We consider the problem of optimizing the achievable EPR-pair distribution rate between multiple source-destination pairs in a quantum Internet, where the repeaters may perform a probabilistic Bell-state measurement and we may impose a minimum end-to-end fidelity as a requirement. We construct an efficient linear programming (LP) formulation that computes the maximum total achievable entanglement distribution rate, satisfying the end-to-end fidelity constraint in polynomial time (in the number of nodes in the network). Our LP formulation gives the optimal rate for a class of entanglement generation protocols where the repeaters have very short-lived quantum memories. We also propose an efficient algorithm that takes the output of the LP solver as an input and runs in polynomial time (in the number of nodes) to produce the set of paths to be used to achieve the entanglement distribution rate. Moreover, we point out a practical entanglement generation protocol that can achieve those rates.

No abstract

Present study reveals the low concentrations (∼4 ppm) of pesticide sensing vis-à-vis degradation of pesticides with the help of nontoxic zinc oxide quantum dots (QD). In our study, we have taken four different pesticides viz., aldrin, tetradifon, glyphosate, and atrazine, which are widely used in agriculture and have structural dissimilarities/diversity. By using optical sensing techniques such as steady state and time-resolved fluorescence, we have analyzed the detailed exciton dynamics of QD in the presence of different pesticides. It has been found that the pesticide containing good leaving groups (-Cl) can interact with QD promptly and has high binding affinity (∼10 M). The different binding signatures of QD with different pesticides enable us to differentiate between the pesticides. Time resolved fluorescence spectroscopy provides significant variance (∼150-300 ns) for different pesticides. Furthermore, a large variation (10 Ω to 7 × 10 Ω) in the resistance of QD in the presence of different pesticides was revealed by electrochemical sensing technique. Moreover, during the interaction with pesticides, QD can also act as a photocatalyst to degrade pesticides. Present investigation explored the fact that the rate of degradation is positively affected by the binding affinity, i.e., the greater the binding, the greater is the degradation. What is more, both optical and electrochemical measurements of QD, in tandem, as described in our study could be utilized as the pattern recognition sensor for detection of several pesticides.

The DNA metabolic processes often involve single-stranded DNA (ss-DNA) molecules as important intermediates. In the absence of base complementarity, ss-DNAs are more flexible and interact strongly with water in aqueous media. Ss-DNA-water interactions are expected to control the conformational flexibility of the DNA strand, which in turn should influence the properties of the surrounding water molecules. We have performed room temperature molecular dynamics simulation of an aqueous solution containing the ss-DNA dodecamer, 5'-CGCGAATTCGCG-3'. The conformational flexibility of the DNA strand and the microscopic structure and ordering of water molecules around it have been explored. The simulation reveals transformation of the initial base-stacked form of the ss-DNA to a fluctuating collapsed coil-like conformation with the formation of a few non-sequentially stacked base pairs. A preliminary analysis shows further collapse of the DNA conformation in presence of additional salt (NaCl) due to screening of negative charges along the backbone by excess cations. Additionally, higher packing of water molecules within a short distance from the DNA strand is found to be associated with realignment of water molecules by breaking their regular tetrahedral ordering.

We investigate the spacetime of anisotropic stars admitting conformal motion. The Einstein field equations are solved using different ansatz of the surface tension. In this investigation, we study two cases in details with the anisotropy as:where, n, c 1 and c 2 are arbitrary constants. The solutions yield expressions of the physical quantities like pressure gradients and the mass.

We consider the recent relativistic bit commitment protocol introduced by Lunghi et al [Phys. Rev. Lett. 2015] and present a new security analysis against classical attacks. In particular, while the initial complexity of the protocol scaled double-exponentially with the commitment time, our analysis shows that the correct dependence is only linear. This has dramatic implications in terms of implementation: in particular, the commitment time can easily be made arbitrarily long, by only requiring both parties to communicate classically and perform efficient classical computation.Over the last decades, which witnessed the rapid expansion of quantum information, a new trend has developed: trying to obtain security guarantees based solely on the laws of physics. Perhaps the most compelling example is quantum key distribution [1,2] where two distant parties can exploit quantum theory to extract unconditionally secure keys provided that they have access to an untrusted quantum channel and an authenticated classical channel. However, many cryptographic applications cannot be obtained only with secure key distribution. One important example is two-party cryptography, which deals with the setting where Alice and Bob want to perform a cryptographic task but do not trust each other. This is in contrast with key distribution where Alice and Bob cooperate and fight against a possible eavesdropper. Two-party cryptography has numerous applications, ranging from authentication to distributed cryptography in the cloud. These protocols are usually separated into building blocks, called primitives. One of the most studied primitives is bit commitment, which often gives a strong indication of whether two-party cryptography is possible or not in a given model. For example, there are many constructions of bit commitment protocols under computational assumptions [3][4][5][6]. It is then natural to ask whether quantum theory can provide security for two-party cryptographic primitives such as bit commitment or oblivious transfer. A general no-go theorem was proved in 1996 by Mayers and Lo-Chau [7,8]. Several attempts were made to circumvent this impossibility result by limiting the storage possibilities of the cheating party [9,10]. An alternative approach to obtain secure primitives, pioneered by Kent [11], consists in combining quantum theory with special relativity, more precisely with the physical principle that information cannot propagate faster than the speed of light. This has opened the way to new, secure, bit commitment protocols [12][13][14][15], with the caveat that the commitment time is not arbitrary long in general but depends on the physical distance between the parties or on the number of parties involved.A major open question of the field is therefore to design a secure practical bit commitment protocol, for which the commitment time can be increased arbitrarily at a reasonable cost in terms of implementation complexity. In this paper, we examine a protocol due to Lunghi et al. [16], which is itself adapted from based...

Abstract. In this paper, we consider the multi-bit Differential Power Analysis (DPA) in the Hamming weight model. In this regard, we revisit the definition of Transparency Order (TO) from the work of Prouff (FSE 2005) and find that the definition has certain limitations. Although this work has been quite well referred in the literature, surprisingly, these limitations remained unexplored for almost a decade. We analyse the definition from scratch, modify it and finally provide a definition with better insight that can theoretically capture DPA in Hamming weight model for hardware implementation with precharge logic. At the end, we confront the notion of (revised) transparency order with attack simulations in order to study to what extent the low transparency order of an s-box impacts the efficiency of a side channel attack against its processing. To the best of our knowledge, this is the first time that such a critical analysis is conducted (even considering the original notion of Prouff). It practically confirms that the transparency order is indeed related to the resistance of the s-box against side-channel attacks, but it also shows that it is not sufficient alone to directly achieve a satisfying level of security. Regarding this point, our conclusion is that the (revised) transparency order is a valuable criterion to consider when designing a cryptographic algorithm, and even if it does not preclude to also use classical countermeasures like masking or shuffling, it enables to improve their effectiveness.

This review describes recent progress in the area of molecular simulations of peptide assemblies, including peptide-amphiphiles, and drug-amphiphiles. The ability to predict the structure and stability of peptide self-assemblies from the molecular level up is vital to the field of nanobiotechnology. Computational methods such as molecular dynamics offer the opportunity to characterize intermolecular forces between peptide-amphiphiles that are critical to the self-assembly process. Furthermore, these computational methods provide the ability to computationally probe the structure of these supramolecular assemblies at the molecular level, which is a challenge experimentally. Herein, we briefly highlight progress in the areas of all-atomistic and coarse-grained simulation studies investigating the self-assembly process of short peptides and peptide amphiphiles. We also discuss recent all-atomistic and coarse-grained simulations of the self-assembly of a drug-amphiphile into elongated filaments. Next, we discuss how these computational methods can provide further insight on the pathway of cylindrical nanofiber formation and predict their biocompatibility by studying the interaction of these peptide-amphiphile nanostructures with model cell membranes.