title: Measuring the complex admittance of a carbon nanotube double quantum dot.
abstract: We investigate radio-frequency (rf) reflectometry in a tunable carbon nanotube double quantum dot coupled to a resonant circuit. By measuring the in-phase and quadrature components of the reflected rf signal, we are able to determine the complex admittance of the double quantum dot as a function of the energies of the single-electron states. The measurements are found to be in good agreement with a theoretical model of the device in the incoherent limit. In addition to being of fundamental interest, our results present an important step forward towards noninvasive charge and spin state readout in carbon nanotube quantum dots.
authors.affiliation: Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom.
authors.forename: S J
authors.initials: SJ
authors.lastname: Chorley
authors.forename: J
authors.initials: J
authors.lastname: Wabnig
authors.forename: Z V
authors.initials: ZV
authors.lastname: Penfold-Fitch
authors.forename: K D
authors.initials: KD
authors.lastname: Petersson
authors.forename: J
authors.initials: J
authors.lastname: Frake
authors.forename: C G
authors.initials: CG
authors.lastname: Smith
authors.forename: M R
authors.initials: MR
authors.lastname: Buitelaar