Barthel, CKjærgaard, M.Medford, James ReddingStopa, Michael PMarcus, CHanson, M. P.Gossard, Arthur C.2011-08-152010Barthel, Christian, M. Kjærgaard, James Redding Medford, Michael Stopa, Charles Masamed Marcus, M. P. Hanson, and Arthur C. Gossard. 2010. Fast sensing of double-dot charge arrangement and spin state with a radio-frequency sensor quantum dot. Physical Review B 81(161308R).1098-0121http://nrs.harvard.edu/urn-3:HUL.InstRepos:5110749Single-shot measurement of the charge arrangement and spin state of a double quantum dot are reported with measurement times down to 100 ns. Sensing uses radio-frequency reflectometry of a proximal quantum dot in the Coulomb blockade regime. The sensor quantum dot is up to 30 times more sensitive than a comparable quantum point-contact sensor and yields three times greater signal to noise in rf single-shot measurements. Numerical modeling is qualitatively consistent with experiment and shows that the improved sensitivity of the sensor quantum dot results from reduced lifetime broadening and screening.en-USCoulomb-blockadesingle-electron transistorJournal Article2011-08-1510.1103/PhysRevB.81.161308