arXiv subjects

Wanki Park

Publications and source records attributed to Wanki Park.

3 recordsLinked to original sources

arXiv2025

Method for rapid estimation of the energy-time covariance matrix of single electrons

The ability to emit and control single electrons in a dynamical manner enables their use in electron quantum optics and sensing. To characterize the electron states emitted with energy far above the Fermi energy, a dynamic barrier has been used. In this work, we extract the energy-time covariance matrix of single electrons by analyzing the energy variance obtained from the transconductance through the dynamic barrier. This method enables efficient and precise characterization of electron states, especially when a sinusoidal waveform is used. An effective phase-space area and the elliptical distribution are constructed from the covariance matrix and qualitatively compared with the distribution reconstructed from a tomographic method. The area constrained by the uncertainty relation serves as a measure of proximity to the quantum limit. Our results demonstrate an efficient method for characterizing electron states, paving the way for their application in quantum technologies.

cond-mat.mes-hall↗

arXiv2023

Measuring the arrival time of an electron wave packet using a dynamical potential barrier

A time-dependent potential barrier has been used to probe the arrival-time distribution of the wave packet of a hot electron by raising the barrier to block the packet upon arrival of the packet at the barrier. To see whether the barrier precisely detects the distribution, it is necessary to study an error caused by a finite rising speed of the barrier. For this purpose, we study transmission of an electron wave packet through the dynamical barrier, and identify two regimes, the semiclassical regime and the quasistatic regime. In each regime, we calculate the arrival-time distribution reconstructed by using the barrier and quantify the error in the detection, the difference of the temporal uncertainty between the wave-packet distribution and the reconstructed distribution. Our finding suggests that for precise detection, the time scale, in which the barrier height rises over the energy distribution of the wave packet and the tunneling energy window of the barrier, has to be much shorter than the temporal uncertainty of the wave packet. The analytical results are confirmed with numerical calculations.

cond-mat.mes-hall↗

arXiv2022

Coulomb-mediated antibunching of an electron pair surfing on sound

Electron flying qubits are envisioned as potential information link within a quantum computer, but also promise -- alike photonic approaches -- a self-standing quantum processing unit. In contrast to its photonic counterpart, electron-quantum-optics implementations are subject to Coulomb interaction, which provide a direct route to entangle the orbital or spin degree of freedom. However, the controlled interaction of flying electrons at the single particle level has not yet been established experimentally. Here we report antibunching of a pair of single electrons that is synchronously shuttled through a circuit of coupled quantum rails by means of a surface acoustic wave. The in-flight partitioning process exhibits a reciprocal gating effect which allows us to ascribe the observed repulsion predominantly to Coulomb interaction. Our single-shot experiment marks an important milestone on the route to realise a controlled-phase gate for in-flight quantum manipulations.

cond-mat.mes-hall↗