arXiv subjects

Vadim V. Cheianov

Publications and source records attributed to Vadim V. Cheianov.

At least 19 recordsLinked to original sources

arXiv2018

The impact of the injection protocol on an impurity's stationary state

We examine stationary state properties of an impurity particle injected into a one-dimensional quantum gas. We show that the value of the impurity's end velocity lies between zero and the speed of sound in the gas, and is determined by the injection protocol. This way, the impurity's constant motion is a dynamically emergent phenomenon whose description goes beyond accounting for the kinematic constraints of Landau approach to superfluidity. We provide exact analytic results in the thermodynamic limit, and perform finite-size numerical simulations to demonstrate that the predicted phenomena are within the reach of the existing ultracold gases experiments.

cond-mat.quant-gas↗

arXiv2017

Two-terminal transport along a proximity induced superconducting quantum Hall edge

We study electric transport along an integer quantum Hall edge where the proximity effect is induced due to a coupling to a superconductor. Such an edge exhibits two Majorana-Weyl fermions with different group velocities set by the induced superconducting pairing. We show that this structure of the spectrum results in interference fringes that can be observed in both the two-terminal conductance and shot noise. We develop a complete analytical theory of such fringes for an arbitrary smooth profile of the induced pairing.

cond-mat.mes-hall↗

arXiv2013

Counting free fermions on a line: a Fisher-Hartwig asymptotic expansion for the Toeplitz determinant in the double-scaling limit

We derive an asymptotic expansion for a Wiener-Hopf determinant arising in the problem of counting one-dimensional free fermions on a line segment at zero temperature. This expansion is an extension of the result in the theory of Toeplitz and Wiener-Hopf determinants known as the generalized Fisher-Hartwig conjecture. The coefficients of this expansion are conjectured to obey certain periodicity relations, which renders the expansion explicitly periodic in the "counting parameter". We present two methods to calculate these coefficients and verify the periodicity relations order by order: the matrix Riemann-Hilbert problem and the Painleve V equation. We show that the expansion coefficients are polynomials in the counting parameter and list explicitly first several coefficients.

cond-mat.str-el↗

arXiv2012

Phase transitions in dipolar gases in optical lattices

We investigate the phase diagrams of two-dimensional lattice dipole systems with variable geometry. For bipartite square and triangular lattices with tunable vertical sublattice separation, we find rich phase diagrams featuring a sequence of easy-plane magnetically ordered phases separated by incommensurate spin-wave states.

cond-mat.quant-gas↗

arXiv2009

Ordered states of adatoms on graphene

We show that a dilute ensemble of epoxy-bonded adatoms on graphene has a tendency to form a spatially correlated state accompanied by a gap in graphene's electron spectrum. This effect emerges from the electron-mediated interaction between adatoms with a peculiar $1/r^3$ distance dependence. The partial ordering transition is described by a random bond three state Potts model.

cond-mat.mtrl-sci↗

arXiv2008

Resonant dephasing in the electronic Mach-Zehnder interferometer

We address the recently-observed unexpected behavior of Aharonov-Bohm oscillations in the electronic Mach-Zehnder interferometer that was realized experimentally in a quantum Hall system [1]. We argue that the measured lobe structure in the visibility of oscillations and the phase rigidity result from a strong long-range interaction between two adjacent counter-propagating edge states, which leads to a resonant scattering of plasmons. The visibility and phase shift, which we expressed in terms of the transmission coefficient for plasmons, can be used for the tomography of edge states.

cond-mat.mes-hall↗

arXiv2007

Veselago Lens for Electrons: Focusing and Caustics in Graphene p-n Junctions

The focusing of electric current by a single \textit{p-n} junction in graphene is predicted. We show that precise focusing can be achieved by fine-tuning the densities of carriers on the n- and p-sides of the junction to equal values, whereas the current distribution in junctions with different densities resembles caustics in optics. This finding can be utilized in the engineering of electronic lenses and focused beam-splitters using gate-controlled \textit{n-p-n} junctions in graphene-based transistors.

cond-mat.mes-hall↗

arXiv2006

Friedel oscillations, impurity scattering and temperature dependence of resistivity in graphene

We show that Friedel oscillations (FO) in grapehene are strongly affected by the chirality of electrons in this material. In particular, the FO of the charge density around an impurity show a faster, $1/r^3$, decay than in conventional 2D electron systems and do not contribute to a linear temperature-dependent correction to the resistivity. In contrast, the FO of the exchange field which surrounds atomically sharp defects breaking the hexagonal symmetry of the honeycomb lattice lead to a negative linear T dependence of the resistivity.

cond-mat.mes-hall↗

arXiv2006

Selective transmission of Dirac electrons and ballistic magnetoresistance of \textit{n-p} junctions in graphene

We show that an electrostatically created n-p junction separating the electron and hole gas regions in a graphene monolayer transmits only those quasiparticles that approach it almost perpendicularly to the n-p interface. Such a selective transmission of carriers by a single n-p junction would manifest itself in non-local magnetoresistance effect in arrays of such junctions and determines the unusual Fano factor in the current noise universal for the n-p junctions in graphene.

cond-mat.mes-hall↗

arXiv2006

Three-body local correlation function in the Lieb-Liniger model: bosonization approach

We develop a method for the calculation of vacuum expectation values of local operators in the Lieb-Liniger model. This method is based on a set of new identities obtained using integrability and effective theory (``bosonization'') description. We use this method to get an explicit expression for the three-body local correlation function, measured in a recent experiment [1].

cond-mat.other↗

arXiv2005

Exact Results for Three-Body Correlations in a Degenerate One-Dimensional Bose Gas

Motivated by recent experiments we derive an exact expression for the correlation function entering the three-body recombination rate for a one-dimensional gas of interacting bosons. The answer, given in terms of two thermodynamic parameters of the Lieb-Liniger model, is valid for all values of the dimensionless coupling $γ$ and contains the previously known results for the Bogoliubov and Tonks-Girardeau regimes as limiting cases. We also investigate finite-size effects by calculating the correlation function for small systems of 3, 4, 5 and 6 particles.

cond-mat.other↗

arXiv2004

Fermions in the harmonic potential and string theory

We explicitly derive collective field theory description for the system of fermions in the harmonic potential. This field theory appears to be a coupled system of free scalar and (modified) Liouville field. This theory should be considered as an exact bosonization of the system of non-relativistic fermions in the harmonic potential. Being surprisingly similar to the world-sheet formulation of c=1 string theory, this theory has quite different physical features and it is conjectured to give space-time description of the string theory, dual to the fermions in the harmonic potential. A vertex operator in this theory is shown to be a field theoretical representation of the local fermion operator, thus describing a D0 brane in the string language. Possible generalization of this result and its derivation for the case of c=1 string theory (fermions in the inverse harmonic potential) is discussed.

hep-th↗

arXiv2004

Non-Markovian Effects on the Two-Dimensional Magnetotransport: Low-field Anomaly in Magnetoresistance

We discuss classical magnetotransport in a two-dimensional system with strong scatterers. Even in the limit of very low field, when $ω_c τ\ll 1$ ($ω_c$ is the cyclotron frequency, $τ$ is the scattering time) such a system demonstrates strong negative magnetoresistance caused by non-Markovian memory effects. A regular method for the calculation of non-Markovian corrections to the Drude conductivity is presented. A quantitative theory of the recently discovered anomalous low-field magnetoresistance is developed for the system of two-dimensional electrons scattered by hard disks of radius $a,$ randomly distributed with concentration $n.$ For small magnetic fields the magentoresistance is found to be parabolic and inversely proportional to the gas parameter, $ δρ_{xx}/ρ\sim - (ω_c τ)^2 / n a^2.$ In some interval of magnetic fields the magnetoresistance is shown to be linear $δρ_{xx}/ρ\sim - ω_c τ$ in a good agreement with the experiment and numerical simulations. Magnetoresistance saturates for $ω_c τ\gg na^2$, when the anomalous memory effects are totally destroyed by the magnetic field. We also discuss magnetotransport at very low fields and show that at such fields magnetoresistance is determined by the trajectories having a long Lyapunov region.

cond-mat.mes-hall↗

arXiv2004

Low-temperature crossover in the momentum distribution of cold atomic gases in one dimension

The momentum distribution function for the two-component 1D gases of bosons and fermions is studied in the limit of strong interatomic repulsion. A pronounced reconstruction of the distribution is found at a temperature much smaller than the Fermi temperature. This new temperature scale, which equals the Fermi temperature divided by the dimensionless coupling strength, is a feature of the two-component model and does not exist in the one-component case. We estimate the parameters relevant for the experimental observation of the crossover effect.

cond-mat.other↗

arXiv2004

Microscopic construction of the chiral Luttinger liquid theory of the quantum Hall edge

We give a microscopic derivation of the chiral Luttinger liquid theory for the Laughlin states. Starting from the wave function describing an arbitrary incompressibly deformed Laughlin state (IDLS) we quantize these deformations. In this way we obtain the low-energy projections of local microscopic operators and derive the quantum field theory of edge excitations directly from quantum mechanics of electrons. This shows that to describe experimental and numeric deviations from chiral Luttinger liquid theory one needs to go beyond Laughlin's approximation. We show that in the large N limit the IDLS is described by the dispersionless Toda hierarchy.

cond-mat.mes-hall↗

arXiv2003

One-particle irreducible density matrix for the spin disordered infinite $U$ Hubbard chain

In this Letter we present a calculation of the one-particle irreducible density matrix $ρ(x)$ for the one-dimensional (1D) Hubbard model in the infinite $U$ limit. We consider the zero temperature spin disordered regime, which is obtained by first taking the limit $U\to \infty$ and then the limit $T\to 0.$ Using the determinant representation for $ρ(x)$ we derive analytical expressions for both large and small $x$ at an arbitrary filling factor $0<\varrho<1/2.$ The large $x$ asymptotics of $ρ(x)$ is found to be remarkably accurate starting from $x\sin(2π\varrho)\sim 1.$ We find that the one-particle momentum distribution function $ρ(k)$ is a smooth function of $k$ peaked at $k=2k_F,$ thus violating the Luttinger theorem.

cond-mat.str-el↗

arXiv2003

Anomalous Negative Magnetoresistance Caused by Non-Markovian Effects

A theory of recently discovered anomalous low-field magnetoresistance is developed for the system of two-dimensional electrons scattered by hard disks of radius $a,$ randomly distributed with concentration $n.$ For small magnetic fields the magentoresistance is found to be parabolic and inversely proportional to the gas parameter, $ δρ_{xx}/ρ\sim - (ω_c τ)^2 / n a^2.$ With increasing field the magnetoresistance becomes linear $δρ_{xx}/ρ\sim - ω_c τ$ in a good agreement with the experiment and numerical simulations.

cond-mat.mes-hall↗

arXiv2003

Non-Unitary Spin-Charge Separation in One-Dimensional Fermion Gas

In this Letter we report exact results on the infrared asymptotics of one-particle dynamical correlation function of the gas of impenetrable spin 1/2 fermions at infinitesimal temperature. The correlation function shows signs of spin-charge separation with scaling behavior in the charge part and exponential decay as a function of the space coordinate in the spin part. Surprisingly, the anomalous dimensions in the charge part do not correspond to any unitary conformal field theory. We find that the fermion spectral weight has a power law divergency at low energy with the anomalous exponent $-1/2.$

cond-mat.str-el↗