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

• Published in: New journal of physics Vol. 17; no. 2; pp. 23037 - 7
• Main Author: Li, Ying
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 13-02-2015
• Subjects: Accuracy; Distillation; Error analysis; Fault tolerance; fault tolerant quantum computing; Gates; Hardware; magic state; Mathematical analysis; Physics; Quantum computing; Qubits (quantum computing); Retarding; surface code; Tasks
• ISSN: 1367-2630; 1367-2630
• DOI: 10.1088/1367-2630/17/2/023037

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.