34 research outputs found
Multifractality and its role in anomalous transport in the disordered XXZ spin-chain
The disordered XXZ model is a prototype model of the many-body localization
transition (MBL). Despite numerous studies of this model, the available
numerical evidence of multifractality of its eigenstates is not very conclusive
due severe finite size effects. Moreover it is not clear if similarly to the
case of single-particle physics, multifractal properties of the many-body
eigenstates are related to anomalous transport, which is observed in this
model. In this work, using a state-of-the-art, massively parallel, numerically
exact method, we study systems of up to 24 spins and show that a large fraction
of the delocalized phase flows towards ergodicity in the thermodynamic limit,
while a region immediately preceding the MBL transition appears to be
multifractal in this limit. We discuss the implication of our finding on the
mechanism of subdiffusive transport.Comment: 13 pages, 8 figure
On-chip Maxwell's demon as an information-powered refrigerator
We present an experimental realization of an autonomous Maxwell's Demon,
which extracts microscopic information from a System and reduces its entropy by
applying feedback. It is based on two capacitively coupled single electron
devices, both integrated on the same electronic circuit. This setup allows a
detailed analysis of the thermodynamics of both the Demon and the System as
well as their mutual information exchange. The operation of the Demon is
directly observed as a temperature drop in the System. We also observe a
simultaneous temperature rise in the Demon arising from the thermodynamic cost
of generating the mutual information.Comment: 10 pages, 7 figure
Quasiparticle trapping in Meissner and vortex states of mesoscopic superconductors
Nowadays superconductors serve in numerous applications, from high-field
magnets to ultra-sensitive detectors of radiation. Mesoscopic superconducting
devices, i.e. those with nanoscale dimensions, are in a special position as
they are easily driven out of equilibrium under typical operating conditions.
The out-of-equilibrium superconductors are characterized by non-equilibrium
quasiparticles. These extra excitations can compromise the performance of
mesoscopic devices by introducing, e.g., leakage currents or decreased
coherence times in quantum devices. By applying an external magnetic field, one
can conveniently suppress or redistribute the population of excess
quasiparticles. In this article we present an experimental demonstration and a
theoretical analysis of such effective control of quasiparticles, resulting in
electron cooling both in the Meissner and vortex states of a mesoscopic
superconductor. We introduce a theoretical model of quasiparticle dynamics
which is in quantitative agreement with the experimental data
Evaluation of the prognostic utility of the combination of platelet count with mean platelet volume as a prognostic indicator in head and neck cancer.
The combination of platelet count to mean platelet volume (COP-MPV) has been recently reported as a prognostic indicator of oral cavity cancer and other cancer sites. The aim of the present study was to validate the utility of the COP-MPV as a prognostic indicator in all head and neck cancer (HNC) sites. The clinicopathological characteristics of the COP-MPV with HNC were also investigated. This is a retrospective cohort study that recruited consecutively treated patients at a tertiary level academic hospital. Clinicopathological characteristics were recorded, including the COP-MPV scores. Survival was analyzed using Kaplan-Meier analysis, as well as multivariate Cox Proportional Hazards regression. COP-MPV was not associated with the survival outcome in univariate or multivariate analysis. In the multivariate model, tumor differentiation, tumor stage, nodal stage, surgical margins and hemoglobin were revealed to be significantly associated with survival. The results demonstrated that the COP-MPV is not a suitable prognostic factor for HNC
Thermodynamics in single-electron circuits and superconducting qubits
| openaire: EC/H2020/742559/EU//SQHClassical and quantum electronic circuits provide ideal platforms to investigate stochastic thermodynamics, and they have served as a stepping stone to realize Maxwell's Demons with highly controllable protocols. In this article, we first review the central thermal phenomena in quantum nanostructures. Thermometry and basic refrigeration methods are described as enabling tools for thermodynamics experiments. Next, we discuss the role of information in thermodynamics that leads to the concept of Maxwell's Demon. Various Maxwell's Demons realized in single-electron circuits over the past couple of years are described. Currently, true quantum thermodynamics in superconducting circuits is a focus of attention, and we end the review by discussing the ideas and first experiments in this exciting area of research.Peer reviewe
Nonlocality and dynamic response of Majorana states in fermionic superfluids
We suggest a microscopic model describing the nonlocal ac response of a pair of Majorana states in fermionic superfluids beyond the tunneling approximation. The time-dependent perturbations of quasiparticle transport are shown to excite finite period beating of the wavefunction between the distant Majorana states. We propose an experimental test to measure the characteristic time scales of quasiparticle transport through the pair of Majorana states defining, thus, quantitative characteristics of nonlocality known to be a generic feature of Majorana particles.Peer reviewe
Charge-vortex interplay in a superconducting Coulomb-blockaded island
VK: Low Temperature LaboratoryWe show that charge transfer through a small superconducting (S) island of a single-electron transistor is strongly affected by vorticity. This interplay of charge and rotational degrees of freedom in a mesoscopic superconductor occurs through the effect of vorticity on the quantum mechanical spectrum of electron-hole excitations. The subgap quasiparticle levels in vortices can host an extra electron, thus suppressing the so-called parity effect in the S island. We propose to measure the collective dynamics of vorticity and electric charge via the charge pumping effect caused by alternating vortex entry and exit controlled by a periodic magnetic field.Peer reviewe