title: Fault tolerance with noisy and slow measurements and preparation.
abstract: It is not so well known that measurement-free quantum error correction protocols can be designed to achieve fault-tolerant quantum computing. Despite their potential advantages in terms of the relaxation of accuracy, speed, and addressing requirements, they have usually been overlooked since they are expected to yield a very bad threshold. We show that this is not the case. We design fault-tolerant circuits for the 9-qubit Bacon-Shor code and find an error threshold for unitary gates and preparation of p((p,g)thresh)=3.76×10(-5) (30% of the best known result for the same code using measurement) while admitting up to 1/3 error rates for measurements and allocating no constraints on measurement speed. We further show that demanding gate error rates sufficiently below the threshold pushes the preparation threshold up to p((p)thresh)=1/3.
authors.affiliation: Centre for Quantum Computer Technology, Macquarie University, Sydney, NSW 2109, Australia. gerardo.paz-silva@mq.edu.au
authors.forename: Gerardo A
authors.initials: GA
authors.lastname: Paz-Silva
authors.forename: Gavin K
authors.initials: GK
authors.lastname: Brennen
authors.forename: Jason
authors.initials: J
authors.lastname: Twamley