ShantanuT01/DACTYL-Pretraining huggingface dataset:
Evolution of systems in which Hamiltonians are generators of gauge transformations is a notion that requires more structure than the canonical theory provides. We identify and study this additional structure in the framework of relational observables ("partial observables"). We formulate necessary and sufficient conditions for the resulting evolution in the physical phase space to be a symplectomorphism. We give examples which satisfy those conditions and examples which do not. We point out that several classic positions in the literature on relational observables contain an incomplete approach to the issue of evolution and false statements. Our work provides useful clarification and opens the door to studying correctly formulated definitions.
Dopant-based quantum computing implementations often require the dopants to be situated close to an interface to facilitate qubit manipulation with local gates. Interfaces not only modify the energies of the bound states but also affect their symmetry. Making use of the successful effective mass theory we study the energy spectra of acceptors in Si or Ge taking into account the quantum confinement, the dielectric mismatch and the central cell effects. The presence of an interface puts constraints to the allowed symmetries and lead to the splitting of the ground state in two Kramers doublets [J. Mol et al, App. Phys. Lett. 106, 203110 (2015)]. Inversion symmetry breaking also implies parity mixing which affects the allowed optical transitions. Consequences for acceptor qubits are discussed.
Shell Model Monte Carlo (SMMC) techniques are used to calculate two-neutrino double beta decay matrix elements. We validate the approach against direct diagonalization for $^{48}$Ca in the complete $pf$-shell using the KB3 interaction. The method is then applied to the decay of $^{76}$Ge in the $(0f_{5/2},1p,0g_{9/2})$ model space using a newly calculated realistic interaction. Our result for the matrix element is $0.13\pm0.05$ MeV$^{-1}$, in agreement with the experimental value.
Exciton-polaron formation in one-dimensional lattice models with short or long-range carrier-phonon interaction is studied by quantum Monte Carlo simulations. Depending on the relative sign of electron and hole-phonon coupling, the exciton-polaron size increases or decreases with increasing interaction strength. Quantum phonon fluctuations determine the (exciton-)polaron size and yield translation-invariant states at all finite couplings.
In this paper we investigate gravitational perturbations of a regular black hole, particularly Bardeen solution. Such system is solution of Einstein equations that do not have a singularity at the origin of the radial symmetry. However it still have events horizons depending on the values of the characteristic parameters of the solution. When a black hole is perturbed, it oscillates. It gives rise to damped vibrating modes which are known as quasinormal modes. It is calculated the quasinormal frequencies of a regular black hole using the third order WKB approximation for gravitational perturbations. The results are presented in tables I, II and III.
We present a formalism based on nonequilibrium dynamical mean field theory (DMFT) which allows to compute the time-resolved X-ray absorption spectrum (XAS) of photo-excited solids. By applying this formalism to the photo-doped half-filled and quarter-filled two-orbital Hubbard models in the Mott insulating regime we clarify how the time-resolved XAS signal reflects the nonequilibrium population of different local states. Apart from the missing broadening associated with continuum excitations, the atomic XAS spectrum computed with the nonthermal state populations provides a good approximation to the full nonequilibrium DMFT result. This suggest a route to combine the accurate DMFT description of nonequilibrum states of solids with cluster calculations of the XAS signal.
We present a correlation between the average temporal decay ({\alpha}X,avg,>200s) and early-time luminosity (LX,200s) of X-ray afterglows of gamma-ray bursts as observed by Swift-XRT. Both quantities are measured relative to a rest frame time of 200 s after the {\gamma}-ray trigger. The luminosity average decay correlation does not depend on specific temporal behavior and contains one scale independent quantity minimizing the role of selection effects. This is a complementary correlation to that discovered by Oates et al. (2012) in the optical light curves observed by Swift-UVOT. The correlation indicates that on average, more luminous X-ray afterglows decay faster than less luminous ones, indicating some relative mechanism for energy dissipation. The X-ray and optical correlations are entirely consistent once corrections are applied and contamination is removed. We explore the possible biases introduced by different light curve morphologies and observational selection effects, and how either geometrical effects or intrinsic properties of the central engine and jet could explain the observed correlation.
We have analyzed available full-disc data from the Michelson Doppler Imager (MDI) on board SoHO using the "ring diagram" technique to determine the behavior of solar meridional flows over solar cycle 23 in the outer 2% of the solar radius. We find that the dominant component of meridional flows during solar maximum was much lower than that during the minima at the beginning of cycles 23 and 24. There were differences in the flow velocities even between the two minima. The meridional flows show a migrating pattern with higher-velocity flows migrating towards the equator as activity increases. Additionally, we find that the migrating pattern of the meridional flow matches those of sunspot butterfly diagram and the zonal flows in the shallow layers. A high latitude band in meridional flow appears around 2004, well before the current activity minimum. A Legendre polynomial decomposition of the meridional flows shows that the latitudinal pattern of the flow was also different during the maximum as compared to that during the two minima. The different components of the flow have different time-dependences, and the dependence is different at different depths.
The pulsar B1822-09 (J1825-0935) experienced a series of five unusual slow glitches over the 1995-2004 interval. The results of further study of this unusual glitch phenomenon are presented. It is also reported the detection a new glitch of typical signature that occurred in the pulsar period in 2006 January.
On the base of analysis of experimental observations and critical assessment of existing models for oxide fuel structure evolution under operation conditions of fast reactors, new models for fuel restructuring and coring are proposed. The restructuring model describes coherent motion in the temperature gradient of various voids (gas bubbles, sintering pores and large lenticular pores) and grain boundaries, to which the voids are attached. As a result, the model explains elongation of thermally growing equiaxed grains and formation of columnar grains, and predicts a rapid formation of extended columnar grain zone during a relatively short initial period of fast reactor irradiation. The coring model describes formation and growth of the central void in the fuel pellet, activated by mass transport from the inner to the outer zone of the pellet under stresses induced by inhomogeneous fuel densification in the initial period of irradiation.
We extend a recently developed method to solve semi-linear PDEs to the case of a degenerated diffusion. Being a pure Monte Carlo method it does not suffer from the so called curse of dimensionality and it can be used to solve problems that were out of reach so far. We give some results of convergence and show numerically that it is effective. Besides we numerically show that the new scheme developed can be used to solve some full non linear PDEs. At last we provide an effective algorithm to implement the scheme.
In this work, we present a general theoretical framework for the study of autonomously corrected quantum devices. First, we identify a necessary and sufficient revised version of the Knill-Laflamme conditions for the existence of an engineered Lindbladian providing protection against at most $c$ consecutive errors of natural dissipation, giving rise to an effective logical decoherence rate suppressed to order $c$. Moreover, we demonstrate that such engineered dissipation can be combined with generalized realizations of error-transparent Hamiltonians (ETH) in order to perform a quantum computation in the logical space while maintaining the same degree of suppression of decoherence. Finally, we introduce a formalism predicting with precision the emergent dynamics in the logical code space resulting from the interplay of natural, engineered dissipations sources and the generalized ETH.
We present measurements of the luminosity and color-dependence of galaxy clustering at 0.2<z<1.0 in the PRIsm MUlti-object Survey (PRIMUS). We quantify the clustering with the redshift-space and projected two-point correlation functions, xi(rp,pi) and wp(rp), using volume-limited samples constructed from a parent sample of over 130,000 galaxies with robust redshifts in seven independent fields covering 9 sq. deg. of sky. We quantify how the scale-dependent clustering amplitude increases with increasing luminosity and redder color, with relatively small errors over large volumes. We find that red galaxies have stronger small-scale (0.1<rp<1 Mpc/h) clustering and steeper correlation functions compared to blue galaxies, as well as a strong color dependent clustering within the red sequence alone. We interpret our measured clustering trends in terms of galaxy bias and obtain values between b_gal=0.9-2.5, quantifying how galaxies are biased tracers of dark matter depending on their luminosity and color. We also interpret the color dependence with mock catalogs, and find that the clustering of blue galaxies is nearly constant with color, while redder galaxies have stronger clustering in the one-halo term due to a higher satellite galaxy fraction. In addition, we measure the evolution of the clustering strength and bias, and we do not detect statistically significant departures from passive evolution. We argue that the luminosity- and color-environment (or halo mass) relations of galaxies have not significantly evolved since z=1. Finally, using jackknife subsampling methods, we find that sampling fluctuations are important and that the COSMOS field is generally an outlier, due to having more overdense structures than other fields; we find that 'cosmic variance' can be a significant source of uncertainty for high-redshift clustering measurements.
A family of potential-density pairs that represent spherical shells with finite thickness is obtained from the superposition of spheres with finite radii. Other families of shells with infinite thickness with a central hole are obtained by inversion transformations of spheres and of the finite shells. We also present a family of double shells with finite thickness. All potential-density pairs are analytical and can be stated in terms of elementary functions. For the above-mentioned structures, we study the circular orbits of test particles and their stability with respect to radial perturbations. All examples presented are found to be stable. A particular isotropic form of a metric in spherical coordinates is used to construct a General Relativistic version of the Newtonian families of spheres and shells. The matter of these structures is anisotropic, and the degree of anisotropy is a function of the radius.
A systematic analysis of phonon-plasmon coupled excitations in three-dimensional (3D) polar systems is provided through the prism of both raw and integrated electron energy loss spectroscopy (EELS) and phonon spectra in the whole relevant parametric space, spanned by the adiabaticity parameter and the electron-phonon interaction (EPI) strength. We show that the EPI strength plays a prominent role in distributing spectral weights among excitations, providing an experimentally convenient way to estimate it from integrated spectra. By projecting the excitations onto the phonon degree of freedom, we also report for strong couplings large phonon production contributions, which are of very different origins depending on the adiabaticity parameter. In parallel to this thorough spectral weights analysis, excitations' dispersion evolutions, dampings, and various limiting behaviors are qualitatively and quantitatively correctly accounted for in the whole parametric space.
We present ComCTQMC, a GPU accelerated quantum impurity solver. It uses the continuous-time quantum Monte Carlo (CTQMC) algorithm wherein the partition function is expanded in terms of the hybridisation function (CT-HYB). ComCTQMC supports both partition and worm-space measurements, and it uses improved estimators and the reduced density matrix to improve observable measurements whenever possible. ComCTQMC efficiently measures all one and two-particle Green's functions, all static observables which commute with the local Hamiltonian, and the occupation of each impurity orbital. ComCTQMC can solve complex-valued impurities with crystal fields that are hybridized to both fermionic and bosonic baths. Most importantly, ComCTQMC utilizes graphical processing units (GPUs), if available, to dramatically accelerate the CTQMC algorithm when the Hilbert space is sufficiently large. We demonstrate acceleration by a factor of over 600 (100) in a simulation of $\delta$-Pu at 600 K with (without) crystal fields. In easier problems, the GPU offers less impressive acceleration or even decelerates the CTQMC. Here we describe the theory, algorithms, and structure used by ComCTQMC in order to achieve this set of features and level of acceleration.
We present general and rigorous results showing that the microcanonical and canonical ensembles are equivalent at all three levels of description considered in statistical mechanics - namely, thermodynamics, equilibrium macrostates, and microstate measures - whenever the microcanonical entropy is concave as a function of the energy density in the thermodynamic limit. This is proved for any classical many-particle systems for which thermodynamic functions and equilibrium macrostates exist and are defined via large deviation principles, generalizing many previous results obtained for specific classes of systems and observables. Similar results hold for other dual ensembles, such as the canonical and grand-canonical ensembles, in addition to path ensembles used for describing nonequilibrium systems driven in steady states.
We consider a family of second-order parabolic systems in divergence form with rapidly oscillating and time-dependent coefficients, arising in the theory of homogenization. We obtain uniform interior $W^{1,p}$, H\"older, and Lipschitz estimates as well as boundary $W^{1,p}$ and H\"older estimates, using compactness methods. As a consequence, we establish uniform $W^{1,p}$ estimates for the initial-Dirichlet problems in $C^{1}$ cylinders.
We present a heavy traffic analysis of a single-server polling model, with the special features of retrials and glue periods. The combination of these features in a polling model typically occurs in certain optical networking models, and in models where customers have a reservation period just before their service period. Just before the server arrives at a station there is some deterministic glue period. Customers (both new arrivals and retrials) arriving at the station during this glue period will be served during the visit of the server. Customers arriving in any other period leave immediately and will retry after an exponentially distributed time. As this model defies a closed-form expression for the queue length distributions, our main focus is on their heavy-traffic asymptotics, both at embedded time points (beginnings of glue periods, visit periods and switch periods) and at arbitrary time points. We obtain closed-form expressions for the limiting scaled joint queue length distribution in heavy traffic and use these to accurately approximate the mean number of customers in the system under different loads.
Coherent manipulation of binary degrees of freedom is at the heart of modern quantum technologies. Graphene offers two binary degrees: the electron spin and the valley. Efficient spin control has been demonstrated in many solid state systems, while exploitation of the valley has only recently been started, yet without control on the single electron level. Here, we show that van-der Waals stacking of graphene onto hexagonal boron nitride offers a natural platform for valley control. We use a graphene quantum dot induced by the tip of a scanning tunneling microscope and demonstrate valley splitting that is tunable from -5 to +10 meV (including valley inversion) by sub-10-nm displacements of the quantum dot position. This boosts the range of controlled valley splitting by about one order of magnitude. The tunable inversion of spin and valley states should enable coherent superposition of these degrees of freedom as a first step towards graphene-based qubits.
The BL Lacertae object H1426+428 is the most distant, confirmed source of TeV gamma rays. At a redshift of 0.129, its detection at TeV energies has important implications for estimating the density of the extragalactic infra-red background radiation. H1426+428 was observed extensively during the 2001/2002 observing season with the Whipple 10 m gamma-ray telescope. The results of these observations are presented here and are combined with the results of previous observations made between 1999 and 2001 at Whipple.
Rest frame Stromgren photometry (3500A, 4100A, 4750A and 5500A) is presented for 509 galaxies in 17 rich clusters between z=0 and z=1 as a test of color evolution. Our observations confirm a strong, rest frame, Butcher-Oemler effect where the fraction of blue galaxies increases from 20% at z=0.4 to 80% at z=0.9. We also find that a majority of these blue cluster galaxies are composed of normal disk or post-starbursts systems based on color criteria. When comparing our colors to the morphological results from HST imaging, we propose that the blue cluster galaxies are a population of late-type, LSB objects who fade and are then destroyed by the cluster tidal field. After isolating the red objects from Butcher-Oemler objects, we have compared the mean color of these old, non-star forming objects with SED models in the literature as a test for passive galaxy evolution in ellipticals. We find good agreement with single burst models which predict a mean epoch of galaxy formation at z=5. Tracing the red envelope for ellipticals places the earliest epoch of galaxy formation at z=10.
We derive single-particle and two-particle correlators of anyons in the presence of a magnetic field in the lowest Landau level. We show that the two-particle correlator exhibits signatures of fractional statistics which can distinguish anyons from their fermionic and bosonic counterparts. These signatures include the zeroes of the two-particle correlator and its exclusion behavior. We find that the single-particle correlator in finite geometries carries valuable information relevant to experiments in which quasiparticles on the edge of a quantum Hall system tunnel through its bulk.
We analyze the spatially resolved star formation history of 300 nearby galaxies from the CALIFA integral field spectroscopic survey to investigate the radial structure and gradients of the present day stellar populations properties as a function of Hubble type and galaxy stellar mass. A fossil record method based on spectral synthesis techniques is used to recover spatially and temporally resolved maps of stellar population properties of spheroidal and spiral galaxies with masses $10^9$ to $7 \times 10^{11}$ M$_\odot$. The results show that galaxy-wide spatially averaged stellar population properties (stellar mass, mass surface density, age, metallicity, and extinction) match those obtained from the integrated spectrum, and that these spatially averaged properties match those at $R = 1$ HLR (half light radius), proving that the effective radii are really effective.   Further, the individual radial profiles of the stellar mass surface density ($\mu_\star$), luminosity weighted ages ($< {\rm log}\,age>_L$), and mass weighted metallicity ($< \log Z_\star >_M$) are stacked in bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc and Sd). All these properties show negative gradients as a sign of the inside-out growth of massive galaxies. However, the gradients depend on the Hubble type in different ways. For the same galaxy mass, E and S0 galaxies show the largest inner gradients in $\mu_\star$; while MW-like galaxies (Sb with $M_\star \sim 10^{11} M_\odot$) show the largest inner age and metallicity gradients. The age and metallicity gradients suggest that major mergers have a relevant role in growing the center (within 3 HLR) of massive early type galaxies; and radial mixing may play a role flattening the radial metallicity gradient in MW-like disks.
We consider stochastic Volterra integral equations driven by a fractional Brownian motion with Hurst parameter H > 1/2 . We first derive supremum norm estimates for the solution and its Malliavin derivative. We then show existence and smoothness of the density under suitable nondegeneracy conditions. This extends the results in Hu-Nualart and Nualart-Saussereau where stochastic differential equations driven by fractional Brownian motion are considered. The proof uses a priori estimates for deterministic differential equations driven by a function in a suitable Sobolev space.
We obtain an approximate global stationary and axisymmetric solution of Einstein's equations which can be considered as a simple star model: a self-gravitating perfect fluid ball with constant mass density rotating in rigid motion. Using the post-Minkowskian formalism (weak-field approximation) and considering rotation as a perturbation (slow-rotation approximation), we find approximate interior and exterior (asymptotically flat) solutions to this problem in harmonic and quo-harmonic coordinates. In both cases, interior and exterior solutions are matched, in the sense of Lichnerowicz, on the surface of zero pressure to obtain a global solution. The resulting metric depends on three arbitrary constants: mass density, rotational velocity and the star radius at the non-rotation limit. The mass, angular momentum, quadrupole moment and other constants of the exterior metric are determined by these three parameters. It is easy to show that this type of fluid cannot be a source of the Kerr metric
Polycrystalline Sr$_3$OsO$_6$, which is an ordered double-perovskite insulator, is synthesized via solid-state reaction under high-temperature and high-pressure conditions of 1200 $^\circ$C and 6 GPa. The synthesis enables us to conduct a comparative study of the bulk form of Sr$_3$OsO$_6$ toward revealing the driving mechanism of 1000 K ferromagnetism, which has recently been discovered for epitaxially grown Sr$_3$OsO$_6$ films. Unlike the film, the bulk is dominated by antiferromagnetism rather than ferromagnetism. Therefore, robust ferromagnetic order appears only when Sr$_3$OsO$_6$ is under the influence of interfaces. A specific heat capacity of 39.6(9) 10$^{-3}$ J mol$^{-1}$ K$^{-2}$ is found at low temperatures ($<$17 K). This value is remarkably high, suggesting the presence of possible fermionic-like excitations at the magnetic ground state. Although the bulk and film forms of Sr$_3$OsO$_6$ share the same lattice basis and electrically insulating state, the magnetism is entirely different between them.