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Quantum parallelism of the controlled-NOT operation: an experimental criterion for the evaluation of device performance

Holger F. Hofmann
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Abstract

It is shown that a quantum controlled-NOT gate simultaneously performs the logical functions of three distinct conditional local operations. Each of these local operations can be verified by measuring a corresponding truth table of four local inputs and four local outputs. The quantum parallelism of the gate can then be observed directly in a set of three simple experimental tests, each of which has a clear intuitive interpretation in terms of classical logical operations. Specifically, quantum parallelism is achieved if the average fidelity of the three classical operations exceeds 2/3. It is thus possible to evaluate the essential quantum parallelism of an experimental controlled-NOT gate by testing only three characteristic classical operations performed by the gate.

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Holger F. Hofmann. 2005-04-21. Quantum parallelism of the controlled-NOT operation: an experimental criterion for the evaluation of device performance. https://doi.org/10.1103/physreva.72.022329

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