ShantanuT01/DACTYL-Pretraining huggingface dataset:
A two-dimensional arrangement of quantum dots with finite inter-dot tunnel coupling provides a promising platform for studying complicated spin correlations as well as for constructing large-scale quantum computers. Here, we fabricate a tunnel-coupled triangular triple quantum dot with a novel gate geometry in which three dots are defined by positively biasing the surface gates. At the same time, the small area in the center of the triangle is depleted by negatively biasing the top gate placed above the surface gates. The size of the small center depleted area is estimated from the Aharonov-Bohm oscillation measured for the triangular channel but incorporating no gate-defined dots, with a value consistent with the design. With this approach, we can bring the neighboring gate-defined dots close enough to one another to maintain a finite inter-dot tunnel coupling. We finally confirm the presence of the inter-dot tunnel couplings in the triple quantum dot from the measurement of tunneling current through the dots in the stability diagram. We also show that the charge occupancy of each dot and that the inter-dot tunnel couplings are tunable with gate voltages.
Possibility to use ultra pure liquid Xenon as a low energy solar neutrino detector by means of $\nu$+e scatterings is evaluated. A possible detector with 10 tons of fiducial volume will give $\sim$14 events for pp-neutrinos and $\sim$6 events for $^{7}$Be neutrinos with the energy threshold at 50 keV. The detector can be built with known and established technologies. High density of the liquid- Xe would provide self-shields against the incoming backgrounds originating from the container and outer environments. Internal backgrounds can be reduced by distillation and other techniques. Purification of the liquid Xe can be done continuously throughout the experiment. The spallation backgrounds are estimated to be small though an experimental determination is neccessary. The liquid-Xe detector can also provide a significantly better sensitivity for the double beta decay and a dark matter search. However the 2$\nu$ double beta decay of $^{136}$Xe would be most background. It could be overcome if the 2$\nu$ lifetime is longer than 10$^{22}$yr. However, an isotope separation of $^{136}$Xe is inevitable for a shorter lifetime.   The isotope separations would, intoroduce a new opportunity to definitively identify dark matter. The interesting feature in addition to the solar neutrino measurements will also be discussed.
This paper addresses the problem of transparent object matting. Existing image matting approaches for transparent objects often require tedious capturing procedures and long processing time, which limit their practical use. In this paper, we first formulate transparent object matting as a refractive flow estimation problem. We then propose a deep learning framework, called TOM-Net, for learning the refractive flow. Our framework comprises two parts, namely a multi-scale encoder-decoder network for producing a coarse prediction, and a residual network for refinement. At test time, TOM-Net takes a single image as input, and outputs a matte (consisting of an object mask, an attenuation mask and a refractive flow field) in a fast feed-forward pass. As no off-the-shelf dataset is available for transparent object matting, we create a large-scale synthetic dataset consisting of 158K images of transparent objects rendered in front of images sampled from the Microsoft COCO dataset. We also collect a real dataset consisting of 876 samples using 14 transparent objects and 60 background images. Promising experimental results have been achieved on both synthetic and real data, which clearly demonstrate the effectiveness of our approach.
Wigner crystallization in mesoscopic quantum dots containing only few ($N < 50$) electrons exhibits a number of interesting peculiarities: (i) there exist two distinct crystal phases, and (ii) the phase boundary sensitively depends on the precise particle number. In this paper we demonstrate that this behavior can be used to control the {\em collective} transport properties by adding or removing a {\em single electron}.
Indoor scenes exhibit significant appearance variations due to myriad interactions between arbitrarily diverse object shapes, spatially-changing materials, and complex lighting. Shadows, highlights, and inter-reflections caused by visible and invisible light sources require reasoning about long-range interactions for inverse rendering, which seeks to recover the components of image formation, namely, shape, material, and lighting. In this work, our intuition is that the long-range attention learned by transformer architectures is ideally suited to solve longstanding challenges in single-image inverse rendering. We demonstrate with a specific instantiation of a dense vision transformer, IRISformer, that excels at both single-task and multi-task reasoning required for inverse rendering. Specifically, we propose a transformer architecture to simultaneously estimate depths, normals, spatially-varying albedo, roughness and lighting from a single image of an indoor scene. Our extensive evaluations on benchmark datasets demonstrate state-of-the-art results on each of the above tasks, enabling applications like object insertion and material editing in a single unconstrained real image, with greater photorealism than prior works. Code and data are publicly released at https://github.com/ViLab-UCSD/IRISformer.
The [CII] fine--structure line at 158um is an excellent tracer of the warm diffuse gas in the ISM and the interfaces between molecular clouds and their surrounding atomic and ionized envelopes. Here we present the initial results from Galactic Observations of Terahertz C+ (GOTC+), a Herschel Key Project devoted to study the [CII] fine structure emission in the galactic plane using the HIFI instrument. We use the [CII] emission together with observations of CO as a probe to understand the effects of newly--formed stars on their interstellar environment and characterize the physical and chemical state of the star-forming gas. We collected data along 16 lines--of--sight passing near star forming regions in the inner Galaxy near longitudes 330 degrees and 20 degrees. We identify fifty-eight [CII] components that are associated with high--column density molecular clouds as traced by 13CO emission. We combine [CII], 12CO, and 13CO observations to derive the physical conditions of the [CII]--emitting regions in our sample of high--column density clouds based on comparison with results from a grid of Photon Dominated Region (PDR) models. From this unbiased sample, our results suggest that most of [CII] emission originates from clouds with H2 volume densities between 10e3.5 and 10e5.5 cm^-3 and weak FUV strength (CHI_0=1-10). We find two regions where our analysis suggests high densities >10e5 cm^-3 and strong FUV fields (CHI=10e4-10e6), likely associated with massive star formation. We suggest that [CII] emission in conjunction with CO isotopes is a good tool to differentiate between regions of massive star formation (high densities/strong FUV fields) and regions that are distant from massive stars (lower densities/weaker FUV fields) along the line--of--sight
These lecture notes discuss several related features of the exactly solvable two-dimensional corner growth model with exponentially distributed weights. A key property of this model is the availability of a fairly explicit stationary version that possesses useful independence properties. With the help of couplings and estimates, we prove the existence of Busemann functions for this model, and the precise values of the longitudinal and transversal fluctuation exponents for the stationary corner growth model. The Busemann functions in turn furnish extremals for variational formulas that describe limiting shape functions.
We investigate the clustering properties of 13 QSO lines of sight in flat space, with average redshifts from z~2 to 4. We estimate the 1-D power spectrum and the integral density of neighbours, and discuss their variation with respect to redshift and column density. We compare the results with standard CDM models, and estimate the power spectrum of Lyman-alpha clustering as a function both of redshift and column density. We find that a) there is no significant periodicity or characteristic scale; b) the clustering depends both on column density and redshift; c) the clustering increases linearly only if at the same time the HI column density decreases strongly with redshift. The results remain qualitatively the same assuming an open cosmological model.
Non-equilibrium real-space condensation is a phenomenon in which a finite fraction of some conserved quantity (mass, particles, etc.) becomes spatially localised. We review two popular stochastic models of hopping particles that lead to condensation and whose stationary states assume a factorized form: the zero-range process and the misanthrope process, and their various modifications. We also introduce a new model - a misanthrope process with parallel dynamics - that exhibits condensation and has a pair-factorized stationary state.
In addition to the well known ferromagnetism, double perovskites are also expected to exhibit antiferromagnetic (AF) order driven by electron delocalisation. This has been seen in model Hamiltonian studies and confirmed via ab initio calculations. The AF phases should occur, for example, on sufficient electron doping of materials like Sr_2FeMoO_6 (SFMO) via La substitution for Sr. Clear experimental indication of such AF order is limited, possibly because of increase in antisite disorder with La doping on SFMO, although intriguing signatures of non ferromagnetic behaviour are seen. We study the survival of electronically driven antiferromagnetism in the presence of spatially correlated antisite disorder and extract the signals in magnetism and transport. We discover that A and G type AF order, that is predicted in the clean limit, is actually suppressed less strongly than ferromagnetism by antisite disorder. The AF phases are metallic, and, remarkably, more conducting that the ferromagnet for similar antisite disorder. We also highlight the phase coexistence window that connects the ferromagnetic regime to the A type antiferromagnetic phase.
With the help of analytical and numerical studies of the $t$-$J_z$ model we argue that the charge stripe in an antiferromagnetic insulator should be understood as a system of holon-spin-polaron excitations condensed at the self-induced antiphase domain wall. The structure of such a charge excitation is studied in detail with numerical and analytical results for various quantities being in a very close agreement. An analytical picture of these excitations occupying an effective 1D stripe band is also in a very good accord with numerical data. The emerging concept advocates the primary role of the kinetic energy in favoring the stripe as a ground state. A comparative analysis suggests the effect of pairing and collective meandering on the energetics of the stripe formation to be secondary.
The energy-based stochastic extension of the Schrodinger equation is a rather special nonlinear stochastic differential equation on Hilbert space, involving a single free parameter, that has been shown to be very useful for modelling the phenomenon of quantum state reduction. Here we construct a general closed form solution to this equation, for any given initial condition, in terms of a random variable representing the terminal value of the energy and an independent Brownian motion. The solution is essentially algebraic in character, involving no integration, and is thus suitable as a basis for efficient simulation studies of state reduction in complex systems.
The supergravity dual to N regular and M fractional D2-branes on the cone over \mathbb{CP}^3 has a naked singularity in the infrared. One can resolve this singularity and obtain a regular fractional D2-brane solution dual to a confining 2+1 dimensional N = 1 supersymmetric field theory. The confining vacuum of this theory is described by the solution of Cvetic, Gibbons, Lu and Pope. In this paper, we explore the alternative possibility for resolving the singularity - the creation of a regular horizon. The black-hole solution we find corresponds to the deconfined phase of this dual gauge theory in three dimensions. This solution is derived in perturbation theory in the number of fractional branes. We argue that there is a first-order deconfinement transition. Connections to Chern--Simons matter theories, the ABJM proposal and fractional M2-branes are presented.
A deeper understanding of the origin of quantum correlations is expected to shred light on the physical principles underlying quantum mechanics. In this work, we reconsider the possibility of devising "crypto-nonlocal theories", using a terminology firstly introduced by Leggett. We generalize and simplify the investigations on this subject which can be found in the literature. At their deeper level, such theories allow nonlocal correlations which can overcome the quantum limit.
Let $X$ be a complex submanifold of dimension $d$ of $\mathbb P^m\times\mathbb P^n$ ($m\geq n\geq 2$) and denote by $\alpha\colon\Pic(\mathbb P^m\times\mathbb P^n)\to \Pic(X)$ the restriction map of Picard groups, by $N_{X|\mathbb P^m\times\mathbb P^n}$ the normal bundle of $X$ in $\mathbb P^m\times\mathbb P^n$. Set $t:=\max\{\dim\pi_1(X),\dim\pi_2(X)\}$, where $\pi_1$ and $\pi_2$ are the two projections of $\mathbb P^m\times\mathbb P^n$. We prove a Barth-Lefschetz type result as follows: {\em Theorem.} {\it If $d\geq \frac{m+n+t+1}{2}$ then $X$ is algebraically simply connected, the map $\alpha$ is injective and $\Coker(\alpha)$ is torsion-free. Moreover $\alpha$ is an isomorphism if $d\geq\frac{m+n+t+2}{2}$, or if $d=\frac{m+n+t+1}{2}$ and $N_{X|\mathbb P^m\times\mathbb P^n}$ is decomposable.} These bounds are optimal. The main technical ingredients in the proof are: the Kodaira-Le Potier vanishing theorem in the generalized form of Sommese (\cite{LP}, \cite{ShS}), the join construction and an algebraisation result of Faltings concerning small codimensional subvarieties in $\mathbb P^N$ (see \cite{Fa}).
We study the radiative $\phi\to K^0\bar{K}^0\gamma$ decay within a phenomenological framework by considering the contributions of the $f_{0}(980)$ and $a_{0}(980)$ scalar resonances. We calculate the branching ratio $B(\phi\to K^0\bar{K}^0\gamma)$ by employing the coupling constants $g_{f_0K^{+}K^{-}}$ and $g_{a_0K^{+}K^{-}}$ as determined by different experimental groups.
We briefly discuss some open problems and recent developments in the investigation of the origin and propagation of ultra high energy cosmic rays (UHECRs).
The puzzle of finding consistent nuclear configurations for explaining both the decay probabilities and moments of the ${9/2}^-$, ${8}^+$ and ${21/2}^-$ isomers in and around $N=126$ closed shell has been approached in the generalized seniority scheme. Though $h_{9/2}$ is the dominant orbital near Fermi energy, the role of configuration mixing from the surrounding $f_{7/2}$ and $i_{13/2}$ orbitals is found to be very important for the consistent explanation of all the isomeric properties such as the $B(E2)$ rates, $Q-$moments and $g-$factors. The structural behavior of the closed shell $N=126$ isotonic isomers turns out to be very similar to the $N=124$ and $N=128$ isotonic isomers which have two neutron-holes and two neutron-particles, respectively. This is due to the pairing symmetries of nuclear many-body Hamiltonian. As a confirmation, the microscopic shell model occupancies are also calculated for these isomers in $N=126$ chain which support the generalized seniority results. Additional arguments using the systematics of odd-proton ${9/2}^-$ states in Tl ($Z=81$), Bi ($Z=83$), At ($Z=85$) and Fr ($Z=87$) isotopes are also presented.
The high-energy radiation from short period binaries containing a massive star with a compact relativistic companion was detected from radio to TeV gamma rays. We show here that PeV regime protons can be efficiently accelerated in the regions of collision of relativistic outflows of a compact object with stellar winds in these systems. The accelerated proton spectra in the presented Monte Carlo model have an upturn in the PeV regime and can provide very hard spectra of sub-PeV photons and neutrinos by photo-meson processes in the stellar radiation field. Recent report of a possible sub-PeV gamma-ray flare in coincidence with a high-energy neutrino can be understood in the frame of this model. The gamma-ray binaries may contribute substantially to the Galactic component of the detected high-energy neutrino flux.
Consider non-homogeneous zero-drift random walks in $\mathbb{R}^d$, $d \geq 2$, with the asymptotic increment covariance matrix $\sigma^2 (\mathbf{u})$ satisfying $\mathbf{u}^\top \sigma^2 (\mathbf{u}) \mathbf{u} = U$ and $\mathrm{tr}\ \sigma^2 (\mathbf{u}) = V$ in all in directions $\mathbf{u}\in\mathbb{S}^{d-1}$ for some positive constants $U<V$. In this paper we establish weak convergence of the radial component of the walk to a Bessel process with dimension $V/U$. This can be viewed as an extension of an invariance principle of Lamperti.
The semiclassical propagation of spin coherent states is considered in complex phase space. For two time-independent systems we find the appropriate classical trajectories and show that their combined contributions are able to describe quantum interference with great accuracy. Not only the modulus but also the phase of the quantum propagator, both dynamical and geometric terms combined, are accurately reproduced.
Galactic star clusters are known to harbour a significant amount of binary stars, yet their role in the dynamical evolution of the cluster as a whole is not comprehensively understood. We investigated the influence of binary stars on the total mass estimate for the case of the moderately populated Galactic star cluster NGC 225. The analysis of multi-epoch radial velocities of the 29 brightest cluster members, obtained over two observational campaigns, in 1990-1991 and in 2019-2020, yields a value of binary fraction of $\alpha =0.52$ (15 stars out of 29). Using theoretical isochrones and Monte Carlo simulations we found that the cluster mass increases at least 1.23 times when binaries are properly taken into account. By combining Gaia EDR3 photometric data with our spectroscopic observations, we derived estimates of NGC 225 fundamental parameters as follows: mean radial velocity $<V_r> = -9.8 \pm 0.7$ km s$^{-1}$, $\log(\tau)$=8.0-8.2 dex, distance $ D = 676 \pm 22$ pc, and colour excess $E(B-V) = 0.29 \pm 0.01$ mag.
Here we report the recovery of the binary underlying the classical nova of 11 March 1437 A.D. whose age is independently confirmed by proper motion-dating, and show that in the 20th century it exhibits dwarf nova eruptions. The four oldest recovered classical novae are now all dwarf novae. Taken together they strongly suggest that mass transfer rates decrease by an order of magnitude or more in the centuries after a classical nova event, greatly slowing the evolution, and lengthening the lifetimes of these explosive binary stars.
We present the results of a systematic search for large-scale spectroscopic variability in apparently single Wolf-Rayet stars brighter than ~12.5. In this first paper we characterize the various forms of variability detected and distinguish several separate groups. For each star in our sample, we obtained 4-5 high-resolution spectra with a signal-to-noise ratio ~100. Our ultimate goal is to identify new candidates presenting variability that potentially comes from Co-rotating Interaction Regions (CIR).   Out of a sample of 25 stars, 10 were found to display large-scale changes of which 4 are of CIR-type (WR1, WR115, WR120 and WR134). The star WR134 was already known to show such changes from previous studies. Three WN8 stars present a different type of large-scale variability and we believe deserve a group of their own. Also, all three WC9d stars in our sample present large-scale variability, but it remains to be checked if these are binaries, as many dust-making WR stars are double. Finally, of the remaining stars, 10 were found to show small-amplitude spectral changes which we attribute to normal line-profile variability due to inhomogeneities in the wind, and 5 were found to show no spectral variability, as far as can be concluded from the data in hand.   Follow-up studies are required to identify potential periods for our candidates showing CIR-type changes and eventually estimate a rotation rate for these WR stars.
We present simulations of evacuation processes using a recently introduced cellular automaton model for pedestrian dynamics. This model applies a bionics approach to describe the interaction between the pedestrians using ideas from chemotaxis. Here we study a rather simple situation, namely the evacuation from a large room with one or two doors. It is shown that the variation of the model parameters allows to describe different types of behaviour, from regular to panic. We find a non-monotonic dependence of the evacuation times on the coupling constants. These times depend on the strength of the herding behaviour, with minimal evacuation times for some intermediate values of the couplings, i.e. a proper combination of herding and use of knowledge about the shortest way to the exit.
The dynamical properties of the finite-size magnetization M in the critical region T<T_{KTB} of the planar rotor model on a L x L square lattice are analyzed by means of microcanonical simulations . The behavior of the q=0 structure factor at high frequencies is consistent with field-theoretical results, but new additional features occur at lower frequencies. The motion of M determines a region of spectral lines and the presence of a central peak, which we attribute to phase diffusion. Near T_{KTB} the diffusion constant scales with system size as D ~ L^{-1.6(3)}.
Let (\Omega,\mathcal{B},P) be a probability space, \mathcal{A} a sub-sigma-field of \mathcal{B}, and \mu a regular conditional distribution for P given \mathcal{A}. For various, classically interesting, choices of \mathcal{A} (including tail and symmetric) the following 0-1 law is proved: There is a set A_0 in \mathcal{A} such that P(A_0)=1 and \mu(\omega)(A) is 0 or 1 for all A in \mathcal{A} and \omega in A_0. Provided \mathcal{B} is countably generated (and certain regular conditional distributions exist), the result applies whatever P is.
CrSb is a layered antiferromagnet (AFM) with perpendicular magnetic anisotropy, a high N\'{e}el temperature, and large spin-orbit coupling (SOC), which makes it interesting for AFM spintronic applications. To elucidate the various mechanisms of N\'{e}el vector control, the effects of strain, band filling, and electric field on the magnetic anisotropy energy (MAE) of bulk and thin-film CrSb are determined and analysed using density functional theory. The MAE of the bulk crystal is large (1.2 meV per unit cell). Due to the significant ionic nature of the Cr-Sb bond, finite slabs are strongly affected by end termination. Truncation of the bulk crystal to a thin film with one surface terminated with Cr and the other surface terminated with Sb breaks inversion symmetry, creates a large charge dipole and average electric field across the film, and breaks spin degeneracy, such that the thin film becomes a ferrimagnet. The MAE is reduced such that its sign can be switched with realistic strain, and the large SOC gives rise to an intrinsic voltage controlled magnetic anisotropy (VCMA). A slab terminated on both faces with Cr remains a compensated AFM, but with the compensation occurring nonlocally between mirror symmetric Cr pairs. In-plane alignment of the moments is preferred, the magnitude of the MAE remains large, similar to that of the bulk, and it is relatively insensitive to filling.