These models are based on a quantum version of the Brownian-motion models describing the erratic movement of molecules in a fluid. 5 pages. Xiaoliang Qi (Stanford) “Eternal traversable wormhole” Seminar Organizer July 31, 2018. Extending the approach to operator scrambling, however, is generally hard. "We are kind of in the early exploration of the science at this moment," Lai said. A major goal of Xu and Swingle’s work is to provide a quantitative description of such dynamics. As foreign-funded enterprises export over 50 percent of China's total exports, such energy efficiency improvements will affect the coefficient of exports on the sub-sector energy intensity. Dept.) and ; Nordita), Masao Ninomiya . Attendee List Download Talk Schedule Videos. https://profiles.stanford.edu/xiaoliang-qi, Ideas from superresolution imaging inspire a way to measure time intervals with unprecedented precision—an ability that could enhance our understanding of ultrafast processes. His research interests include string theory, quantum field theory, quantum … In a system of qubits, such as an ensemble of electron spins in a crystal, flipping a single qubit (or a few qubits) in a chaotic system is like triggering a localized earthquake in the middle of the ocean. Welcome to the new INSPIRE! cond-mat. D. in 2007 from Tsinghua University and did postdoctoral research at Stanford University and the University of California, Santa Barbara, before joining the Stanford faculty. Authors: Xiao-Liang Qi, Zhao Yang. Consider, for example, two states of a system of N qubits that only differ in the state of one bit (Fig. The duo compares the results of their random-Hamiltonian approach with those obtained for a specific Hamiltonian (without randomness), which can only be computed numerically. Due to the lack of comprehensive reviews in this emerging field, this review may catch great interest and inspire many new opportunities across a broad range of disciplines. Douglas Stanford Associate Professor Theoretical Astrophysics and Cosmology. We released the new INSPIRE API Learn more. Modular Flow as a Disentangler #15. In a quantum measurement process, classical information about the measured system spreads throughout the environment. Xiaoliang Qi. Such models characterize chaos in terms of quantum-mechanical operators that grow more complex over time. 6 (2010) 284 • e-Print: 0908.1537 • DOI: 10.1038/nphys1534; Electron fractionalization in two-dimensional graphene-like structures. Read More », For an important quantum many-body problem, a hybrid quantum-classical algorithm could outperform purely classical approaches using surprisingly few quantum resources. Associate Professor of Physics and of Photon Science Leonardo Senatore. Download PDF Abstract: We show that the fundamental time reversal invariant (TRI) insulator exists in 4+1 dimensions, where the effective field theory is described by the 4+1 dimensional Chern-Simons theory and the topological properties of the electronic structure is classified by the second Chern number. It is important to note, however, that there is a fundamental difference between Brownian models and Hamiltonian models without randomness: in the latter, the energy of the system is not conserved. This research is published in Physical Review X. Xiaoliang Qi is a professor of physics at Stanford University. Date: October 23, 2018 3:40 pm – 4:40 pm; Categories: String Seminar; We construct a nearly-AdS2 solution describing an eternal traversable wormhole. The details of the wave front, such as its speed and shape, can reveal important information about the underlying linear or nonlinear effects that govern the propagation of the wave. Recent work has explored how this “operator scrambling” is related to quantum chaos [5, 6]. D. in 2007 from Tsinghua University and did postdoctoral research at Stanford University and the University of California, Santa Barbara, before joining the Stanford faculty. Researchers uncover the mechanism that makes some oil droplets change shape from spheres to icosahedrons to flattened plates. To overcome these difficulties, Xu and Swingle turn to so-called Brownian coupled cluster (BCC) models. In quantum mechanics, physical observables like position and momentum become operators, which cannot be simultaneously determined with arbitrary accuracy because of the Heisenberg uncertainty principle. Research in the Stanford Institute for Theoretical Physics (SITP) spans a wide range of topics from understanding the fundamental nature of forces, particles and space-time geometry, to condensed matter physics and quantum information. Sciences is established to inspire Asia's most promising young Ph_D_ students to become future leaders in life sciences_ ChÌnese BÌobgÌca0 Investögators SocÌety Bdennbao Conference The Ray wu Awards and the CBIS Young Investigator Awards August 2016 Chengdue Chlna . But how does the chaos observed in the classical, macroscopic world emerge from the quantum-mechanical laws that govern the microscopic world? 4 citations. There is considerable cross-fertilization in some of these endeavors with faculty in the SLAC Theory Group and the Kavli Institute for Particle Dept.) Video from a new technique reveals the chaotic motion of a fluid flowing through a pile of gravel. Organized by: Matthew Headrick, Alex Maloney, and Mark Van Raamsdonk. Leonard Susskind is the Felix Bloch professor of Theoretical physics at Stanford University. . Dept. Using tensor networks with random link projections, we define boundary theories with interesting holographic properties, such as the Renyi entropies satisfying the covariant Hubeny-Rangamani-Takayanagi … His current research focuses on the relations between quantum entanglement, quantum chaos, and quantum gravity. Over the past few decades we have witnessed a rapid exchange and infuse of ideas across different fields: from entanglement in quantum information to quantum phase transitions and topological order in many-body systems, and also to the holographic principle in the gravity-field theory (AdS/CFT) duality. Use of the American Physical Society websites and journals implies that the user has read and agrees to our Terms and Conditions and any applicable Subscription Agreement. The two states are related by a simple operator X4 that flips the fourth bit. It is natural to ask whether a counterpart of chaos exists in the quantum world. ... Xiaoliang Qi (Stanford U., Phys. 2). We present evidence that the answer is "yes" for generic local Hamiltonians, given either the ground state or an excited eigenstate. Developing a theory that fully describes information scrambling remains, however, a daunting task. Learn more. Suh, “Entanglement tsunami: Universal scaling in holographic thermalization,”. By removing the memory of previous rounds, the game gets easier, as players don’t have to remember what happened in past rounds. This scrambling is a memory-loss mechanism that can cause the unpredictability of chaos. Theoretical Physics. In recent years, progress in holographic duality [9] led to the idea that gravity might be an emergent phenomenon arising from many-body interactions in a quantum chaotic system. As the authors suggest, future work may look into developing frameworks that could quantitatively describe quantum chaos while respecting energy conservation. Here we prove a result about quantum channels indicating that an aspect of this phenomenon is completely general. An analogous family of model with discrete time steps, named as random circuits, have been studied in literature (see Ref. Recent developments in transport phenomena in Weyl semimetals Pavan Hosur, Xiaoliang Qi The last decade has witnessed great advancements in the science and engineering of systems with unconventional band structures, seeded by studies of graphene and topological insulators. Presented By: Definition The Hall effect is the production of a voltage difference (the Hall voltage) across a current carrying conductor (in presence of magnetic ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 441f02-NDBiN Dept.) Their support will thus be defined by a smooth distribution—like the smooth front of a water wave—and chaotic dynamics may further reshape the wave front. However, as the operators evolve in time, they may turn into linear superpositions of several operators acting on different qubits. ), Shou-Cheng Zhang (Stanford U., Phys. Tsinghua U., Beijing. In physics, the term has a more specific meaning: It refers to systems that, while subject to deterministic laws, are totally unpredictable because of an exponential sensitivity to initial conditions—think of the butterfly flapping its wings and causing a distant tornado. The key idea behind the researchers’ work is that introducing randomness may simplify the problem. [6]). Origin and Unification of Elementary Particles (such as light and electrons) Following in the tradition of Albert Einstein, Niels Bohr, and Richard Feynman, the goals of SITP are to uncover the basic physical principles governing the world of natural phenomena. This means that the operator X4 evolves into a more complicated operator that flips more qubits. World's Best PowerPoint Templates - CrystalGraphics offers more PowerPoint templates than anyone else in the world, with over 4 million to choose from. Aug 12, 2009. Read More », The discovery that copernicium can decay into a new isotope of darmstadtium and the observation of a previously unseen excited state of copernicium provide clues to the location of the “island of stability.”. Special operators, like a single-spin flipping operator, have a sharply defined “support”—the set of qubits on which they act. Learn more. Initially, the quake only creates local waves, but its effect can result in a large-scale tsunami, whose propagation is described by a nonlinear equation [7]. Xiaoliang Qi (Stanford U., Phys. Professor of Physics Douglas Stanford. If the system evolves in time, the states may become very different, such that they can only be related by flipping many qubits. Xiao-Liang Qi (Stanford U., Phys. The future positions and momenta are deterministically related to the initial conditions, but this connection grows more mathematically complex with time. Published in: Nature Phys. Topological insulators materialize a topological quantum state of matter where unusual gapless metallic state protected by time-reversal symmetry appears at the edge or surface. Starting with infinitely large N—to simplify the analysis—they determine that the wave front moves as a solitary wave without changing shape. They'll give your presentations a professional, memorable appearance - the kind of sophisticated look that today's audiences expect. In four dimensions Weyl fermions possess a chiral anomaly which leads to several special features in the transport phenomena, such as the negative longitudinal magnetoresistivity. Xu and Swingle show that this formalism enables a quantitative description of how chaos spreads in a many-body system. D. A. Roberts, D. Stanford, and L. Susskind, “Localized shocks,”, Physical Review Physics Education Research, https://profiles.stanford.edu/xiaoliang-qi, Locality, Quantum Fluctuations, and Scrambling, Ultrabright Photons for Single-Chip Quantum Devices, Gaining a Quantum Advantage Sooner than Expected, An Octad for Darmstadtium and Excitement for Copernicium, Psychedelic View of Fluid in Porous Materials, Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305, USA. Welcome to the new INSPIRE! ), Shou-Cheng Zhang (Stanford U., Phys. He received his Ph. Take the survey. Theoretical Astrophysics and Cosmology Theoretical Physics. Hinted at some characteristic features of quantum gravity the fourth bit ground state or an excited eigenstate without changing.... Approach may contribute to unlocking the mystery of quantum chaos while respecting energy conservation ; show all 8 Hide! Related by a simple operator X4 that flips the fourth bit the School Humanities! 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