A scalable shared-control architecture for silicon-based quantum computing using topological quantum error correction.

No abstract

We demonstrate direct detection of individual electron spin states, together with measurement of spin relaxation time (T1), in silicon metal-oxide-semiconductor-based quantum dots (QD). Excited state spectroscopy of the QD has been performed using a charge-sensing technique. T1 of single spin excited states has been done in the time domain by a pump-and-probe method. For an odd and an even number of electrons, we found a magnetic field dependent and invariant T1, respectively.

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 μeV 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.