Novosibirsk State Technical University
Scientific discoveries often hinge on synthesizing decades of research, a task that potentially outstrips human information processing capacities. Large language models (LLMs) offer a solution. LLMs trained on the vast scientific literature could potentially integrate noisy yet interrelated findings to forecast novel results better than human experts. To evaluate this possibility, we created BrainBench, a forward-looking benchmark for predicting neuroscience results. We find that LLMs surpass experts in predicting experimental outcomes. BrainGPT, an LLM we tuned on the neuroscience literature, performed better yet. Like human experts, when LLMs were confident in their predictions, they were more likely to be correct, which presages a future where humans and LLMs team together to make discoveries. Our approach is not neuroscience-specific and is transferable to other knowledge-intensive endeavors.
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The LLM-PM framework introduces a training-free method for automatic query hint selection in database systems by leveraging pre-trained Large Language Model embeddings of execution plans. This approach achieved an average 21.1% total aggregate speed-up in query latency on the JOB-CEB workload with OpenGauss, primarily by optimizing the slowest queries.
We extend the scheme of neutral atom Rydberg CZC_Z gate based on double sequence of adiabatic pulses applied symmetrically to both atoms using counterdiabatic driving in the regime of Rydberg blockade. This provides substantial reducing of quantum gate operation times (at least five times) compared to previously proposed adiabatic schemes, which is important for high-fidelity entanglement due to finite Rydberg lifetimes. We analyzed schemes of adiabatic rapid passage with counterdiabatic driving for single-photon, two-photon and three-photon schemes of Rydberg excitation for rubidium and cesium atoms. We designed laser pulse profiles with fully analytical shapes and calculated the Bell fidelity taking into account atomic lifetimes and finite blockade strengths. We show that the upper limit of the Bell fidelity reaches F0.9999{\mathcal F}\simeq0.9999 in a room-temperature environment.
We show the possibility of implementing a deep dissipative optical lattice for neutral atoms with a macroscopic period. The depth of the lattice can reach magnitudes comparable to the depth of the magneto-optical traps (MOT), while the presence of dissipative friction forces allows for trapping and cooling of atoms. The area of localization of trapped atoms reaches sub-millimeter size, and the number of atoms is comparable to the number trapped in MOT. As an example, we study lithium atoms for which the macroscopic period of the lattice Λ=1.5\Lambda=1.5 cm. Such deep optical lattices with a macroscopic period open up possibility for developing effective methods for cooling and trapping neutral atoms without use of magnetic field as an alternative to MOT. This is important for developing compact systems based on cold atoms.
Academia SinicaWuhan UniversityKyungpook National UniversityChinese Academy of Sciences logoChinese Academy of SciencesBudker Institute of Nuclear Physics SB RASBeijing Normal University logoBeijing Normal UniversityUniversity of Oxford logoUniversity of OxfordFudan University logoFudan UniversityUniversity of Science and Technology of China logoUniversity of Science and Technology of ChinaShanghai Jiao Tong University logoShanghai Jiao Tong UniversityNanjing University logoNanjing UniversityZhejiang University logoZhejiang UniversityUniversity of Bristol logoUniversity of BristolNankai UniversityPeking University logoPeking UniversityJoint Institute for Nuclear ResearchXiamen UniversityNanchang UniversityHuazhong University of Science and Technology logoHuazhong University of Science and TechnologyAnhui UniversityChongqing UniversityUniversité Paris-Saclay logoUniversité Paris-SaclaySoutheast UniversityJilin UniversityCentral China Normal UniversityShandong University logoShandong UniversityNovosibirsk State UniversityYunnan UniversityInstitute for Basic ScienceLanzhou UniversitySoochow UniversityEast China Normal UniversityUniversity of South ChinaUniversity of JinanHunan UniversityNanjing Normal UniversityGuangxi UniversityCapital Normal UniversityRuhr-Universität BochumInner Mongolia UniversityZhengzhou UniversityXian Jiaotong UniversityJohannes Gutenberg University MainzGuilin University of Electronic TechnologyCNRS/IN2P3Guizhou Normal UniversityNational Research Nuclear University MEPhI (Moscow Engineering Physics Institute)Liaoning Normal UniversityUniversity of Science and Technology LiaoningNovosibirsk State Technical UniversityUniversity of La LagunaP.N. Lebedev Physical Institute of the Russian Academy of SciencesUniversity of LancasterLiaocheng UniversityInstitute for Theoretical and Experimental Physics named by A.I. Alikhanov of NRC “Kurchatov Institute”
The Super τ\tau-Charm facility (STCF) is an electron-positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×1035cm2s10.5\times 10^{35}{\rm cm}^{-2}{\rm s}^{-1} or higher. The STCF will produce a data sample about a factor of 100 larger than that by the present τ\tau-Charm factory -- the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R\&D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R\&D and physics case studies.
A precise measurement of the cross section for the process e+e- --> K+K-(gamma) from threshold to an energy of 5 GeV is obtained with the initial-state radiation (ISR) method using 232 fb^{-1} of data collected with the BaBar detector at e+e- center-of-mass energies near 10.6 GeV. The measurement uses the effective ISR luminosity determined from the e+e- --> mu+mu-(gamma)gamma_ISR process with the same data set. The corresponding lowest-order contribution to the hadronic vacuum polarization term in the muon magnetic anomaly is found to be a_mu^{KK, LO}=(22.93 +- 0.18_{stat} +- 0.22_{syst}) * 10^{-10}. The charged kaon form factor is extracted and compared to previous results. Its magnitude at large energy significantly exceeds the asymptotic QCD prediction, while the measured slope is consistent with the prediction.
We investigate the propagation of microwave photons in a one-dimensional open waveguide interacting with a number of artificial atoms (qubits). Within the formalism of projection operators and non-Hermitian Hamiltonian approach we develop a one-photon approximation scheme for the calculation of the transmission and reflection factors of the microwave signal in a waveguide which contains an arbitrary number \emph{N} of non-interacting qubits. We considered in detail the resonances and photon mediated entanglement for two and three qubits in a chain. We showed that in non Markovian case the resonance widths, which define the decay rates of the entangled state, can be much smaller than the decay width of individual qubit. It is also shown that for identical qubits in the long wavelength limit a coherent superradiant state is formed with the width being equal to the sum of the widths of spontaneous transitions of \emph{N} individual qubits. The results obtained in the paper are of general nature and can be applied to any type of qubits. The specific properties of the qubit are only encoded in the two parameters: the qubit energy Ω\Omega and the rate of spontaneous emission Γ\Gamma.
In this paper a new scalable hydrodynamic code GPUPEGAS (GPU-accelerated PErformance Gas Astrophysic Simulation) for simulation of interacting galaxies is proposed. The code is based on combination of Godunov method as well as on the original implementation of FlIC method, specially adapted for GPU-implementation. Fast Fourier Transform is used for Poisson equation solution in GPUPEGAS. Software implementation of the above methods was tested on classical gas dynamics problems, new Aksenov's test and classical gravitational gas dynamics problems. Collisionless hydrodynamic approach was used for modelling of stars and dark matter. The scalability of GPUPEGAS computational accelerators is shown.
The ground-state Hanle effect (GSHE) in alkali-metal atomic vapors using a single circularly polarized wave underlies one of the most robust and simplest techniques in atomic magnetometry. This effect causes a narrow (subnatural-width) resonance in the light wave intensity transmitted through a vapor cell. Usually, GSHE-based sensors operate in the spin-exchange-relaxation-free (SERF) regime. However, this regime requires a relatively high temperature of vapors (150 C or higher), leading to a relatively large heat release and power consumption of the sensor head. Besides, without applying special measures, SERF regime significantly limits a dynamic range of measurements. Here, we study a pump-probe scheme involving a single elliptically polarized wave and a polarimetric detection technique. The wave is in resonance with two adjacent optical transitions in the cesium D1 line (894.6 nm) owing to their overlapping in presence of a buffer gas (Ne, 130 Torr). Using a small (0.1 cm3^3) glass vapor cell, we demonstrate a possibility of observing subnatural-width resonances with a high contrast-to-width ratio (up to 45 %/mG) under a low-temperature (60 C) regime of operation thanks to a strong light-induced circular dichroism. Basing on a Λ\Lambda scheme of atomic energy levels, we obtain explicit analytical expressions for the line shape. The model reveals a linewidth narrowing effect due to openness of the scheme. This result is unusual for magneto-optical atomic spectroscopy because the openness is commonly considered as a undesirable effect, degrading the resonance characteristics. We estimate a sensitivity of 1.8 pT/\surdHz with a 60 fT/\surdHz sensitivity in the photon-shot-noise limit. The results contribute to the theory of GSHE resonances and can be applied to development of a low-temperature high-sensitivity miniaturized magnetic field sensor with an extended dynamic range.
Volumetric modification of glass materials by ultrashort laser pulses is a powerful technique enabling direct writing of three-dimensional structures for fabrication of optical, photonic, and microfluidic devices. The level of modification is determined by the locally absorbed energy density, which depends on numerous factors. In this work, the effect of the spatial pulse shape on the ultrashort laser excitation of fused silica was investigated experimentally and theoretically for the volumetric modification regimes. We focused on two shapes of laser pulses, Gaussian and doughnut-shaped (DS) ones. It was found that, at relatively low pulse energies, in the range of 1-5 microjoules, the DS pulses are more efficient in volumetric structural changes than Gaussian pulses. It is explained by the intensity clamping effect for the Gaussian pulses, which leads to the delocalization of the laser energy absorption. In the DS case, this effect is overcome due to the geometry of the focused beam propagation, accompanied by the electron plasma formation, which scatters light toward the beam axis. The thermoelastoplastic modeling performed for the DS pulses revealed intriguing dynamics of the shock waves generated because of tubular-like energy absorption. It is anticipated that such a double shock wave structure can induce the formation of high-pressure polymorphs of transparent materials that can be used for investigations of nonequilibrium thermodynamics of warm dense matter. The DS laser pulses of low energies of the order of 100 nanojoules which generate a gentle tubular-like modification can be perspective for a miniature waveguide writing in glass.
The search for photocathode materials with low mean transverse energies (MTEs) and, hence, low intrinsic emittance is of crucial importance for various fields of particle and solid state physics. Here, we demonstrate that polycrystalline multialkali Na2_{2}KSb(Cs,Sb) photocathodes with negative effective electron affinity (NEA) have MTE values at room temperature by a factor of 2 lower than those of monocrystalline \textit{p}-GaAs(Cs,O) photocathodes. These low MTE values are due to the electron refraction on the jump in mass, between a small effective mass in Na2_{2}KSb and free electron mass in vacuum. It is proved that, at the NEA state, up to half of photoelectrons are emitted in a narrow-angle cone with the fractional MTE of 9\,meV at room temperature. We also showed that the transition from NEA to positive effective affinity results in the subthermal total MTE of the Na2_{2}KSb(Cs,Sb) photocathode, along with quantum efficiency of about 102^{-2}. The physical reasons for the manifestation of the refraction effect in multialkali photocathodes are discussed, opening up opportunities for the development of high-brightness and ultracold robust electron sources.
We propose a concept of a superconducting photodiode - a device that transforms the energy and `spin' of an external electromagnetic field into the rectified steady-state supercurrent and develop a microscopic theory describing its properties. For this, we consider a two-dimensional thin film cooled down below the temperature of superconducting transition with the injected dc supercurrent and exposed to an external electromagnetic field with a frequency smaller than the superconducting gap. As a result, we predict the emergence of a photoexcited quasiparticle current, and, as a consequence, oppositely oriented stationary flow of Cooper pairs. The strength and direction of this photoinduced supercurrent depend on (i) such material properties as the effective impurity scattering time and the nonequilibrium quasiparticles' energy relaxation time and (ii) such electromagnetic field properties as its frequency and polarization.
We study the influence of a strong off-resonant driving signal to the energy levels of a superconducting flux qubit both experimentally and theoretically. In the experiment, we carry out a three-tone spectroscopy. This allows us to directly observe the modification of the qubit's energy levels by the dynamical Stark shift caused by the driving signal. A theoretical treatment including corrections from both, rotating and counter-rotating frame, allowed us to completely explain the observed experimental results and to reconstruct the influence of the strong driving to the dissipative dynamics as well as to the coupling constants of the qubit. As one potential application, the tunability of the minimal energy-level splitting of a superconducting qubit by a microwave induced dynamical Stark shift can help to overcome the parameter spread induced by the micro fabrication of superconducting artificial quantum circuits.
For the isotope 229^{229}Th we investigate the possibility of two-photon laser spectroscopy of the nuclear clock transition (148.38 nm) using intense monochromatic laser field at twice the wavelength (296.76 nm). Our estimates show that due to the electron bridge process in the doubly ionized ion 229^{229}Th2+^{2+} the sufficient intensity of a continuous laser field is about 10-100 kW/cm2^2, which is within the reach of modern laser systems. This unique possibility is an result of the presence in the electronic spectrum of the ion 229^{229}Th2+^{2+} of an exceptionally close intermediate (for the two-photon transition) energy level, forming a strong dipole (E1E1) transition with the ground state at the wavelength of 297.86 nm, which differs from the probe field wavelength (296.76 nm) by only 1.1 nm. The obtained results can be used for the practical creation of ultra-precise nuclear optical clocks based on thorium-229 ions. In addition, we develop an alternative approach to the description of the electron bridge phenomenon in an isolated ion (atom) using the hyperfine interaction operator, that is important for the general quantum theory of an atom. In particular, this approach shows that the contribution to the electron bridge from the nuclear quadrupole moment can be comparable to the contribution from the nuclear magnetic moment.
The MEG experiment, designed to search for the mu+->e+ gamma decay at a 10^-13 sensitivity level, completed data taking in 2013. In order to increase the sensitivity reach of the experiment by an order of magnitude to the level of 6 x 10-14 for the branching ratio, a total upgrade, involving substantial changes to the experiment, has been undertaken, known as MEG II. We present both the motivation for the upgrade and a detailed overview of the design of the experiment and of the expected detector performance.
We analyze a photon transport through an 1D open waveguide side coupled to the NN-photon microwave cavity with embedded artificial two- level atom (qubit). The qubit state is probed by a weak signal at the fundamental frequency of the waveguide. Within the formalism of projection operators and non-Hermitian Hamiltonian approach we develop a one-photon approximation scheme to obtain the photon wavefunction which allows for the calculation of the probability amplitudes of the spontaneous transitions between the levels of two Rabi doublets in NN- photon cavity. We obtain analytic expressions for the transmission and reflection factors of the microwave signal through a waveguide, which contain the information of the qubit parameters. We show that for small number of cavity photons the Mollow spectrum consists of four spectral lines which is a direct manifestation of quantum nature of light. The results obtained in the paper are of general nature and can be applied to any type of qubits. The specific properties of the qubit are only encoded in the two parameters: the energy Ω\Omega of the qubit and its coupling λ\lambda to the cavity photons.
Efficient and biologically safe mode of cold atmospheric plasma jet (CAPJ) is crucial for the development of CAPJ-based anticancer therapy. In the experiment and numerical simulations, by changing the pulse duration of a positive-pulsed voltage, we found the optimal CAPJ mode with regular streamer propagation. CAPJ regimes with a maximum discharge current at a temperature T<42 C substantially suppressed the viability of cancer cells. To enhance cell killing, gold nanoparticles (NPs) were added to the cells before and after the CAPJ exposure. Combination of CAPJ, generated with positive pulsed voltage, and gold nanoparticles decreased viability of NCI-H23 epithelial-like lung adenocarcinoma, A549 lung adenocarcinoma, BrCCh4e-134 breast adenocarcinoma and uMel1 uveal melanoma cells. Polyethylene glycol-modified nanoparticles with attached fluorescent label were used to visualize the uptake of NPs. We demonstrated that NPs efficiently entered the cells when were added to the cells just before CAPJ exposure or up to two hours afterwards. The efficiency ofNPs penetration into cells positively correlated with the induced cytotoxic effect: it was maximal when NPs was added to cells right before or immediately after CAPJ exposure. Summarizing, the treatment with optimal CAPJ modes in combination with modified NPs, bearing the cancer-addressed molecules and therapeutics may be next strategy of strengthening the CAPJ-based antitumor approaches.
The final results of the search for the lepton flavour violating decay μ+e+γ\mu^{+} \rightarrow {\rm e^{+}} \gamma based on the full dataset collected by the MEG experiment at the Paul Scherrer Institut in the period 2009--2013 and totalling 7.5×10147.5\times 10^{14} stopped muons on target are presented. No significant excess of events is observed in the dataset with respect to the expected background and a new upper limit on the branching ratio of this decay of BR( \mu^{+} \rightarrow {\rm e^{+}} \gamma ) &lt; 4.2 \times 10^{-13} (90\%\ confidence level) is established, which represents the most stringent limit on the existence of this decay to date.
The problem of deep laser cooling of 24^{24}Mg atoms is theoretically studied. We propose two-stage sub-Doppler cooling strategy using electro-dipole transition 33P23^3P_2\to33D33^3D_3 (λ\lambda=383.9 nm). The first stage implies exploiting magneto-optical trap with σ+\sigma^+ and σ\sigma^- light beams, while the second one uses a lin\perplin molasses. We focus on achieving large number of ultracold atoms (Teff_{eff} < 10 μ\muK) in a cold atomic cloud. The calculations have been done out of many widely used approximations and based on quantum treatment with taking full account of recoil effect. Steady-state average kinetic energies and linear momentum distributions of cold atoms are analysed for various light-field intensities and frequency detunings. The results of conducted quantum analysis have revealed noticeable differences from results of semiclassical approach based on the Fokker-Planck equation. At certain conditions the second cooling stage can provide sufficiently lower kinetic energies of atomic cloud as well as increased fraction of ultracold atoms than the first one. We hope that the obtained results can assist overcoming current experimental problems in deep cooling of 24^{24}Mg atoms by means of laser fields. Cold magnesium atoms, being cooled in large number down to several microkelvins, have certain interest, for example, in quantum metrology.
In this article, we consider two dynamical systems: the McMillan sextupole and octupole integrable mappings, originally proposed by Edwin McMillan. Both represent the simplest symmetric McMillan maps, characterized by a single intrinsic parameter. While these systems find numerous applications across various domains of mathematics and physics, some of their dynamical properties remain unexplored. We aim to bridge this gap by providing a comprehensive description of all stable trajectories, including the parametrization of invariant curves, Poincar\'e rotation numbers, and canonical action-angle variables. In the second part, we establish connections between these maps and general chaotic maps in standard form. Our investigation reveals that the McMillan sextupole and octupole serve as first-order approximations of the dynamics around the fixed point, akin to the linear map and quadratic invariant (known as the Courant-Snyder invariant in accelerator physics), which represents zeroth-order approximations (referred to as linearization). Furthermore, we propose a novel formalism for nonlinear Twiss parameters, which accounts for the dependence of rotation number on amplitude. This stands in contrast to conventional betatron phase advance used in accelerator physics, which remains independent of amplitude. Notably, in the context of accelerator physics, this new formalism demonstrates its capability in predicting dynamical aperture around low-order resonances for flat beams, a critical aspect in beam injection/extraction scenarios.
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