High-frequency transport and zero-sound in an array of SYK quantum dots
We study an array of strongly correlated quantum dots of complex SYK type and account for the effects of quadratic terms added to the SYK Hamiltonian; both local terms and inter-dot tunneling are considered in the non-Fermi-liquid temperature range T≫TFL. Electric σ(ω,p) and thermal κ(ω,p) conductivities are calculated as functions of frequency and momentum, for arbitrary values of the particle-hole asymmetry parameter . At low-frequencies ω≪T we find the Lorentz ratio L=κ(0,0)/σ(0,0) to be non-universal and temperature-dependent. At ω≫T the conductivity σ(ω,p) contains a pole with nearly linear dispersion ω≈splnωT reminiscent of the "zero-sound", known for Fermi-liquids.
, , , Physical Review Letters 2020 Vol. 125 No. 19 P. 196602-1-196602-6
We study the Sachdev-Ye-Kitaev (SYK4) model with a weak SYK2 term of magnitude Γ beyond the simplest perturbative limit considered previously. For intermediate values of the perturbation strength, J/N≪Γ≪J/√N, fluctuations of the Schwarzian mode are suppressed, and the SYK4 mean-field solution remains valid beyond the timescale t0∼N/J up to t∗∼J/Γ2. The out-of-time-order correlation function displays at short time intervals exponential growth with maximal Lyapunov exponent 2πT, ...
Added: November 12, 2020
, JETP Letters 2022 Vol. 115 No. 5 P. 297-304
A method has been proposed to calculate the out-of-time time ordered correlator in the generalization of the Sachdev–Ye–Kitaev model with a nonzero spatial dimension. The result is applicable not only at small times, when the chaotic properties of the system are developed weakly, but also at large times of about the Erenfest time. It has ...
Added: June 24, 2022
, , SCIPOST PHYSICS 2022 Vol. 12 Article 031
We consider a non-equilibrium generalization of the mixed SYK$_4$+SYK$_2$ model and calculate the energy dissipation rate $W(\omega)$ that results due to periodic modulation of random quadratic matrix elements with a frequency $\omega$. We find that $W(\omega)$ possesses a peak at $\omega$ close to the polaron energy splitting $\omega_R$ found recently (PRL 125, 196602), demonstrating the ...
Added: June 24, 2022
, , , Physical Review B: Condensed Matter and Materials Physics 2012 Vol. 86 No. 04-5429 P. 1-6
Condensation of pairs formed by spatially separated electrons and holes in a system of two isolated graphene layers is studied beyond the mean-field approximation. Suppression of the screening of the pairing interaction at large distances, caused by the appearance of the gap, is considered self-consistently. A mutual positive feedback between the appearance of the gap ...
Added: March 14, 2013
, , Physical Review B: Condensed Matter and Materials Physics 2020 Vol. 102 Article 155411
We calculate the electrical and thermal conductivity of a two-dimensional electron gas with strong spin-orbit coupling in which the scattering is dominated by electron-electron collisions. Despite the apparent absence of Galilean invariance in the system, the two-particle scattering does not affect the electrical conductivity above the band-crossing point where both helicity bands are filled. Below the band-crossing point ...
Added: October 14, 2021
, , et al., Journal of Lightwave Technology 2004 Vol. 22 No. 4 P. 1155-1168
This paper presents a method that allows evaluating the performance of an optical fiber system where bit errors result from a complex interplay of spontaneous noise generated in optical amplifiers and birefringent disorder of the transmission fiber. We demonstrate that in the presence of temporal fluctuations of birefringence characteristics, the bit-error rate (BER) itself is ...
Added: February 23, 2017
М.: National Instruments Russia, 2017
Содержание сборника составляют доклады с результатами оригинальных исследований и технических решений, ранее не публиковавшиеся. Мы надеемся, что предлагаемый сборник окажется полезным для специалистов, работающих в различных областях науки и техники, для широкого круга преподавателей, аспирантов и студентов ВУЗов, а также для преподавателей средних школ и технических колледжей. ...
Added: May 10, 2017
Intrinsic arrested nanoscale phase separation near a topological Lifshitz transition in strongly correlated two-band metals
, , et al., Superconductor Science and Technology 2015 Vol. 28 No. 2 P. 024005-1-024005-8
The arrested nanoscale phase separation in a two-band Hubbard model for strongly correlated charge carriers is shown to occur in a particular range in the vicinity of the topological Lifshitz transition, where the Fermi energy crosses the bottom of the narrow band and a new sheet of the Fermi surface related to the charge carriers ...
Added: March 12, 2016
Estimation of Intraband and Interband Relative Coupling Constants from Temperature Dependences of the Order Parameter for Two-Gap Superconductors
, , et al., Journal of Superconductivity and Novel Magnetism 2016 Vol. 29 No. 4 P. 1111-1116
We present temperature dependences of the large and the small superconducting gaps measured directly by SnS-Andreev spectroscopy in various Fe-based superconductors and MgB2. The experimental L,S(T ) are wellfitted with a two-gap model based on Moskalenko and Suhl system of equations (supplemented with a BCS integral renormalization). From the fitting procedure, we estimate the key ...
Added: March 19, 2016
, , et al., Известия РАН. Серия физическая 2021 Т. 85 № 8 С. 1088-1094
FeCo and FeNi alloyed nanowires (NW) were obtained by the matrix synthesis method: the effect of the growth voltage and the effect of using a reference electrode were studied. It is shown that the composition of FeNi nanowires strongly depends on the growth potential (with its increase, the bcc structure is changing into fcc), and it is also ...
Added: November 12, 2021
, , et al., Optoelectronics, Instrumentation and Data Processing 2017 Vol. 54 No. 1 P. 1-8
This paper presents an algorithm for processing the transmission spectra of whisperinggallery optical microcavities for use as a nanoparticle detector. The algorithm is based on the broadening of the microcavity resonance curve during precipitation of nanoparticles on the microcavity surface. Experimental results on the detection of particles are compared with Langmuir adsorption theory. The contribution ...
Added: May 25, 2018
, , Journal of High Energy Physics 2022 No. 01 Article 43
We study regularization scheme dependence of beta-function for sigma models with two-dimensional target space. Working within four-loop approximation, we conjecture the scheme in which the beta-function retains only two tensor structures up to certain terms containing zeta_3. Using this scheme, we provide explicit solutions to RG flow equation corresponding to Yang-Baxter- and lambda-deformed SU(2)/U(1) sigma ...
Added: February 1, 2022
Unconventional superconductivity in low density electron systems and conventional superconductivity in hydrogen metallic alloys
, JETP Letters 2016 Vol. 103 No. 11 P. 728-738
In this short review, we first discuss the results, which are mainly devoted to the generalizations of the famous Kohn–Luttinger mechanism of superconductivity in purely repulsive fermion systems at low electron densities. In the context of repulsive-U Hubbard model and Shubin–Vonsovsky model we consider briefly the superconducting phase diagrams and the symmetries of the order parameter ...
Added: November 18, 2016
, Эпистемология и философия науки 2019 Т. 56 № 1 С. 169-184
The framework of simple opposition realism - anti-realism is not enough to analyze the views on the reality of unobservable objects of quantum theory. First, it is necessary to distinguish between realism in relation to the theory and realism in relation to the theory’s objects. Secondly, realism in relation to classical objects can be combined, ...
Added: February 12, 2020
, , et al., JETP Letters 2019 Vol. 110 No. 11 P. 748-749
We present results of nuclear magnetic resonance (NMR) experiments in superﬂuid 3He in two samples of nematic aerogel consisting of nearly parallel mullite strands. The samples were cut from the same piece of the aerogel, but one of them was squeezed by 30% in the direction transverse to the strands. In both samples the superﬂuid ...
Added: November 21, 2019
, Applied Mathematics 2010 Vol. 1 P. 1-7
Added: October 5, 2019
, , et al., Physical Review Special Topics - Accelerators and Beams 2012 Vol. 15 P. 053501
This paper describes the surface environment of the dense plasma arcs that damage rf accelerators, tokamaks, and other high gradient structures. We simulate the dense, nonideal plasma sheath near a metallic surface using molecular dynamics (MD) to evaluate sheaths in the non-Debye region for high density, low temperature plasmas. We use direct two-component MD simulations ...
Added: October 28, 2013
, Russian Journal of Mathematical Physics 2019 Vol. 26 No. 2 P. 168-173
The parameters of unstable short-living isotopes are studied from the mathematical point of view. The values of the chemical potential and activity parameters that determine the neutron halo arising when the neutron separates from the nucleus of an unstable isotope are calculated. The analogy between nuclear physics and economics is considered from the point of view of such parameters as ...
Added: August 25, 2019
, , , Journal of Experimental and Theoretical Physics 2011 Vol. 140 No. 2 P. 387-400
We analyze magnetic kinematic dynamo in a conducting fluid where the stationary shear flow is accompanied by relatively weak random velocity fluctuations. The diffusionless and diffusion regimes are described. The growth rates of the magnetic field moments are related to the statistical characteristics of the flow describing divergence of the Lagrangian trajectories. The magnetic field ...
Added: February 2, 2017
, Russian Journal of Physical Chemistry A 2021 Vol. 95 P. 2059-2064
Molecular dynamic models are created for properties of bivalent ions in organic solvents. It is shown that molecules of the considered solvents bound to ions via oxygen atoms. A theoretical model is developed that describes the ion coordination number. The coordination number in this model is determined by the ratio between the sizes of the ...
Added: October 14, 2021
M.: Faculty of Physics, MSU, 2017
The Low Temperature Physics Conference is an international event held every three years, under the auspices of the IUPAP through its Commission C5 on Low Temperature Physics. The aim of these conferences is to exchange information and views among the members of the international scientific community in the general field of Low Temperature Physics. It ...
Added: October 1, 2017
, Теоретическая и математическая физика 2019 Т. 201 № 1 С. 65-83
We study the process of a nucleon separating from an atomic nucleus from the mathematical standpoint using experimental values of the binding energy for the nucleus of the given substance. A nucleon becomes a boson at the instant of separating from a fermionic nucleus. We study the further transformations of boson and fermion states of separation in a ...
Added: November 1, 2019
, , Scientific Reports 2018 Vol. 8 No. 1 P. 16915-1-16915-18
Sequential state discrimination is a strategy for quantum state discrimination of a sender’s quantum states when N receivers are separately located. In this report, we propose optical designs that can perform sequential state discrimination of two coherent states. For this purpose, we consider not only binary phase-shifting-key (BPSK) signals but also general coherent states, with arbitrary prior probabilities. Since ...
Added: November 16, 2020
, , et al., Труды НГТУ им. Р.Е. Алексеева 2012 № 2(95) С. 48-65
Purpose: Numerical modeling of internal baroclinic disturbances of different shapes in a model lake with variable depth, analysis of velocity field of wave-induced current, especially in the near-bed layer. Approach: The study is carried out with the use of numerical full nonlinear nonhydrostatic model for stratified fluid. Findings: The full nonlinear numerical modeling of internal wave dynamics ...
Added: October 6, 2012