Strong-coupling Cavity QED with Single Electron Charge and Spin Qubits in Silicon1*

Coherent coupling of single qubits to microwave photons provides a scalable pathway toward long-range qubit-qubit entanglement. We first demonstrate strong-coupling between a single electron charge qubit in a gate-defined Si double quantum dot to a microwave photon in a superconducting cavity². Combining electric-dipole interaction with spin-charge hybridization in the presence of a magnetic field gradient, we also achieve the strong-coupling regime between a single electron spin and a single microwave photon³. Spin-photon coupling rates up to 11 MHz are supported by the device architecture, exceeding direct magnetic-dipole coupling rates by five orders of magnitude. Furthermore, we demonstrate all-electric control and quantum non-demolition readout of the single-spin qubit using its dispersive interaction with the microwave cavity. These results allow for the construction of a large-scale Si quantum processor with “all-to-all” connectivity.

[1] In collaboration with J. V. Cady, D. M. Zajac, P. W. Deelman, M. Benito, S. Putz, J. M. Taylor, G. Burkard, and J. R. Petta.
[2] X. Mi, J. V. Cady, D. M. Zajac, P. W. Deelman, and J. R. Petta, Science 355, 156 (2017).
[3] X. Mi, M. Benito, S. Putz, D. M. Zajac, J. M. Taylor, G. Burkard, and J. R. Petta, arXiv:1710.03265 (2017).