Single-Photon Quantum Computer Chips Are Scaling Up

Image: ​MIT/Nature
A team of MIT engineers has developed a technique for creating integrated chip-mounted arrays of light detectors with single-photon sensitivity. Moreover, these sensors can be mounted on regular old silicon computer chips using regular old manufacturing processes, opening yet another door in the long hallway toward practical quantum computing.

By Michael Byrne|MOTHERBOARD

To put the achievement into perspective, we need to look at what a photon even is. Sure, it’s a particle of light, but it’s not a “particle of” like anything else. In a sense, it’s the particle; with no mass, it becomes the fastest thing in the universe, setting the cosmic speed limit that governs space and time itself. A photon has no size in any sense that we normally think of “size” (though it’s a frau​ght question), nor does it have most of the properties we usually associate with subatomic particles.

Photons have energy, but are fundamentally neutral. They have no charge themselves, but, at the same time, photons are charge. That is, photons are gauge bosons, a force carrier; in this case, the force is electromagnetism. So, the task is that: detecting a single one of these on a computer chip in such a way that it might be used for information processing, particularly quantum information processing (or just quantum computing).

Photons, compared to other particles, are relatively stable when entangled with other photons. Quantum entanglement is the phenomenon in which multiple distinct particles can inhabit the same state, becoming in some sense the same particle. Add this behavior to the concept of quantum bits or qubits, in which a particle can occupy many states at once, and we have unimaginable, change-everything parallel computing potential.

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