Mobile Electron Spin Qubits: Silicon ICs meet Superfluid Helium
It has become clear that large-scale quantum computers will require thousands or millions of qubits and quantum gates. I will discuss an approach which shows evidence for such scalability and combines features of trapped ion technologies - individual quantum particles held in a vacuum and moved about electrostatically - with features of semiconductor-based qubits - electrons held tightly at a material interface. These qubits are the spin of electrons held in the vacuum above the surface of a thin superfluid helium film. This system sidesteps many of the materials issues which can complicate solid state approaches, while the helium-vacuum interface eliminates the need for rf-trapping and preserves the qubit and gate density of sub-micron IC technology. I will discuss existing data which places limits on electron spin decoherence and recent experiments which demonstrate well-controlled clocked electron transport across silicon ICs.