Boson samplers offering promise for new kinds of computing devices

While interest remains high in creating a true quantum computer, thus far, real world results have been less than promising. Because of that, some experts in the field have suggested that perhaps what's needed is a new way of looking at the problem. MIT's Scott Aaronson, for example, has suggested that rather than trying to start by building a quantum computer from the ground up, a better approach might be to build specialty devices that solve just one type of problem. He has suggested that a Galton board created using quantum mechanics principles should be possible. In response, several research teams around the globe have been trying to do just that.

Quantum versions of the Galton board take the form of a board that uses photons instead of wooden balls and pegs and are named after the family of particles to which they belong: bosons. The sampling devices work much the same as the Victorian models except in one important way. When a photon in the sampler meets another photon, both must go left, or right – in the real-world physical board, balls can go individually either way on their own. The result should be a device that can calculate far faster than any conventional computer.

Using such a setup, one team, led by Justin Spring, has built a sampler capable of computing the permanent of a matrix. Another led by Matthew Broome, has sent three photons through a maze that describe a 6 node optical circuit.

What's perhaps most compelling about the work being done by all of the teams in this area is the promise of scalability. Not in making the boards or balls bigger, but in making the samplers more and more complex by adding more ways that the photons can be manipulated as they move through the device. Theoretically, doing so offers the promise of a universal computer capable of performing limitless numbers of applications. Whether it will be possible to construct such complex devices in the real world however, remains to be seen.