Simulating hadronic physics on noisy intermediate-scale quantum devices using basis light-front quantization
Not Available
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
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Quantum fluctuations drive nonmonotonic correlations in a qubit lattice
Abstract Fluctuations may induce the degradation of order by overcoming ordering interactions, consequently leading to an increase of entropy. This is particularly evident in magnetic systems characterized by nontrivial, constrained disorder, where thermal or quantum fluctuations can yield counterintuitive forms of ordering. Using the proven efficiency of quantum annealers as programmable spin system simulators, we present a study based on entropy postulates and experiments on a platform of programmable superconducting qubits to show that a low level of uncertainty can promote ordering in a system impacted by both thermal and quantum fluctuations. A set of experiments is proposed on a lattice of interacting qubits arranged in a triangular geometry with precisely controlled disorder, effective temperature, and quantum fluctuations. Our results demonstrate the creation of ordered ferrimagnetic and layered anisotropic disordered phases, displaying characteristics akin to the elegant order-by-disorder phenomenon. Extensive experimental evidence is provided for the role of quantum fluctuations in lowering the total energy of the system by increasing entropy and defect clustering. Our thorough and comprehensive application of an intentionally introduced noise on a quantum platform provides insight into the dynamics of defects and fluctuations in quantum devices, which may help to reduce the cost associated with quantum processing.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Evaluating the Limits of QAOA Parameter Transfer at High-Rounds on Sparse Ising Models With Geometrically Local Cubic Terms
The emergent practical applicability of the Quantum Approximate Optimization Algorithm (QAOA) for approximate combinatorial optimization is a subject of considerable interest. One of the primary limitations of QAOA is the task of finding a set of good parameters, which is usually done using a variational optimization loop. Parameter transfer, or parameter concentration, is a phenomenon where QAOA angles trained on problem instances that are self-similar tend to perform well for other problem instances from that similar class. This suggests a potentially highly efficient and scalable non-variational learning method for QAOA angle finding. In this work, we systematically study QAOA parameter transferability from small problem sizes (16 and 27 decision variables) onto large problem instances (up to 156 qubits) for heavy-hex graph Ising models with geometrically local higher order terms using the Julia based QAOA simulation tool \texttt{JuliQAOA} to perform classical angle finding for up to $49$ QAOA layers ($p$). Parameter transfer of the fixed angles is validated using a combination of full statevector, Projected Entangled Pair States (PEPS), Matrix Product State (MPS), and LOWESA numerical simulations. We find that the QAOA parameter transfer from single instances applied to other (unseen) problem instances does not in general provide monotonically improving performance as a function of $p$ - there are many cases where the performance temporarily decreases as a function of $p$ - but despite this the transferred angles have a general trend of improved expectation value as the QAOA depth increases, in many cases converging close to the true ground-state energy of the $100+$ qubit instances. We also sample the hardware-compatible Ising models using the ensemble of transfer-learned QAOA parameters on several superconducting qubit IBM Quantum processors with 127, 133, and 156 qubits. We find continuous solution quality improvement of the hardware-compatible QAOA circuits run on the IBM NISQ processors up to $p=5$ on \texttt{ibm\_fez}, up to $p=9$ on \texttt{ibm\_torino}, and up to $p=10$ on \texttt{ibm\_pittsburgh}.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Architecture for Quantum-in-the Loop Real-Time Simulations for Designing Resilient Smart Grids
With the power grid growing more complex every day with the inclusion of new sensors and regulatory approvals that enable end-users and small local developers to participate in the grid, it is becoming challenging for conventional smart grid simulation, emulation, and testing technologies to keep up. In this work, we propose that quantum-encoded real-time simulations can be helpful under the new paradigm and operational circumstances to solve optimization problems for power grids. By leveraging the principles of quantum mechanics, the proposed quantum-in-loop (QIL) framework will enable better and faster optimization solutions based on real-world, real-time data streams, facilitating the real-time planning and operations of electrical grids that rely on millions of distributed sensors and controllers. Furthermore, QIL will allow researchers and engineers to assist utilities in designing, developing, and de-risking algorithms to optimize power grid operation and resilience by considering inputs from millions of grid-connected devices. QIL framework is being developed to have a self-limiting triage mechanism, which will help engineers and practitioners identify fundamental physical limits on quantum processors, revealing what quantum algorithms can and cannot do in utility-specific use cases and must continue to count on classical high-performance computing infrastructure.
digital real-time simulation↗
Benchmarking Solid-State Quantum Simulators for Applications in Lattice Gauge Theory DE-SC0023710
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36 MATERIALS SCIENCE↗
Los Alamos National Laboratory Quantum Overview
Los Alamos supports the National Quantum Initiative and the Laboratory's national security mission by tackling quantum science and technology challenges. Los Alamos is a strategic partner of the Quantum Science Center hub and leads the simulations and algorithms thrusts.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Effect of finite ion mass on relativistic self-induced transparency of plasma layers with a sharp boundary
We consider the effect of ion mobility on the threshold of relativistic self-induced transparency under irradiation of thin plasma layers by circularly polarised laser radiation. An analytical model of the motion of ions during the removal of electrons from the layer surface by the ponderomotive force of laser radiation is constructed. The model is used to analyse the motion of probe electrons in the resulting electromagnetic field. It is shown that the higher the ion mobility and the longer the laser pulse, the more stable the plasma layer to longitudinal perturbations of a finite value and the higher the threshold of self-induced transparency. These conclusions are verified by one-dimensional numerical simulation of a complete system of kinetic equations for plasma and Maxwell’s equations. (paper)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Long-period Jovian Tilts the Orbits of Two sub-Neptunes Relative to Stellar Spin Axis in Kepler-129
We present the discovery of Kepler-129 d (P{sub d}=7.2{sub -0.3}{sup +0.4} yr, msini{sub d}=8.3{sub -0.7}{sup +1.1} M{sub Jup}, e{sub d}=0.15{sub -0.05}{sup +0.07}) based on six years of radial-velocity observations from Keck/HIRES. Kepler-129 also hosts two transiting sub-Neptunes: Kepler-129 b (P {sub b} = 15.79 days, r {sub b} = 2.40 ± 0.04 R {sub ⊕}) and Kepler-129 c (P {sub c} = 82.20 days, r {sub c} = 2.52 ± 0.07 R {sub ⊕}) for which we measure masses of m {sub b} < 20 M {sub ⊕} and m{sub c}=43{sub -12}{sup +13} M{sub ⊕}. Kepler-129 is a hierarchical system consisting of two tightly packed inner planets and a massive external companion. In such a system, two inner planets precess around the orbital normal of the outer companion, causing their inclinations to oscillate with time. Based on an asteroseismic analysis of Kepler data, we find tentative evidence that Kepler-129 b and c are misaligned with stellar spin axis by ≳38°, which could be torqued by Kepler-129 d if it is inclined by ≳19° relative to inner planets. Using N-body simulations, we provide additional constraints on the mutual inclination between Kepler-129 d and inner planets by estimating the fraction of time during which two inner planets both transit. The probability that two planets both transit decreases as their misalignment with Kepler-129 d increases. We also find a more massive Kepler-129 c enables the two inner planets to become strongly coupled and more resistant to perturbations from Kepler-129 d. The unusually high mass of Kepler-129 c provides a valuable benchmark for both planetary dynamics and interior structure, since the best-fit mass is consistent with this 2.5 R {sub ⊕} planet having a rocky surface.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Medium-Scale Methanol Pool Fire Model Validation
In this work, medium scale (30 cm diameter) methanol pool fires were simulated using the latest fire modeling suite implemented in Sierra/Fuego, a low Mach number multiphysics reacting flow code. The sensitivity of model outputs to various model parameters was studied with the objective of providing model validation. This work also assesses model performance relative to other recently published large eddy simulations (LES) of the same validation case. Two pool surface boundary conditions were simulated. The first was a prescribed fuel mass flux and the second used an algorithm to predict mass flux based on a mass and energy balance at the fuel surface. Gray gas radiation model parameters (absorption coefficients and gas radiation sources) were varied to assess radiant heat losses to the surroundings and pool surface. The radiation model was calibrated by comparing the simulated radiant fraction of the plume to experimental data. The effects of mesh resolution were also quantified starting with a grid resolution representative of engineering type fire calculations and then uniformly refining that mesh in the plume region. Simulation data were compared to experimental data collected at the University of Waterloo and the National Institute of Standards and Technology (NIST). Validation data included plume temperature, radial and axial velocities, velocity temperature turbulent correlations, velocity velocity turbulent correlations, radiant and convective heat fluxes to the pool surface, and plume radiant fraction. Additional analyses were performed in the pool boundary layer to assess simulated flame anchoring and the effect on convective heat fluxes. This work assesses the capability of the latest Fuego physics and chemistry model suite and provides additional insight into pool fire modeling for nonluminous, non-sooting flames.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
GenASiS Basics: Object-oriented utilitarian functionality for large-scale physics simulations (Version 4)
GenASiS Basics provides modern Fortran classes furnishing extensible object-oriented utilitarian functionality for large-scale physics simulations on distributed memory supercomputers. This functionality includes physical units and constants; display to the screen or standard output device; message passing; I/O to disk; and runtime parameter management and usage statistics. Herein, this revision—Version 4 of Basics—includes a name change and additions to functionality, including the facilitation of direct communication between GPUs.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Design of a readout circuit incorporating a 12-bit analog-to-digital converter for cooled infrared focal plane array
The infrared focal plane array (IRFPA) is gradually becoming more systematic. In order to enhance the signal processing capabilities, analog-to-digital converters (ADC) integrated into the readout integrated circuit (ROIC) is an important development trend. However, the cryogenic effects of MOSFET devices will affect the conversion accuracy of the ADC at 77 K. In this paper, the main parameters of MOSFET are extracted at 77 K in 0.18 μm CMOS process, and a cryogenic model is established. Based on this, a digital ROIC is designed, which integrates a 12-bit single-slope integral ADC in pixel unit. By applying continuous integral ramp generator and mixed-voltage comparator, a high-linearity and low-power consumption single-slope ADC is realized for the cooled readout circuit. The measured dynamic effective number of bits of the ADC at 77 K is 10.92 bits, the static no-missing code resolution reaches 11.99 bits, the maximum differential nonlinear |DNL| < 1LSB and maximum integral nonlinear |INL| < 1LSB. This paper realizes the design of a digital ROIC for IRFPA and improves the simulation accuracy at 77 K.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Low-dose high-resolution $\mathrm{TOF}$-$\mathrm{PET}$ using ionization-activated multi-state low-$\mathrm{Z}$ detector media
We propose PET scanners using low atomic number media that undergo a persistent local change of state along the paths of the Compton recoil electrons. Measurement of the individual scattering locations and angles, deposited energies, and recoil electron directions allows using the kinematical constraints of the 2-body Compton scattering process to perform a statistical time-ordering of the scatterings, with a high probability of precisely identifying where the gamma first interacted in the detector. In these cases the Line-of-Response is measured with high resolution, determined by the underlying physics processes and not the detector segmentation. There are multiple such media that act through different mechanisms. As an example in which the change of state is quantum-mechanical through a change in molecular configuration, rather than thermodynamic, as in a bubble chamber, we present simulations of a two-state photoswitchable organic dye, a ‘Switchillator’, that is activated to a fluorescent-capable state by the ionization of the recoil electrons. The activated state is persistent, and can be optically excited multiple times to image individual activated molecules. Energy resolution is provided by counting the activated molecules. Location along the LOR is implemented by large-area time-of-flight MCP-PMT photodetectors with single photon time resolution in the tens of ps and sub-mm spatial resolution. Simulations indicate a large reduction of dose.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Combining Force Fields and Neural Networks for an Accurate Representation of Chemically Diverse Molecular Interactions
A key goal of molecular modeling is the accurate reproduction of the true quantum mechanical potential energy of arbitrary molecular ensembles with a tractable classical approximation. The challenges are that analytical expressions found in general purpose force fields struggle to faithfully represent the intermolecular quantum potential energy surface at close distances and in strong interaction regimes; that the more accurate neural network approximations do not capture crucial physics concepts, e.g., nonadditive inductive contributions and application of electric fields; and that the ultra-accurate narrowly targeted models have difficulty generalizing to the entire chemical space. We therefore designed a hybrid wide-coverage intermolecular interaction model consisting of an analytically polarizable force field combined with a short-range neural network correction for the total intermolecular interaction energy. Here, we describe the methodology and apply the model to accurately determine the properties of water, the free energy of solvation of neutral and charged molecules, and the binding free energy of ligands to proteins. The correction is subtyped for distinct chemical species to match the underlying force field, to segment and reduce the amount of quantum training data, and to increase accuracy and computational speed. For the systems considered, the hybrid ab initio parametrized Hamiltonian reproduces the two-body dimer quantum mechanics (QM) energies to within 0.03 kcal/mol and the nonadditive many-molecule contributions to within 2%. Simulations of molecular systems using this interaction model run at speeds of several nanoseconds per day.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Topology induced crossover between Langevin, subdiffusion, and Brownian diffusion regimes in supercooled water
Despite extensive studies of supercooled water, it remains challenging to understand its peculiar dynamic anomalous properties. In this work, we integrated full atomistic simulations of supercooled water over the temperature range of room temperature to 200 K using a quantum-mechanics-based polarizable force field with the dressed dynamics method that couples fast collision events and slow reorganization dynamics of hydrogen-bond networks. Our analysis unveils the salient multiscale features in the transient relaxation dynamics of supercooled water. A classical Langevin behavior dominates at fast timescales, while long-time relaxations unveil two different activation barriers in two temperature regions: below and above 230 K. The modulation of the entropy spectrum by temperature is elucidated in terms of a three-state model underlined by the complexity of the water dynamics associated with a topological transition of a strong hydrogen-bond network. This state-dependent network topology is quantitatively characterized by power-law exponents of inverse network connectivity from 200 to 298 K. Finally, this work provides valuable guidance for further studies on the transient relaxation dynamics of supercooled water.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Efficiently Measuring 𝑑-Wave Pairing and Beyond in Quantum Gas Microscopes
Understanding the mechanism of high-temperature superconductivity is among the most important problems in physics, one for which quantum simulation can provide new insights. However, it remains challenging to characterize superconductivity in existing cold-atom quantum simulation platforms. Here, in this work, we introduce a protocol for measuring a broad class of observables in fermionic quantum gas microscopes, including long-range superconducting pairing correlations (after a repulsive-to-attractive mapping). The protocol only requires global controls followed by site-resolved particle number measurements—capabilities that have been already demonstrated in multiple experiments—and is designed by analyzing the Hilbert space of fermions on two sites. The protocol is sample-efficient and we further optimize our pulses for robustness to experimental imperfections such as lattice inhomogeneity. Our Letter introduces a general tool for manipulating quantum states on optical lattices, enhancing their ability to tackle problems such as high-temperature superconductivity.
Hubbard model↗
Numerical simulations of onset and growth of Rayleigh–Taylor instability involving solids in converging geometry
Numerical simulation of Rayleigh–Taylor instabilities involving solids has been carried out in a spherically converging geometry. A solid shell is driven toward the center by high-pressure gas outside. Low-pressure gas inside the shell is then compressed, causing the solid shell to slow down and eventually bounce back. Here, simulation results show the absence of the onset condition unlike in the planar geometry equivalent. Results also show that disturbance growth seems to be strongly associated with the deformation direction instead of the acceleration direction. For example, when the interface is compressed in the cross-stream direction, the disturbance at the gas–solid interface grows even under the Rayleigh–Taylor stable situation.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
A Reaction Mechanism for Carbon Soot in Post-Detonation Flows
This report documents the generation of a mechanism to predict the inclusion of carbon soot particles in a high explosive flow. The mechanism includes gasification and oxidation reactions, formation, sublimation, radiation, and agglomeration. Each part of the mechanism is derived from properties in the literature. The influence of each part of the mechanism is explored using simple, example simulations consisting of a 12 mm diameter 2,4,6-Trinitrotoluene charge detonated in ambient air. The mechanism has not been quantitatively compared to experiments. Additional efforts will be required to tune and validate it, which will require continued advancements in experimental diagnostics and simulation techniques.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Efficient product formulas for commutators and applications to quantum simulation
Not Available
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗