Bulletin of the American Physical Society
51st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 65, Number 4
Monday–Friday, June 1–5, 2020; Portland, Oregon
Session P03: Quantum Simulation with Trapped IonsLive

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Chair: David Allcock, University of Oregon Room: D135136 
Thursday, June 4, 2020 2:00PM  2:12PM Live 
P03.00001: New Methods for Quantum Simulation of Spin Systems with Trapped Ions Tom Manovitz, Yotam Shapira, Nitzan Akerman, Roee Ozeri, Ady Stern By simulating the behavior of quantum systems with highly controlled engineered quantum machines, one can study the complex behavior of a variety of quantum phenomena. Ions in a linear Paul trap have proven to be a leading platform for such simulations, primarily relying on a set of spin Hamiltonians produced using the MolmerSorensen interaction. In this work, we significantly extend the range of Hamiltonians that can be directly simulated in trapped ions using a simple variation of the standard scheme. For $N$ ions our method can produce a Hamiltonian with a general form $\sum_{n=1}^{N1}\Omega_n e^{i(\phi_n\omega_n t)} \sum_{i=1}^{Nn}\sigma_i^+\sigma_{i+n}^ + h.c.$ where parameters $\{\Omega_n,\phi_n,\omega_n \}$ can be fully controlled. Using this form, it is possible to generate Hamiltonians with closed boundary conditions; $d>1$ dimension Hamiltonians; and Hamiltonians with gauge field (AharonovBohm) terms. An assortment of interesting physical models previously unreachable with analog simulations in trapped ions are made possible using our scheme. [Preview Abstract] 
Thursday, June 4, 2020 2:12PM  2:24PM Live 
P03.00002: Theory of robust multiqubit nonadiabatic gates for trappedions Yotam Shapira, Ravid Shaniv, Tom Manovitz, Nitzan Akerman, Lee Peleg, Lior Gazit, Roee Ozeri, Ady Stern Trapped ion qubits are a leading platform for performing quantum computations and quantum simulations. These are achieved with entanglement gates acting on the ions, by coupling to the normalmodes of motion of the ionchain. Typically, a single normalmode is coupled and the remaining modes are decoupled by operating slowly. Analog quantum simulations are also performed in an adiabatic regime and allow only spinspin interactions that scale as a powerlaw in the ion distance. We propose multiqubit entanglement gates for trappedions [arXiv:1911.03073 (2019)]. Our gates utilize all the normalmodes of motion allowing for fast operation that was previously inaccessible, and require reasonable resources. Furthermore, we use our methods to generalize the coupling between the ions, and generate fast spinHamiltonian interactions, which are not limited to a power law. For example, a nearestneighbor Ising model and the topological SuSchrieferHeeger Hamiltonian. Our gates use a multitone laser field, which couples uniformly to all ions, there is no need to individually address the ions. We endow our gate with robustness properties, making them resilient to various sources of system noise and imperfections. Our method is natural to common trappedion architectures. [Preview Abstract] 
Thursday, June 4, 2020 2:24PM  2:36PM Live 
P03.00003: Holographic optical manipulation of trapped ions for quantum simulation ChungYou Shih, Sainath Motlakunta, Manas Sajjan, Nikhil Kotibhaskar, Thiago Bergamaschi, Roland Hablutzel, Rajibul Islam Trapped ions are an ideal experimental platform for quantum simulation of interacting manybody Hamiltonians. Arbitrary and programmable control over individual ions is needed for maximum versatility in simulation. In this talk, we will present progress towards developing a holographic optical ion addressing system using Digital Micromirror Devices. The technique uses reprogrammable holograms to modulate the wavefront of the addressing beam to control the amplitude and phase of light at each ion. We implement a novel iterative Fourier transform algorithm to compute holograms that compensate for optical aberrations and produce minimal ‘crosstalk’ error between ions. Individual ions can be used as aberration sensors for ultimate precision. Such highprecision optical control will enable quantum simulation of dynamical and higher dimensional lattice geometry of spins in a 1D chain of ions, such as to investigate quantum quenches and phase transitions and topological phases. [Preview Abstract] 
Thursday, June 4, 2020 2:36PM  2:48PM Live 
P03.00004: Observation of Domain Wall Confinement and Dynamics in a Quantum Simulator P. Becker, W. L. Tan, F. Liu, G. Pagano, K. S. Collins, A. De, L. Feng, H. B. Kaplan, A. Kyprianidis, R. Lundgren, W. Morong, S. Whitsitt, A. V. Gorshkov, C. Monroe Confinement is a ubiquitous mechanism in nature, whereby particles feel an attractive force that increases without bound as they separate. A prominent example is color confinement in particle physics, in which baryons and mesons are produced by quark confinement. Analogously, confinement can also occur in lowenergy quantum manybody systems when elementary excitations are confined into bound quasiparticles [1]. Here, we report the first observation of magnetic domain wall confinement in interacting spin chains with a trappedion quantum simulator [2]. By measuring how correlations spread, we show that confinement can dramatically suppress information propagation and thermalization in such manybody systems. We determine the excitation energy of domain wall bound states from nonequilibrium quench dynamics. Furthermore, we study the number of domain wall excitations created for different quench parameters, in a regime that is difficult to model with classical computers. This work demonstrates the capability of quantum simulators for investigating exotic highenergy physics phenomena, such as quark collision and string breaking. [1] F. Liu, et al., Phys. Rev. Lett. 122, 150601 (2019). [2] W. L. Tan, P. Becker, et al., arXiv: 1912.11117 (2019). [Preview Abstract] 
Thursday, June 4, 2020 2:48PM  3:00PM Live 
P03.00005: ManyBody Dephasing in a TrappedIon Quantum Simulator Wen Lin Tan, Harvey Kaplan, Arinjoy De, Guido Pagano, Christopher Monroe, Lingzhen Guo, Florian Marquardt We observe and analyze the persistent temporal fluctuations after a quantum quench of a tunable longrange interacting transversefield Ising Hamiltonian realized with a trappedion quantum simulator [1]. By measuring temporal fluctuations in the average magnetization of a finitesize system of spin1/2 particles encoded in an array of 171Yb+ atomic ions, we observe experimental evidence for manybody dephasing [2]. The properties of the system are closely related to that of an integrable Hamiltonian with a uniform spinspin coupling, which enables approximate analytical predictions even for the longtime nonintegrable dynamics. We find that the measured fluctuations are exponentially suppressed with increasing system size, consistent with theoretical predictions. [1] H. B. Kaplan, et al., arXiv: 2001.02477 (2020). [2] T.Kiendl, F.Marquardt, Phys. Rev. Lett. 118, 130601 (2017) [Preview Abstract] 
Thursday, June 4, 2020 3:00PM  3:12PM Live 
P03.00006: Analog quantum simulation of superradiance and subradiance in trapped ions R. T. Sutherland We discuss a protocol for the analog quantum simulation of superradiance and subradiance using a linear chain of N trapped qubit ions with a single sympathetic cooling ion. We develop a simple analytic model that shows the dynamics of the qubit subspace converge to those of a cloud undergoing Dicke superradiance and subradiance. We provide numerical simulations of the full ion chain and show that they converge to the dynamics predicted by our analytic model with no fitting parameters. We also map out the parameter regime needed to reach this convergence. [Preview Abstract] 
Thursday, June 4, 2020 3:12PM  3:24PM Live 
P03.00007: Matrix product state simulations on a quantum computer Michael FossFeig, Andrew Potter, David Hayes Matrix product states (MPS) afford a compressed representation of many states that are relevant to physical systems. While classical algorithms have been developed to compute the properties of physical systems using MPS as an ansatz, in many cases of practical interest these algorithms still require exponential resources (for example in the size of the system for 2D or 3D systems, or in the evolution time when out of equilibrium). We discuss nearterm prospects for using small and nonerrorcorrected quantum computers to aid in MPS simulations, and show examples of MPS based quantum algorithms run on a trappedion quantum computer. [Preview Abstract] 
Thursday, June 4, 2020 3:24PM  3:36PM On Demand 
P03.00008: Overlap measurements of infinitedimensional quantum states for quantumenhanced machine learning. ChiHuan Nguyen, KoWei Tseng, Jaren Gan, Gleb Maslennikov, Dzmitry Matsukevich Estimation of overlap between quantum states is a ubiquitous task in quantum information processing protocols and has great significance for quantum machine learning applications. Implementing the overlap measurement with the standard discretevariables approach in noisy intermediatescale quantum computers requires scaling the number of physical qubits and entanglement gates with the dimensions of the Hilbert space. Hybrid quantum computation offers an alternative approach; whereby utilizing both discrete and continuous variables, a gatebased overlap measurement in an infinitedimensional system with constant circuit depth can be realized. Here, we experimentally demonstrate the overlap measurement using this approach in a system of two trapped Yb 171 ions. We employ the nonlinear interaction between the internal and motional degrees of freedom to enact a controlledswap gate between two motional modes. To illustrate the versatility of our method, we measure the overlap between a variety of quantum states: Fock states, coherent states, squeezed states, and cat states. We also discuss how to employ the overlap test in an unsupervised quantumenhanced kmeans algorithm. [Preview Abstract] 
Thursday, June 4, 2020 3:36PM  3:48PM On Demand 
P03.00009: Characterization of Radial 2D Ion Crystals for Quantum Simulation Yuanheng Xie, Marissa D'Onofrio, AJ Rasmusson, Paula Madetzke, Evangeline Wolanski, Philip Richerme Quantum simulations of complex materials address fundamental problems that cannot be analytically solved due to the exponential scaling of the Hilbert space with increasing particle number. Simulations using trapped ions have had great success investigating onedimensional quantum interacting spin models, and we seek to extend these ideas to two dimensions by exploiting new crystal geometries in a rf Paul trap. This 2D quantum simulation will allow us to address open questions related to geometric frustration, ground states and dynamics of longrange spin models, and quantum spin liquids. To characterize the variety of different ion geometries, we have measured the ion lattice positions and the frequencies of structural phase transitions for 1D, 2D, and 3D crystal configurations, showing good agreement with numerical predictions. In addition, we have created quantum superpositions of 10+ ions in radial 2D crystals that persist for long coherence times, despite the presence of micromotion in this configuration. [Preview Abstract] 
Thursday, June 4, 2020 3:48PM  4:00PM Not Participating 
P03.00010: Experimental progress towards a prethermal discrete time crystal A. Kyprianidis, P. Becker, K. Collins, W. Morong, L. Feng, W.L. Tan, A. De, G. Pagano, P.W. Hess, F.L. Machado, D. Else, C. Nayak, N. Yao, C. Monroe Driven quantum systems offer opportunities for studying novel phases of nonequilibrium matter, such as time crystals [1,2,3]. To avoid continuously absorbing energy from the drive, we investigate a strategy based on Floquet prethermalization. In this case, even without disorder, one can observe a slow heating time scale with exponential dependence on the drive frequency, leading to a longlived intermediate "prethermal" regime. We use a trappedion quantum simulator with chains of Yb ions confined in a rf Paul trap that realize a transverse field Ising model with tunable range interactions. By varying the initial state and drive parameters of our system, we characterize this prethermal regime. [1] F. Wilczek, Phys. Rev. Lett. 109, 160401 (2012) [2] J. Zhang et al. Observation of a discrete time crystal. Nature 543, 217220 (2017) [3] S. Choi et al. Observation of discrete timecrystalline order in a disordered dipolar manybody system. Nature 543, 221225 (2017) [Preview Abstract] 
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