A higher key rate is obtained, since a single photon bell state measurement (BSM) setup is applied to DDI-QKD. Subsequently, Qi has proposed two attacks for this protocol. However, the first attack, in which Bob's BSM setup is assumed to be completely a "black box", is easily prevented by using some additional monitoring devices or by specifically characterizing the BSM. The second attack, which combines the blinding attack and the detector wavelength-dependent efficiency, is not explicitly discussed, and its feasibility is not experimentally confirmed. Here, we show that the second attack is not technically viable because of an intrinsically wavelength-dependent property of a realistic beam splitter, which is an essential component in DDI-QKD. Moreover, we propose a feasible attack that combines a well-known attack-detector blinding attack with intrinsic imperfections of single-photon detectors. The experimental measurement and proof-of-principle test results confirm that our attack can allow Eve to get a copy of quantum keys without being detected and that it is feasible with current technology.
Measurement-device-independent entanglement witness (MDI-EW) plays an important role for detecting entanglement with untrusted measurement device. We present a double blinding-attack on a quantum ...secret sharing (QSS) protocol based on GHZ state. Using the MDI-EW method, we propose a QSS protocol against all detector side-channels. We allow source flaws in practical QSS system, so that Charlie can securely distribute a key between the two agents Alice and Bob over long distances. Our protocol provides condition on the extracted key rate for the secret against both external eavesdropper and arbitrary dishonest participants. A tight bound for collective attacks can provide good bounds on the practical QSS with source flaws. Then we show through numerical simulations that using single-photon source a secure QSS over 136 km can be achieved.
The recently proposed twin-field quantum key distribution (TF-QKD) effectively overcomes the key capacity limitation without quantum relay and achieves long-distance quantum key distribution. In this ...paper, based on the TF-QKD protocol by Lucamarini et al. M. Lucamarini, Z.L. Yuan, J.F. Dynes, A.J. Shields, Nature
557
, 400 (2018), we propose a scheme where the weak coherent state (WCS) is replaced by a heralded single photon source (HSPS), and compare their performance by calculating the key rate. The numerical simulation results show that TF-QKD using HSPS can still break through the rate-distance limitation. Specifically, compared with the WCS TF-QKD protocol, the HSPS TF-QKD protocol has a lower secret key rate but a greater distance. Thus we show the TF-QKD with HSPS is a more preferable protocol for long distance transmittance.
Graphical abstract
Quantum key distribution (QKD) generates information-theoretical secret keys between two parties based on the physical laws of quantum mechanics. Following the advancement in quantum communication ...networks, it becomes feasible and economical to combine QKD with classical optical communication through the same fiber using dense wavelength division multiplexing (DWDM) technology. This study proposes a detailed scheme of TF-QKD protocol with DWDM technology and analyzes its performance, considering the influence of quantum channel number and adjacent quantum crosstalk on the secret key rates. The simulation results show that the scheme further increases the secret key rate of TF-QKD and its variants. Therefore, this scheme provides a method for improving the secret key rate for practical quantum networks.
We propose a new classified mixed model prediction (CMMP) procedure, called pseudo-Bayesian CMMP, that uses network information in matching the group index between the training data and new data, ...whose characteristics of interest one wishes to predict. The current CMMP procedures do not incorporate such information; as a result, the methods are not consistent in terms of matching the group index. Although, as the number of training data groups increases, the current CMMP method can predict the mixed effects of interest consistently, its accuracy is not guaranteed when the number of groups is moderate, as is the case in many potential applications. The proposed pseudo-Bayesian CMMP procedure assumes a flexible working probability model for the group index of the new observation to match the index of a training data group, which may be viewed as a pseudo prior. We show that, given any working model satisfying mild conditions, the pseudo-Bayesian CMMP procedure is consistent and asymptotically optimal both in terms of matching the group index and in terms of predicting the mixed effect of interest associated with the new observations. The theoretical results are fully supported by results of empirical studies, including Monte-Carlo simulations and real-data validation.
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