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Quantum, Nano and Micro Technologies, 2009. ICQNM '09. Third International Conference on

Date 1-7 Feb. 2009

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Displaying Results 1 - 25 of 42
  • [Front cover]

    Page(s): C1
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  • [Title page i]

    Page(s): i
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  • [Title page iii]

    Page(s): iii
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  • [Copyright notice]

    Page(s): iv
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  • Table of contents

    Page(s): v - vii
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  • Preface

    Page(s): viii
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  • Committee

    Page(s): ix - xii
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  • Spectral Characterisation of Spontaneous Parametric-Down Conversion Entangled Photons Source in Femtosecond Pulsed Regime

    Page(s): 1 - 4
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    We report on experimental measurements of coincidence and single particle spectral shapes of biphoton signals when frequency entangled states are generated by SPDC crystals pumped by short pulses. It is shown evidence for biphoton coincidence spectrum narrower and single-particle one wider than the pump spectrum, with a large contrast between coincidence and singles distributions. The investigation of biphoton correlations has been performed by fixing one monochromator at the maximal transmission wavelength on down-converted signal gate and scanning the one placed in the idler branch in order to observe the spectral distribution of single counts and coincidences. The degree of entanglement is evaluated by the ratio of the FWHM of single particle and coincidence distributions: the greater the ratio, the greater is the entanglement. The degree of entanglement in frequency variables can be very high: it increases linearly with the length of the crystal, and decreases with the growing pump pulse. View full abstract»

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  • Quantum-Zeno Control of Collisional Entanglement in a Bose-Josephson Junction

    Page(s): 5 - 10
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    We propose a scheme to control the collision-induced entanglement between atoms in the two-site Bose-Hubbard model, by means of site-indiscriminate noise. This decoherence mechanism induces the continuous measurement of the quasi-momentum, protecting single-particle coherence via a Bose-enhanced many-body Quantum-Zeno effect. View full abstract»

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  • Does Quantum Mechanics Need Interpretation?

    Page(s): 11 - 16
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    Since the beginning, quantum mechanics has raised major foundational and interpretative problems. Foundational research has been an important factor in the development of quantum cryptography, quantum information theory and, perhaps one day, practical quantum computers. Many believe that, in turn, quantum information theory has bearing on foundational research. This is largely related to the so-called epistemic view of quantum states, which maintains that the state vector represents information on a system and has led to the suggestion that quantum theory needs no interpretation. I will argue that this and related approaches fail to take into consideration two different explanatory functions of quantum mechanics, namely that of accounting for classically unexplainable correlations between classical phenomena and that of explaining the microscopic structure of classical objects. If interpreting quantum mechanics means answering the question, "How can the world be for quantum mechanics to be true?", there seems to be no way around it. View full abstract»

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  • Experimentally Testable State-Independent Violation of Bell-Type Inequalities for Quantum Contextuality

    Page(s): 17 - 19
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    There are experimentally testable correlation Bell inequalities which are satisfied by any noncontextual theory but are violated by any quantum state. We discuss how to test one of them. View full abstract»

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  • Game-Theoretic Security Analysis of Quantum Networks

    Page(s): 20 - 25
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    Unconditional security is the key-feature of quantum cryptography, which makes it superior to any classical encryption scheme. Most research in this area focuses on analyzing the theoretical properties and performance of particular quantum key distribution protocols, but a rigorous analysis on the network level seems to be missing. We present a game-theoretic approach which gives simple and tight bounds to the risk of communication that any two peers in a quantum network have to take when communicating, even if quantum cryptography is used. This work is motivated by recent (IM)possibility results regarding unconditionally secure message transmission in arbitrary networks, which puts stringent constraints on the network topology. Hence, our model naturally accounts for a given graph topology (existing fibre-optic networks which are natural candidates for a roll-out of a quantum network), as well as measuring risk in terms of probability or the designers subjective understanding. As a by-product, our model gives optimal path selection strategies, and the optimal design of network topologies under given constraints (like geographic or monetary ones). View full abstract»

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  • An Efficient Method to Convert Arbitrary Quantum Circuits to Ones on a Linear Nearest Neighbor Architecture

    Page(s): 26 - 33
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    A variety of quantum circuits have been designed. Most of them assume that arbitrary pairs of qubits can interact. However, several promising implementations of quantum computation rely on a Linear Nearest Neighbor (LNN) architecture, which arranges quantum bits on a line, and allows neighbor interactions only. Therefore, several specific circuits have been designed on an LNN architecture. However, a general and efficient conversion technique for an arbitrary circuit has not been established. Therefore, this paper gives an efficient method that converts an arbitrary quantum circuit to one on an LNN architecture. Our method achieves small overhead and time complexity compared with naive techniques. To develop the method, we introduce two key theorems that may be interesting on their own. In addition, our method also achieves smaller overhead for some known circuits designed on an LNN architecture. View full abstract»

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  • All Languages in NP Have Very Short Quantum Proofs

    Page(s): 34 - 37
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    In this paper, we show that all languages in NP have logarithmic-size quantum proofs which can be verified provided that two unentangled copies are given. More formally, we introduce the complexity class QMAlog(2) and show that 3COL isin QMAlog(2). To obtain this strong and surprising result we have to relax the usual requirements: the completeness is one but the soundness is 1-1/poly. Since the natural classical equivalent of QMAlog(2) is uninteresting (it would be equal to P), this result, like many others, stresses the fact that quantum information is fundamentally different from classical information. It also contributes to our understanding of entanglement since QMAlog = BQP. View full abstract»

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  • Eavesdropping of Two-Way Coherent-State Quantum Cryptography via Gaussian Quantum Cloning Machines

    Page(s): 38 - 41
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    We consider one of the quantum key distribution protocols recently introduced in Ref. [Pirandola et al., Nature Phys. 4, 726 (2008)]. This protocol consists of a two-way quantum communication between Alice and Bob, where Alice encodes secret information via a random phase-space displacement of a coherent state. In particular, we study its security against a specific class of individual attacks which are based on combinations of Gaussian quantum cloning machines. View full abstract»

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  • Spin-Chains as Quantum Channels for Qubit-State Transfer

    Page(s): 42 - 47
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (390 KB) |  | HTML iconHTML  

    In this paper, we provide a simple strategy to optimize the performances of a spin chain as a quantum channel for state transfer. We investigate the most general conditions under which a long range interacting chain achieves the highest fidelity and the shortest transfer time. In this respect, we show that the symmetry of the spin chain plays a key role to identify the ideal system, which involves sender and receiver only, and provide numerical evidence. However, the two-spin ideal chain is unpractical due to the decrease of the coupling strength with distance. Therefore we show how to design a spin chain, which nearly approaches the optimal behaviour, while keeping the interaction strength still reasonably high. View full abstract»

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  • Encoding Subsystem Codes with and without Noisy Gauge Qubits

    Page(s): 48 - 53
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    In this paper, we investigate a rather neglected aspect of subsystem codes viz. that of encoding. We show that encoding of subsystem codes can be reduced to encoding of a related stabilizer code making it possible to use the known results on encoding of stabilizer codes. Along the way we also show how Clifford codes can be encoded. These encoding schemes can tolerate initialization errors on the gauge qubits. This tolerance can be traded for reduced encoding complexity. View full abstract»

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  • On/off Detection Method for Reconstructing the Statistics of Quantum Optical States: An Overview

    Page(s): 54 - 58
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    We give a brief overview of the demonstration of a photon statistics reconstruction method based on Maximum Likelihood estimation and on/off detection. This method has been successfully applied to a large number of cases and, recently, extended to a scheme for a full reconstruction of the density matrix. Experimental results concerning the heralded single-photon state and the seeded parametric down-conversion are presented in some details. View full abstract»

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  • The GHZ State in Secret Sharing and Entanglement Simulation

    Page(s): 59 - 62
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    In this note, we study some properties of the GHZ state. First, we present a quantum secret sharing scheme in which the participants require only classical channels in order to reconstruct the secret; our protocol is significantly more efficient than the trivial usage of teleportation. Second, we show that the classical simulation of an n-party GHZ state requires at least n log2 n - 2n bits of communication. Finally, we present a problem simpler than the complete simulation of the multi-party GHZ state, that could lead to a no-go theorem for GHZ state simulation. View full abstract»

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  • The Quantum Locker Puzzle

    Page(s): 63 - 66
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    The locker puzzle is a game played by multiple players against a referee. It has been previously shown that the best strategy that exists cannot success with probability greater than than 1-ln2 sime 0.31, no matter how many players are involved. Our contribution is to show that quantum players can do much better---they can succeed with probability 1. By making the rules of the game significantly stricter, we show a scenario where the quantum players still succeed perfectly, while the classical players win with vanishing probability. Other variants of the locker puzzle are considered, as well as a cheating referee. View full abstract»

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  • Six Conjectures in Quantum Physics and Computational Neuroscience

    Page(s): 67 - 72
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    A paradox on Hilbertpsilas problem 6 is identified. To avoid the paradox, equilibrium-based YinYang bipolar sets and bipolar dynamic logic (BDL) are introduced. Bipolar quantum entanglement is defined. BDL leads to a bipolar axiomatization for physics. Applicability of BDL is discussed. Six conjectures in quantum physics and computational neuronotscience are posted. View full abstract»

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  • Heat Transfer in Thin Films

    Page(s): 73 - 76
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    Heat transfer in thin films treats phonons as particles in the Boltzmann Transport Equation (BTE). However, phonons only allow slow thermal response. Rapid film heat transfer is possible provided films are allowed to promptly emit non-thermal electromagnetic (EM) radiation. Quantum mechanics (QM) used in the response of nanoparticles (NPs) is extended to thin films through the theory of QED induced EM radiation. Here QED stands for quantum electrodynamics. Atoms in thin films are generally under EM confinement at vacuum ultraviolet (VUV) levels that by QM are restricted to vanishing small levels of thermal kT energy, and therefore heat gain cannot be conserved by an increase in temperature. Heat is low frequency EM energy, and therefore the gain is conserved by VUV emission following QED induced up-conversion to the VUV confinement frequency of the film. The effective conductivity appears reduced only because EM emission is excluded from the heat balance. If included, the film maintains bulk conductivity through the thickness. The generality of QED induced EM radiation in thin films is extended to NPs that enhance heat transfer in nanofluids and as nanocatalysts increase the rate of chemical reactions. View full abstract»

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  • Efficient Frequency Converters Based on Stimulated Raman Scattering in Hollow Core Photonic Crystal Fibres Filled with Nonlinear Liquids

    Page(s): 77 - 80
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    Recent developments in the field of nonlinear optics with photonic crystal fibers have led to the realization of supercontinuum spectra or parametric sources of correlated photons. However the nonlinearities were still limited by the use of silica. Hollow core photonic crystal fibers (HCPCF) filled with highly nonlinear liquids or gases enable the implementation of more performing nonlinear devices and open the scope of potential applications thanks to the large variety of usable liquids and gases. Moreover liquid and gas filled HCPCF present several original propagation properties such as transmission bands that can be tailored to favor or prevent a given nonlinear mechanism. In this work we will show that the on-purpose limited transmission band enables a high conversion efficiency towards a single Stokes component even at high pump intensities. Moreover such Raman converters generate single spatial mode at specific wavelengths that can be determined to fit desired applications. View full abstract»

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  • Micromotor of Less Than 1 mm^3 Volume for In Vivo Medical Procedures

    Page(s): 81 - 85
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    The body's stress response to surgery has been cited as a primary cause of post-operative morbidity and has prompted growth in minimally invasive surgical techniques. The future of such techniques lies in the use of in vivo procedures, but is currently limited by the availability of motors with a volume of less than 1 mm3. In response to this we present a piezoelectric ultrasonic resonant micromotor with a volume of approximately 0.75 mm3. The motor has a novel helically cut stator that couples axial and torsional resonant frequencies, excited by a lead zirconate titanate element 0.03 mm3 in volume. The motor performance reaches a start-up torque of 47 nNm and no load angular velocity of 830 rad/s. This gives the motor a power density of 18.4 kW/m3. This performance is on the order necessary to propel a swimming microbot in small human arteries. View full abstract»

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  • Fabrication and Testing of a TMMF S2030 Based Micro Fluidic Device for Single Cell Analysis

    Page(s): 86 - 89
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    Current paper describes the fabrication and testing of a Lab-on-a-chip device using TMMF S2030 dry film resist for single cell analysis. The device typically consists of a bigger channel (20 mum deep), 3 smaller channels (2 mum deep) with embedded reservoir in between and a detector towards the downstream.Whole device has been fabricated on a standard glass wafer. Electrode configuration is the notable factor in which pre-sorter electrodes were introduced to bring far-off particles to the trapping range. Dielectrophores is technique will be used to trap a single particle/cell with in the reservoir. Bigger channels were fabricated in TMMF and that of the smaller channels in silicon dioxide. Testing of the channels as successfully done using carboxylate modified fluorescent polystyrene beads (wavelength 605 nm).Currently we are working towards trapping a tumorcell and study the viability and detection mechanisms. View full abstract»

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