A Converse for Fault-tolerant Quantum Computation
- URL: http://arxiv.org/abs/2211.00697v4
- Date: Wed, 9 Aug 2023 07:31:49 GMT
- Title: A Converse for Fault-tolerant Quantum Computation
- Abstract summary: In this paper, we obtain a lower bound on the redundancy required for $epsilon$-accurate implementation of a class of operations that includes unitary operators.
For the practically relevant case of sub-exponential depth and sub-linear gate size, our bound on redundancy is tighter than the known lower bounds.
- Score: 1.2031796234206134
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: As techniques for fault-tolerant quantum computation keep improving, it is
natural to ask: what is the fundamental lower bound on redundancy? In this
paper, we obtain a lower bound on the redundancy required for
$\epsilon$-accurate implementation of a large class of operations that includes
unitary operators. For the practically relevant case of sub-exponential depth
and sub-linear gate size, our bound on redundancy is tighter than the known
lower bounds. We obtain this bound by connecting fault-tolerant computation
with a set of finite blocklength quantum communication problems whose accuracy
requirements satisfy a joint constraint. The lower bound on redundancy obtained
here leads to a strictly smaller upper bound on the noise threshold for
non-degradable noise. Our bound directly extends to the case where noise at the
outputs of a gate are non-i.i.d. but noise across gates are i.i.d.
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