30,197 research outputs found

    Photonic millimeter-wave frequency multiplication based on cascaded four-wave mixing and polarization pulling

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    This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.37.005055. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] A technique for the frequency multiplication of microwave signals based on the combination of two optical nonlinear phenomena in a single nonlinear fiber is investigated. Multiple four-wave mixing is used to generate harmonics on an externally modulated optical carrier while polarization pulling through stimulated Brillouin scattering is used to filter the desired harmonics. Microwave signals in the 60 GHz region are generated showing harmonic frequency multiplication factors of up to 25 with a suppression of undesired harmonics better than 20 dB. © 2012 Optical Society of America.This research was supported in part by the Spanish Ministerio de Economia y Competitividad through TEC2009-08078 and TEC2012-35797 projects.Vidal Rodriguez, B. (2012). Photonic millimeter-wave frequency multiplication based on cascaded four-wave mixing and polarization pulling. Optics Letters. 37(24):25478-25488. https://doi.org/10.1364/OL.37.005055S25478254883724Kawanishi, T., Oikawa, S., Yoshiara, K., Sakamoto, T., Shinada, S., & Izutsu, M. (2005). Low noise photonic Millimeter-wave generation using an integrated reciprocating optical Modulator. IEEE Photonics Technology Letters, 17(3), 669-671. doi:10.1109/lpt.2004.842377Li, W., & Yao, J. (2010). Investigation of Photonically Assisted Microwave Frequency Multiplication Based on External Modulation. IEEE Transactions on Microwave Theory and Techniques, 58(11), 3259-3268. doi:10.1109/tmtt.2010.2075671Vidal, B., Huggard, P. G., Ellison, B. N., & Gomes, N. J. (2010). Optoelectronic generation of W-band millimetre-wave signals using Brillouin amplification. Electronics Letters, 46(21), 1449. doi:10.1049/el.2010.2310Wiberg, A., Perez-Millan, P., Andres, M. V., & Hedekvist, P. O. (2006). Microwave-photonic frequency multiplication utilizing optical four-wave mixing and fiber Bragg gratings. Journal of Lightwave Technology, 24(1), 329-334. doi:10.1109/jlt.2005.860164Wang, Q., Rideout, H., Zeng, F., & Yao, J. (2006). Millimeter-Wave Frequency Tripling Based on Four-Wave Mixing in a Semiconductor Optical Amplifier. IEEE Photonics Technology Letters, 18(23), 2460-2462. doi:10.1109/lpt.2006.886826Li, Y., Naderi, N. A., Kovanis, V., & Lester, L. F. (2010). Enhancing the 3-dB Bandwidth via the Gain-Lever Effect in Quantum-Dot Lasers. IEEE Photonics Journal, 2(3), 321-329. doi:10.1109/jphot.2010.2046481McKinstrie, C. J., & Raymer, M. G. (2006). Four-wave-mixing cascades near the zero-dispersion frequency. Optics Express, 14(21), 9600. doi:10.1364/oe.14.009600Cerqueira Sodre, A., Chavez Boggio, J. M., Rieznik, A. A., Hernandez-Figueroa, H. E., Fragnito, H. L., & Knight, J. C. (2008). Highly efficient generation of broadband cascaded four-wave mixing products. Optics Express, 16(4), 2816. doi:10.1364/oe.16.002816Wise, A., Tur, M., & Zadok, A. (2011). Sharp tunable optical filters based on the polarization attributes of stimulated Brillouin scattering. Optics Express, 19(22), 21945. doi:10.1364/oe.19.021945Hansryd, J., Andrekson, P. A., Westlund, M., Jie Li, & Hedekvist, P.-O. (2002). Fiber-based optical parametric amplifiers and their applications. IEEE Journal of Selected Topics in Quantum Electronics, 8(3), 506-520. doi:10.1109/jstqe.2002.101635

    Nonperturbative renormalization group approach to the Ising model: a derivative expansion at order 4\partial^4

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    On the example of the three-dimensional Ising model, we show that nonperturbative renormalization group equations allow one to obtain very accurate critical exponents. Implementing the order 4\partial^4 of the derivative expansion leads to ν=0.632\nu=0.632 and to an anomalous dimension η=0.033\eta=0.033 which is significantly improved compared with lower orders calculations.Comment: 4 pages, 3 figure

    An evaluation of superminicomputers for thermal analysis

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    The feasibility and cost effectiveness of solving thermal analysis problems on superminicomputers is demonstrated. Conventional thermal analysis and the changing computer environment, computer hardware and software used, six thermal analysis test problems, performance of superminicomputers (CPU time, accuracy, turnaround, and cost) and comparison with large computers are considered. Although the CPU times for superminicomputers were 15 to 30 times greater than the fastest mainframe computer, the minimum cost to obtain the solutions on superminicomputers was from 11 percent to 59 percent of the cost of mainframe solutions. The turnaround (elapsed) time is highly dependent on the computer load, but for large problems, superminicomputers produced results in less elapsed time than a typically loaded mainframe computer

    Entropy growth of shift-invariant states on a quantum spin chain

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    We study the entropy of pure shift-invariant states on a quantum spin chain. Unlike the classical case, the local restrictions to intervals of length NN are typically mixed and have therefore a non-zero entropy SNS_N which is, moreover, monotonically increasing in NN. We are interested in the asymptotics of the total entropy. We investigate in detail a class of states derived from quasi-free states on a CAR algebra. These are characterised by a measurable subset of the unit interval. As the entropy density is known to vanishes, SNS_N is sublinear in NN. For states corresponding to unions of finitely many intervals, SNS_N is shown to grow slower than (logN)2(\log N)^2. Numerical calculations suggest a logN\log N behaviour. For the case with infinitely many intervals, we present a class of states for which the entropy SNS_N increases as NαN^\alpha where α\alpha can take any value in (0,1)(0,1).Comment: 18 pages, 2 figure

    Classical simulation of quantum many-body systems with a tree tensor network

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    We show how to efficiently simulate a quantum many-body system with tree structure when its entanglement is bounded for any bipartite split along an edge of the tree. This is achieved by expanding the {\em time-evolving block decimation} simulation algorithm for time evolution from a one dimensional lattice to a tree graph, while replacing a {\em matrix product state} with a {\em tree tensor network}. As an application, we show that any one-way quantum computation on a tree graph can be efficiently simulated with a classical computer.Comment: 4 pages,7 figure

    Characterization of non-local gates

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    A non-local unitary transformation of two qubits occurs when some Hamiltonian interaction couples them. Here we characterize the amount, as measured by time, of interaction required to perform two--qubit gates, when also arbitrarily fast, local unitary transformations can be applied on each qubit. The minimal required time of interaction, or interaction cost, defines an operational notion of the degree of non--locality of gates. We characterize a partial order structure based on this notion. We also investigate the interaction cost of several communication tasks, and determine which gates are able to accomplish them. This classifies two--qubit gates into four categories, differing in their capability to transmit classical, as well as quantum, bits of information.Comment: revtex, 14 pages, no pictures; proof of result 1 simplified significantl
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