A5075163502- Quantum many-body systems
- Quantum Computing Algorithms and Architecture
- Quantum and electron transport phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Topological Materials and Phenomena
- Quantum Information and Cryptography
- Quantum, superfluid, helium dynamics
- Advanced Thermodynamics and Statistical Mechanics
- Physics of Superconductivity and Magnetism
- Theoretical and Computational Physics
- Graphene research and applications
- Nonlinear Photonic Systems
- Quantum chaos and dynamical systems
- Neural Networks and Applications
- Opinion Dynamics and Social Influence
- advanced mathematical theories
- Advanced Fiber Laser Technologies
- Neural Networks and Reservoir Computing
- Quantum Mechanics and Applications
- Advanced Condensed Matter Physics
- Semiconductor Quantum Structures and Devices
- Atomic and Subatomic Physics Research
- Quantum Mechanics and Non-Hermitian Physics
- stochastic dynamics and bifurcation
- Topological and Geometric Data Analysis
Ames National Laboratory
2021-2025
Iowa State University
2019-2025
Fermi National Accelerator Laboratory
2023
Boston University
2013-2022
Joint Quantum Institute
2018-2020
University of Maryland, College Park
2018-2020
University of California, Santa Barbara
2018-2019
We study the spin-1 $XY$ model on a hypercubic lattice in $d$ dimensions and show that this well-known nonintegrable hosts an extensive set of anomalous finite-energy-density eigenstates with remarkable properties. Namely, they exhibit subextensive entanglement entropy spatiotemporal long-range order, both believed to be impossible typical highly excited quantum many-body systems. While generic initial states are expected thermalize, we analytically construct lead weak ergodicity breaking...
We study one-dimensional spin-$1/2$ models in which strict confinement of Ising domain walls leads to the fragmentation Hilbert space into exponentially many disconnected subspaces. Whereas most previous works emphasize dipole moment conservation as an essential ingredient for such fragmentation, we instead require two commuting U(1) conserved quantities associated with total domain-wall number and magnetization. The latter arises naturally from walls. Remarkably, while some connected...
Strongly interacting systems with quantum many-body scars exhibit persistent fidelity oscillations when prepared in a certain class of initial states, but otherwise undergo ergodic dynamics. Previous examples have interpreted the characteristic periodic dynamics terms precession macroscopic SU(2) spin an effective magnetic field. Here, authors uncover new exactly solvable example spin-\textonehalf{} model and show that scarred this evades such interpretation. This unusual coherent arises due...
Weakly interacting quasiparticles play a central role in the low-energy description of many phases quantum matter. At higher energies, however, cease to be well-defined generic many-body systems due proliferation decay channels. In this review, we discuss phenomenon scars, which can give rise certain species stable throughout energy spectrum. This goes along with set unusual non-equilibrium phenomena including revivals and non-thermal stationary states. We provide pedagogical exposition...
We propose a general-purpose, self-adaptive approach to construct variational wavefunction ans\"atze for highly accurate quantum dynamics simulations based on McLachlan's principle. The key idea is dynamically expand the ansatz along time-evolution path such that ``McLachlan distance'', which measure of simulation accuracy, remains below set threshold. apply this adaptive (AVQDS) integrable Lieb-Schultz-Mattis spin chain and nonintegrable mixed-field Ising model, where it captures both...
Quantum many-body systems away from equilibrium host a rich variety of exotic phenomena that are forbidden by thermodynamics. A prominent example is discrete time crystals
According to quantum statistical mechanics, generic many-body systems decohere and thermalize regardless of their initial state. A recent experiment found a surprising exception this rule, wherein an otherwise thermalizing system maintains its coherence only for particular condition, phenomenon dubbed ``quantum scarring.'' Here, the authors propose provide numerical evidence physical mechanism underlying observed phenomena: Bose-Einstein condensation, macroscopic numbers quasiparticles...
Floquet topological insulators are noninteracting quantum systems that, when driven by a time-periodic field, described effective Hamiltonians whose bands carry nontrivial invariants. A longstanding question concerns the possibility of selectively populating one these bands, thereby maximizing system's resemblance to static insulator. We study such coupled zero-temperature thermal reservoir that provides dissipation. find resulting electronic steady states generically characterized finite...
We demonstrate the existence of exact atypical many-body eigenstates in a class disordered, interacting one-dimensional quantum systems that includes Fermi-Hubbard model as special case. These eigenstates, which generically have finite energy density and are exponentially many number, populated by noninteracting excitations. They can exhibit Anderson localization with area-law eigenstate entanglement or, surprisingly, ballistic transport at any disorder strength. properties differ strikingly...
Quantum many-body scars (QMBS) constitute a new quantum dynamical regime in which rare "scarred" eigenstates mediate weak ergodicity breaking. One open question is to understand the most general setting these states arise. In this work, we develop generic construction that embeds class of QMBS, rainbow scars, into spectrum an arbitrary Hamiltonian. Unlike other examples display extensive bipartite entanglement entropy while retaining simple structure. Specifically, scaling volume-law for...
Quantum many-body scars are an intriguing dynamical regime in which quantum systems exhibit coherent dynamics and long-range correlations when prepared certain initial states. We use this combination of coherence to benchmark the performance present-day computing devices by using them simulate antiferromagnetic state mixed-field Ising chains up 19 sites. In addition calculating local observables, we also calculate Loschmidt echo a nontrivial unequal-time connected correlation function that...
We uncover a dynamical entanglement transition in monitored quantum system that is heralded by local order parameter. Classically, chaotic systems can be stochastically controlled onto unstable periodic orbits and exhibit uncontrolled phases as function of the rate at which control applied. show such transitions persist open where implemented with measurements unitary feedback. Starting from simple classical model known transition, we define exhibits diffusive between volume-law entangled...
We review various features of interacting Abelian topological phases matter in two spatial dimensions, placing particular emphasis on fractional Chern insulators (FCIs) and (FTIs). highlight aspects these systems that challenge the intuition developed from quantum Hall physics - for instance, FCIs are stable limit where interaction energy scale is much larger than band gap, FTIs can possess fractionalized excitations bulk despite absence gapless edge modes.
Protected zero modes in quantum physics traditionally arise the context of ground states many-body Hamiltonians. Here we study case where exist center a reflection-symmetric spectrum, giving rise to notion protected ``infinite-temperature'' degeneracy. For certain class nonintegrable spin chains, show that number is determined by chiral index grows exponentially with system size. We propose dynamical protocol, feasible ongoing experiments Rydberg atom simulators, detect these and their...
Many topological phenomena first proposed and observed in the context of electrons solids have recently found counterparts photonic acoustic systems. In this work, we demonstrate that non-Abelian Berry phases can arise when coherent states light are injected into "topological guided modes" specially-fabricated waveguide arrays. These modes analogues zero electronic Light traveling inside spatially well-separated be braided, leading to accumulation phases, which depend on order beams wound...
Highly excited states of quantum many-body systems are central objects in the study dynamics and thermalization that challenge classical computational methods due to their volume-law entanglement content. In this work, we explore potential variational algorithms approximate such states. We propose an adaptive eigensolver (VQE) for (X) self-generates a ansatz arbitrary eigenstates Hamiltonian $H$ by attempting minimize energy variance with respect $H$. benchmark method applying it Ising spin...
We demonstrate a postquench dynamics simulation of Heisenberg model on present-day IBM quantum hardware that extends beyond the coherence time device. This is achieved using hybrid quantum-classical algorithm propagates state Trotter evolution and then performs classical optimization effectively compresses time-evolved into variational form. When iterated, this procedure enables simulations to arbitrary times with an error controlled by compression fidelity fixed step size. show how measure...
Quantum spin systems may offer the first opportunities for beyond-classical quantum computations of scientific interest. While general simulation algorithms likely require error-corrected qubits, there be applications interest prior to practical implementation error correction. The variational eigensolver (VQE) is a promising approach finding energy eigenvalues on noisy computers. Lattice models are broad use near-term hardware due sparsity number Hamiltonian terms and possibility matching...
Topologically ordered phases of matter elude Landau's symmetry-breaking theory, featuring a variety intriguing properties such as long-range entanglement and intrinsic robustness against local perturbations. Their extension to periodically driven systems gives rise exotic new phenomena that are forbidden in thermal equilibrium. Here, we report the observation signatures phenomenon-a prethermal topologically time crystal-with programmable superconducting qubits arranged on square lattice. By...
Controlling the properties of materials by driving them out equilibrium is an exciting prospect that has only recently begun to be explored. In this paper we give a striking theoretical example such design: tunable gap in monolayer graphene generated particular optical phonon. We show system reaches steady state whose transport are same as if had static electronic gap, controllable amplitude. Moreover, displays topological phenomena: there chiral edge currents, which circulate fractional...
We study gapped boundaries of Abelian type-I fracton systems in three spatial dimensions. Using the X-cube model as our motivating example, we give a conjecture, with partial proof, conditions for boundary to be gapped. In order state use precise definition braiding and show that bulk fractons has several features make it insufficient classify boundaries. Most notable among these is sensitive geometry ``nonreciprocal''; is, an excitation $a$ around $b$ need not yield same phase $a$. Instead,...
Classical reversible cellular automata (CAs), which describe the discrete-time dynamics of classical degrees freedom in a finite state space, can exhibit exact, nonthermal quantum eigenstates despite being classically chaotic. We show that every CA defines family generically nonintegrable, periodically driven (Floquet) with eigenstates. These Floquet are nonergodic sense certain product states on periodic orbit fail to thermalize, while generic initial thermalize as expected chaotic system....
Scalable quantum algorithms for the simulation of many-body systems in thermal equilibrium are important predicting properties matter at finite temperatures. Here we describe and benchmark a computing version minimally entangled typical states (METTS) algorithm which adopt an adaptive variational approach to perform required imaginary time evolution. The algorithm, name AVQMETTS, dynamically generates compact problem-specific circuits, suitable noisy intermediate-scale (NISQ) hardware. We...
Quantum many-body scar states are highly excited eigenstates of systems that exhibit atypical entanglement and correlation properties relative to typical at the same energy density. Scar also give rise infinitely long-lived coherent dynamics when system is prepared in a special initial state having finite overlap with them. Many models exact have been constructed, but fate scarred these perturbed difficult study classical computational techniques. In this work, we propose preparation...