Abstract
AbstractIndividual impurity atoms in silicon can make superb individual qubits, but it remains an immense challenge to build a multi-qubit processor: there is a basic conflict between nanometre separation desired for qubit–qubit interactions and the much larger scales that would enable control and addressing in a manufacturable and fault-tolerant architecture. Here we resolve this conflict by establishing the feasibility of surface code quantum computing using solid-state spins, or ‘data qubits’, that are widely separated from one another. We use a second set of ‘probe’ spins that are mechanically separate from the data qubits and move in and out of their proximity. The spin dipole–dipole interactions give rise to phase shifts; measuring a probe’s total phase reveals the collective parity of the data qubits along the probe’s path. Using a protocol that balances the systematic errors due to imperfect device fabrication, our detailed simulations show that substantial misalignments can be handled within fault-tolerant operations. We conclude that this simple ‘orbital probe’ architecture overcomes many of the difficulties facing solid-state quantum computing, while minimising the complexity and offering qubit densities that are several orders of magnitude greater than other systems.
Highlights
The problem of scalability remains one of the great challenges facing the development of quantum computers
We specify our main results: the physics we exploit for the parity measurement process: the architecture that can harness this physics; and our detailed numerical simulations establishing the robustness of the device against various kinds of imperfection
We have described a new scheme for implementing surface code quantum computing, based on an array of donor spins in silicon, which can be seen as a reworking of the Kane proposal to where X is the Pauli x operator and 1 is the identity
Summary
The problem of scalability remains one of the great challenges facing the development of quantum computers. The semiconductor revolution enabled a spectacularly successful scaling that has led to today’s highly complex consumer devices. An influential early paper exploring this possibility was written by Kane.[1] According to this proposal, impurity atoms implanted in a pure silicon matrix constitute the means of storing qubits. This proposal proved highly influential, and progress towards realising it has been made both through theoretical work advancing the architecture[2] and at the experimental level, including impurity positioning via STM techniques that have achieved nanometre precision.[3,4] it remains extremely challenging as a path to practical quantum computing
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