Radio frequency measurements of tunnel couplings and singlet-triplet spin states in Si:P quantum dots.

ABSTRACT: Spin states of the electrons and nuclei of phosphorus donors in silicon are strong candidates for quantum information processing applications given their excellent coherence times. Designing a scalable donor-based quantum computer will require both knowledge of the relationship between device geometry and electron tunnel couplings, and a spin readout strategy that uses minimal physical space in the device. Here we use radio frequency reflectometry to measure singlet-triplet states of a few-donor Si:P double quantum dot and demonstrate that the exchange energy can be tuned by at least two orders of magnitude, from 20??eV to 8?meV. We measure dot-lead tunnel rates by analysis of the reflected signal and show that they change from 100?MHz to 22?GHz as the number of electrons on a quantum dot is increased from 1 to 4. These techniques present an approach for characterizing, operating and engineering scalable qubit devices based on donors in silicon.

SUBMITTER: House MG 

PROVIDER: S-EPMC4667619 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature