Scheme of constructing three-qubit quantum logic gates.

Quantum Fredkin and Toffoli gates on a versatile programmable silicon photonic chip

This research demonstrates a groundbreaking implementation of three-qubit Fredkin and Toffoli gates on a programmable quantum photonic chip, overcoming previous limitations of pre-entangled input states and bulk optics systems by using controlled Mach-Zehnder interferometers to enable independent input photons, marking a significant advance toward scalable quantum processors.