A linear triple quantum dot system in isolated configuration

The scaling up of electron spin qubit based nanocircuits has remained challenging up to date and involves the development of efficient charge control strategies. Here we report on the experimental realization of a linear triple quantum dot in a regime isolated from the reservoir. We show how this regime can be reached with a fixed number of electrons. Charge stability diagrams of the one, two and three electron configurations where only electron exchange between the dots is allowed are observed. They are modelled with established theory based on a capacitive model of the dot systems. The advantages of the isolated regime with respect to experimental realizations of quantum simulators and qubits are discussed. We envision that the results presented here will make more manipulation schemes for existing qubit implementations possible and will ultimately allow to increase the number of tunnel coupled quantum dots which can be simultaneously controlled

Injection of a single electron from static to moving quantum dots

We study the injection mechanism of a single electron from a static quantum dot into a moving quantum dot created in a long depleted channel with surface acoustic waves (SAWs). We demonstrate that such a process is characterized by an activation law with a threshold that depends on the SAW amplitude and the dot-channel potential gradient. By increasing sufficiently the SAW modulation amplitude, we can reach a regime where the transfer is unitary and potentially adiabatic. This study points at the relevant regime to use moving dots in quantum information protocols.Comment: 5 pages, 4 figure

Generation of a single-cycle acoustic pulse: a scalable solution for transport in single-electron circuits

The synthesis of single-cycle, compressed optical and microwave pulses sparked novel areas of fundamental research. In the field of acoustics, however, such a generation has not been introduced yet. For numerous applications, the large spatial extent of surface acoustic waves (SAW) causes unwanted perturbations and limits the accuracy of physical manipulations. Particularly, this restriction applies to SAW-driven quantum experiments with single flying electrons, where extra modulation renders the exact position of the transported electron ambiguous and leads to undesired spin mixing. Here, we address this challenge by demonstrating single-shot chirp synthesis of a strongly compressed acoustic pulse. Employing this solitary SAW pulse to transport a single electron between distant quantum dots with an efficiency exceeding 99%, we show that chirp synthesis is competitive with regular transduction approaches. Performing a time-resolved investigation of the SAW-driven sending process, we outline the potential of the chirped SAW pulse to synchronize single-electron transport from many quantum-dot sources. By superimposing multiple pulses, we further point out the capability of chirp synthesis to generate arbitrary acoustic waveforms tailorable to a variety of (opto)nanomechanical applications. Our results shift the paradigm of compressed pulses to the field of acoustic phonons and pave the way for a SAW-driven platform of single-electron transport that is precise, synchronized, and scalable.Comment: To be published in Physical Review

Sound-driven single-electron transfer in a circuit of coupled quantum rails

Abstract: Surface acoustic waves (SAWs) strongly modulate the shallow electric potential in piezoelectric materials. In semiconductor heterostructures such as GaAs/AlGaAs, SAWs can thus be employed to transfer individual electrons between distant quantum dots. This transfer mechanism makes SAW technologies a promising candidate to convey quantum information through a circuit of quantum logic gates. Here we present two essential building blocks of such a SAW-driven quantum circuit. First, we implement a directional coupler allowing to partition a flying electron arbitrarily into two paths of transportation. Second, we demonstrate a triggered single-electron source enabling synchronisation of the SAW-driven sending process. Exceeding a single-shot transfer efficiency of 99%, we show that a SAW-driven integrated circuit is feasible with single electrons on a large scale. Our results pave the way to perform quantum logic operations with flying electron qubits

Structural and Electrostatic Confinement of a Single Electron in a Scalable 2D Array of Quantum Dots

International audienceThe usefulness of mesa patterning in building a two-dimensional array of silicon quantum dots is explored using TCAD simulations at low temperature. We compare different structures and study the impact of geometric parameters on the charge confinement and control

Electron qubits surfing on acoustic waves: review of recent progress

International audienceThe displacement of a single electron enables exciting avenues for nanotechnology with vast application potential in quantum metrology, quantum communication and quantum computation. Surface acoustic waves (SAW) have proven itself as a surprisingly useful solution to perform this task over large distance with outstanding precision and reliability. Over the last decade, important milestones have been achieved bringing SAW-driven single-electron transport from first proof-of-principle demonstrations to accurate, highly-controlled implementations, such as coherent spin transport, charge-to-photon conversion, or antibunching of charge states. Beyond the well-established piezoelectric gallium-arsenide platform, first realisations of acousto-electronic transport have also been carried out on the surface of liquid helium. In this review article, we aim to keep track of this remarkable progress by explaining these recent achievements from basic principles, with an outlook on follow-up experiments and near-term applications