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Oxford Quantum Talks Archive

Finding the true flow in measurement-based quantum computation

Ross Duncan, University of Brussels
Flowin'Cat 2010, October 2010, University of Oxford

Is it possible to perform a given measurement-based computation deterministically, or will the inherent randomness of quantum measurements defeat the brave quantum programmer? This question was settled by Browne, Kashefi, Mhalla and Perdrix, who showed that the determinism of an MBQC program depends upon the geometry of the information flow in the underlying quantum state, called the GFlow. Bizarrely, these information flows appear acausal---they are mediated by parts of the resource which have already been consumed. In this talk I will show how, by viewing entangled quantum states as expressions in a certain categorical algebra, we can replace the GFlow with a simple, forwards-in-time-only information flow, and in so doing derive (space)-optimal quantum circuits equivalent to the original program.

[video] [streaming video] [slides]