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

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 minimizes 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 initializations, measurements and single-qubit gates. This approach may dramatically reduce the size of the hardware needed for a given quantum computing task.