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Nuclear Theory·nucl-th

Monday·April 13, 2020

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 04

    [Submitted on 8 Apr 2020] (cross-list from quant-ph)

    Hybrid Quantum Annealing via Molecular Dynamics

    Hirotaka Irie🇯🇵 · Haozhao Liang🇯🇵 · Takumi Doi🇯🇵 · Shinya Gongyo🇯🇵 · Tetsuo Hatsuda🇯🇵

    A novel quantum-classical hybrid scheme is proposed to efficiently solve large-scale combinatorial optimization problems. The key concept is to introduce a Hamiltonian dynamics of the classical flux variables associated with the quantum spins of the transverse-field Ising model. Molecular dynamics of the classical fluxes can be used as a powerful preconditioner to sort out the frozen and ambivalent spins for quantum annealers. The performance and accuracy of our smooth hybridization in comparison to the standard classical algorithms (the tabu search and the simulated annealing) are demonstrated by employing the MAX-CUT and Ising spin-glass problems.

    Comments:
    14 pages, 10 figures; v2: 17 pages, 14 figures, supplementary note added, to be published in Scientific Reports
    Subjects:
    Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
    arXiv:
    2004.03972 [pdf]
    Sci.Rep.(2021)·30 citations
  2. 05

    [Submitted on 10 Apr 2020] (cross-list from quant-ph)

    Spectral density estimation with the Gaussian Integral Transform

    Alessandro Roggero

    The spectral density operator plays a central role in linear response theory as its expectation value, the dynamical response function, can be used to compute scattering cross-sections. In this work, we describe a near optimal quantum algorithm providing an approximation to the spectral density with energy resolution and error using operations. This is achieved without using expensive approximations to the time-evolution operator but exploiting instead qubitization to implement an approximate Gaussian Integral Transform (GIT) of the spectral density. We also describe appropriate error metrics to assess the quality of spectral function approximations more generally.

    Comments:
    12 pages - published version
    Subjects:
    Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
    arXiv:
    2004.04889 [pdf]
    PRA(2020)·47 citations
  3. 06

    [Submitted on 10 Apr 2020] (cross-list from cond-mat.quant-gas)

    Emergence of a pseudogap in the BCS-BEC crossover

    Adam Richie-Halford · Joaquín E. Drut · Aurel Bulgac

    Strongly correlated Fermi systems with pairing interactions become superfluid below a critical temperature . The extent to which such pairing correlations alter the behavior of the liquid at temperatures is a subtle issue that remains an area of debate, in particular regarding the appearance of the so-called pseudogap in the BCS-BEC crossover of unpolarized spin- nonrelativistic matter. To shed light on this, we extract several quantities of crucial importance at and around the unitary limit, namely: the odd-even staggering of the total energy, the spin susceptibility, the pairing correlation function, the condensate fraction, and the critical temperature , using a non-perturbative, constrained-ensemble quantum Monte Carlo algorithm.

    Comments:
    6 pages (including references), 4 figures; Added Journal Reference
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Superconductivity (cond-mat.supr-con); Nuclear Theory (nucl-th)
    arXiv:
    2004.05014 [pdf]
    PRL(2020)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE