Uncomputation
![Creating a Not gate with five controls out of Toffoli gates and ancilla bits. Uncomputation is used to restore the ancilla bits to the OFF state before finishing.](/Images/godic/202502/18/Using_Toffoli_Gates_and_Ancilla_Bits_to_make_a_Not_Gate_with_many_controls1725.png")
Uncomputation is a technique, used in reversible circuits, for cleaning up temporary side effects on ancilla bits so they can be re-used.
Uncomputation is important to quantum computing. Whether or not intermediate effects have been uncomputed affects how states interfere with each other when measuring results.