title: Controlling charge quantization with quantum fluctuations.
abstract: In 1909, Millikan showed that the charge of electrically isolated systems is quantized in units of the elementary electron charge e. Today, the persistence of charge quantization in small, weakly connected conductors allows for circuits in which single electrons are manipulated, with applications in, for example, metrology, detectors and thermometry. However, as the connection strength is increased, the discreteness of charge is progressively reduced by quantum fluctuations. Here we report the full quantum control and characterization of charge quantization. By using semiconductor-based tunable elemental conduction channels to connect a micrometre-scale metallic island to a circuit, we explore the complete evolution of charge quantization while scanning the entire range of connection strengths, from a very weak (tunnel) to a perfect (ballistic) contact. We observe, when approaching the ballistic limit, that charge quantization is destroyed by quantum fluctuations, and scales as the square root of the residual probability for an electron to be reflected across the quantum channel; this scaling also applies beyond the different regimes of connection strength currently accessible to theory. At increased temperatures, the thermal fluctuations result in an exponential suppression of charge quantization and in a universal square-root scaling, valid for all connection strengths, in agreement with expectations. Besides being pertinent for the improvement of single-electron circuits and their applications, and for the metal-semiconductor hybrids relevant to topological quantum computing, knowledge of the quantum laws of electricity will be essential for the quantum engineering of future nanoelectronic devices.
authors.affiliation: Centre de Nanosciences et de Nanotechnologies (C2N), CNRS, Université Paris Sud-Université Paris-Saclay, Université Paris Diderot-Sorbonne Paris Cité, 91120 Palaiseau, France.
authors.forename: S
authors.initials: S
authors.lastname: Jezouin
authors.affiliation: Centre de Nanosciences et de Nanotechnologies (C2N), CNRS, Université Paris Sud-Université Paris-Saclay, Université Paris Diderot-Sorbonne Paris Cité, 91120 Palaiseau, France.
authors.forename: Z
authors.initials: Z
authors.lastname: Iftikhar
authors.affiliation: Centre de Nanosciences et de Nanotechnologies (C2N), CNRS, Université Paris Sud-Université Paris-Saclay, Université Paris Diderot-Sorbonne Paris Cité, 91120 Palaiseau, France.
authors.forename: A
authors.initials: A
authors.lastname: Anthore
authors.affiliation: Centre de Nanosciences et de Nanotechnologies (C2N), CNRS, Université Paris Sud-Université Paris-Saclay, Université Paris Diderot-Sorbonne Paris Cité, 91120 Palaiseau, France.
authors.forename: F D
authors.initials: FD
authors.lastname: Parmentier
authors.affiliation: Centre de Nanosciences et de Nanotechnologies (C2N), CNRS, Université Paris Sud-Université Paris-Saclay, Université Paris Diderot-Sorbonne Paris Cité, 91120 Palaiseau, France.
authors.forename: U
authors.initials: U
authors.lastname: Gennser
authors.affiliation: Centre de Nanosciences et de Nanotechnologies (C2N), CNRS, Université Paris Sud-Université Paris-Saclay, Université Paris Diderot-Sorbonne Paris Cité, 91120 Palaiseau, France.
authors.forename: A
authors.initials: A
authors.lastname: Cavanna
authors.affiliation: Centre de Nanosciences et de Nanotechnologies (C2N), CNRS, Université Paris Sud-Université Paris-Saclay, Université Paris Diderot-Sorbonne Paris Cité, 91120 Palaiseau, France.
authors.forename: A
authors.initials: A
authors.lastname: Ouerghi
authors.affiliation: Institute for Theoretical Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: I P
authors.initials: IP
authors.lastname: Levkivskyi
authors.affiliation: Département de Physique Théorique, Université de Genève, CH-1211 Genève, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Idrisov
authors.affiliation: Département de Physique Théorique, Université de Genève, CH-1211 Genève, Switzerland.
authors.forename: E V
authors.initials: EV
authors.lastname: Sukhorukov
authors.affiliation: Department of Physics, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: L I
authors.initials: LI
authors.lastname: Glazman
authors.affiliation: Centre de Nanosciences et de Nanotechnologies (C2N), CNRS, Université Paris Sud-Université Paris-Saclay, Université Paris Diderot-Sorbonne Paris Cité, 91120 Palaiseau, France.
authors.forename: F
authors.initials: F
authors.lastname: Pierre