检索结果-内蒙古大学图书馆

Enhancing quantum control by bootstrapping a quantum processor of 12 qubits

学校读者我要写书评

暂无评论

arXiv 2017年

作者： Lu, Dawei Li, Keren Li, Jun Katiyar, Hemant Park, Annie Jihyun Feng, Guanru Xin, Tao Li, Hang Long, Guilu Brodutch, Aharon Baugh, Jonathan Zeng, Bei Laflamme, Raymond Department of Physics Southern University of Science and Technology Shenzhen518055 China Institute for Quantum Computing Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China Beijing Computational Science Research Center Beijing100193 China Max-Planck-Institutfür Quantenoptik GarchingD-85748 Germany Center for Quantum Information and Quantum Control Department of Physics Department of Electrical and Computer Engineering University of Toronto TorontoONM5S 3H6 Canada Department of Mathematics and Statistics University of Guelph GuelphONN1G 2W1 Canada Perimeter Institute for Theoretical Physics Waterloo ONN2L 2Y5 Canada

Accurate and efficient control of quantum systems is one of the central challenges for quantum information processing. Current state-of-the-art experiments rarely go beyond 10 qubits and in most cases demonstrate only limited control. Here we demonstrate control of a 12-qubit system, and show that the system can be employed as a quantum processor to optimize its own control sequence by using measurement-based feedback control (MQFC). The final product is a control sequence for a complex 12-qubit task: preparation of a 12-coherent state. The control sequence is about 10% more accurate than the one generated by the standard (classical) technique, showing that MQFC can correct for unknown imperfections. Apart from demonstrating a high level of control over a relatively large system, our results show that even at the 12-qubit level, a quantum processor can be a useful lab instrument. As an extension of our work, we propose a method for combining the MQFC technique with a twirling protocol, to optimize the control sequence that produces a desired Clifford gate. Copyright © 2017, The Authors. All rights reserved.

关键词： Quantum optics

The Assessment of Vibrational Non-equilibrium Effect on Detonation

学校读者我要写书评

暂无评论

The Assessment of Vibrational Non-equilibrium Effect on Deto...

第二届高温气体动力学国际会议

作者： Lisong Shi Hua Shen Peng Zhang Deliang Zhang Chihyung Wen Department of Mechanical Engineering The Hong Kong Polytechnic University Applied Mathematics and Computational Science King Abdullah University of Science and Technology State Key Laboratory of High Temperature Gas Dynamics Institute of Mechanics Chinese Academy of sciences

Published simulations indicated that the calculated detonation cell sizes are significantly smaller compared to the experimental *** research targets to narrow down this discrepancy,by accounting the non-equilibrium effect between vibrational energy and translational-rotational energy,and the influence on reaction rates.A series of 1D and 2D numerical investigation are

关键词： The Assessment of Vibrational Non-equilibrium Effect on Detonation

Parkes Pulsar Timing Array constraints on ultralight scalar-field dark matter

学校读者我要写书评

暂无评论

arXiv 2018年

作者： Porayko, Nataliya K. Zhu, Xingjiang Levin, Yuri Hui, Lam Hobbs, George Grudskaya, Aleksandra Postnov, Konstantin Bailes, Matthew Bhat, N.D. Ramesh Coles, William Dai, Shi Dempsey, James Keith, Michael J. Kerr, Matthew Kramer, Michael Lasky, Paul D. Manchester, Richard N. Oslowski, Stefan Parthasarathy, Aditya Ravi, Vikram Reardon, Daniel J. Rosado, Pablo A. Russell, Christopher J. Shannon, Ryan M. Spiewak, Renée van Straten, Willem Toomey, Lawrence Wang, Jingbo Wen, Linqing You, Xiaopeng Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany School of Physics and Astronomy Monash University ClaytonVIC3800 Australia School of Physics University of Western Australia CrawleyWA6009 Australia Australian Research Council Centre of Excellence for Gravitational Wave Discovery Center for Theoretical Physics Department of Physics Columbia University New YorkNY10027 United States Center for Computational Astrophysics Flatiron Institute New YorkNY10010 United States CSIRO Astronomy and Space Science P.O. Box 76 EppingNSW1710 Australia Sternberg Astronomical Institute Lomonosov Moscow State University Universitetskii pr. 13 Moscow119234 Russia Kazan Federal University Kremlevskaya 18 Kazan420008 Russia Centre for Astrophysics and Supercomputing Swinburne University of Technology P.O. Box 218 HawthornVIC3122 Australia International Centre for Radio Astronomy Research Curtin University BentleyWA6102 Australia Department of Electrical and Computer Engineering University of California at San Diego La JollaCA92093 United States CSIRO Information Management and Technology PO Box 225 DicksonACT2602 Australia Jodrell Bank Centre for Astrophysics University of Manchester ManchesterM13 9PL United Kingdom Space Science Division Naval Research Laboratory WashingtonDC20375 United States Cahill Center for Astronomy and Astrophysics California Institute of Technology MC 249-17 PasadenaCA91125 United States CSIRO Scientific Computing Australian Technology Park Locked Bag 9013 AlexandriaNSW1435 Australia Institute for Radio Astronomy & Space Research Auckland University of Technology Private Bag 92006 Auckland1142 New Zealand Xinjiang Astronomical Observatory Chinese Academy of Sciences 150 Science 1-Street Urumqi Xinjiang830011 China School of Physical Science and Technology Southwest University Chongqing400715 China

It is widely accepted that dark matter contributes about a quarter of the critical mass-energy density in our Universe. The nature of dark matter is currently unknown, with the mass of possible constituents spanning nearly one hundred orders of magnitude. The ultralight scalar field dark matter, consisting of extremely light bosons with m ∼ 10−22 eV and often called "fuzzy" dark matter, provides intriguing solutions to some challenges at sub-Galactic scales for the standard cold dark matter model. As shown by Khmelnitsky and Rubakov, such a scalar field in the Galaxy would produce an oscillating gravitational potential with nanohertz frequencies, resulting in periodic variations in the times of arrival of radio pulses from pulsars. The Parkes Pulsar Timing Array (PPTA) has been monitoring 20 millisecond pulsars at two to three weeks intervals for more than a decade. In addition to the detection of nanohertz gravitational waves, PPTA offers the opportunity for direct searches for fuzzy dark matter in an astrophysically feasible range of masses. We analyze the latest PPTA data set which includes timing observations for 26 pulsars made between 2004 and 2016. We perform a search in this data set for evidence of ultralight dark matter in the Galaxy using Bayesian and Frequentist methods. No statistically significant detection has been made. We, therefore, place upper limits on the local dark matter density. Our limits, improving on previous searches by a factor of 2 to 5, constrain the dark matter density of ultralight bosons with m ≤ 10−23 eV to be below 6 GeV cm−3 with 95% confidence in the Earth neighborhood. Finally, we discuss the prospect of probing the astrophysically favored mass range m & 10−22 eV with next-generation pulsar timing facilities. Copyright © 2018, The Authors. All rights reserved.

关键词： Timing circuits

The Atacama Cosmology Telescope: A measurement of the cosmic microwave background power spectra at 98 and 150 GHZ

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Choi, Steve K. Hasselfield, Matthew Ho, Shuay-Pwu Patty Koopman, Brian Lungu, Marius Abitbol, Maximilian H. Addison, Graeme E. Ade, Peter A.R. Aiola, Simone Alonso, David Amiri, Mandana Amodeo, Stefania Angile, Elio Austermann, Jason E. Baildon, Taylor Battaglia, Nick Beall, James A. Bean, Rachel Becker, Daniel T. Bond, J. Richard Bruno, Sarah Marie Calabrese, Erminia Calafut, Victoria Campusano, Luis E. Carrero, Felipe Chesmore, Grace E. Cho, Hsiao-Mei Clark, Susan E. Cothard, Nicholas F. Crichton, Devin Crowley, Kevin T. Darwish, Omar Datta, Rahul Denison, Edward V. Devlin, Mark J. Duell, Cody J. Duff, Shannon M. Duivenvoorden, Adriaan J. Dunkley, Jo Dünner, Rolando Essinger-Hileman, Thomas Fankhanel, Max Ferraro, Simone Fox, Anna E. Fuzia, Brittany Gallardo, Patricio A. Gluscevic, Vera Golec, Joseph E. Grace, Emily Gralla, Megan Guan, Yilun Hall, Kirsten Halpern, Mark Han, Dongwon Hargrave, Peter Henderson, Shawn Hensley, Brandon Hill, J. Colin Hilton, Gene C. Hilton, Matt Hincks, Adam D. Hložek, Renée Hubmayr, Johannes Huffenberger, Kevin M. Hughes, John P. Infante, Leopoldo Irwin, Kent Jackson, Rebecca Klein, Jeff Knowles, Kenda Kosowsky, Arthur Lakey, Victoria Li, Dale Li, Yaqiong Li, Zack Lokken, Martine Louis, Thibaut MacInnis, Amanda Madhavacheril, Mathew Maldonado, Felipe Mallaby-Kay, Maya Marsden, Danica Maurin, Loïc McMahon, Jeff Menanteau, Felipe Moodley, Kavilan Morton, Tim Naess, Sigurd Namikawa, Toshiya Nati, Federico Newburgh, Laura Nibarger, John P. Nicola, Andrina Niemack, Michael D. Nolta, Michael R. Orlowski-Sherer, John Page, Lyman A. Pappas, Christine G. Partridge, Bruce Phakathi, Phumlani Prince, Heather Puddu, Roberto Qu, Frank J. Rivera, Jesus Robertson, Naomi Rojas, Felipe Salatino, Maria Schaan, Emmanuel Schillaci, Alessandro Schmitt, Benjamin L. Sehgal, Neelima Sherwin, Blake D. Sierra, Carlos Sievers, Jon Sifon, Cristobal Sikhosana, Precious Simon, Sara Spergel, David N. Staggs, Suzanne T. Stevens, Jason Storer, Emilie Sunder, Dhaneshwar D. Switzer, Eric R. Thorne, Ben Thornton, Robe Department of Physics Cornell University IthacaNY14853 United States Department of Astronomy Cornell University IthacaNY14853 United States Joseph Henry Laboratories of Physics Jadwin Hall Princeton University PrincetonNJ08544 United States Center for Computational Astrophysics Flatiron Institute 162 5th Avenue New YorkNY10010 United States Department of Astronomy and Astrophysics The Pennsylvania State University University ParkPA16802 United States Institute for Gravitation and the Cosmos The Pennsylvania State University University ParkPA16802 United States Department of Physics Yale University 217 Prospect St New HavenCT06511 United States Department of Physics and Astronomy University of Pennsylvania 209 South 33rd Street PhiladelphiaPA19104 United States Department of Physics University of Oxford Keble Road OxfordOX1 3RH United Kingdom Dept. of Physics and Astronomy The Johns Hopkins University 3400 N. Charles St. BaltimoreMD21218-2686 United States School of Physics and Astronomy Cardiff University The Parade Wales CardiffCF24 3AA United Kingdom Department of Physics and Astronomy University of British Columbia VancouverBCV6T 1Z4 Canada NIST Quantum Devices Group 325 Broadway Mailcode 817.03 BoulderCO80305 United States Department of Physics University of Michigan Ann Arbor48103 United States Canadian Institute for Theoretical Astrophysics University of Toronto TorontoONM5S 3H8 Canada Universidad de Chile Dept Astronomía Casilla Santiago36-D Chile Sociedad Radiosky Asesorías de Ingeniería Limitada Camino a Toconao 145-A Ayllu de Solor San Pedro de Atacama Chile Department of Physics University of Chicago ChicagoIL60637 United States SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo ParkCA94025 United States Institute for Advanced Study 1 Einstein Dr PrincetonNJ08540 United States Department of Applied and Engineering Physics Cornell University IthacaNY14853 United States Astrophysics Res

We present the temperature and polarization angular power spectra of the CMB measured by the Atacama Cosmology Telescope (ACT) from 5400 deg2 of the 2013-2016 survey, which covers >15000 deg2 at 98 and 150 GHz. For this analysis we adopt a blinding strategy to help avoid confirmation bias and, related to this, show numerous checks for systematic error done before unblinding. Using the likelihood for the cosmological analysis we constrain secondary sources of anisotropy and foreground emission, and derive a "CMB-only" spectrum that extends to = 4000. At large angular scales, foreground emission at 150 GHz is ∼1% of TT and EE within our selected regions and consistent with that found by Planck. Using the same likelihood, we obtain the cosmological parameters for ΛCDM for the ACT data alone with a prior on the optical depth of τ = 0.065 ± 0.015. ΛCDM is a good fit. The best-fit model has a reduced χ2 of 1.07 (PTE = 0.07) with H0 = 67.9 ± 1.5 km/s/Mpc. We show that the lensing BB signal is consistent with ΛCDM and limit the celestial EB polarization angle to ψP = −0.07◦ ± 0.09◦. We directly cross correlate ACT with Planck and observe generally good agreement but with some discrepancies in TE. All data on which this analysis is based will be publicly released. Copyright © 2020, The Authors. All rights reserved.

关键词： Cosmology

Correlating the Structure and Optical Absorption Properties of Au76（SR）44 Cluster

学校读者我要写书评

暂无评论

Correlating the Structure and Optical Absorption Properties ...

第九届计算纳米科学与新能源材料国际研讨会

作者： Zhongyun Ma P.Wang G.Zhou J.Tang H.Li Y.Pei Department of Chemistry Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of EducationXiangtan University Hunan Key Laboratory for Computation and Simulation in Science and Engineering Institute for Computational and Applied MathematicsXiangtan University School of Materials Science and Engineering Central South University

The atomic structure of recently synthesized thiolate-protected Au cluster is theoretically predicted via a simple structural rule summarized from the crystal structures of thiolate-protected Au（SR）, Au（SR） and Au（SR） clusters. We find that the Au（SR）（N = 7） and recently reported Au（SR）（N = 4）, Au（SR）（N = 3）, Au（SR）（N = 2） and Au（SR）（N = 1） belong to a family of homologous Au（SR） cluster whose Au-cores follow one-dimensional polytetrahedral growth pathway. The Au（SR） cluster is predicted to contain an anisotropic face-centered cubic（FCC） Au-core, which can be viewed as combination of two helical tetrahedra-Au4 chains and is remarkably different from the well-known spherical Au-core in ligand protected gold clusters in the size region of 1-2 nm. The intense near infrared（NIR） absorption of Au（SR） is attributed to the synergistic effect of anisotropic Au-core structure and ligand protections. A plausible cluster-to-cluster transformation mechanism is further suggested.

关键词： thiolated-protected gold nanocluster Au76SR44 face-centered cubic near infrared adsorption

The Atacama Cosmology Telescope: DR4 maps and cosmological parameters

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Aiola, Simone Calabrese, Erminia Maurin, Loïc Naess, Sigurd Schmitt, Benjamin L. Abitbol, Maximilian H. Addison, Graeme E. Ade, Peter A.R. Alonso, David Amiri, Mandana Amodeo, Stefania Angile, Elio Austermann, Jason E. Baildon, Taylor Battaglia, Nick Beall, James A. Bean, Rachel Becker, Daniel T. Bond, J. Richard Bruno, Sarah Marie Calafut, Victoria Campusano, Luis E. Carrero, Felipe Chesmore, Grace E. Cho, Hsiao-Mei Choi, Steve K. Clark, Susan E. Cothard, Nicholas F. Crichton, Devin Crowley, Kevin T. Darwish, Omar Datta, Rahul Denison, Edward V. Devlin, Mark J. Duell, Cody J. Duff, Shannon M. Duivenvoorden, Adriaan J. Dunkley, Jo Dünner, Rolando Essinger-Hileman, Thomas Fankhanel, Max Ferraro, Simone Fox, Anna E. Fuzia, Brittany Gallardo, Patricio A. Gluscevic, Vera Golec, Joseph E. Grace, Emily Gralla, Megan Guan, Yilun Hall, Kirsten Halpern, Mark Han, Dongwon Hargrave, Peter Hasselfield, Matthew Helton, Jakob M. Henderson, Shawn Hensley, Brandon Hill, J. Colin Hilton, Gene C. Hilton, Matt Hincks, Adam D. Hložek, Renée Ho, Shuay-Pwu Patty Hubmayr, Johannes Huffenberger, Kevin M. Hughes, John P. Infante, Leopoldo Irwin, Kent Jackson, Rebecca Klein, Jeff Knowles, Kenda Koopman, Brian Kosowsky, Arthur Lakey, Victoria Li, Dale Li, Yaqiong Li, Zack Lokken, Martine Louis, Thibaut Lungu, Marius MacInnis, Amanda Madhavacheril, Mathew Maldonado, Felipe Mallaby-Kay, Maya Marsden, Danica McMahon, Jeff Menanteau, Felipe Moodley, Kavilan Morton, Tim Namikawa, Toshiya Nati, Federico Newburgh, Laura Nibarger, John P. Nicola, Andrina Niemack, Michael D. Nolta, Michael R. Orlowski-Sherer, John Page, Lyman A. Pappas, Christine G. Partridge, Bruce Phakathi, Phumlani Pisano, Giampaolo Prince, Heather Puddu, Roberto Qu, Frank J. Rivera, Jesus Robertson, Naomi Rojas, Felipe Salatino, Maria Schaan, Emmanuel Schillaci, Alessandro Sehgal, Neelima Sherwin, Blake D. Sierra, Carlos Sievers, Jon Sifon, Cristobal Sikhosana, Precious Simon, Sara Spergel, David N. Staggs, Suzanne T. Stevens, Jason Storer, Emilie Sunder, Dhaneshwar D. Switzer, Center for Computational Astrophysics Flatiron Institute 162 5th Avenue New YorkNY10010 United States Joseph Henry Laboratories of Physics Jadwin Hall Princeton University PrincetonNJ08544 United States School of Physics and Astronomy Cardiff University The Parade Wales CardiffCF24 3AA United Kingdom Université Paris-Saclay CNRS Institut d'astrophysique spatiale Orsay 91405 France Instituto de Astrofísica Centro de Astro-Ingeniería Facultad de Fìsica Pontificia Universidad Católica de Chile Av. Vicuña Mackenna 4860 Macul Santiago7820436 Chile Department of Physics and Astronomy University of Pennsylvania 209 South 33rd Street PhiladelphiaPA19104 United States Department of Physics University of Oxford Keble Road OxfordOX1 3RH United Kingdom Dept. of Physics and Astronomy The Johns Hopkins University 3400 N. Charles St. BaltimoreMD21218-2686 United States Department of Physics and Astronomy University of British Columbia VancouverBCV6T 1Z4 Canada Department of Astronomy Cornell University IthacaNY14853 United States NIST Quantum Devices Group 325 Broadway Mailcode 817.03 BoulderCO80305 United States Department of Physics University of Michigan Ann Arbor48103 United States Canadian Institute for Theoretical Astrophysics University of Toronto TorontoONM5S 3H8 Canada Universidad de Chile Dept Astronomía Casilla Santiago36-D Chile Sociedad Radiosky Asesorías de Ingeniería Limitada Camino a Toconao 145-A Ayllu de Solor San Pedro de Atacama Chile Department of Physics University of Chicago ChicagoIL60637 United States SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo ParkCA94025 United States Department of Physics Cornell University IthacaNY14853 United States Institute for Advanced Study 1 Einstein Dr PrincetonNJ08540 United States Department of Applied and Engineering Physics Cornell University IthacaNY14853 United States Astrophysics Research Centre School of Mathematics Statistics and Computer Scie

We present new arcminute-resolution maps of the Cosmic Microwave Background temperature and polarization anisotropy from the Atacama Cosmology Telescope, using data taken from 2013-2016 at 98 and 150 GHz. The maps cover more than 17,000 deg2, the deepest 600 deg2 with noise levels below 10µK-arcmin. We use the power spectrum derived from almost 6,000 deg2 of these maps to constrain cosmology. The ACT data enable a measurement of the angular scale of features in both the divergence-like polarization and the temperature anisotropy, tracing both the velocity and density at last-scattering. From these one can derive the distance to the last-scattering surface and thus infer the local expansion rate, H0. By combining ACT data with large-scale information from WMAP we measure H0 = 67.6±1.1 km/s/Mpc, at 68% confidence, in excellent agreement with the independently-measured Planck satellite estimate (from ACT alone we find H0 = 67.9 ±1.5 km/s/Mpc). The ΛCDM model provides a good fit to the ACT data, and we find no evidence for deviations: both the spatial curvature, and the departure from the standard lensing signal in the spectrum, are zero to within 1σ;the number of relativistic species, the primordial Helium fraction, and the running of the spectral index are consistent with ΛCDM predictions to within 1.5-2.2σ. We compare ACT, WMAP, and Planck at the parameter level and find good consistency;we investigate how the constraints on the correlated spectral index and baryon density parameters readjust when adding CMB large-scale information that ACT does not measure. The DR4 products presented here will be publicly released on the NASA Legacy Archive for Microwave Background Data Analysis. Copyright © 2020, The Authors. All rights reserved.

关键词： Cosmology

Measuring holographic entanglement entropy on a quantum simulator

学校读者我要写书评

暂无评论

arXiv 2017年

作者： Li, Keren Han, Muxin Qu, Dongxue Huang, Zichang Long, Guilu Wan, Yidun Lu, Dawei Zeng, Bei Laflamme, Raymond Shenzhen Institute for Quantum Science and Engineering Department of Physics Southern University of Science and Technology Shenzhen518055 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen518055 China Institute for Quantum Computing and Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics Tsinghua University Beijing100084 China Department of Physics Florida Atlantic University 777 Glades Road Boca RatonFL33431 United States Institut für Quantengravitation Universität Erlangen-Nürnberg Staudtstr. 7/B2 Erlangen91058 Germany State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Department of Physics and Center for Field Theory and Particle Physics Fudan University Shanghai200433 China Institute for Nanoelectronic devices and Quantum computing Fudan University Shanghai200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China Shenzhen Key Laboratory of Quantum Science and Engineering Shenzhen518055 China Department of Mathematics and Statistics University of Guelph GuelphONN1G 2W1 Canada Perimeter Institute for Theoretical Physics WaterlooONN2L 2Y5 Canada

Quantum simulation promises to have wide applications in many fields where problems are hard to model with classical computers. Various quantum devices of different platforms have been built to tackle the problems in, say, quantum chemistry, condensed matter physics, and high-energy physics. Here, we report an experiment towards the simulation of quantum gravity by simulating the holographic entanglement entropy. On a six-qubit nuclear magnetic resonance quantum simulator, we demonstrate a key result of Anti-de Sitter/conformal field theory(AdS/CFT ) correspondence-the Ryu-Takayanagi formula is demonstrated by measuring the relevant entanglement entropies on the perfect tensor state. The fidelity of our experimentally prepared the six-qubit state is 85.0% via full state tomography and reaches 93.7%if the signal-decay due to decoherence is taken into account. Our experiment serves as the basic module of simulating more complex tensor network states that exploring AdS/CFT correspondence. As the initial experimental attempt to study AdS/CFT via quantum information processing, our work opens up new avenues exploring quantum gravity phenomena on quantum simulators. Copyright © 2017, The Authors. All rights reserved.

关键词： Quantum chemistry

The second data release of the kodiaq survey

学校读者我要写书评

暂无评论

arXiv 2017年

作者： O'Meara, J.M. Lehner, N. Howk, J.C. Prochaska, J.X. Fox, A.J. Peeples, M.S. Tumlinson, J. O'Shea, B.W. Department of Chemistry and Physics Saint Michael's College One Winooski Park ColchesterVT05439 United States Department of Physics University of Notre Dame 225 Nieuwland Science Hall Notre DameIN46556 United States University of California/Lick Observatory 1156 High Street Santa CruzCA95064 United States Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Department of Physics and Astronomy Johns Hopkins University BaltimoreMD21218 United States Department of Computational Mathematics Science and Engineering Michigan State University East LansingMI48824 United States

We present and make publicly available the second data release (DR2) of the Keck Observatory Database of Ionized Absorption toward Quasars (KODIAQ) survey. KODIAQ DR2 consists of a fullyreduced sample of 300 quasars a... 详细信息

关键词： Surveys

Bounds on the dynamics of periodic quantum walks and emergence of the gapless and gapped Dirac equation

学校读者我要写书评

暂无评论

arXiv 2017年

作者： Pradeep Kumar, N. Balu, Radhakrishna Laflamme, Raymond Chandrashekar, C.M. Institute of Mathematical Sciences C. I. T Campus Taramani Chennai600113 India U.S. Army Research Laboratory Computational and Information Sciences Directorate AdelphiMD20783 United States Computer Science and Electrical Engineering University of Maryland Baltimore County 1000 Hilltop Circle BaltimoreMD21250 United States Institute for Quantum Computing Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Perimeter Institute for Theoretical Physics WaterlooONN2L 2Y5 Canada Homi Bhabha National Institute Training School Complex Anushakti Nagar Mumbai400094 India

We study the dynamics of discrete-time quantum walk using quantum coin operations, Ĉ(θ1) and Ĉ(θ2) in time-dependent periodic sequence. For the two-period quantum walk with the parameters θ1 and θ2 in the coin operations we show that the standard deviation [σθ1,θ2(t)] is the same as the minimum of standard deviation obtained from one of the one-period quantum walks with coin operations θ1 or θ2, σθ1,θ2(t) = min{σθ1(t), σθ2(t)}. Our numerical result is analytically corroborated using the dispersion relation obtained from the continuum limit of the dynamics. Using the dispersion relation for one- and two-period quantum walks, we present the bounds on the dynamics of three- and higher period quantum walks. We also show that the bounds for the two-period quantum walk will hold good for the split-step quantum walk which is also defined using two coin operators using θ1 and θ2. Unlike the previous known connection of discrete-time quantum walks with the massless Dirac equation where coin parameter θ = 0, here we show the recovery of the massless Dirac equation with non-zero θ parameters contributing to the intriguing interference in the dynamics in a totally non-relativistic situation. We also present the effect of periodic sequence on the entanglement between coin and position space. Copyright © 2017, The Authors. All rights reserved.

关键词： Coin operated equipment