Partagez sur
STAGE offre de stage : Electron tunneling time and its fluctuations
Date de mise à jour de l’offre
Service de Physique de l'Etat Condensé : SPEC - UMR 3680 CEA-CNRS. :
Challenging our classical intuition, quantum tunneling has fascinated physicists for decades. Very soon after its discovery, it raised the question of how much time do particles spend under the classically forbidden barrier. Despite its simplicity, such a question is ill defined in terms of quantum observables and does not admit a single answer, thus triggering over the past decades a bunch of different definitions corresponding to different (thought) scenarios.
Following a proposal by Büttiker & collaborators [1], we will address this question from the perspective of a well-defined observable: that is, measuring the spectrum of time fluctuations of the number of particles residing within the classically forbidden barrier. The idea is to exploit semiconducting 2D electron gases where electrostatically coupled metallic gates are used to generate the electrostatic potential barrier upon which the electrons are scattered. Moreover, we will equally use them to collect the mirror influence
Description de la mission
Challenging our classical intuition, quantum tunneling has fascinated physicists for decades. Very soon after its discovery, it raised the question of how much time do particles spend under the classically forbidden barrier. Despite its simplicity, such a question is ill defined in terms of quantum observables and does not admit a single answer, thus triggering over the past decades a bunch of different definitions corresponding to different (thought) scenarios.
Following a proposal by Büttiker & collaborators [1], we will address this question from the perspective of a well-defined observable: that is, measuring the spectrum of time fluctuations of the number of particles residing within the classically forbidden barrier. The idea is to exploit semiconducting 2D electron gases where electrostatically coupled metallic gates are used to generate the electrostatic potential barrier upon which the electrons are scattered. Moreover, we will equally use them to collect the mirror influence-charges fluctuating in response to the tunneling electrons residing within the electrostatic barrier. Despite its conceptual simplicity, implementing such a scenario is a formidable task since it demands collecting a tiny radiofrequency (RF) signal emitted by a huge output-impedance source in a sub-Kelvin (dilution) refrigerator. We will build upon the group’s expertise in RF design and ultra-low noise measurements in cryogenic environments in order to overcome this challenge, notably implementing recently developed high impedance RF matching circuits [2] allowing us to efficiently collect the signal into a RF detection chain.
The student will participate to the radiofrequency design of the samples, to their fabrication in a clean-room environment, and to their measurement exploiting low noise measurement techniques both in the near DC and the few GHz range. He will become familiar with sub-Kelvin cryogenic techniques as well.
References:
[1] Pedersen, van Langen, and Büttiker, Phys. Rev. B 57, 1838 (1998)
[2] Rolland et al., https://arxiv.org/abs/1810.06217
[3] Anthore et al., Phys. Rev. X 8, 031075 (2018)
[4] Altimiras, Portier and Joyez, Phys. Rev. X 6, 031002 (2016)
Following a proposal by Büttiker & collaborators [1], we will address this question from the perspective of a well-defined observable: that is, measuring the spectrum of time fluctuations of the number of particles residing within the classically forbidden barrier. The idea is to exploit semiconducting 2D electron gases where electrostatically coupled metallic gates are used to generate the electrostatic potential barrier upon which the electrons are scattered. Moreover, we will equally use them to collect the mirror influence-charges fluctuating in response to the tunneling electrons residing within the electrostatic barrier. Despite its conceptual simplicity, implementing such a scenario is a formidable task since it demands collecting a tiny radiofrequency (RF) signal emitted by a huge output-impedance source in a sub-Kelvin (dilution) refrigerator. We will build upon the group’s expertise in RF design and ultra-low noise measurements in cryogenic environments in order to overcome this challenge, notably implementing recently developed high impedance RF matching circuits [2] allowing us to efficiently collect the signal into a RF detection chain.
The student will participate to the radiofrequency design of the samples, to their fabrication in a clean-room environment, and to their measurement exploiting low noise measurement techniques both in the near DC and the few GHz range. He will become familiar with sub-Kelvin cryogenic techniques as well.
References:
[1] Pedersen, van Langen, and Büttiker, Phys. Rev. B 57, 1838 (1998)
[2] Rolland et al., https://arxiv.org/abs/1810.06217
[3] Anthore et al., Phys. Rev. X 8, 031075 (2018)
[4] Altimiras, Portier and Joyez, Phys. Rev. X 6, 031002 (2016)
Profil recherché
Etudiant intéressé par la recherche fondamentale dans des circuits électriques quantiques
Niveau de qualification requis
Bac + 4/5 et +
Les offres de stage ou de contrat sont définies par les recruteurs eux-mêmes.
En sa qualité d’hébergeur dans le cadre du dispositif des « 100 000 stages », la Région Île-de-France est soumise à un régime de responsabilité atténuée prévu aux articles 6.I.2 et suivants de la loi n°2204-575 du 21 juin 2004 sur la confiance dans l’économie numérique.
La Région Île-de-France ne saurait être tenue responsable du contenu des offres.
Néanmoins, si vous détectez une offre frauduleuse, abusive ou discriminatoire vous pouvez la signaler
en cliquant sur ce lien.
-
EmployeurService de Physique de l'Etat Condensé : SPEC - UMR 3680 CEA-CNRS.
-
Secteur d’activité de la structureEnseignement - Formation - Recherche
-
Effectif de la structurePlus de 250 salariés
-
Site internet de la structurehttp://www.iramis.fr
-
Type de stage ou contratStage pour lycéens et étudiants en formation initiale
-
Date prévisionnelle de démarrage
-
Durée du stage ou contratPlus de 4 mois et jusqu'à 6 mois
-
Le stage est-il rémunéré ?Oui
-
Niveau de qualification requis
Bac + 4/5 et + -
Lieu du stageSPEC CEA
L'Orme des Merisiers
91190 SAINT-AUBIN -
Accès et transportsRER B à Massy puis bus 91 06