Getting closer ...

Artistic representation of metasurface quantum graphs. Credit: Joshua Mornhinweg

QC, aka Quantum Computing, has been a nightmare to scale due to the inherent fragility of entangled photonic qubits, but there may be a solution at hand if this new approach rings true as the benefits gained with viable QC goes beyond words.

Bloch sphere representation of a qubit. The state  |ψ⟩=α|0⟩+β|1⟩{\displaystyle |\psi \rangle =\alpha |0\rangle +\beta |1\rangle } is a point on the surface of the sphere, partway between the poles, |0⟩{\displaystyle |0\rangle } and |1⟩{\displaystyle |1\rangle }.

The binary version ...

The general definition of a qubit as the quantum state of a two-level quantum system.

To whit.

In the race toward practical quantum computers and networks, photons—fundamental particles of light—hold intriguing possibilities as fast carriers of information at room temperature.

Photons are typically controlled and coaxed into quantum states via waveguides on extended microchips, or through bulky devices built from lenses, mirrors, and beam splitters. The photons become entangled—enabling them to encode and process quantum information in parallel—through complex networks of these optical components. But such systems are notoriously difficult to scale up due to the large numbers and imperfections of parts required to do any meaningful computation or networking.

Could all those optical components be collapsed into a single, flat, ultra-thin array of subwavelength elements that control light in the exact same way, but with far fewer fabricated parts?

Optics researchers in the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) did just that. The research team led by Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, created specially designed metasurfaces—flat devices etched with nanoscale light-manipulating patterns—to act as ultra-thin upgrades for quantum-optical chips and setups.

Tech never sleeps ...