Controlling quantum many-body dynamics in driven Rydberg atom arrays

The control of nonequilibrium quantum dynamics in many-body systems is challenging because interactions typically lead to thermalization and a chaotic spreading throughout Hilbert space. We investigate nonequilibrium dynamics after rapid quenches in a many-body system composed of 3 to 200 strongly interacting qubits in one and two spatial dimensions. Using a programmable quantum simulator based on Rydberg atom arrays, we show that coherent revivals associated with so-called quantum many-body scars can be stabilized by periodic driving, which generates a robust subharmonic response akin to discrete time-crystalline order. We map Hilbert space dynamics, geometry dependence, phase diagrams, and system-size dependence of this emergent phenomenon, demonstrating new ways to steer complex dynamics in many-body systems and enabling potential applications in quantum information science.

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QUANTUM DYNAMICS WITH AN ENSEMBLE OF HAMILTONIANS

Modern Physics Letters B ◽

10.1142/s0217984913300196 ◽

2013 ◽

Vol 27 (26) ◽

pp. 1330019 ◽

Cited By ~ 7

Author(s):

ARMIN RAHMANI

Keyword(s):

Disordered Systems ◽

Quantum Dynamics ◽

Nonequilibrium Dynamics ◽

Quantum Evolution ◽

Many Body ◽

Driven Systems ◽

Shortcuts To Adiabaticity ◽

New Directions ◽

Time Quantum ◽

Many Body Systems

We review recent progress in the nonequilibrium dynamics of thermally isolated many-body quantum systems, evolving with an ensemble of Hamiltonians as opposed to deterministic evolution with a single time-dependent Hamiltonian. Such questions arise in (i) quantum dynamics of disordered systems, where different realizations of disorder give rise to an ensemble of real-time quantum evolutions, (ii) quantum evolution with noisy Hamiltonians (temporal disorder), which leads to stochastic Schrödinger equations, and, (iii) in the broader context of quantum optimal control, where one needs to analyze an ensemble of permissible protocols in order to find one that optimizes a given figure of merit. The theme of ensemble quantum evolution appears in several emerging new directions in noneqilibrium quantum dynamics of thermally isolated many-body systems, which include many-body localization, noise-driven systems, and shortcuts to adiabaticity.

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Sign-Problem-Free Fermionic Quantum Monte Carlo: Developments and Applications

Annual Review of Condensed Matter Physics ◽

10.1146/annurev-conmatphys-033117-054307 ◽

2019 ◽

Vol 10 (1) ◽

pp. 337-356 ◽

Cited By ~ 23

Author(s):

Zi-Xiang Li ◽

Hong Yao

Keyword(s):

Monte Carlo ◽

Quantum Monte Carlo ◽

Hot Spot ◽

High Temperature Superconductors ◽

System Size ◽

Many Body ◽

Broken Symmetries ◽

Sign Problem ◽

Universal Quantum ◽

Many Body Systems

Reliable simulations of correlated quantum systems, including high-temperature superconductors and frustrated magnets, are increasingly desired nowadays to further our understanding of essential features in such systems. Quantum Monte Carlo (QMC) is a unique numerically exact and intrinsically unbiased method to simulate interacting quantum many-body systems. More importantly, when QMC simulations are free from the notorious fermion sign problem, they can reliably simulate interacting quantum models with large system size and low temperature to reveal low-energy physics such as spontaneously broken symmetries and universal quantum critical behaviors. Here, we concisely review recent progress made in developing new sign-problem-free QMC algorithms, including those employing Majorana representation and those utilizing hot-spot physics. We also discuss applications of these novel sign-problem-free QMC algorithms in simulations of various interesting quantum many-body models. Finally, we discuss possible future directions of designing sign-problem-free QMC methods.

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Discrete Time Crystals

Annual Review of Condensed Matter Physics ◽

10.1146/annurev-conmatphys-031119-050658 ◽

2020 ◽

Vol 11 (1) ◽

pp. 467-499 ◽

Cited By ~ 12

Author(s):

Dominic V. Else ◽

Christopher Monroe ◽

Chetan Nayak ◽

Norman Y. Yao

Keyword(s):

Discrete Time ◽

Quantum Dynamics ◽

Many Body ◽

Time Translation ◽

Translation Symmetry ◽

Interesting Class ◽

Many Body Systems ◽

Definition Of ◽

Many Body Interactions ◽

Time Crystals

Experimental advances have allowed for the exploration of nearly isolated quantum many-body systems whose coupling to an external bath is very weak. A particularly interesting class of such systems is those that do not thermalize under their own isolated quantum dynamics. In this review, we highlight the possibility for such systems to exhibit new nonequilibrium phases of matter. In particular, we focus on discrete time crystals, which are many-body phases of matter characterized by a spontaneously broken discrete time-translation symmetry. We give a definition of discrete time crystals from several points of view, emphasizing that they are a nonequilibrium phenomenon that is stabilized by many-body interactions, with no analog in noninteracting systems. We explain the theory behind several proposed models of discrete time crystals, and compare several recent realizations, in different experimental contexts.

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RELATIVISTIC QUANTUM DYNAMICS OF MANY-BODY SYSTEMS

150 Years of Quantum Many-Body Theory ◽

10.1142/9789812799760_0004 ◽

2001 ◽

Author(s):

F. COESTER ◽

W. N. POLYZOU

Keyword(s):

Quantum Dynamics ◽

Relativistic Quantum ◽

Many Body ◽

Many Body Systems

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Quantum scale anomaly and spatial coherence in a 2D Fermi superfluid

Science ◽

10.1126/science.aau4402 ◽

2019 ◽

Vol 365 (6450) ◽

pp. 268-272 ◽

Cited By ~ 13

Author(s):

Puneet A. Murthy ◽

Nicolò Defenu ◽

Luca Bayha ◽

Marvin Holten ◽

Philipp M. Preiss ◽

...

Keyword(s):

Spatial Coherence ◽

Theoretical Description ◽

Critical Properties ◽

Many Body ◽

Fermi Superfluid ◽

Quantum Anomaly ◽

Momentum Distributions ◽

Quantum Anomalies ◽

Many Body Systems ◽

Space Dynamics

Quantum anomalies are violations of classical scaling symmetries caused by divergences that appear in the quantization of certain classical theories. Although they play a prominent role in the quantum field theoretical description of many-body systems, their influence on experimental observables is difficult to discern. In this study, we discovered a distinctive manifestation of a quantum anomaly in the momentum-space dynamics of a two-dimensional (2D) Fermi superfluid of ultracold atoms. The measured pair momentum distributions of the superfluid during a breathing mode cycle exhibit a scaling violation in the strongly interacting regime. We found that the power-law exponents that characterize long-range phase correlations in the system are modified by the quantum anomaly, emphasizing the influence of this effect on the critical properties of 2D superfluids.

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Generation of multicomponent atomic Schrödinger cat states of up to 20 qubits

Science ◽

10.1126/science.aay0600 ◽

2019 ◽

Vol 365 (6453) ◽

pp. 574-577 ◽

Cited By ~ 61

Author(s):

Chao Song ◽

Kai Xu ◽

Hekang Li ◽

Yu-Ran Zhang ◽

Xu Zhang ◽

...

Keyword(s):

Quantum Information ◽

Information Science ◽

Quantum Information Processing ◽

Ghz State ◽

Many Body ◽

Time Intervals ◽

Fundamental Physics ◽

Schrödinger Cat ◽

Many Body Systems ◽

Cat States

Multipartite entangled states are crucial for numerous applications in quantum information science. However, the generation and verification of multipartite entanglement on fully controllable and scalable quantum platforms remains an outstanding challenge. We report the deterministic generation of an 18-qubit Greenberger-Horne-Zeilinger (GHZ) state and multicomponent atomic Schrödinger cat states of up to 20 qubits on a quantum processor, which features 20 superconducting qubits, also referred to as artificial atoms, interconnected by a bus resonator. By engineering a one-axis twisting Hamiltonian, the system of qubits, once initialized, coherently evolves to multicomponent atomic Schrödinger cat states—that is, superpositions of atomic coherent states including the GHZ state—at specific time intervals as expected. Our approach on a solid-state platform should not only stimulate interest in exploring the fundamental physics of quantum many-body systems, but also enable the development of applications in practical quantum metrology and quantum information processing.

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