arXiv subjects

A. Larrouy

Publications and source records attributed to A. Larrouy.

3 recordsLinked to original sources

arXiv2024

Microsecond-lived quantum states in a carbon-based circuit driven by cavity photons

Semiconductor quantum dots are an attractive platform for the realisation of quantum processors. To achieve long-range coupling between them, quantum dots have been integrated into microwave cavities. However, it has been shown that their coherence is then reduced compared to their cavity-free implementations. Here, we manipulate the quantum states of a suspended carbon nanotube double quantum dot with ferromagnetic contacts embedded in a microwave cavity. By performing quantum manipulations via the cavity photons, we demonstrate coherence times of the order of $1.3\mu s$, two orders of magnitude larger than those measured so far in any carbon quantum circuit and one order of magnitude larger than silicon-based quantum dots in comparable environment. This holds promise for carbon as a host material for spin qubits in circuit quantum electrodynamics.

cond-mat.mes-hall↗

arXiv2020

Preparation of Long-Lived, Non-Autoionizing Circular Rydberg States of Strontium

Alkaline earth Rydberg atoms are very promising tools for quantum technologies. Their highly excited outer electron provides them with the remarkable properties of Rydberg atoms and, notably, with a huge coupling to external fields or to other Rydberg atoms while the ionic core retains an optically active electron. However, low angular-momentum Rydberg states suffer almost immediate autoionization when the core is excited. Here, we demonstrate that strontium circular Rydberg atoms with a core excited in a $4D$ metastable level are impervious to autoionization over more than a few millisecond time scale. This makes it possible to trap and laser-cool Rydberg atoms. Moreover, we observe singlet to triplet transitions due to the core optical manipulations, opening the way to a quantum microwave to optical interface.

physics.atom-ph↗

arXiv2018

Quantum-enabled electrometer measures field transients and correlation function

We realize a non-invasive electrometer based on state engineering in a Rydberg hydrogenic manifold. A quantum interference process involving states with very different dipoles measures directly the time correlation of a stochastic electric field, with a 200~ns time resolution and with a $83.2\pm1.4$~mV/m single-atom sensitivity, beyond the Standard Quantum Limit in this context. This quantum-enabled correlation electrometer opens the way to applications in mesoscopic physics, e.g. for the study of individual charge transits in nano-structures.

quant-ph↗