Large quantum alphabets with a tiny footprint.

High-dimensional quantum states are known to offer advantages over their two-dimensional qubit counterparts, but their preparation and manipulation has been bulky and cumbersome. Now, quantum state control has been demonstrated on-chip with a ~1 μm 2 footprint and nm-scale features, producing up to eight-dimensional quantum states and ushering in a new route to large quantum information encoding on a small footprint.