arXiv subjects

Thomas Vasselon

Publications and source records attributed to Thomas Vasselon.

4 recordsLinked to original sources

arXiv2026

Active control of THz plasmon propagation in a one-dimensional electronic waveguide

Quantum nanoelectronics is pushing towards ever higher operating frequencies in order to realise quantum technologies capable of processing information at unprecedented speeds. A particularly promising direction is the development of flying electron qubits, which offer the prospect of quantum operations on picosecond timescales. Achieving in-flight quantum control in this regime would establish a fundamentally new paradigm for studying quantum entanglement and enable a novel form of quantum information processing based on propagating electronic wavepackets. Here we report a first step towards this goal by injecting ultrashort electron wavepackets into an engineered quantum nanoelectronic device. We demonstrate active control over the propagation speed of an electron wavepacket with a temporal duration as short as 4 ps in a quasi-one-dimensional electron waveguide with a length ranging from 10 $\mathrmμ$m to 40 $\mathrmμ$m. This advance provides a key building block for ultrafast quantum operations using flying electrons. Beyond its technological implications, our approach offers a platform for exploring the intrinsic dynamical processes that govern quantum transport and coherence in nanoscale electronic systems.

cond-mat.mes-hall↗

arXiv2025

Evidence of Coulomb liquid phase in few-electron droplets

Emergence of universal collective behaviour from interactions within a sufficiently large group of elementary constituents is a fundamental scientific paradigm. In physics, correlations in fluctuating microscopic observables can provide key information about collective states of matter such as deconfined quark-gluon plasma in heavy-ion collisions or expanding quantum degenerate gases. Mesoscopic colliders, through shot-noise measurements, have provided smoking-gun evidence on the nature of exotic electronic excitations such as fractional charges, levitons and anyon statistics. Yet, bridging the gap between two-particle collisions and the emergence of collectivity as the number of interacting particles increases remains a challenging task at the microscopic level. Here we demonstrate all-body correlations in the partitioning of electron droplets containing up to N = 5 electrons, driven by a moving potential well through a Y-junction in a semiconductor device. Analyzing the partitioning data using high-order multivariate cumulants and finite-size scaling towards the thermodynamic limit reveals distinctive fingerprints of a strongly-correlated Coulomb liquid. These fingerprints agree well with a universal limit where the partitioning of a droplet is predicted by a single collective variable. Our electron-droplet collider provides critical insight into the interplay of confinement and interaction effects in small electron systems and highlights a new way to study engineered states of matter.

cond-mat.mes-hall↗

arXiv2025

Electronic interferometry with ultrashort plasmonic pulses

Electronic flying qubits offer an interesting alternative to photonic qubits: electrons propagate slower, hence easier to control in real time, and Coulomb interaction enables direct entanglement between different qubits. Although their coherence time is limited, flying electrons in the form of picosecond plasmonic pulses could be competitive in terms of the number of achievable coherent operations. The key challenge in achieving this critical milestone is the development of a new technology capable of injecting 'on-demand' single-electron wavepackets into quantum devices, with temporal durations comparable to or shorter than the device dimensions. Here, we take a significant step towards achieving this regime in a quantum nanoelectronic system by injecting ultrashort single-electron plasmonic pulses into a 14-micrometer-long Mach-Zehnder interferometer. Our results establish that quantum coherence is robust under the on-demand injection of ultrashort plasmonic pulses, as evidenced by the observation of coherent oscillations in the single-electron regime. Building on this, our results demonstrate for the first time the existence of a new "non-adiabatic" regime that is prominent at high frequencies. This breakthrough highlights the potential of flying qubits as a promising alternative to localised qubit architectures, offering advantages such as a reduced hardware footprint, enhanced connectivity, and scalability for quantum information processing.

cond-mat.mes-hall↗

arXiv2023

Ultrashort electron wavepackets via frequency-comb synthesis

Single-electron sources are an essential component of modern quantum nanoelectronic devices. Owing to their high accuracy and stability, they have been successfully employed for metrology applications, studying fundamental matter interactions and more recently for electron quantum optics. They are traditionally driven by state-of-the-art arbitrary waveform generators that are capable of producing single-electron pulses in the sub-100 ps timescale. In this work, we use an alternative approach for generating ultrashort electron wavepackets. By combining several harmonics provided by a frequency comb, we synthesise Lorentzian voltage pulses and then use them to generate electron wavepackets. Through this technique, we report on the generation and detection of an electron wavepacket with temporal duration of 27 ps generated on top of the Fermi sea of a 2-dimensional electron gas - the shortest reported to date. Electron pulses this short enable studies on elusive, ultrafast fundamental quantum dynamics in nanoelectronic systems and pave the way to implement flying electron qubits by means of Levitons.

cond-mat.mes-hall↗