title: Observation of the frozen charge of a Kondo resonance.
abstract: The ability to control electronic states at the nanoscale has contributed to our modern understanding of condensed matter. In particular, quantum dot circuits represent model systems for the study of strong electronic correlations, epitomized by the Kondo effect. We use circuit quantum electrodynamics architectures to study the internal degrees of freedom of this many-body phenomenon. Specifically, we couple a quantum dot to a high-quality-factor microwave cavity to measure with exceptional sensitivity the dot's electronic compressibility, that is, its ability to accommodate charges. Because electronic compressibility corresponds solely to the charge response of the electronic system, it is not equivalent to the conductance, which generally involves other degrees of freedom such as spin. Here, by performing dual conductance and compressibility measurements in the Kondo regime, we uncover directly the charge dynamics of this peculiar mechanism of electron transfer. The Kondo resonance, visible in transport measurements, is found to be 'transparent' to microwave photons trapped in the high-quality cavity, thereby revealing that (in such a many-body resonance) finite conduction is achieved from a charge frozen by Coulomb interaction. This freezing of charge dynamics is in contrast to the physics of a free electron gas. We anticipate that the tools of cavity quantum electrodynamics could be used in other types of mesoscopic circuits with many-body correlations, providing a model system in which to perform quantum simulation of fermion-boson problems.
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: M M
authors.initials: MM
authors.lastname: Desjardins
authors.affiliation: JILA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Viennot
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: M C
authors.initials: MC
authors.lastname: Dartiailh
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: L E
authors.initials: LE
authors.lastname: Bruhat
authors.affiliation: Center for Emergent Matter Science, RIKEN, 147 Main Building, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: M R
authors.initials: MR
authors.lastname: Delbecq
authors.affiliation: Department of Applied Physics, College of Applied Science, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, South Korea.
authors.forename: M
authors.initials: M
authors.lastname: Lee
authors.affiliation: Department of Physics, Korea University, 145 Anam-ro, Seoul 02841, South Korea.
authors.forename: M-S
authors.initials: MS
authors.lastname: Choi
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: A
authors.initials: A
authors.lastname: Cottet
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: T
authors.initials: T
authors.lastname: Kontos