Walkthrough ‐ Quantum II.D: Drive‐by AND

Learning Objectives

• The player is challenged produce the quantum equivalent of an AND gate (also known as the Toffoli gate).
• This task is significantly more difficult than producing the classical AND gate; this follows since the quantum version needs to be reversible while the classical version does not.
• A key difference from the classical AND gate is that the qubits in the initial two channels must be returned to their original states, with the result stored in a separate third channel. This usage of a third channel is necessary in order to realize the AND gate while allowing the full circuit to be reversible.

Solution

The solution here follows the Sleator-Weinfurter construction:

1. Controlled rotations of +90° are performed from A to α and from from B to α.
2. A controlled rotation of -90° is performed from A XOR B to α.

Level File (copy then paste into Qubit Factory)

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