IA Scholar Query: Temporal decoupling with error-bounded predictive quantum control.
https://scholar.archive.org/
Internet Archive Scholar query results feedeninfo@archive.orgWed, 03 Aug 2022 00:00:00 GMTfatcat-scholarhttps://scholar.archive.org/help1440Modeling Cosmic Reionization
https://scholar.archive.org/work/dwx46ig32baubewfmlvc5lap2e
The transformation of cold neutral intergalactic hydrogen into a highly ionized warm plasma marks the end of the cosmic dark ages and the beginning of the age of galaxies. The details of this process reflect the nature of the early sources of radiation and heat, the statistical characteristics of the large-scale structure of the Universe, the thermodynamics and chemistry of cosmic baryons, and the histories of star formation and black hole accretion. A number of massive data sets from new ground- and space-based instruments and facilities over the next decade are poised to revolutionize our understanding of primeval galaxies, the reionization photon budget, the physics of the intergalactic medium (IGM), and the fine-grained properties of hydrogen gas in the "cosmic web". In this review we survey the physics and key aspects of reionization-era modeling and describe the diverse range of computational techniques and tools currently available in this field.Nickolay Y. Gnedin, Piero Madauwork_dwx46ig32baubewfmlvc5lap2eWed, 03 Aug 2022 00:00:00 GMTDynamic deformables
https://scholar.archive.org/work/ail7xnlyuzeblargndqwropb3e
Simulating dynamic deformation has been an integral component of Pixar's storytelling since Boo's shirt in Monsters, Inc. (2001). Recently, several key transformations have been applied to Pixar's core simulator Fizt that improve its speed, robustness, and generality. Starting with Coco (2017), improved collision detection and response were incorporated into the cloth solver, then with Cars 3 (2017) 3D solids were introduced, and in Onward (2020) clothing is allowed to interact with a character's body with two-way coupling. The 3D solids are based on a fast, compact, and powerful new formulation that we have published over the last few years at SIGGRAPH. Under this formulation, the construction and eigendecomposition of the force gradient, long considered the most onerous part of the implementation, becomes fast and simple. We provide a detailed, self-contained, and unified treatment here that is not available in the technical papers. We also provide, for the first time, open-source C++ implementations of many of the described algorithms. This new formulation is only a starting point for creating a simulator that is up challenges of a production environment. One challenge is performance: we discuss our current best practices for accelerating system assembly and solver performance. Another challenge that requires considerable attention is robust collision detection and response. Much has been written about collision detection approaches such as proximity-queries, continuous collisions and global intersection analysis. We discuss our strategies for using these techniques, which provides us with valuable information that is needed to handle challenging scenarios.Theodore Kim, David Eberlework_ail7xnlyuzeblargndqwropb3eTue, 02 Aug 2022 00:00:00 GMTQuantum Mechanics and General Relativity are fully compatible, and have a common origin: the expanding (hyper) balloon universe
https://scholar.archive.org/work/ahrw5avjlzedtmp3dydkf4d2y4
Please download the paper and then read the abstract (since crucial formulas are not appearing in this window, and also hyperlinks are not working). This is just an overall view: Relativity is 'inside the light cone' phenomena, while Quantum Mechanics is 'outside the light cone' phenomena, dictated just by the scale (whether we use human/astronomical scale or sub-atomic scale). This recent paper ['Quantum principle of relativity'; Andrzej Dragan, Artur Ekert, New. J. Phys. 22 (2020) 033098] has shown that every exotic Quantum effect like superposition, entanglement, probabilistic behavior, multiple paths etc. can be explained just by allowing superluminal possibility. The 'inside the light cone' phenomena, and the 'outside the light cone' phenomena together span the entire region within the space and time axes. Only in unison they complete the entire picture. We failed to realize that the same spacetime is getting split into 'space like' and 'time like' regions based on scale. And the reason behind this is not the magical (?) speed of light. That would have turned relativity into just a branch of electromagnetism. It turns out that the c is the radial expansion velocity of our universe. Special Relativity and Quantum Mechanics (QM) are like two sides of the same coin. But understanding the relation between QM and General Relativity (GR) is a bit tricky, because according to GR, gravity is the warping/curvature of the 4 dimensional spacetime itself. Once I cover this topic, it becomes clear that QM and GR are fully compatible. Nature simply cannot afford to make our two greatest theories incompatible. We do not need to quantize gravity, since gravity is not a true force, and we have already achieved all the necessary quantizations for the other 3 forces of nature. Unfortunately all modern research towards unifying QM and GR are intensely focused on 'Quantum Gravity'. [By the way, LHC (CERN) results are tightening the noose on the [...]Subhajit Waughwork_ahrw5avjlzedtmp3dydkf4d2y4Sat, 30 Jul 2022 00:00:00 GMTQuantum Mechanics and General Relativity are fully compatible, and have a common origin: the expanding (hyper) balloon universe
https://scholar.archive.org/work/vc3qbtcxgnatrod47bcpqwmopu
Please download the paper and then read the abstract (since crucial formulas are not appearing in this window, and also hyperlinks are not working). This is just an overall view: [Please feel free to offer your comments at sub2007waugh@gmail.com Your feedback/suggestions are most welcome] Relativity is 'inside the light cone' phenomena, while Quantum Mechanics is 'outside the light cone' phenomena, dictated just by the scale (whether we use human/astronomical scale or sub-atomic scale). This recent paper ['Quantum principle of relativity'; Andrzej Dragan, Artur Ekert, New. J. Phys. 22 (2020) 033098] has shown that every exotic Quantum effect like superposition, entanglement, probabilistic behavior, multiple paths etc. can be explained just by allowing superluminal possibility. The 'inside the light cone' phenomena, and the 'outside the light cone' phenomena together span the entire region within the space and time axes. Only in unison they complete the entire picture. We failed to realize that the same spacetime is getting split into 'space like' and 'time like' regions based on scale. And the reason behind this is not the magical (?) speed of light. That would have turned relativity into just a branch of electromagnetism. It turns out that the c is the radial expansion velocity of our universe. Special Relativity and Quantum Mechanics (QM) are like two sides of the same coin. But understanding the relation between QM and General Relativity (GR) is a bit tricky, because according to GR, gravity is the warping/curvature of the 4 dimensional spacetime itself. Once I cover this topic, it becomes clear that QM and GR are fully compatible. Nature simply cannot afford to make our two greatest theories incompatible. We do not need to quantize gravity, since gravity is not a true force, and we have already achieved all the necessary quantizations for the other 3 forces of nature. Unfortunately all moder [...]Subhajit Waughwork_vc3qbtcxgnatrod47bcpqwmopuSat, 30 Jul 2022 00:00:00 GMTKATRIN: Status and Prospects for the Neutrino Mass and Beyond
https://scholar.archive.org/work/56fp7qi3r5gofiqsm2fub4qpqi
The Karlsruhe Tritium Neutrino (KATRIN) experiment is designed to measure a high-precision integral spectrum of the endpoint region of T2 beta decay, with the primary goal of probing the absolute mass scale of the neutrino. After a first tritium commissioning campaign in 2018, the experiment has been regularly running since 2019, and in its first two measurement campaigns has already achieved a sub-eV sensitivity. After 1000 days of data-taking, KATRIN's design sensitivity is 0.2 eV at the 90% confidence level. In this white paper we describe the current status of KATRIN; explore prospects for measuring the neutrino mass and other physics observables, including sterile neutrinos and other beyond-Standard-Model hypotheses; and discuss research-and-development projects that may further improve the KATRIN sensitivity.M. Aker, M. Balzer, D. Batzler, A. Beglarian, J. Behrens, A. Berlev, U. Besserer, M. Biassoni, B. Bieringer, F. Block, S. Bobien, L. Bombelli, D. Bormann, B. Bornschein, L. Bornschein, M. Böttcher, C. Brofferio, C. Bruch, T. Brunst, T. S. Caldwell, M. Carminati, R. M. D. Carney, S. Chilingaryan, W. Choi, O. Cremonesi, K. Debowski, M. Descher, D. Díaz Barrero, P. J. Doe, O. Dragoun, G. Drexlin, F. Edzards, K. Eitel, E. Ellinger, R. Engel, S. Enomoto, A. Felden, D. Fink, C. Fiorini, J. A. Formaggio, C. Forstner, F. M. Fränkle, G. B. Franklin, F. Friedel, A. Fulst, K. Gauda, A. S. Gavin, W. Gil, F. Glück, A. Grande, R. Grössle, M. Gugiatti, R. Gumbsheimer, V. Hannen, J. Hartmann, N. Haußmann, K. Helbing, S. Hickford, R. Hiller, D. Hillesheimer, D. Hinz, T. Höhn, T. Houdy, A. Huber, A. Jansen, C. Karl, J. Kellerer, P. King, M. Kleifges, M. Klein, C. Köhler, L. Köllenberger, A. Kopmann, M. Korzeczek, A. Kovalík, B. Krasch, H. Krause, T. Lasserre, L. La Cascio, O. Lebeda, P. Lechner, B. Lehnert, T. L. Le, A. Lokhov, M. Machatschek, E. Malcherek, D. Manfrin, M. Mark, A. Marsteller, E. L. Martin, E. Mazzola, C. Melzer, S. Mertens, J. Mostafa, K. Müller, A. Nava, H. Neumann, S. Niemes, P. Oelpmann, A. Onillon, D. S. Parno, M. Pavan, A. Pigliafreddo, A. W. P. Poon, J. M. L. Poyato, S. Pozzi, F. Priester, M. Puritscher, D. C. Radford, J. Ráliš, S. Ramachandran, R. G. H. Robertson, W. Rodejohann, C. Rodenbeck, M. Röllig, C. Röttele, M. Ryšavý, R. Sack, A. Saenz, R. W. J. Salomon, P. Schäfer, L. Schimpf, K. Schlösser, M. Schlösser, L. Schlüter, S. Schneidewind, M. Schrank, A. K. Schütz, A. Schwemmer, A. Sedlak, M. Šefčík, V. Sibille, D. Siegmann, M. Slezák, F. Spanier, D. Spreng, M. Steidl, M. Sturm, H. H. Telle, L. A. Thorne, T. Thümmler, N. Titov, I. Tkachev, P. Trigilio, K. Urban, K. Valerius, D. Vénos, A. P. Vizcaya Hernández, P. Voigt, C. Weinheimer, S. Welte, J. Wendel, C. Wiesinger, J. F. Wilkerson, J. Wolf, L. Wunderl, S. Wüstling, J. Wydra, W. Xu, S. Zadoroghny, G. Zellerwork_56fp7qi3r5gofiqsm2fub4qpqiSat, 30 Jul 2022 00:00:00 GMTBenchmarking verified logic operations for fault tolerance
https://scholar.archive.org/work/w2elgcoxtzgjbh3pivexwybog4
The promise of quantum computing depends upon the eventual achievement of fault-tolerant quantum error correction, which requires that the total rate of errors falls below some threshold. However, most contemporary methods for benchmarking noisy quantum processors measure average error rates (infidelities), which can differ from worst-case error rates -- defined via the diamond norm -- by orders of magnitude. One method for resolving this discrepancy is to randomize the physical implementation of quantum gates, using techniques like randomized compiling (RC). In this work, we use gate set tomography to perform precision characterization of a set of two-qubit logic gates to study RC on a superconducting quantum processor. We find that, under RC, gate errors are accurately described by a stochastic Pauli noise model without coherent errors, and that spatially-correlated coherent errors and non-Markovian errors are strongly suppressed. We further show that the average and worst-case error rates are equal for randomly compiled gates, and measure a maximum worst-case error of 0.0197(3) for our gate set. Our results show that randomized benchmarks are a viable route to both verifying that a quantum processor's error rates are below a fault-tolerance threshold, and to bounding the failure rates of near-term algorithms, if -- and only if -- gates are implemented via randomization methods which tailor noise.Akel Hashim, Stefan Seritan, Timothy Proctor, Kenneth Rudinger, Noah Goss, Ravi K. Naik, John Mark Kreikebaum, David I. Santiago, Irfan Siddiqiwork_w2elgcoxtzgjbh3pivexwybog4Thu, 28 Jul 2022 00:00:00 GMTRandom Quantum Circuits
https://scholar.archive.org/work/57bh7e2hhbawvbw6cngsbn555e
Quantum circuits -- built from local unitary gates and local measurements -- are a new playground for quantum many-body physics and a tractable setting to explore universal collective phenomena far-from-equilibrium. These models have shed light on longstanding questions about thermalization and chaos, and on the underlying universal dynamics of quantum information and entanglement. In addition, such models generate new sets of questions and give rise to phenomena with no traditional analog, such as new dynamical phases in quantum systems that are monitored by an external observer. Quantum circuit dynamics is also topical in view of experimental progress in building digital quantum simulators that allow control of precisely these ingredients. Randomness in the circuit elements allows a high level of theoretical control, with a key theme being mappings between real-time quantum dynamics and effective classical lattice models or dynamical processes. Many of the universal phenomena that can be identified in this tractable setting apply to much wider classes of more structured many-body dynamics.Matthew P. A. Fisher, Vedika Khemani, Adam Nahum, Sagar Vijaywork_57bh7e2hhbawvbw6cngsbn555eThu, 28 Jul 2022 00:00:00 GMTHigher-Curvature Gravity and Entanglement Entropy
https://scholar.archive.org/work/rs6j2xcnyvfuhczrvg6oypszkq
In this thesis, we focus on higher-curvature extensions of Einstein gravity as toy models to probe universal properties of conformal field theory (CFT) using the gauge/gravity duality. In this context, we are particularly interested in generalized quasi-topological gravities, i.e., theories whose equations of motion for statically spherically symmetric solutions are of second order at most. Here, we characterize the number of these theories existing at a given curvature order and dimensions. Moreover, we show that any effective higher-curvature theory is connected, via field redefinitions to some generalized quasi-topological gravity. The situation is special for three spacetime dimensions, as theories of this type have trivial equations of motion. However, when matter fields are added into the picture, the equations of motion become non-trivial, describing, among other solutions, multiparametric generalizations of the Ba\~nados-Teitelboim-Zanelli black hole. From the CFT side, entanglement entropy arises as a prominent quantity that encodes important information about the field theory, such as the type A and type B trace anomalies in even dimensions and the sphere free energy of the theory in odd dimensions when considering spherical entangling regions. As entanglement entropy also includes divergences, we employ the Kounterterms scheme to extract the physically relevant quantities. In the case of three-dimensional CFTs dual to Einstein gravity, we show that the finite part is isolated and can be written in terms of the Willmore energy, providing an upper bound based on its properties. We extend this remarkable result to arbitrary CFTs under consideration. Besides, we show the validity of the Kounterterms scheme for general quadratic curvature gravity, extracting the type A, type B anomalies of the theory in even dimensions and the sphere free energy in odd ones.Javier Morenowork_rs6j2xcnyvfuhczrvg6oypszkqTue, 26 Jul 2022 00:00:00 GMTContinuous Symmetry Breaking in a Two-dimensional Rydberg Array
https://scholar.archive.org/work/ksovx3x6bfadlkyibwslbfl5wa
Spontaneous symmetry breaking underlies much of our classification of phases of matter and their associated transitions. It provides an example of the power of many-body interactions, enabling a collection of individual degrees of freedom to align its behavior across large spatial and temporal scales. Crucially, the nature of the underlying symmetry being broken determines many of the qualitative properties of the phase; this is illustrated by the case of discrete versus continuous symmetry breaking. Indeed, in contrast to the discrete case, the breaking of a continuous symmetry is governed by Goldstone's theorem, which predicts the existence of gapless modes that mediate power-law correlations. In this work, we realize a two-dimensional dipolar XY model - which exhibits a continuous spin-rotational symmetry - utilizing a Rydberg quantum simulator. We demonstrate the adiabatic preparation of correlated low-temperature states of both the XY ferromagnet and the XY antiferromagnet. In the ferromagnetic case, we characterize the presence of long-range XY order, a feature prohibited in absence of the long-range dipolar interaction. Complementing recent works utilizing the Rydberg-blockade mechanism to realize Ising-type interactions (with a discrete spin rotation symmetry), our work opens the door to exploring the many-body physics of XY interactions in a programmable quantum simulator.Cheng Chen, Guillaume Bornet, Marcus Bintz, Gabriel Emperauger, Lucas Leclerc, Vincent S. Liu, Pascal Scholl, Daniel Barredo, Johannes Hauschild, Shubhayu Chatterjee, Michael Schuler, Andreas M. Laeuchli, Michael P. Zaletel, Thierry Lahaye, Norman Y. Yao, Antoine Browaeyswork_ksovx3x6bfadlkyibwslbfl5waTue, 26 Jul 2022 00:00:00 GMTControl of dephasing in spin qubits during coherent transport in silicon
https://scholar.archive.org/work/zwzpdv2msjhhjop2qwfazflj2q
One of the key pathways towards scalability of spin-based quantum computing systems lies in achieving long-range interactions between electrons and increasing their inter-connectivity. Coherent spin transport is one of the most promising strategies to achieve this architectural advantage. Experimental results have previously demonstrated high fidelity transportation of spin qubits between two quantum dots in silicon and identified possible sources of error. In this theoretical study, we investigate these errors and analyze the impact of tunnel coupling, magnetic field and spin-orbit effects on the spin transfer process. The interplay between these effects gives rise to double dot configurations that include regimes of enhanced decoherence that should be avoided for quantum information processing. These conclusions permit us to extrapolate previous experimental conclusions and rationalize the future design of large scale quantum processors.MengKe Feng, Jun Yoneda, Wister Huang, Yue Su, Tuomo Tanttu, Chih Hwan Yang, Jesus D. Cifuentes, Kok Wai Chan, William Gilbert, Ross C. C. Leon, Fay E. Hudson, Kohei M. Itoh, Arne Laucht, Andrew S. Dzurak, Andre Saraivawork_zwzpdv2msjhhjop2qwfazflj2qMon, 25 Jul 2022 00:00:00 GMTQuantum optimal control in quantum technologies. Strategic report on current status, visions and goals for research in Europe
https://scholar.archive.org/work/4dbgk7ym4reebpaet7ahboxl2i
AbstractQuantum optimal control, a toolbox for devising and implementing the shapes of external fields that accomplish given tasks in the operation of a quantum device in the best way possible, has evolved into one of the cornerstones for enabling quantum technologies. The last few years have seen a rapid evolution and expansion of the field. We review here recent progress in our understanding of the controllability of open quantum systems and in the development and application of quantum control techniques to quantum technologies. We also address key challenges and sketch a roadmap for future developments.Christiane P. Koch, Ugo Boscain, Tommaso Calarco, Gunther Dirr, Stefan Filipp, Steffen J. Glaser, Ronnie Kosloff, Simone Montangero, Thomas Schulte-Herbrüggen, Dominique Sugny, Frank K. Wilhelmwork_4dbgk7ym4reebpaet7ahboxl2iWed, 20 Jul 2022 00:00:00 GMTSuppressing quantum errors by scaling a surface code logical qubit
https://scholar.archive.org/work/5himghrjlvfifnja7ltkjxrysq
Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number of error sources, so the density of errors must be sufficiently low in order for logical performance to improve with increasing code size. Here, we report the measurement of logical qubit performance scaling across multiple code sizes, and demonstrate that our system of superconducting qubits has sufficient performance to overcome the additional errors from increasing qubit number. We find our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, both in terms of logical error probability over 25 cycles and logical error per cycle (2.914%± 0.016% compared to 3.028%± 0.023%). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a 1.7×10^-6 logical error per round floor set by a single high-energy event (1.6×10^-7 when excluding this event). We are able to accurately model our experiment, and from this model we can extract error budgets that highlight the biggest challenges for future systems. These results mark the first experimental demonstration where quantum error correction begins to improve performance with increasing qubit number, illuminating the path to reaching the logical error rates required for computation.Rajeev Acharya, Igor Aleiner, Richard Allen, Trond I. Andersen, Markus Ansmann, Frank Arute, Kunal Arya, Abraham Asfaw, Juan Atalaya, Ryan Babbush, Dave Bacon, Joseph C. Bardin, Joao Basso, Andreas Bengtsson, Sergio Boixo, Gina Bortoli, Alexandre Bourassa, Jenna Bovaird, Leon Brill, Michael Broughton, Bob B. Buckley, David A. Buell, Tim Burger, Brian Burkett, Nicholas Bushnell, Yu Chen, Zijun Chen, Ben Chiaro, Josh Cogan, Roberto Collins, Paul Conner, William Courtney, Alexander L. Crook, Ben Curtin, Dripto M. Debroy, Alexander Del Toro Barba, Sean Demura, Andrew Dunsworth, Daniel Eppens, Catherine Erickson, Lara Faoro, Edward Farhi, Reza Fatemi, Leslie Flores Burgos, Ebrahim Forati, Austin G. Fowler, Brooks Foxen, William Giang, Craig Gidney, Dar Gilboa, Marissa Giustina, Alejandro Grajales Dau, Jonathan A. Gross, Steve Habegger, Michael C. Hamilton, Matthew P. Harrigan, Sean D. Harrington, Oscar Higgott, Jeremy Hilton, Markus Hoffmann, Sabrina Hong, Trent Huang, Ashley Huff, William J. Huggins, Lev B. Ioffe, Sergei V. Isakov, Justin Iveland, Evan Jeffrey, Zhang Jiang, Cody Jones, Pavol Juhas, Dvir Kafri, Kostyantyn Kechedzhi, Julian Kelly, Tanuj Khattar, Mostafa Khezri, Mária Kieferová, Seon Kim, Alexei Kitaev, Paul V. Klimov, Andrey R. Klots, Alexander N. Korotkov, Fedor Kostritsa, John Mark Kreikebaum, David Landhuis, Pavel Laptev, Kim-Ming Lau, Lily Laws, Joonho Lee, Kenny Lee, Brian J. Lester, Alexander Lill, Wayne Liu, Aditya Locharla, Erik Lucero, Fionn D. Malone, Jeffrey Marshall, Orion Martin, Jarrod R. McClean, Trevor Mccourt, Matt McEwen, Anthony Megrant, Bernardo Meurer Costa, Xiao Mi, Kevin C. Miao, Masoud Mohseni, Shirin Montazeri, Alexis Morvan, Emily Mount, Wojciech Mruczkiewicz, Ofer Naaman, Matthew Neeley, Charles Neill, Ani Nersisyan, Hartmut Neven, Michael Newman, Jiun How Ng, Anthony Nguyen, Murray Nguyen, Murphy Yuezhen Niu, Thomas E. O'Brien, Alex Opremcak, John Platt, Andre Petukhov, Rebecca Potter, Leonid P. Pryadko, Chris Quintana, Pedram Roushan, Nicholas C. Rubin, Negar Saei, Daniel Sank, Kannan Sankaragomathi, Kevin J. Satzinger, Henry F. Schurkus, Christopher Schuster, Michael J. Shearn, Aaron Shorter, Vladimir Shvarts, Jindra Skruzny, Vadim Smelyanskiy, W. Clarke Smith, George Sterling, Doug Strain, Marco Szalay, Alfredo Torres, Guifre Vidal, Benjamin Villalonga, Catherine Vollgraff Heidweiller, Theodore White, Cheng Xing, Z. Jamie Yao, Ping Yeh, Juhwan Yoo, Grayson Young, Adam Zalcman, Yaxing Zhang, Ningfeng Zhuwork_5himghrjlvfifnja7ltkjxrysqWed, 20 Jul 2022 00:00:00 GMTDirac bands in the topological insulator Bi2Se3 mapped by time-resolved momentum microscopy
https://scholar.archive.org/work/vgn34bdkz5hfzekhfycnvmkfxm
We have studied the energy dispersion of the Dirac bands of the topological insulator Bi2Se3 at large parallel momenta using a setup for laser-based time-resolved momentum microscopy with 6 eV probe-photons. Using this setup, we can probe the manifold of unoccupied states up to higher intermediate-state energies in a wide momentum window. We observe a strongly momentum-dependent evolution of the topologically protected Dirac states into a conduction band resonance, highlighting the anisotropy dictated by the surface symmetry. Our results are in remarkable agreement with the theoretical surface spectrum obtained from a GW-corrected tight-binding model, suggesting the validity of the approach in the prediction of the quasiparticle excitation spectrum of large systems with non-trivial topology. After photoexcitation with 0.97 eV photons, assigned to a bulk valence band-conduction band transition, the out-of-equilibrium population of the surface state evolves on a multi-picosecond time scale, in agreement with a simple thermodynamical model with a fixed number of particles, suggesting a significant decoupling between bulk and surface states.Stefano Ponzoni, Felix Paßlack, Matija Stupar, David Maximilian Janas, Giovanni Zamborlini, Mirko Cinchettiwork_vgn34bdkz5hfzekhfycnvmkfxmWed, 20 Jul 2022 00:00:00 GMTA Lightweight Space-based Solar Power Generation and Transmission Satellite
https://scholar.archive.org/work/dfr7tdzdjzhxlkznpdezpz2yj4
We propose a novel design for a lightweight, high-performance space-based solar power array combined with power beaming capability for operation in geosynchronous orbit and transmission of power to Earth. We use a modular configuration of small, repeatable unit cells, called tiles, that each individually perform power collection, conversion, and transmission. Sunlight is collected via lightweight parabolic concentrators and converted to DC electric power with high efficiency III-V photovoltaics. Several CMOS integrated circuits within each tile generates and controls the phase of multiple independently-controlled microwave sources using the DC power. These sources are coupled to multiple radiating antennas which act as elements of a large phased array to beam the RF power to Earth. The power is sent to Earth at a frequency chosen in the range of 1-10 GHz and collected with ground-based rectennas at a local intensity no larger than ambient sunlight. We achieve significantly reduced mass compared to previous designs by taking advantage of solar concentration, current CMOS integrated circuit technology, and ultralight structural elements. Of note, the resulting satellite has no movable parts once it is fully deployed and all beam steering is done electronically. Our design is safe, scalable, and able to be deployed and tested with progressively larger configurations starting with a single unit cell that could fit on a cube satellite. The design reported on here has an areal mass density of 160 g/m2 and an end-to-end efficiency of 7-14%. We believe this is a significant step forward to the realization of space-based solar power, a concept once of science fiction.Behrooz Abiri, Manan Arya, Florian Bohn, Austin Fikes, Matan Gal-Katziri, Eleftherios Gdoutos, Ashish Goel, Pilar Espinet Gonzalez, Michael Kelzenberg, Nicolas Lee, Michael A. Marshall, Tatiana Roy, Fabien Royer, Emily C. Warmann, Nina Vaidya, Tatiana Vinogradova, Richard Madonna, Harry Atwater, Ali Hajimiri, Sergio Pellegrinowork_dfr7tdzdjzhxlkznpdezpz2yj4Wed, 20 Jul 2022 00:00:00 GMTDesign and Implementation of the Illinois Express Quantum Metropolitan Area Network
https://scholar.archive.org/work/uxqua4ktk5db5ooijtb2idnilm
The Illinois Express Quantum Network (IEQNET) is a program to realize metropolitan scale quantum networking over deployed optical fiber using currently available technology. IEQNET consists of multiple sites that are geographically dispersed in the Chicago metropolitan area. Each site has one or more quantum nodes (Q-nodes) representing the communication parties in a quantum network. Q-nodes generate or measure quantum signals such as entangled photons and communicate the measurement results via standard, classical signals and conventional networking processes. The entangled photons in IEQNET nodes are generated at multiple wavelengths, and are selectively distributed to the desired users via transparent optical switches. Here we describe the network architecture of IEQNET, including the Internet-inspired layered hierarchy that leverages software-defined networking (SDN) technology to perform traditional wavelength routing and assignment between the Q-nodes. Specifically, SDN decouples the control and data planes, with the control plane being entirely implemented in the classical domain. We also discuss the IEQNET processes that address issues associated with synchronization, calibration, network monitoring, and scheduling. An important goal of IEQNET is to demonstrate the extent to which the control plane classical signals can co-propagate with the data plane quantum signals in the same fiber lines (quantum-classical signal "coexistence"). This goal is furthered by the use of tunable narrow-band optical filtering at the receivers and, at least in some cases, a wide wavelength separation between the quantum and classical channels. We envision IEQNET to aid in developing robust and practical quantum networks by demonstrating metro-scale quantum communication tasks such as entanglement distribution and quantum-state teleportation.Joaquin Chung, Ely M. Eastman, Gregory S. Kanter, Keshav Kapoor, Nikolai Lauk, Cristián Peña, Robert Plunkett, Neil Sinclair, Jordan M. Thomas, Raju Valivarthi, Si Xie, Rajkumar Kettimuthu, Prem Kumar, Panagiotis Spentzouris, Maria Spiropuluwork_uxqua4ktk5db5ooijtb2idnilmTue, 19 Jul 2022 00:00:00 GMTLift at low Reynolds number
https://scholar.archive.org/work/szoslttkwfffzfz5z3kjgmud4a
Lift forces are widespread in hydrodynamics. These are typically observed for big and fast objects, and are often associated with a combination of fluid inertia (i.e. large Reynolds numbers) and some specific symmetry-breaking mechanism. In contrast, low-Reynolds-number flows are usually overdamped and do not exhibit such peculiar and interesting features. However, the inclusion of boundary effects qualitatively changes this picture. Indeed, in the context of soft and biological matter, recent studies have revealed the emergence of novel lift forces generated by boundary softness, flow gradients and/or surface charges. The aim of the present review is to gather and analyse this corpus of literature, in order to identify and unify the questioning within the associated communities, and pave the way towards future research around lift effects at low Reynolds numbers.Lionel Bureau, Gwennou Coupier, Thomas Salezwork_szoslttkwfffzfz5z3kjgmud4aTue, 19 Jul 2022 00:00:00 GMTUnified Light-Matter Floquet Theory and its Application to Quantum Communication
https://scholar.archive.org/work/uzmj365wgnb6voq7z6zzz5keb4
Periodically-driven quantum systems can exhibit a plethora of intriguing non-equilibrium phenomena, that can be analyzed using Floquet theory. Naturally, Floquet theory is employed to describe the dynamics of atoms interacting with intense laser fields. However, this semiclassical analysis can not account for quantum-optical phenomena that rely on the quantized nature of light. In this paper, we take a significant step to go beyond the semiclassical description of atom-photon coupled systems by unifying Floquet theory with quantum optics using the framework of Full-Counting Statistics. This is achieved by introducing counting fields that keep track of the photonic dynamics. This formalism, which is dubbed "Photon-resolved Floquet theory" (PRFT), is based on two-point tomographic measurements, instead of the two-point projective measurements used in standard Full-Counting Statistics. Strikingly, the PRFT predicts the generation of macroscopic light-matter entanglement when atoms interact with multi-frequency electromagnetic fields, thereby leading to complete decoherence of the atomic subsystem in the basis of the Floquet states. This decoherence occurs rapidly in the optical frequency regime, but is negligible in the radio frequency regime. Intriguingly, time crystals can act as good quantum memories even in the optical frequency regime. Our results thus pave the way for the design of efficient quantum memories and quantum operations. Finally, employing the PRFT, we propose a quantum communication protocol that can significantly outperform the state-of-art few-photon protocols by two orders of magnitude or better. The PRFT potentially leads to new insights in various Floquet settings including spectroscopy, thermodynamics, quantum metrology, and quantum simulations.Georg Engelhardt, Sayan Choudhury, W. Vincent Liuwork_uzmj365wgnb6voq7z6zzz5keb4Mon, 18 Jul 2022 00:00:00 GMTInstanton gas approach to the Hubbard model
https://scholar.archive.org/work/wjjrmrnxb5b6dj3ku55vzqzime
In this article we consider a path integral formulation of the Hubbard model based on a SU(2)-symmetrical Hubbard-Stratonovich transformation that couples auxiliary field to the local electronic density. This decoupling is known to have a regular saddle-point structure: each saddle point is a set of elementary field configurations localized in space and imaginary time which we coin instantons. We formulate a classical partition function for the instanton gas that has predictive power. Namely, we can predict the distribution of instantons and show that the instanton number is sharply defined in the thermodynamic limit, thus defining a unique dominant saddle point. Despite the fact that the instanton approach does not capture the magnetic transition inherent to the Hubbard model on the honeycomb lattice, we were able to describe the local moment formation accompanied by short-ranged anti-ferromagnetic correlations. This aspect is also seen in the single particle spectral function that shows clear signs of the upper and lower Hubbard bands. Our instanton approach bears remarkable similarities to local dynamical approaches, such as dynamical mean field theory, in the sense that it has the unique property of allowing for local moment formation without breaking the SU(2) spin symmetry. In contrast to local approaches, it captures short-ranged magnetic fluctuations. Furthermore, it also offers possibilities for systematic improvements by taking into account fluctuations around the dominant saddle point. Finally, we show that the saddle point structure depends upon the choice of lattice geometry. For the square lattice at half-filling, the saddle point structure reflects the itinerant to localized nature of the magnetism as a function of the coupling strength. The implications of our results for Lefschetz thimbles approaches to alleviate the sign problem are also discussed.Maksim Ulybyshev, Christopher Winterowd, Fakher Assaad, Savvas Zafeiropouloswork_wjjrmrnxb5b6dj3ku55vzqzimeWed, 13 Jul 2022 00:00:00 GMTQuantum Mechanics and General Relativity are fully compatible, and have a common origin: the expanding (hyper) balloon universe
https://scholar.archive.org/work/sfk2nfctsvborpec3o2yfnsloq
Please see the abstract directly from the paper (since the crucial formulas are not appearing in this window). This is just an overall view: The greatest challenges facing physics/cosmology today are dark matter, dark energy, information loss (paradox) due to singularity inside black hole etc. which are relics of mistakes in our understanding of General Relativity. The mistake started with Special Relativity, with our misinterpretation of Minkowski SpaceTime equation. We have mistaken a dynamic (moving) 3d hypersheet composed of field & particles in a 4d hyperspace, for 4d spacetime continuum. This mistake took place due to our lack of understanding of i (square root of -1). Imaginary numbers cannot be taken as an independent axis. As an immediate consequence of making this correction, one dimension got freed up (which we were reserving unnecessarily). Kaluza's miracle of obtaining Maxwell's equation in addition to Einstein's equations seemed to demand a heavy price: a 5th dimension was required as an embedding space. Actually, 4 dimension is sufficient (and we get electromagnetic phenomena as a bonus!). Using logical reasoning, the correct model of the universe is constructed, whose theoretical value of Hubble constant agrees very well with observed (accepted) value. From this model, we can see that there are 2 viewpoints involved. From our viewpoint, locality is absolute, while from the center of the universe viewpoint (nature's viewpoint) simultaneity is absolute. Why exotic Quantum Mechanics phenomena arises is also explained.Subhajit Waughwork_sfk2nfctsvborpec3o2yfnsloqWed, 13 Jul 2022 00:00:00 GMTSachdev-Ye-Kitaev Models and Beyond: A Window into Non-Fermi Liquids
https://scholar.archive.org/work/nhjlxjzsirft3hic564pw2hyuy
We present a review of the Sachdev-Ye-Kitaev (SYK) model of compressible quantum many-body systems without quasiparticle excitations, and its connections to various theoretical studies of non-Fermi liquids in condensed matter physics. The review is placed in the context of numerous experimental observations on correlated electron materials. Strong correlations in metals are often associated with their proximity to a Mott transition to an insulator created by the local Coulomb repulsion between the electrons. We explore the phase diagrams of a number of models of such local electronic correlation, employing a dynamical mean field theory in the presence of random spin exchange interactions. Numerical analyses and analytical solutions, using renormalization group methods and expansions in large spin degeneracy, lead to critical regions which display SYK physics. The models studied include the single-band Hubbard model, the t-J model and the two-band Kondo-Heisenberg model in the presence of random spin exchange interactions. We also examine non-Fermi liquids obtained by considering each SYK model with random four-fermion interactions to be a multi-orbital atom, with the SYK-atoms arranged in an infinite lattice. We connect to theories of sharp Fermi surfaces without any low-energy quasiparticles in the absence of spatial disorder, obtained by coupling a Fermi liquid to a gapless boson; a systematic large N theory of such a critical Fermi surface, with SYK characteristics, is obtained by averaging over an ensemble of theories with random boson-fermion couplings. Finally, we present an overview of the links between the SYK model and quantum gravity and end with an outlook on open questions.Debanjan Chowdhury, Antoine Georges, Olivier Parcollet, Subir Sachdevwork_nhjlxjzsirft3hic564pw2hyuyMon, 11 Jul 2022 00:00:00 GMT