Authors
Craig Gidney, Austin G Fowler
Publication date
2019/4/30
Journal
Quantum
Volume
3
Pages
135
Publisher
Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften
Description
We present magic state factory constructions for producing states and states. For the factory we apply the surface code lattice surgery construction techniques described in [15] to the fault-tolerant Toffoli [21, 12]. The resulting factory has a footprint of (where is the code distance) and produces one every surface code cycles. Our state factory uses the factory's output and a catalyst state to exactly transform one state into two states. It has a footprint smaller than the factory in [15] but outputs states twice as quickly. We show how to generalize the catalyzed transformation to arbitrary phase angles, and note that the case produces a particularly efficient circuit for producing states. Compared to using the factory of [15], our factory can quintuple the speed of algorithms that are dominated by the cost of applying Toffoli gates, including Shor's algorithm [31] and the chemistry algorithm of Babbush et al.[1]. Assuming a physical gate error rate of , our CCZ factory can produce states on average before an error occurs. This is sufficient for classically intractable instantiations of the chemistry algorithm, but for more demanding algorithms such as Shor's algorithm the mean number of states until failure can be increased to by increasing the factory footprint .
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