Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session N4: Quantum Simulation |
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Chair: Steven Olmschenk, Denison University Room: 554AB |
Thursday, May 26, 2016 10:30AM - 10:42AM |
N4.00001: Return of the Quantum Cellular Automata: Episode VI Lincoln D. Carr, Logan E. Hillberry, Patrick Rall, Nicole Yunger Halpern, Ning Bao, Simone Montangero There are now over 150 quantum simulators or analog quantum computers worldwide. Although exploring quantum phase transitions, many-body localization, and the generalized Gibbs ensemble are exciting and worthwhile endeavors, there are totally untapped directions we have not yet pursued. One of these is quantum cellular automata. In the past a principal goal of quantum cellular automata was to reproduce continuum single particle quantum physics such as the Schrodinger or Dirac equation from simple rule sets. Now that we begin to really understand entanglement and many-body quantum physics at a deeper level, quantum cellular automata present new possibilities. We explore several time evolution schemes on simple spin chains leading to high degrees of quantum complexity and nontrivial quantum dynamics. We explain how the 256 known classical elementary cellular automata reduce to just a few exciting quantum cases. Our analysis tools include mutual information based complex networks as well as more familiar quantifiers like sound speed and diffusion rate. [Preview Abstract] |
Thursday, May 26, 2016 10:42AM - 10:54AM |
N4.00002: Cryogenic Linear Ion Trap for Large-Scale Quantum Simulations H. B. Kaplan, P. W. Hess, G. Pagano, E. J. Birckelbaw, M. Hernandez, A. C. Lee, J. Smith, J. Zhang, C. Monroe Ions confined in RF Paul traps are a useful tool for quantum simulation of long-range spin-spin interaction models. As the system size increases, classical simulation methods become incapable of modeling the exponentially growing Hilbert space, necessitating quantum simulation for precise predictions. Current experiments are limited to less than 30 qubits due to collisions with background gas that regularly destroys the ion crystal. We present progress toward the construction of a cryogenic ion trap apparatus, which uses differential cryopumping to reduce vacuum pressure to a level where collisions do not occur. This should allow robust trapping of about 100 ions/qubits in a single chain with long lifetimes. Such a long chain will provide a platform to investigate simultaneously cooling of various vibrational modes and will enable quantum simulations that outperform their classical counterpart. Our apparatus will provide a powerful test-bed to investigate a large variety of Hamiltonians, including spin 1 and spin 1/2 systems with Ising or XY interactions. [Preview Abstract] |
Thursday, May 26, 2016 10:54AM - 11:06AM |
N4.00003: Sensitive magnetometer based on sub-coherence-lifetime limited resonance Jian Sun, Weizhi Qu, Pengxiong Li, Jianming Wen, Liang Jiang, Yanhong Xiao Previously, we have developed a subtransittime limited resonance technique [PRL 109, 233006(2012)], where a resonance linewidth 2.4 kHz was reported in a vacuum vapor cell with transittime limited width of 75 kHz. Here, we demonstrate subcoherence lifetime limited resonance linewidth of 0.13 Hz by using an alkene coated vapor cell. Furthermore, we apply this technique to DC magnetometry and achieve sensitivity of 11.5 fT per root Hz, even in a vapor cell at room temperature. Also, we will show theoretically how this resonance scheme is essentially a new type of weak measurement. [Preview Abstract] |
Thursday, May 26, 2016 11:06AM - 11:18AM |
N4.00004: Quantifying coherence and entanglement in trapped ions using the multiple quantum spectrum Martin Gaerttner, Arghavan Safavi-Naini, Michael Wall, Justin Bohnet, Brian Sawyer, Joseph Britton, John Bollinger, Ana Maria Rey The multiple quantum coherence (MQC) spectrum of a quantum state, originally introduced for highly mixed states in the context of NMR, quantifies coherence between different magnetization sectors. The MQC spectrum of a spin system is measurable by a sequence of rotations and evolution under an interaction Hamiltonian, provided that the evolution can be time reversed. Such a many-body echo can be realized in systems of trapped ions. We study the relation of the multiple quantum intensities with entanglement measures and witnesses such as Fisher information and concurrence and discuss the impact of decoherence mechanisms present in current trapped ion experiments on the proposed scheme for measuring the MQC spectrum. Supported by: JILA-NSF-PFC-1125844, NSF-PHY-1521080, ARO, AFOSR, AFOSR-MURI [Preview Abstract] |
Thursday, May 26, 2016 11:18AM - 11:30AM |
N4.00005: Role of spin-motion entanglement in quantum trapped ion simulators Arghavan Safavi-Naini, Michael Wall, Asier Pi\~neiro-Orioli, Ana Maria Rey Arrays of trapped ions realize quantum simulators of long-range spin models by coupling the ion spin to the phonon modes of the Coulomb crystal. In addition to spin-spin interactions, the spin-motion coupling may also lead to significant spin-motion entanglement, which degrades the fidelity of the quantum simulator. Here, we present results from two numerical approaches which allow us to simulate the full spin-phonon dynamics for tens to hundreds of ions. The first approach is numerically exact and uses a recently developed variant of the t-DMRG method, while the second approach is is based on the Truncated Wigner Approximation [1,2]. We first benchmark the two methods by studying the dynamics of the spin-phonon model in the absence of a transverse field, where as previously shown, spin-motion entanglement introduces oscillations to various observables, such as spin-spin correlations and spin squeezing [3]. We then present results for the analytically intractable case of a large transverse magnetic field, where we find a more drastic effect of spin-motion entanglement is more drastic. \\ [1] A. Polkovnikov, Ann. Phys. {\bf 325}, 1790, (2010).\\ [2] J. Schachenmayer,{\it et. al.}, PRX {\bf 5},011022, (2015).\\ [3] D. Dylewsky, {\it et. al.} PRA {\bf 93}, 013415, (2016). [Preview Abstract] |
Thursday, May 26, 2016 11:30AM - 11:42AM |
N4.00006: Simulating spin-boson models with matrix product states Michael Wall, Arghavan Safavi-Naini, Ana Maria Rey The global coupling of few-level quantum systems (``spins") to a discrete set of bosonic modes is a key ingredient for many applications in quantum science, including large-scale entanglement generation, quantum simulation of the dynamics of long-range interacting spin models, and hybrid platforms for force and spin sensing. In many situations, the bosons are integrated out, leading to effective long-range interactions between the spins; however, strong spin-boson coupling invalidates this approach, and spin-boson entanglement degrades the fidelity of quantum simulation of spin models. We present a general numerical method for treating the out-of-equilibrium dynamics of spin-boson systems based on matrix product states. While most efficient for weak coupling or small numbers of boson modes, our method applies for any spatial and operator dependence of the spin-boson coupling. In addition, our approach allows straightforward computation of many quantities of interest, such as the full counting statistics of collective spin measurements and quantum simulation infidelity due to spin-boson entanglement. We apply our method to ongoing trapped ion quantum simulator experiments in analytically intractable regimes. [Preview Abstract] |
Thursday, May 26, 2016 11:42AM - 11:54AM |
N4.00007: Quantum simulations with a trilinear Hamiltonian in trapped-ion system Shiqian Ding, Gleb Maslennikov, Roland Hablutzel, Dzmitry Matsukevich A non-degenerate parametric oscillator, described by a trilinear Hamiltonian, is one of the most fundamental models in quantum optics. We experimentally realize this kind of interaction in fully quantum regime with three motional modes of three trapped ytterbium ions. This interaction is induced by the intrinsic anharmonicity of Coulomb potential and manifests itself by more than 100 cycles of coherent energy exchange at single quantum level between different motional modes. By exploiting this interaction, we simulate the process of non-degenerate parametric down conversion in a regime of depleted pump, demonstrate deviation from the thermal statistic for the `signal' and `idler' modes and discuss its relation with a simple model of Hawking radiation. We also present experimental results on simulation of Jaynes-Cummings model using this trilinear Hamiltonian. [Preview Abstract] |
Thursday, May 26, 2016 11:54AM - 12:06PM |
N4.00008: Trapped ion simulation of molecular spectrum Yangchao Shen, Yao Lu, Kuan Zhang, Shuaining Zhang, Joonsuk Huh, Kihwan Kim Boson sampling had been suggested as a classically intractable and quantum mechanically manageable problem via computational complexity theory arguments [1]. Recently, Huh and co-workers [2] proposed theoretically a modified version of boson sampling, which is designed to simulate a molecular problem, as a practical application. Here, we report the experimental implementation of the theoretical proposal with a trapped ion system. As a first demonstration, we perform the quantum simulation of molecular vibronic profile of SO2, which incorporates squeezing, rotation and coherent displacement\sout{s} operations, and the collective projection measurement on phonon modes. [1] S. Aaronson, A. Arkhipov,~STOC 11, 333 (2011). [2] Joonsuk Huh. et al. Nature Photon. 9, 615 (2015). [Preview Abstract] |
Thursday, May 26, 2016 12:06PM - 12:18PM |
N4.00009: Quantum Simulation with 2D Arrays of Trapped Ions Philip Richerme The computational difficulty of solving fully quantum many-body spin problems is a significant obstacle to understanding the behavior of strongly correlated quantum matter. This work proposes the design and construction of a 2D quantum spin simulator to investigate the physics of frustrated materials, highly entangled states, mechanisms potentially underpinning high-temperature superconductivity, and other topics inaccessible to current 1D systems. The effective quantum spins will be encoded within the well-isolated electronic levels of trapped ions, confined in a two-dimensional planar geometry, and made to interact using phonon-mediated optical dipole forces. The system will be scalable to 100+ quantum particles, far beyond the realm of classical intractability, while maintaining individual-ion control, long quantum coherence times, and site-resolved projective spin measurements. Once constructed, the two-dimensional quantum simulator will implement a broad range of spin models on a variety of reconfigurable lattices and characterize their behavior through measurements of spin-spin correlations and entanglement. This versatile tool will serve as an important experimental resource for exploring difficult quantum many-body problems in a regime where classical methods fail. [Preview Abstract] |
Thursday, May 26, 2016 12:18PM - 12:30PM |
N4.00010: ABSTRACT WITHDRAWN |
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