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We demonstrate the systematic implementation of recently-developed fast explicit kinetic integration algorithms on modern graphics processing unit (GPU) accelerators. We take as representative test cases Type Ia supernova explosions with extremely stiff thermonuclear reaction networks having 150–365 isotopic species and 1600–4400 reactions, assumed coupled to hydrodynamics using operator splitting. In such examples we demonstrate the capability to integrate independent thermonuclear networks from ~250–500 hydro zones (assumed to be deployed on CPU cores) in parallel on a single GPU in the same wall clock time that standard implicit methods can integrate the network for a single zone. This two or more orders of magnitude increase in efficiency for solving systems of realistic thermonuclear networks coupled to fluid dynamics implies that important coupled, multiphysics problems in various scientific and technical disciplines that were intractable, or could be simulated only with highly schematic kinetic networks, are now computationally feasible. As examples of such applications I will discuss our ongoing deployment of these new methods for Type Ia supernova explosions in astrophysics and for simulation of the complex atmospheric chemistry entering into weather and climate problems.

We review a strategy to use an ion-based analog quantum simulator to study the many-body electron-electron Coulomb interaction of an electron gas. This is made possible by an exact unitary dilatation mapping, which allows an experimentally challenging system to be replaced by an alternative one that may be experimentally more accessible. We show the feasibility of this simulation strategy mathematically. As a bonus, the dilatation transformation does not even need to be physically implemented when only the system spectrum is needed, in which case the simulation induces no experimental complexity overhead. This proposal is dimension-agnostic, and could be generalized as a simulation strategy between systems involving terms with different position or momentum dependence. [ABSTRACT FROM AUTHOR]

Strongly-correlated graphene quantum Hall states are described in terms of an SO(8) fermion dynamical symmetry that has pairing as well as particle-hole generators. The SU(4) symmetry of graphene quantum Hall ferromagnetism is recovered as one limit, but the full SO(8) symmetry gives analytical many-body solutions for a rich set of additional states exhibiting spontaneously-broken symmetry. A generalized coherent states solution is obtained that is equivalent to Hartree-Fock-Bogoliubov theory constrained by symmetry, and exhibits the interplay between competing collective degrees of freedom in determining the ground state. [ABSTRACT FROM AUTHOR]

A full Fermi surface exists in underdoped high-temperature superconductors if the temperature T lies above the pseudogap (PG) temperature T*. Below T* the Fermi surface is anomalous. Some experiments indicate that only arcs of Fermi surface survive. Others indicate that the Fermi surface is closed but consists of pockets with a small surface area. We show that generalizing the Bardeen-Cooper-Schrieffer theory of normal superconductivity to include d-wave pairs and antiferromagnetism on a two-dimensional lattice leads to a T* having a pronounced k dependence because of strong anisotropy in the PG correlations. We discuss implications for gapping of the Fermi surface within the Fermi arc and Fermi pockets picture of underdoped cuprates, and propose that related phenomena arising from anisotropic PG correlations may also occur in underdoped iron arsenide superconductors. [ABSTRACT FROM AUTHOR]

Two principles govern the critical temperature for superconducting transitions: (1) intrinsic strength of the pair coupling and (2) the effect of the many-body environments on the efficiency of that coupling. Most discussions take into account only the former, but we argue that the properties of unconventional superconductors are governed more often by the latter, through dynamical symmetry relating to normal and superconducting states. Differentiating these effects is essential to charting a path to the highest-temperature superconductors. [ABSTRACT FROM AUTHOR]

40Ar is among the few sd -shell nuclei known to exhibit superdeformation. An interesting question is whether the experimentally identified superdeformed rotational band in 40Ar has an axially or triaxially deformed shape. Projected shell model calculations assuming an axially deformed basis are performed up to high spins for this nucleus. Our detailed analysis of the wave functions reveals that the high-spin states are dominated by mixed 0-, 2-, and 4-quasiparticle configurations with different K-components. The calculated electric quadrupole transition probabilities reproduce well the known experimental data and suggest a reduced but still significant collectivity in the high spin region. Due to the mixing of various multi-quasiparticle K-configurations, axial asymmetry emerges in the calculation. Throughout the entire rotational band, the extracted triaxial deformation parameters are small but non-zero. Relations of triaxiality and unnatural spin-parity states of the superdeformed side-band are discussed. [ABSTRACT FROM AUTHOR]

The article reports on the several comments concerning the high-transition temperature superconductivity phase diagram. It questions the transition between the antiferromagnetic (AF) and superconducting phases, which is controlled by anomalous properties commonly attributed to a pseudogap in the spectrum. It also discusses whether high-temperature superconductivity is specifically the province of cuprate materials or can it exist in other families of non-copper oxide compounds.

A formalism is presented for treating strongly correlated graphene quantum Hall states in terms of an SO(8) fermion dynamical symmetry that includes pairing as well as particle-hole generators. The graphene SO(8) algebra is isomorphic to an SO(8) algebra that has found broad application in nuclear physics, albeit with physically very different generators, and exhibits a strong formal similarity to SU(4) symmetries that have been proposed to describe high-temperature superconductors. The well-known SU(4) symmetry of quantum Hall ferromagnetism for single-layer graphene is recovered as one subgroup of SO(8), but the dynamical symmetry structure associated with the full set of SO(8) subgroup chains extends quantum Hall ferromagnetism and allows analytical many-body solutions for a rich set of collective states exhibiting spontaneously broken symmetry that may be important for the low-energy physics of graphene in strong magnetic fields. The SO(8) symmetry permits a natural definition of generalized coherent states that correspond to symmetry-constrained Hartree-Fock-Bogoliubov solutions, or equivalently a microscopically derived Ginzburg-Landau formalism, exhibiting the interplay between competing spontaneously broken symmetries in determining the ground state. [ABSTRACT FROM AUTHOR]

We show that a nearly perfect SU(3) symmetry emerges from an extended projected shell model. Starting from a deformed potential we construct separate bases for neutron and proton collective rotational states by exact angular momentum projection. These rotational states are then coupled by diagonalizing a residual pairing plus quadrupole interaction. The states obtained exhibit a one-to-one correspondence with an SU(3) spectrum up to high angular momentum and excitation, and their wave functions have a near-maximal overlap with the SU(3) states. They can also be classified as rotational bands built on spin-1ℎ phonon excitations, which correspond to a geometrical scissors mode and its generalizations. This work is a direct demonstration that numerical angular momentum projection theory extends the Elliott''s original idea to heavy nuclear systems. [Copyright &y& Elsevier]

Background: The interplay between collective and single-particle degrees of freedom is an important structure aspect to study. The nuclei in the A≈180 mass region are often denoted as good examples to study such problems because these nuclei are known to exhibit many rotational bands based on multi-quasiparticle K isomers. Purpose: A large set of high-quality experimental data on high-K isomeric states in the A≈180 mass region has accumulated. A systematic description of them is a theoretical challenge as it requires a method going beyond the usual mean field with multi-quasiparticle configurations built in the shell-model basis. The K-isomer data provide an ideal testing ground for theoretical models. Method: The recently extended projected shell model (PSM) by the Pfaffian method is employed with a sufficiently large configuration space including up to 10 quasiparticles. The restoration of rotational symmetry which is broken in the deformed mean field is obtained by means of angular-momentum projection. With axial symmetry in the basis deformation, each multi-quasiparticle state, classified by a K quantum number, represents the major component of a rotational K band. Shell-model diagonalization in such a projected basis defines the K mixing, which is the key ingredient of the present method. Results: Quasiparticle structure and rotational properties of high-K isomers in even-even neutron-rich 174-186W isotopes are described. The rotational evolution of the yrast and near-yrast bands is discussed with successive band crossings. Multi-quasiparticle K isomers and associated rotational bands in each W isotope are studied with detailed quasiparticle configurations given. Electromagnetic transition properties are also studied and the calculated B(E2),B(M1), and g-factors are compared with experiment if data exist. Conclusions: Many nuclei of the A≈180 mass region exhibit properties of an axially symmetric shape and K is approximately a good quantum number. For such nuclei, the extended PSM assuming an axially symmetric basis but including K mixing through diagonalization of the two-body Hamiltonian is an appropriate method to study multi-quasiparticle K isomers and K violations in these states. For special examples where one finds highly K-forbidden transitions the present model needs to be further improved. [ABSTRACT FROM AUTHOR]

We report microscopic many-body calculations indicating that rotational bands based on nuclear scissors vibrations exhibit systematic splitting between neighboring spin states (ΔI=2 bifurcation) in which the magnitude of the moment of inertia oscillates between states having even and odd spins. We show that this unexpected result is caused by self-organization of the deformed proton and neutron bodies in the scissors motion, which is further amplified by the K^{π}=1^{+} two-quasiparticle configurations near the scissors states. We propose that the puzzling excited state found above the 1^{+} scissors state in ^{156}Gd [Phys. Rev. Lett. 118, 212502 (2017)PRLTAO0031-900710.1103/PhysRevLett.118.212502] is the first evidence of this effect, and predict that bifurcation may generally appear in all other scissors rotational bands of deformed nuclei, and possibly in other systems exhibiting collective scissors vibrations.