In this case, the team made a couple of key variations. The first is that it mostly performed what are called Clifford gates, which are relatively easy to simulate on classical hardware. But it sprinkled in a few non-Clifford gates (specifically T gates) of a specific type chosen in part because they are less prone to error. “Z rotations (including T gates) are special in our hardware: they are implemented by virtual frame tracking and do not add extra noise,” the paper said.
But the T gates also help ensure that this is especially hard to simulate on a classical computer. “It’s got a stronger complexity argument because of
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