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unitaryfund / qrack

Comprehensive, GPU accelerated framework for developing universal virtual quantum processors
https://qrack.readthedocs.io/en/latest/
GNU Lesser General Public License v3.0
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Measurement and control qubits commute #804

Closed WrathfulSpatula closed 3 years ago

WrathfulSpatula commented 3 years ago

I need a citation for this, as I recall reading it in passing, (that control and measurement commute,) but, for the life of me at the moment, I cannot recall the specific source in which I read it. Tested here, also in Q# unit tests, it seems to work, as would make sense. I'm sorry for that.

Think of a quantum control bit as acting in a superposition of |0> and |1>. Measurement, whether immediately before or after the controlled operation, collapses into one or the other, being the same as applying the controlled operation on either side of measurement, (though non-unitary).

WrathfulSpatula commented 3 years ago

With that, said, merging.

WrathfulSpatula commented 3 years ago

(Found on pg. 6 of this, and it's colloquially well-known: https://arxiv.org/abs/1110.2998)