Coherent transport in a linear triple quantum dot made from a pure-phase InAs nanowire

TL;DR

This paper reports the realization of a highly tunable linear triple quantum dot in a pure-phase InAs nanowire, demonstrating coherent electron transfer and complex resonance phenomena, advancing quantum information processing capabilities.

Contribution

It introduces a novel triple quantum dot device in a pure-phase InAs nanowire with demonstrated long-distance coherent electron transfer and detailed charge stability analysis.

Findings

Observation of three distinct current lines in the charge stability diagram.

Confirmation of the diagram via capacitance matrix model simulation.

Achievement of coherent electron transfer between remote quantum dots.

Abstract

A highly tunable linear triple quantum dot (TQD) device is realized in a single-crystalline pure-phase InAs nanowire using a local finger gate technique. The electrical measurements show that the charge stability diagram of the TQD can be represented by three kinds of current lines of different slopes and a simulation performed based on a capacitance matrix model confirms the experiment. We show that each current line observable in the charge stability diagram is associated with a case where a QD is on resonance with the Fermi level of the source and drain reservoirs. At a triple point where two current lines of different slopes move together but show anti-crossing, two QDs are on resonance with the Fermi level of the reservoirs. We demonstrate that an energetically degenerated quadruple point, at which all three QDs are on resonance with the Fermi level of the reservoirs, can be built by moving two separated triple points together via sophistically tuning of energy levels in the three QDs. We also demonstrate the achievement of direct coherent electron transfer between the two remote QDs in the TQD, realizing a long-distance coherent quantum bus operation. Such a long-distance coherent coupling could be used to investigate coherent spin teleportation and super-exchange effects and to construct a spin qubit with an improved long coherent time and with spin state detection solely by sensing the charge states.