About the project
Call: H2020
Type: Individual Fellowship (IF) in the framework of the Marie Skłodowska-Curie Action
Grant agreement number: No. 654503
Span: 2015 - 2017
This is a project under Marie Sklodowska-Curie actions, Individual Fellowships (IF). It is carried out by Shintaro Takada in Quantum Coherence group in Institut Neal, CNRS in Grenoble, France
Fellowship duration: April 2015 to March 2017.
A future objective of the project is performing quantum optics like experiments using flying electrons on sound waves in solid state devices. In contrast to photons electrons are strongly interacting particles. This difference makes quantum optics with flying electrons attractive. For example we can envision an original quantum entanglement schemes for electrons by using Coulomb interaction.
Our goal is to develop the basic elements needed to realise quantum optics experiments with flying electrons [1, 2]. In particular we aim to realise a beam splitter as well as a phase shifter for single flying electrons, which makes it possible to create coherent superposition of single flying electrons. The realization of such experiments will lead to a variety of exciting experiments of quantum electron optics.
[1] S. Hermelin et al., Nature 477, 435 (2011).
[2] R. P. G. McNeil et al., Nature 477, 439 (2011).
Main results
We measured a single electron beam splitter device fabricated in a two dimensional electron gas (2DEG) formed by a GaAs/AlGaAs heterostructure (Fig. 1). The device geometry is defined by a standard Schottky gate technique. The device consists of a tunnel-coupled wire in the middle, where two parallel quantum wires are coupled via a narrow tunnel-barrier. Each end of the tunnel-coupled wire is connected to a quantum dot (QD) through a quantum channel. The two QDs on the left are used as single electron sources and the two QDs on the right are used as single electron detectors. An interdigital transducer (IDT) to generate surface acoustic waves (SAWs) is placed at about 2 mm apart from the center device structure on the left side.
In the experiment we prepare a single electron in one of the source QDs. We then generate a short burst of SAWs, which picks up the electron from the source QD and transfers it through the depleted quantum channel to the tunnel-coupled wire. In the tunnel-coupled wire we manipulate the electron by controlling the energy detuning as well as tunnel-coupling energy between the two wires. Finally we detect the electron in the either one of the QDs on the right side. Sending and receiving electrons in the QDs are detected by monitoring the current flowing through the charge detectors near the QDs.
We have succeeded in transferring a single electron in this device with a probability of above 99 %. We have also demonstrated a directional coupler operation for single flying electrons. In addition we have developed a technique to synchronize the electron injection from different single electron sources. Publication of these results is currently under preparation.
Fig. 1: SEM image of the device and schematic of IDT: The device consists of four quantum dots (QDs). They work as a single electron source or a single electron detector. The number of electrons inside the QD is monitored by the current flowing through the quantum point contact at the vicinity of the QD. Each QD is connected to the tunnel-coupled wire through a quantum channel, which guides electrons to/from the tunnel-coupled wire in the middle. An interdigital transducer (IDT) is placed at about 2 mm apart from the fine structure. Surface acoustic wave (SAW) is generated by applying a radio frequency (RF) voltage on the IDT.
Contact
Shintaro Takada
NMIJ/AIST
Tsukuba Central 3-1
1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan
Tel: +81-29-861-4223
Fax: +81-29-861-3469
Christopher Bäuerle
Institut Neel - CNRS
Department of Nanoscience
25 rue des Martyrs, 38042, Grenoble Cedex 9
christopher.bauerle@neel.cnrs.fr
Tel: +33 (0)4 76 88 78 43