arXiv subjects

Dmitri Averin

Publications and source records attributed to Dmitri Averin.

6 recordsLinked to original sources

arXiv2025

Localizing Individual Exciton on a Quantum Hall Antidot

Quantum Hall systems host quasiparticles demonstrating correlated electron physics and non-trivial quantum statistics. Excitonic phases, archetypical for interaction effect, have attracted significant interest in recent years in double-layer quantum Hall systems where spatially separated electrons and holes form bosonic condensate through Coulomb interaction. Here, employing the approach of quantum Hall antidot with two spatially separated edge channels, we demonstrate a new type of quantum Hall quasiparticle exciton which represents a quantum-coherent bound state of an electron and a hole situated on their corresponding edges coupled through intralayer tunneling and Coulomb interaction. Quantum-coherent dynamics of the exciton is reflected in the observed evolution of the position and magnitude of the antidot conductance peaks around the electron-hole resonance. The quantum Hall antidot setup allows localization and electrical tuning of individual quantum Hall excitons. Quantum superposition of vacuum- and electron-hole pairing states is observed through the gate-dependent tunneling conductance of the antidot. Modeling the electron-hole pair as a coupled two-level system, semi-quantitative understanding of experimental observations is achieved. This work opens avenues for creating quantum systems of multiple quantum Hall quasiparticles.

cond-mat.mes-hall↗

arXiv2019

Dirac Fermion Quantum Hall Antidot in Graphene

The ability to localize and manipulate individual quasiparticles in mesoscopic structures is critical in experimental studies of quantum mechanics and thermodynamics, and in potential quantum information devices, e.g., for topological schemes of quantum computation. In strong magnetic field, the quantum Hall edge modes can be confined around the circumference of a small antidot, forming discrete energy levels that have a unique ability to localize fractionally charged quasiparticles. Here, we demonstrate a Dirac fermion quantum Hall antidot in graphene in the integer quantum Hall regime, where charge transport characteristics can be adjusted through the coupling strength between the contacts and the antidot, from Coulomb blockade dominated tunneling under weak coupling to the effectively non-interacting resonant tunneling under strong coupling. Both regimes are characterized by single -flux and -charge oscillations in conductance persisting up to temperatures over 2 orders of magnitude higher than previous reports in other material systems. Such graphene quantum Hall antidots may serve as a promising platform for building and studying novel quantum circuits for quantum simulation and computation.

cond-mat.mes-hall↗

arXiv2017

Nanoscale superconducting memory based on the kinetic inductance of asymmetric nanowire loops

The demand for low-dissipation nanoscale memory devices is as strong as ever. As Moore's Law is staggering, and the demand for a low-power-consuming supercomputer is high, the goal of making information processing circuits out of superconductors is one of the central goals of modern technology and physics. So far, digital superconducting circuits could not demonstrate their immense potential. One important reason for this is that a dense superconducting memory technology is not yet available. Miniaturization of traditional superconducting quantum interference devices is difficult below a few micrometers because their operation relies on the geometric inductance of the superconducting loop. Magnetic memories do allow nanometer-scale miniaturization, but they are not purely superconducting (Baek et al 2014 Nat. Commun. 5 3888). Our approach is to make nanometer scale memory cells based on the kinetic inductance (and not geometric inductance) of superconducting nanowire loops, which have already shown many fascinating properties (Aprili 2006 Nat. Nanotechnol. 1 15; Hopkins et al 2005 Science 308 1762). This allows much smaller devices and naturally eliminates magnetic-field cross-talk. We demonstrate that the vorticity, i.e., the winding number of the order parameter, of a closed superconducting loop can be used for realizing a nanoscale nonvolatile memory device. We demonstrate how to alter the vorticity in a controlled fashion by applying calibrated current pulses. A reliable read-out of the memory is also demonstrated. We present arguments that such memory can be developed to operate without energy dissipation.

cond-mat.supr-con↗

arXiv2004

Antidot tunneling between Quantum Hall liquids with different filling factors

We consider tunneling through two point contacts between two edges of Quantum Hall liquids of different filling factors $ν_{0,1}=1/ (2m_{0,1}+1)$ with $m_0-m_1\equiv m>0$. Properties of the antidot formed between the point contacts in the strong-tunneling limit are shown to be very different from the $ν_0 =ν_1$ case, and include vanishing average total current in the two contacts and quasiparticles of charge $e/m$. For $m>1$, quasiparticle tunneling leads to non-trivial $m$-state dynamics of effective flux through the antidot which restores the regular ``electron'' periodicity of the current in flux despite the fractional charge and statistics of quasiparticles.

cond-mat.mes-hall↗

arXiv2002

Broken symmetry, hyper-fermions, and universal conductance in transport through a fractional quantum Hall edge

We have found solution to a model of tunneling between a multi-channel Fermi liquid reservoir and an edge of the principal fractional quantum Hall liquid (FQHL) in the strong coupling limit. The solution explains how the absence of the time-reversal symmetry at high energies due to chiral edge propagation makes the universal two-terminal conductance of the FQHL fractionally quantized and different from that of a 1D Tomonaga-Luttinger liquid wire, where a similar model but preserving the time-reversal symmetry predicts unsuppressed free-electron conductance.

cond-mat.mes-hall↗

arXiv2000

Coulomb drag between one-dimensional conductors

We have analyzed Coulomb drag between currents of interacting electrons in two parallel one-dimensional conductors of finite length $L$ attached to external reservoirs. For strong coupling, the relative fluctuations of electron density in the conductors acquire energy gap $M$. At energies larger than $Γ= const \times v_- \exp (-LM/v_-)/L + Γ_{+}$, where $Γ_{+}$ is the impurity scattering rate, and for $L>v_-/M$, where $v_-$ is the fluctuation velocity, the gap leads to an ``ideal'' drag with almost equal currents in the conductors. At low energies the drag is suppressed by coherent instanton tunneling, and the zero-temperature transconductance vanishes, indicating the Fermi liquid behavior.

cond-mat↗