Transmission and reflection of charge-density wave packets in a quantum Hall edge controlled by a metal gate

Abstract

Quantum energy teleportation (QET) is a proposed protocol related to the quantum vacuum. The edge channels in a quantum Hall system is well suited for the experimental verification of QET. For this purpose, we examine a charge density wave excited and detected by capacitively coupled front gate electrodes. We observe the waveform of the charge density wave, which is proportional to the time derivative of the applied square voltage wave. Further, we study the transmission and reflection behaviors of the charge density wave by applying a voltage to another front gate electrode to control the path of the edge state. We show that the threshold voltages where the dominant direction is switched in either transmission or reflection for dense and sparse waves are different from the threshold voltage where the current stops flowing in an equilibrium state.The physics of the quantum vacuum and its fluctuations (zero-point fluctuations) have attracted considerable attention in various fields of modern physics 1 . Quantum energy teleportation (QET) is one quantumvacuum-related protocol 2,3 . By this protocol, the local zero-point energy is extracted from a remote place by only sending classical information, which does not carry energy but contains how to extract energy from the local vacuum. In order to verify this quantum protocol by experiment, a quantum Hall (QH) system has been theoretically suggested to be the best suited physical system 4,5 . The QH states consist of two regions-bulk and edge. When a strong perpendicular magnetic field is applied to the two-dimensional (2D) electrons, the orbital degree of freedom of the electrons in the bulk region is quantized and does not contribute to the transport. However, electrons in the edge region can flow without backscattering, leading to a zero longitudinal resistance 6 . Using intriguing properties of edge channels and the charge density waves propagating along them, pioneering experiments have been performed 7-10,12

Real-time and -space visualization of excitations of the ν= 1/3 fractional quantum Hall edge

“…S3 in SM). Moreover, in a previous study, which also excited wave packets by a front gate in the ν = 1 integer QH edge, waveforms resembling (dV ex )/dt were detected by another front gate [19].…”

“…This QH edge state constitutes a 1D system that exhibits uniquely high coherence [6] and hosts a wide variety of physics [7][8][9][10][11][12][13], such as the Tomonaga-Luttinger liquid [12,13], anyonic statistics [14,15], and charge-neutral upstream Majorana modes of the edge current [7]. Furthermore, it offers the potential for exotic applications, including topological and flying qubit quantum computation [16][17][18] and quantum energy teleportation [19][20][21]. The properties of these edge states are typically examined through electric measurements [6-13, 18, 19, 22], including shot-noise [6][7][8] and heattransport measurements [9].…”

“…The properties of these edge states are typically examined through electric measurements [6-13, 18, 19, 22], including shot-noise [6][7][8] and heattransport measurements [9]. The edge current dynamics have been specifically examined by time-resolved transport measurements [10][11][12][13]19]. In general, measurements that detect electric signals from electrodes attached to a sample are limited in that they only obtain information from a certain fixed region.…”

“…A laser pulse is synchronized to a voltage pulse applied to the excitation gate deposited on top of the sample [19] (Figs. 1, 4(a), and S1) with a controllable time delay ∆t.…”

“…This ensures that the measured PL reflects the electronic state at a moment following the voltage pulse. This pulse creates a local charge disturbance that propagates as an EMP wave packet [10][11][12][13]19] along the boundary of the QH system defined by the interface of the QW and the vacuum. For a specific ∆t, the wave packet arrives at the laser focal point in coincidence with the laser pulse illumination.…”