title: Measuring the Degeneracy of Discrete Energy Levels Using a GaAs/AlGaAs Quantum Dot.
abstract: We demonstrate an experimental method for measuring quantum state degeneracies in bound state energy spectra. The technique is based on the general principle of detailed balance and the ability to perform precise and efficient measurements of energy-dependent tunneling-in and -out rates from a reservoir. The method is realized using a GaAs/AlGaAs quantum dot allowing for the detection of time-resolved single-electron tunneling with a precision enhanced by a feedback control. It is thoroughly tested by tuning orbital and spin degeneracies with electric and magnetic fields. The technique also lends itself to studying the connection between the ground-state degeneracy and the lifetime of the excited states.
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Hofmann
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: V F
authors.initials: VF
authors.lastname: Maisi
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Gold
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Krähenmann
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Rössler
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Basset
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Märki
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Reichl
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: W
authors.initials: W
authors.lastname: Wegscheider
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Ensslin
authors.affiliation: Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Ihn