Measurement and control of electron wave packets from a single-electron source

Abstract

We report an experimental technique to measure and manipulate the arrival-time and energy distributions of electrons emitted from a semiconductor electron pump, operated as both a single-electron source and a two-electron source. Using an energy-selective detector whose transmission we control on picosecond time scales, we can measure directly the electron arrival-time distribution and we determine the upper bound to the distribution width to be 30 ps. We study the effects of modifying the shape of the voltage wave form that drives the electron pump, and show that our results can be explained by a tunneling model of the emission mechanism. This information was in turn used to control the emission-time difference and energy gap between a pair of electrons.

Time-of-Flight Measurements of Single-Electron Wave Packets in Quantum Hall Edge States

“…The detector current I D is monitored as V dc G3 is swept and the relative delay time t d between V rf G1 and V rf G3 [see Fig. 1(c)] is varied with a picosecond resolution [16] (see the Supplemental Material for more information [31]). …”

“…These electrons are injected into an edge where the background two-dimensional electron gas (2DEG) is depleted to avoid the influence of electron-electron interactions. The arrival time of these wave packets is detected by an energyselective detector barrier with a picosecond resolution [13,16]. The travel length between the source and detector is switched by a deflection barrier.…”

“…The demonstration of entanglement and multiparticle interference with such wave packets would set the stage for quantum-technology applications such as quantum information processing [1]. Various theoretical proposals [2][3][4][5][6][7] and experimental realizations [8][9][10][11][12][13][14][15][16][17] employ quantum Hall edge states [18] as electron waveguides. The group velocity and dispersion relation of edge states are important parameters for understanding and controlling electron wave packet propagation.…”

“…The longer route adds an extra length 2L 1 þ L 2 to the electron path, causing a delay in the arrival time at the detector. The arrival time is detected using a timedependent signal [13,16]. A square wave V rf G3 with a peakto-peak amplitude of ∼20 mV is applied to G3 [16] in addition to a dc voltage V dc G3 .…”

“…The arrival time is detected using a timedependent signal [13,16]. A square wave V rf G3 with a peakto-peak amplitude of ∼20 mV is applied to G3 [16] in addition to a dc voltage V dc G3 . The detector current I D is monitored as V dc G3 is swept and the relative delay time t d between V rf G1 and V rf G3 [see Fig.…”