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Recovery from an eavesdropping attack on a qubit of a graph state
No full textGraph states are multipartite entangled pure states that can describe distributed quantum information in a formal setting via the notion of nodes and edges. One qubit is present at each node, and the entangling interactions are represented via the edges. We investigate eavesdropping on one of the qubits of the graph state. The eavesdropper uses an ancilla qubit to unitarily interact with one of the qubits followed by a measurement on the ancilla qubit. We study the effect of eavesdropping on the graph state and its connections to the graph topology. We propose the use of a modified graph state by performing certain controlled unitary operations on the existing graph state. This improves the error correcting ability of the graph state, and the modified graph state can correct any error on one qubit
New isoniazid derivatives with improved pharmaco-toxicological profile: Obtaining, characterization and biological evaluation
No full textTuberculostatic drugs are the most common drug groups with global hepatotoxicity. Awareness of potentially severe hepatotoxic reactions is vital, as hepatic impairment can be a devastating and often fatal condition. The treatment problems that may arise, within this class of medicines, are mainly of two types: adverse reactions (collateral, toxic or hypersensitive reactions) and the initial or acquired resistance of Mycobacterium tuberculosis to one or more antituberculosis drugs. Prevention of adverse reactions, increase treatment adherence and success rates, providing better control of tuberculosis (TB). In this regard, obtaining new drugs with low toxicity and high tuberculostatic potential is essential. Thus, in this work, we have designed or synthesized new derivatives of isoniazid (INH), such as new Isonicotinoylhydrazone (INH-a, INH-b and INH-c). These derivatives demonstrated good biocompatibility, antimicrobial property similar to that of parent isoniazid and last but not least, a significantly improved Pharmacotoxicological profile compared to that of isoniazid
Transport across junctions of pseudospin-one fermions
No full textWe study transport across ballistic junctions of materials which host pseudospin-one fermions as emergent low-energy quasiparticles. The effective low-energy Hamiltonians of such fermions are described by integer spin Weyl models. We show that current conservation in such integer spin-s Weyl systems requires continuity across a boundary of only 2s (out of 2s + 1) components of the wave function. Using the current conservation conditions, we study the transport between normal metal-barrier-normal metal (NBN) and normal metal-barrier-superconductor (NBS) junctions of such systems in the presence of an applied voltage eV. We show that for a specific value of the barrier potential U-0, such NBN junctions act as perfect collimators; any quasiparticle which is incident on the barrier with a nonzero angle of incidence is reflected back with unit probability for any barrier width d. We discover an interesting symmetry of this system, namely, the conductance is invariant under U-0 -> 2(mu(L) +/- eV) - U-0, where mu(L) is the chemical potential and the +(-) sign corresponds to particle (hole) mediated transport. For NBS junctions with a proximity-induced s-wave pairing potential, which also display such a collimation, we chart out the properties of the subgap tunneling conductance G as a function of the barrier strength and applied voltage. We point out the effect of the collimation on the subgap tunneling conductance of these NBS junctions and discuss experiments which can test our theory
UVIT Open Cluster Study. I. Detection of a White Dwarf Companion to a Blue Straggler in M67: Evidence of Formation through Mass Transfer
No full textThe old open cluster M67, populated with blue straggler stars (BSSs), is a well-known test bed to study the BSS formation pathways. Here, we report the first direct detection of a white dwarf (WD) companion to a BSS in M67, using far-UV images from the Ultra-Violet Imaging telescope on ASTROSAT. Near-simultaneous observations in three far-UV bands combined with Galaxy Evolution Explorer, International Ultraviolet Explorer, and ground and space-based photometric data covering a 0.14-11.5 mu m range for WOCS1007 were found to require a binary fit to its spectral energy distribution (SED), consisting of a BSS and a hot companion. On the other hand, a single spectral fit was found to be satisfactory for the SEDs of two other BSSs, WOCS1006 and WOCS2011, with the latter showing a deficient far-UV flux. The hot companion of WOCS1007 is found to have a T-eff similar to 13,250-13,750 K and a radius of 0.09 +/- 0.01 R-circle dot. A comparison with WD models suggests it to be a low-mass WD (similar to 0.18M(circle dot)), in agreement with the kinematic mass from the literature. As a low-mass WD (<0.4M(circle dot)) necessitates formation through mass transfer in close binaries, WOCS1007 with a known period of 4.2 days along with its fast rotation, is likely to be formed by a case A or case B binary evolution
A GENERAL FRAMEWORK FOR GRAPH SPARSIFICATION
No full textWe present a general framework for constructing cut sparsifiers in undirected graphs- weighted subgraphs for which every cut has the same weight as the original graph, up to a multiplicative factor of (1 +/- epsilon). Using this framework, we simplify, unify, and improve upon previous sparsification results. As simple instantiations of this framework, we show that sparsifiers can be constructed by sampling edges according to their strength (a result of Benczur and Karger Approximating s-t minimum cuts in (o) over tilde (n(2)) time, in Proceedings of the Twenty-Eighth Annual ACM Symposium on Theory of Computing, ACM, New York, 1996, pp. 47-55], SIAM T. Comput., 44 (2015), pp. 290-319]), effective resistance (a result of Spielman and Srivastava SIAM J. Comput., 40 (2011), pp. 1913-1926]), or edge connectivity. Sampling according to edge connectivity is the most aggressive method, and the most challenging to analyze. Our proof that this method produces sparsifiers resolves an open question of Benczur and Karger. While the above results are interesting from a combinatorial standpoint, we also prove new algorithmic results. In particular, we give the first (optimal) O(m)-time sparsification algorithm for unweighted graphs. Our algorithm has a running time of O(m) + (O) over tilde (n/epsilon(2)) for weighted graphs, which is also linear unless the input graph is very sparse itself. In both cases, this improves upon the previous best running times (due to Benczur and Karger Approximating s-t minimum cuts in (o) over tilde (n(2)) time, in Proceedings of the Twenty-Eighth Annual ACM Symposium on Theory of Computing, ACM, New York, 1996, pp. 47-551, SIAM T. Comput., 44 (2015), pp. 290-319]) of O(m log(2) n) (for the unweighted case) and O(m log(3) n) (for the weighted case), respectively. Our algorithm constructs sparsifiers that contain O(n log n/epsilon(2)) edges in expectation. A key ingredient of our proofs is a natural generalization of Karger's bound on the number of small cuts in an undirected graph. Given the numerous applications of Karger's bound, we suspect that our generalization will also be of independent interest
Occurrence of Mixed Phase in Bi0.5Sr0.5Mn0.9Cr0.1O3 Bulk Sample: Electron Paramagnetic Resonance and Magnetization Studies
No full textWe study the effects of 10% Cr substitution in Mn sites of Bi0.5Sr0.5MnO3 on the antiferromagnetic (AFM) (T-N similar to 110 K) transition using structural, magnetic and electron paramagnetic resonance (EPR) techniques. Field cooled (FC) and zero field cooled (ZFC) magnetization measurements done from 400 K down to 4 K show that the compound is in the paramagnetic (PM) phase till 50 K where it undergoes a transition to a short-range ferromagnetic phase (FM). Electron paramagnetic resonance measurements performed in the temperature range of 300 K to 80 K conform with the magnetization measurements as symmetric signals are observed owing to the paramagnetic phase. Below 80 K, signals become asymmetric. Electron paramagnetic resonance intensity peaks at similar to 110 K, the decreasing intensity below this temperature confirming the presence of antiferromagnetism. We conclude that below 50 K the magnetization and EPR results are consistent with a cluster glass phase of BSMCO, where ferromagnetic clusters coexist with an antiferromagnetic background
Alignment-tolerant broadband compact taper for low-loss coupling to a silicon-on-insulator photonic wire waveguide
No full textWe experimentally demonstrate a broadband, fabrication-tolerant compact silicon waveguide taper (34.2 mu m) in a silicon-on-insulator wire waveguide. The taper works on multimode interference along the length of the taper. A single taper design has broadband operation with coupling efficiency >70% over 700 nm that can be used in O-, C-, and L-bands. The compact taper is highly tolerant to fabrication variations; +/- 100 nm change in the taper and end waveguide width varies the taper transmission by <5%. The footprint of the device, i.e., the taper along with linear gratings, approximate to 442 mu m(2), 11.5x smaller than the adiabatic taper. The taper with linear gratings provides coupling efficiency comparable to standard focusing gratings. We have also experimentally compared the translational and rotational alignment tolerance of the focusing grating with linear grating couplers
Interdependent Estimation and Guidance With Zero-Effort-Miss Enforcement
No full textAn interdependent estimation and guidance design approach for interceptors is presented by enforcing a stable zero-effort-miss dynamics. The output of the estimator is the demanded lateral acceleration, which serves as the guidance command. A dynamic inversion based inner-loop autopilot design facilitates extensive six degree-of-freedom simulation studies, which shows that the proposed interdependent approach gives improved performance compared to the conventional approach where estimation and guidance are done separately
A high-performance MoS2 synaptic device with floating gate engineering for neuromorphic computing
No full textAs one of the most important members of the two dimensional chalcogenide family, molybdenum disulphide (MoS2) has played a fundamental role in the advancement of low dimensional electronic, optoelectronic and piezoelectric designs. Here, we demonstrate a new approach to solid state synaptic transistors using two dimensional MoS2 floating gate memories. By using an extended floating gate architecture which allows the device to be operated at near-ideal subthreshold swing of 77 mV/decade over four decades of drain current, we have realised a charge tunneling based synaptic memory with performance comparable to the state of the art in neuromorphic designs. The device successfully demonstrates various features of a biological synapse, including pulsed potentiation and relaxation of channel conductance, as well as spike time dependent plasticity (STDP). Our device returns excellent energy efficiency figures and provides a robust platform based on ultrathin two dimensional nanosheets for future neuromorphic applications
Two-dimensional, few-layer NiPS3 for flexible humidity sensor with high selectivity
No full textChemically and electrically sensitive two-dimensional (2D) nanomaterials are of immense interest as probing electrodes for wearable electronic devices. A new family of two dimensional (2D) layered materials, namely metal phosphochalcogenides (MPX3), are potential candidates towards the development of sensors for various analytes. Herein, we demonstrate the ability of few-layer NiPS3 nanosheets for humidity sensing by fabricating a cost-effective, flexible sensor device. The results indicate that the NiPS3 nanosheet-based humidity sensors possess high sensitivity with a responsivity of similar to 10(6), superior selectivity, and most importantly, rapid response, recovery times and good reproducibility. Response times of similar to 1-2 s at low humidity levels and similar to 3 s at high humidity levels with recovery times of similar to 2-3 s are observed. The device was tested in both flat and bent states, causing no prominent changes in the response; hence, the sensor is an excellent candidate for use in flexible devices. The characteristics of the NiPS3-based sensor were further investigated using complex impedance studies and in situ Raman spectroscopy to understand the sensing mechanism. The fast response and recovery associated with the NiPS3-based humidity sensors allow real time monitoring of human respiration and water evaporation on skin. These humidity sensors can also be utilized for non-contact analysis and hence will be an attractive candidate for health and environmental monitoring