Silicon quantum processor with robust long-distance qubit couplings

TL;DR

This paper proposes a scalable silicon quantum processor design utilizing donor spins that enables long-distance qubit interactions, robust against noise, and compatible with current fabrication technology.

Contribution

It introduces a novel scalable silicon quantum processor architecture that does not require precise donor placement and supports long-distance qubit coupling using electrical control.

Findings

Error rates below quantum error correction thresholds

Qubit operations performed via electrical means

Long-distance entanglement enabled by microwave resonators

Abstract

Practical quantum computers require the construction of a large network of highly coherent qubits, interconnected in a design robust against errors. Donor spins in silicon provide state-of-the-art coherence and quantum gate fidelities, in a physical platform adapted from industrial semiconductor processing. Here we present a scalable design for a silicon quantum processor that does not require precise donor placement and allows hundreds of nanometers inter-qubit distances, therefore facilitating fabrication using current technology. All qubit operations are performed via electrical means on the electron-nuclear spin states of a phosphorus donor. Single-qubit gates use low power electric drive at microwave frequencies, while fast two-qubit gates exploit electric dipole-dipole interactions. Microwave resonators allow for millimeter-distance entanglement and interfacing with photonic links. Sweet spots protect the qubits from charge noise up to second order, implying that all operations can be performed with error rates below quantum error correction thresholds, even without any active noise cancellation technique.