A magic state's fidelity can be superior to the operations that created it

TL;DR

This paper demonstrates that raw magic states can have higher fidelity than the two-qubit gates used to produce them, potentially reducing hardware requirements for fault-tolerant quantum computing.

Contribution

The authors introduce a protocol that uses post-selection to produce high-fidelity magic states directly, tolerating finite errors and reducing the need for extensive distillation.

Findings

Raw magic states can surpass the fidelity of their generating gates.

Post-selection enables high-fidelity magic states without slowing generation.

The approach tolerates errors in initializations, measurements, and single-qubit gates.

Abstract

The leading approach to fault tolerant quantum computing requires a continual supply of magic states. When a new magic state is first encoded, its initial fidelity will be too poor for use in the computation. This necessitates a resource-intensive distillation process that occupies the majority of the computer's hardware; creating magic states with a high initial fidelity minimises this cost and is therefore crucial for practical quantum computing. Here we present the surprising and encouraging result that raw magic states can have a fidelity significantly better than that of the two-qubit gate operations used to construct them. Our protocol exploits post-selection without significantly slowing the rate of generation and tolerates finite error rates in initialisations, measurements and single-qubit gates. This approach may dramatically reduce the size of the hardware needed for a given quantum computing task.