Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session Q14: Nuclear Theory |
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Sponsoring Units: DNP Chair: Gerald A. Miller, University of Washington Room: Sheraton Plaza Court 3 |
Monday, April 15, 2019 10:45AM - 10:57AM |
Q14.00001: Unwrapping Complex Phases to Address Sign Problems in Lattice Calculations William Detmold, Gurtej Kanwar, Michael L Wagman Lattice QCD (LQCD) allows non-perturbative theoretical predictions of properties of nuclear states directly from QCD. LQCD estimates of correlators with non-zero baryon number suffer from a signal-to-noise problem at large time separations, limiting the precision of many calculations. Previous work has shown that this is due to a widening distribution of complex phases. Standard estimators suffer from a sign problem and perform exponentially poorly as the distribution approaches uniform. We apply a technique known as "phase unwrapping" to LQCD correlators, to produce an unwrapped phase distribution over the reals. A cumulant expansion provides convergent positive estimates of correlators. Applied to the simple harmonic oscillator as a toy model, we demonstrate an exponential improvement in signal-to-noise at leading order in the cumulant expansion and describe a good unwrapping scheme choice that precisely estimates ground state energies. We discuss incorporating the positive-definite estimate of the correlation function into the Monte Carlo sampling to provide an improvement free of systematic bias from truncation error. |
Monday, April 15, 2019 10:57AM - 11:09AM |
Q14.00002: Realistic simulations of neutron-neutron scattering on an efficient quantum processing unit Kyle A Wendt Real time simulations of quantum systems holds the key to modeling and understanding the dynamics and responses of strongly interacting many-body systems such as atomic nuclei and their interactions with other matter. Classical calculations of such systems are plagued by an exponential growth of particle configurations while the simulated dynamics is plagued by sign problems and inverse problems. Quantum processing units (QPU) provide a pathway to simulate the real time evolution of these systems with a polynomial scaling, no sign problem, and no inverse problem; However, current QPUs are too noisy to implement and execute the formal quantum computing algorithms that have been proposed to compute such real time dynamics. This limitation manifests as a limit in the number of gates that can be applied before the QPU enters a decoherent state and information about the simulated dynamics is lost. We demonstrate an alternative efficient high-fidelity encoding of the many-body dynamics onto the QPU and apply it to the realtime simulation of neutron scattering using Hamiltonian derived from chiral effective field theory including realistic pion exchanges. We will present both simulated data and real data taken on the Lawrence Livermore National Lab’s quantum testbed. |
Monday, April 15, 2019 11:09AM - 11:21AM |
Q14.00003: Efficient Quantum Tomography for Quantum Simulations of Field Theories Andrew N Shaw, Zohreh Davoudi Certain computational problems in physics are estimated to require more computational resources than next-generation Exascale computing hardware will provide. Notable examples are the sign problem in fermionic systems, and real-time dynamics. The sign problem has prevented lattice QCD predictions for properties of dense matter, as well as the evolution of strongly-interacting medium after heavy-ion collisions. Quantum computing has the promise of speeding up certain tasks exponentially. However, modern quantum devices are limited by noise accumulation resulting from the application of imperfect quantum operations, setting a limit on the depth of the circuits that can be implemented. Some of these restrictions could be largely curtailed if scalable quantum tomography algorithms were available. We propose a new algorithm based on quantum interference that allows for quantum tomography of a pure n-qubit state at the cost of an additional n+1 qubits. As a relevant application of this algorithm, we demonstrate how the real-time evolution of few-site 1D QED can be extended far beyond what is possible on current devices. We also find the ground and excited states of the theory with the use of extended adiabatic state preparation enabled by IQT. |
Monday, April 15, 2019 11:21AM - 11:33AM |
Q14.00004: Heavy quarkonium in the basis light-front quantization approach Guangyao Chen We discuss the wavefunction of heavy quarkonium system in the basis light-front quantization approach. Then we apply the obtained wavefunctions in diffractive charmonium and bottomonium production in diffractive deep inelastic scattering and ultra-peripheral heavy-ion collisions, within the dipole picture. The resulting cross sections are in reasonable agreement with existing experimental data at HERA, RHIC, and LHC, including data from LHC run 2. We observe that the coherent production cross-section ratios of excited states to the ground state are insensitive to the dipole model parameters. We also make predictions for the heavy quarkonium production at future electron-ion colliding facilities. We show that the diffractive heavy quarkonium production at future electron-ion collisions provide an opportunity for a quantitative study of the heavy quarkonium system and the nucleon structure. |
Monday, April 15, 2019 11:33AM - 11:45AM |
Q14.00005: What does kinematical target mass sensitivity in DIS reveal about hadron structure? Eric Moffat, Ted C Rogers, Wally Melnitchouk, Nobuo Sato, Fernanda Steffens We study the role of purely external kinematical approximations in inclusive deep-inelastic scattering within QCD factorization, and discuss how an observed improvement obtained by accounting for target mass kinematics could be interpreted in terms of general properties of target structure. We argue that such an improvement implies a hierarchy of nonperturbative scales within the hadron. |
Monday, April 15, 2019 11:45AM - 11:57AM |
Q14.00006: Modelling the Energy of light Nuclei using the IRC model Aran D Stubbs The IRC model has an n-tiered structure where quarks and leptons are comprised of proto-matter above pairs of gravitons. The nuclei consist of monoquarks bound to diquarks in a body centered cubic arrangement. The quarks are wire-rimmed ellipsoids, with circular orbits on charge plain, and elliptic orbits on 1 of the 3 possible color plains. They contain proto-quarks, proto-photons, and proto-gluons. Structures with net charge on an instance of the charge plain are surrounded by a ring again comprised of gravitons topped by proto-photons. The rest energy of the proto-up & proto-down were earlier calculated from the rest energy of the pions: 17.95820(4) MeV and 37.77024(14) MeV respectively. The mean energy of a tachyon in an elliptic orbit was approximated using numeric integration. A general solution to the 1s energy where an ns proto-particle had 1 extra unit of angular momentum relative to n was found of 2n/(2n+1) times the proto-matter particles rest energy. Where 2 proto-quarks of the same type share a diquark, they don’t have to have unit angular momentum, since they can cancel out L at any 1s energy (as in the neutral pion). This appears to be the case in the neutron. Explicit solutions were found for the first 5 stable isotopes, within 12 KeV of reported values. |
Monday, April 15, 2019 11:57AM - 12:09PM |
Q14.00007: Magnetic Monopoles and the Quantum Theory of Magnetism in Matter Amagh Nduka We derive the equations of quantum electrodynamics (QED) from the well known equations of classical electrodynamics (CED) of James Clarke Maxwell. The application of these equations to the solution of the old problem of magnetic monopoles reveals the existence in nature of an entity we call Ampere electron. Ampere electron has similar physical properties as Dirac electron but structurally and dynamically distinct from it (Dirac electron is the source of dia- and para- magnetism and Ampere electron is the source of ferromagnetism). The solution of the magnetic monopole problem enables us to solve two ancient fundamental problems, namely. 1. The quantum theory of magnetism in matter ( Ampere's problem, 19C) and 2. The source of the Earth's magnetic field (a fortiori the source of the magnetic fields of stars). In this paper we discuss the first problem, i.e. the quantum theory of magnetism in matter. |
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