arXiv subjects

Ming Gao

Publications and source records attributed to Ming Gao.

At least 109 records · Page 6Linked to original sources

arXiv2018

Quantum man-in-the-middle attack on the calibration process of quantum key distribution

Quantum key distribution (QKD) protocol has been proved to provide unconditionally secure key between two remote legitimate users in theory. Key distribution signals are transmitted in a quantum channel which is established by the calibration process to meet the requirement of high count rate and low error rate. All QKD security proofs implicitly assume that the quantum channel has been established securely. However, the eavesdropper may attack the calibration process to break the security assumption of QKD and provide precondition to steal information about the final key successfully. Inspired by N. Jain et al., Phys. Rev. Lett.107,110501(2011), we reveal the security risk of the calibration process of a passive-basis-choice BB84 QKD system by launching a quantum man-in-the-middle attack which intercepts all calibration signals and resends faked ones. Large temporal bit-dependent or basis-dependent detector efficiency mismatch can be induced. Then we propose a basis-dependent detector efficiency mismatch (BEM) based faked states attack on a single photon BB84 QKD to stress the threat of BEM. Moreover, the security of single photon QKD systems with BEM is studied simply and intuitively. Two effective countermeasures are suggested to remove the general security risk of the calibration process.

quant-ph↗

arXiv2017

BiRank: Towards Ranking on Bipartite Graphs

The bipartite graph is a ubiquitous data structure that can model the relationship between two entity types: for instance, users and items, queries and webpages. In this paper, we study the problem of ranking vertices of a bipartite graph, based on the graph's link structure as well as prior information about vertices (which we term a query vector). We present a new solution, BiRank, which iteratively assigns scores to vertices and finally converges to a unique stationary ranking. In contrast to the traditional random walk-based methods, BiRank iterates towards optimizing a regularization function, which smooths the graph under the guidance of the query vector. Importantly, we establish how BiRank relates to the Bayesian methodology, enabling the future extension in a probabilistic way. To show the rationale and extendability of the ranking methodology, we further extend it to rank for the more generic n-partite graphs. BiRank's generic modeling of both the graph structure and vertex features enables it to model various ranking hypotheses flexibly. To illustrate its functionality, we apply the BiRank and TriRank (ranking for tripartite graphs) algorithms to two real-world applications: a general ranking scenario that predicts the future popularity of items, and a personalized ranking scenario that recommends items of interest to users. Extensive experiments on both synthetic and real-world datasets demonstrate BiRank's soundness (fast convergence), efficiency (linear in the number of graph edges) and effectiveness (achieving state-of-the-art in the two real-world tasks).

cs.IR↗

arXiv2017

Nontrivial Berry phase and type II Dirac transport in layered material PdTe2

Here we report the evidence of the type II Dirac Fermion in the layered crystal PdTe2. The de Haas-van Alphen oscillations find a small Fermi pocket with a cross section of 0.077nm-2 with a nontrivial Berry phase. First-principal calculations reveal that it is originated from the hole pocket of a tilted Dirac cone. Angle Resolved Photoemission Spectroscopy demonstrates a type II Dirac cone featured dispersion. We also suggest PdTe2 is an improved platform to host the topological superconductors.

cond-mat.mes-hall↗

arXiv2016

Unsaturated magnetoconductance of epitaxial La0.7Sr0.3MnO3 thin films in pulsed magnetic fields up to 60 T

We report on the temperature and field dependence of resistance of La0.7Sr0.3MnO3 thin films over a wide temperature range and in pulsed magnetic fields up to 60 T. The epitaxial La0.7Sr0.3MnO3 thin films were deposited by laser molecular beam epitaxy. High magnetic field magnetoresistance curves were fitted by the Brillouin function, which indicated the existence of magnetically polarized regions and the underlying hopping mechanism. The unsaturated magnetoconductance was the most striking finding observed in pulsed magnetic fields up to 60 T. These observations can deepen the fundamental understanding of the colossal magnetoresistance in manganites with strong correlation of transport properties and magnetic ordering.

cond-mat.str-el↗

arXiv2016

Quantum cloning attacks against PUF-based quantum authentication systems

With the advent of Physical Unclonable Functions (PUFs), PUF-based quantum authentication systems (QAS) have been proposed for security purposes and recently proof-of-principle experiment has been demonstrated. As a further step towards completing the security analysis, we investigate quantum cloning attacks against PUF-based quantum authentication systems and prove that quantum cloning attacks outperform the so-called challenge-estimation attacks. We present the analytical expression of the false accept probability by use of the corresponding optimal quantum cloning machines and extend the previous results in the literature. In light of these findings, an explicit comparison is made between PUF-based quantum authentication systems and quantum key distribution (QKD) protocols in the context of cloning attacks. Moreover, from an experimental perspective, a trade-off between the average photon number and the detection efficiency is discussed in detail.

quant-ph↗

arXiv2016

Evidence of both surface and bulk Dirac bands in ZrSiS and the unconventional magnetoresistance

The unconventional magnetoresistance of ZrSiS single crystals is found unsaturated till the magnetic field of 53 T with the butterfly shaped angular dependence. Intense Shubnikov-de Haas oscillations resolve a bulk Dirac cone with a nontrivial Berry phase, where the Fermi surface area is 1.80*10^-3 Å-2 and reaches the quantum limit before 20 T. Angle resolved photoemission spectroscopy measurement reveals an electronic state with the two-dimensional nature around the X point of Brillouin zone boundary. By integrating the density functional theory calculations, ZrSiS is suggested to be a Dirac material with both surface and bulk Dirac bands.

cond-mat.mtrl-sci↗

arXiv2016

Universally-composable finite-key analysis for efficient four-intensity decoy-state quantum key distribution

We propose an efficient four-intensity decoy-state BB84 protocol and derive concise security bounds for this protocol with the universally composable finite-key analysis method. Comparing with the efficient three-intensity protocol, we find that our efficient four-intensity protocol can increase the secret key rate by at least $30\%$. Particularly, this increasing rate of secret key rate will be raised as the transmission distance increases. At a large transmission distance, our efficient four-intensity protocol can improve the performance of quantum key distribution profoundly.

quant-ph↗

arXiv2016

Quantum oscillation and nontrivial transport in the Dirac Semimetal Cd3As2 nanodevice

Here we demonstrate the Shubnikov de Haas oscillation in high-quality Cd3As2 nanowires grown by a chemical vapor deposition approach. The dominant transport of topological Dirac fermions is evident by the nontrivial Berry phase in the Landau Fan diagram. The quantum oscillations rise at a small field of 2 Tesla and preserves till up to 100K, revealing a sizeable Landau level gap and a mobility of over 2000 cm2/V-1s-1. The angle-variable oscillations indicates the isotropy of the bulk Dirac transport. The large estimated mean free path appeals the one-dimensional transport of Dirac semimetals.

cond-mat.mes-hall↗

arXiv2015

Scaling of liquid-drop impact craters in wet granular media

Combining high-speed photography with laser profilometry, we study the dynamics and the morphology of liquid-drop impact cratering in wet granular media---a ubiquitous phenomenon relevant to many important geological, agricultural, and industrial processes. By systematically investigating important variables such as impact energy, the size of impinging drops and the degree of liquid saturation in granular beds, we uncover a novel scaling for the size of impact craters. We show that this scaling can be explained by considering the balance between the inertia of impinging drops and the strength of impacted surface. Such a theoretical understanding confirms that the unique energy partition originally proposed for liquid-drop impact cratering in dry granular media also applies for impact cratering in wet granular media. Moreover, we demonstrate that compressive stresses, instead of shear stresses, control granular impact cratering. Our study enriches the picture of generic granular impact cratering and sheds light on the familiar phenomena of raindrop impacts in granular media.

cond-mat.soft↗

arXiv2015

Transfer of high-dimensional quantum state through an XXZ-Heisenberg quantum spin chain

We propose and analyze an efficient high-dimensional quantum state transfer scheme through an $XXZ$-Heisenberg spin chain in an inhomogeneous magnetic field. By the use of a combination of coherent quantum coupling and free spin-wave approximation, pure unitary evolution results in a perfect high-dimensional swap operation between two remote quantum registers mediated by a uniform quantum data bus, and the feasibility is confirmed by numerical simulations. Also, we observe that either the strong $z$-directional coupling or high quantum spin number can partly suppress the thermal excitations and protect quantum information from the thermal noises when the quantum data bus is in the thermal equilibrium state.

quant-ph↗

arXiv2015

Stringent Statistical Fluctuation Analysis for Quantum Key Distribution Considering After-pulse Contributions

Statistical fluctuation problems are faced by all quantum key distribution (QKD) protocols under finite-key condition. Most of the current statistical fluctuation analysis methods work based on independent random samples, however, the precondition cannot be always satisfied on account of different choice of samples and actual parameters. As a result, proper statistical fluctuation methods are required to figure out this problem. Taking the after-pulse contributions into consideration, we give the expression of secure key rate and the mathematical model for statistical fluctuations, focusing on a decoy-state QKD protocol (Sci Rep. 3, 2453, 2013) with biased basis choice. On this basis, a classified analysis of statistical fluctuation is represented according to the mutual relationship between random samples. First for independent identical relations, we make a deviation comparison between law of large numbers and standard error analysis. Secondly, we give a sufficient condition that Chernoff bound achieves a better result than Hoeffding's inequality based on independent relations only. Thirdly, by constructing the proper martingale, for the first time we represent a stringent way to deal with statistical fluctuation issues upon dependent ones through making use of Azuma's inequality. In numerical optimization, we show the impact on secure key rate, the ones and respective deviations under various kinds of statistical fluctuation analyses.

quant-ph↗

arXiv2015

Dynamics and entanglement of a membrane-in-the-middle optomechanical system in the extremely-large-amplitude regime

The study of optomechanical systems has attracted much attention, most of which are concentrated in the physics in the small-amplitude regime. While in this article, we focus on optomechanics in the extremely-large-amplitude regime and consider both classical and quantum dynamics. Firstly, we study classical dynamics in a membrane-in-the-middle optomechanical system in which a partially reflecting and flexible membrane is suspended inside an optical cavity. We show that the membrane can present self-sustained oscillations with limit cycles in the shape of sawtooth-edged ellipses and exhibit dynamical multistability. Then, we study the dynamics of the quantum fluctuations around the classical orbits. By using the logarithmic negativity, we calculate the evolution of the quantum entanglement between the optical cavity mode and the membrane during the mechanical oscillation. We show that there is some synchronism between the classical dynamical process and the evolution of the quantum entanglement.

quant-ph↗

arXiv2015

Self-Sustained Oscillation and Dynamical Multistability of Optomechanical Systems in the Extremely-Large-Amplitude Regime

Optomechanics concerns with the coupling between optical cavities and mechanical resonators. Most early works are concentrated in the physics of optomechanics in the small-displacement regime and consider one single optical cavity mode participating in the optomechanical coupling. In this paper, we focus on optomechanics in the extremely-large-amplitude regime in which a mechanical resonator is coupled with multiple optical cavity modes during the oscillation. We explicitly show that the mechanical resonator can present self-sustained oscillations in a novel way with limit cycles in the shape of sawtooth-edged ellipses and exhibit dynamical multistability. By analyzing the mechanical oscillation process and the accompanied variation of the optical cavity occupation, we develop an energy-balanced condition to ensure the stability of self-sustained oscillation. The effect of the mechanical nonlinearities on the dynamics of the mechanical resonator is also investigated.

quant-ph↗

arXiv2015

A global estimation of the lower bound of the privacy amplification term for decoy-state quantum key distribution

The privacy amplification term, of which the lower bound needs to be estimated with the decoy-state method, plays a positive role in the secure key rate formula for decoy-state quantum key distribution. In previous work, the yield and the bit error rate of single-photon state are estimated separately to gain this lower bound. In this work, we for the first time take the privacy amplification term as a whole to consider this lower bound. The mathematical description for the correlation between the yield and the bit error rate of single-photon state is given with just two unknown variables. Based on this, we obtain the global estimation of this lower bound for both BB84 protocol and measurement-device-independent protocol. The results of numerical simulation show that the global estimation can significantly improve the performance of quantum key distribution.

quant-ph↗

arXiv2013

Decoy-state quantum key distribution with biased basis choice

We propose a quantum key distribution scheme that combines a biased basis choice with the decoy-state method. In this scheme, Alice sends all signal states in the $Z$ basis and decoy states in the $X$ and $Z$ basis with certain probabilities, and Bob measures received pulses with optimal basis choice. This scheme simplifies the system and reduces the random number consumption. From the simulation result taking into account of statistical fluctuations, we find that in a typical experimental setup, the proposed scheme can increase the key rate by at least 45% comparing to the standard decoy-state scheme. In the postprocessing, we also apply a rigorous method to upper bound the phase error rate of the single-photon components of signal states.

quant-ph↗

arXiv2013

Practical decoy-state measurement-device-independent quantum key distribution

Measurement-device-independent quantum key distribution (MDI-QKD) is immune to all the detection attacks; thus when it is combined with the decoy-state method, the final key is unconditionally secure, even if a practical weak coherent source is used by Alice and Bob. However, until now, the analysis of decoy-state MDI-QKD with a weak coherent source is incomplete. In this paper, we derive, with only vacuum+weak decoy state, some tight formulas to estimate the lower bound of yield and the upper bound of error rate for the fraction of signals in which both Alice and Bob send a single-photon pulse to the untrusted third party Charlie. The numerical simulations show that our method with only vacuum+weak decoy state can asymptotically approach the theoretical limit of the infinite number of decoy states. Furthermore, the statistical fluctuation due to the finite length of date is also considered based on the standard statistical analysis.

quant-ph↗

arXiv2013

Partially random phase attack to the practical two-way quantum-key-distribution system

Phase randomization is a very important assumption in the Bennett-Brassard 1984 quantum key distribution (QKD) system with a weak coherent source. Thus an active phase modulator is needed to randomize the phase of source. However, it is hard to check whether the phase of source is randomized totally or not in practical QKD systems. In this paper a partially random phase attack is proposed to exploit this imperfection. Our analysis shows that Eve can break the security of a two-way QKD system by using our attack, even if an active phase randomization is adopted by Alice. Furthermore, the numerical simulation shows that in some parameter regimes, our attack is immune to the one-decoy-state method.

quant-ph↗

arXiv2013

Classification of arbitrary-dimensional multipartite pure states under stochastic local operations and classical communication using the rank of coefficient matrix

We study multipartite entanglement under stochastic local operations and classical communication (SLOCC) and propose the entanglement classification under SLOCC for arbitrary-dimensional multipartite ($n$-qudit) pure states via the rank of coefficient matrix, together with the permutation of qudits. The ranks of the coefficient matrices have been proved to be entanglement monotones. The entanglement classification of the $2 \otimes 2 \otimes 2 \otimes 4$ system is discussed in terms of the generalized method, and 22 different SLOCC families are found.

quant-ph↗