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D. V. Khveshchenko

Publications and source records attributed to D. V. Khveshchenko.

At least 37 records · Page 2Linked to original sources
arXiv2013

Simulating holographic correspondence in flexible graphene

In the spirit of the generalized holographic conjecture, we explore a relationship between the bulk and boundary properties of non-interacting massive Dirac fermions living on a flexible surface, such as a sheet of graphene. We demonstrate that the boundary correlations can mimic those normally found in the system of one-dimensional interacting fermions, a specific form of such phantom interaction being determined by the bulk geometry. This geometrical interpretation of the boundary interaction effects offers a new insight into the possible origin of the more sophisticated types of holographic correspondence and suggests potential ways of visualizing 'analogue holography' in the experimentally viable environments.

cond-mat.str-el↗
arXiv2012

Searching for non-Fermi liquids under holographic light

This discussion is aimed at identifying physically relevant, albeit lying off the beaten track, gravity models that may provide a holographic description of some prototypical non-Fermi liquid states of strongly correlated condensed matter systems.

cond-mat.str-el↗
arXiv2011

Arrays of Josephson junctions between unconventional superconductors

We study large arrays of mesoscopic junctions between gapless superconductors where the tunneling processes of both, particle-hole and Cooper, pairs give rise to a strongly retarded effective action which, contrary to the standard case, can not be readily characterized in terms of a local Josephson energy. This complexity is expected to arise in, e.g., the grain boundary and c-axis junctions in layered high-T_c superconductors. A new representation for describing collective phenomena in this system is introduced, and its phase diagram is discussed, alongside the electrical conductivity.

cond-mat.supr-con↗
arXiv2008

Massive Dirac fermions in single-layer graphene

Motivated by the results of recent photoemission and tunneling studies, we discuss potential many-body sources of a finite gap in the Dirac fermion spectrum of graphene. Specifically, we focus on the putative Peierls- and Cooper-like pairing instabilities which can be driven by sufficiently strong Coulomb and electron-phonon interactions, respectively. Our results compare favorably with the available experimental and Monte Carlo data.

cond-mat.str-el↗
arXiv2007

Entanglement propagation through spin chains in the presence of a staggered magnetic field

We study the dynamics of entanglement in the XY spin chain subject to a staggered magnetic field and contrast it to the previously studied uniform field case. We find that, depending on parameter values, a staggered field can provide better conditions for a perfect entanglement transfer, while even a modest amount of exchange anisotropy appears to have a strong detrimental effect. We also study interactions between different waves of entanglement and assess the possibility of simultaneous transmission of multiple bits of quantum information.

cond-mat.str-el↗
arXiv2007

Inelastic scattering rates in d-wave superconductors

The inelastic scattering rates of quasiparticles in a two-dimensional d-wave superconductor, which arise from interactions with either acoustic phonons or other quasiparticles, are calculated within second order perturbation theory. We discover a strong enhancement of scattering with collinear momenta, brouth about by the special kinematics of the two-dimensional fermions with Dirac-like spectrum near the nodes of the d-wave order parameter. In the case of a local instantaneous interparticle potential we find that either an RPA-type resummation of the perturbation series or an inclusion of non-linear corrections to the Dirac spectrum is called for in order to obtain a finite scattering rate in the limit $ω/T\to 0$. In either way, we find drastic changes in the scattering rate, as compared to the naively expected cubic temperature dependence.

cond-mat.str-el↗
arXiv2007

Dirac fermions in a power-law-correlated random vector potential

We study localization properties of two-dimensional Dirac fermions subject to a power-law-correlated random vector potential describing, e.g., the effect of "ripples" in graphene. By using a variety of techniques (low-order perturbation theory, self-consistent Born approximation, replicas, and supersymmetry) we make a case for a possible complete localization of all the electronic states and compute the density of states.

cond-mat.mes-hall↗
arXiv2006

Long-range-correlated disorder in graphene

We study transport of two-dimensional quasi-relativistic electronic excitations in graphene in the presence of static long-range-correlated random scalar and vector potentials. Using a combination of perturbation theory and path-integral techniques, we estimate scattering rates which control Drude conductivity, magneto-transport, and Friedel oscillations in the ballistic regime of large quasiparticle energies. We also discuss properties of zero-energy states and pertinent localization scenarios.

cond-mat.mes-hall↗
arXiv2006

Coulomb interacting Dirac fermions in disordered graphene

We study interacting Dirac quasiparticles in disordered graphene and find that an interplay between the unscreened Coulomb interactions and pseudo-relativistic quasiparticle kinematics can be best revealed in the ballistic regime, whereas in the diffusive limit the behavior is qualitatively (albeit, not quantitatively) similar to that of the ordinary 2DEG with parabolic dispersion. We calculate the quasiparticle width and density of states that can be probed by photoemission, tunneling, and magnetization measurements.

cond-mat.mes-hall↗
arXiv2006

Composite Dirac fermions in graphene

Generalizing the notion of composite fermions to the "pseudo-relativistic" Quantum Hall phenomena in graphene, we discuss a possible emergence of compressible states at the filling factors -3/2, -1/2, 1/2, 3/2. This analysis is further extended to the nearby incompressible states viewed as the Integer Quantum Hall Effect of the composite Dirac fermions, as well as those that might occur at the filling factors -1, 0, 1 as a result of the (pseudo)spin-singlet pairing between them.

cond-mat.mes-hall↗
arXiv2006

The effect of Fermi surface curvature on low-energy properties of fermions with singular interactions

We discuss the effect of Fermi surface curvature on long-distance/time asymptotic behaviors of two-dimensional fermions interacting via a gapless mode described by an effective gauge field-like propagator. By comparing the predictions based on the idea of multi-dimensional bosonization with those of the strong- coupling Eliashberg approach, we demonstrate that an agreement between the two requires a further extension of the former technique.

cond-mat.str-el↗
arXiv2006

Excitonic pairing between nodal fermions

We study excitonic pairing in nodal fermion systems characterized by a vanishing quasiparticle density of states at the pointlike Fermi surface and a concomitant lack of screening for long-range interactions. By solving the gap equation for the excitonic order parameter, we obtain a critical value of the interaction strength for a variety of power-law interactions and densities of states. We compute the free energy and analyze possible phase transitions, thus shedding further light on the unusual pairing properties of this peculiar class of strongly correlated systems.

cond-mat.str-el↗
arXiv2006

On electron (anti)localization in graphene

We discuss localization properties of the Dirac-like electronic states in monolayers of graphite. In the framework of a general disorder model, we identify the conditions under which such standard localization effects as logarithmic temperature-dependent conductivity corrections appear to be strongly suppressed, as compared to the case of a two-dimensional electron gas with parabolic dispersion, in agreement with recent experimental observations.

cond-mat.mes-hall↗
arXiv2006

Dissipative phase transition in two-dimensional d-wave Josephson junctions

Quantum dynamics of in-plane Josephson junctions between two d-wave superconducting films is described by the anisotropic XY-model where both, quasiparticle and Cooper pair tunneling terms, appear to be equally non-local. Applying a combination of the weak and strong coupling analyses to this model, we find a compelling evidence of a dissipative phase transition. The corresponding critical behavior is studied and contrasted with that found previously in the conventional (s-wave) Josephson junctions.

cond-mat.other↗
arXiv2004

Robust two-qubit quantum registers

We carry out a systematic analysis of a pair of coupled qubits, each of which is subject to its own dissipative environment, and argue that a combination of the inter-qubit couplings which provides for the lowest possible decoherence rates corresponds to the incidence of a double spectral degeneracy in the two-qubit system. We support this general argument by the results of of an evolutionary genetic algorithm which can also be used for optimizing time-dependent processes (gates) and their sequences that implement various quantum computing protocols.

cond-mat.str-el↗
arXiv2004

Optimized design of universal two-qubit gates

We construct optimized implementations of the CNOT and other universal two-qubit gates that, unlike many of the previously proposed protocols, are carried out in a single step. The new protocols require tunable inter-qubit couplings but, in return, show a significant improvements in the quality of gate operations. Our optimization procedure can be further extended to the combinations of elementary two-qubit as well as irreducible many-qubit gates.

quant-ph↗
arXiv2004

Quantum impurity models of noisy qubits

We demonstrate that the problem of coupled two-level systems ("qubits") which are also subject to a generic (sub)Ohmic dissipative environment belongs to the same class of models as those describing (non)magnetic impurities embedded in strongly correlated systems. A further insight into the generalized single- and two-impurity Bose/Fermi Kondo models enables one to make specific recommendations towards a systematic engineering of highly coherent multi-qubit assemblies for potential applications in quantum information processing.

cond-mat.str-el↗