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Optimal photons

by Michael Nielsen on May 20, 2005

Optimal photons for quantum information processing, joint with Peter Rohde and Tim Ralph.

Producing single photons is hard work, and there’s no really good single photon sources available, but a plethora of theoretical proposals for sources.

Perhaps somewhat surprisingly, not all photons are created equal. In particular, getting the kind of interference effects necessary for quantum information processing depends a lot on the shape of the wavepacket produced by the source: if you have the wrong shape wavepacket, even a tiny amount of noise may destroy the interference effects. For this reason, it’s important to understand which sources produce photons for which interferenceis stable against the noise.

That’s the subject of this paper. In particular, the main result is to show that for a wide variety of possible applications, Gaussian wavepackets produce the most stable interference effects, with the implication that people designing sources should look for sources which produce Gaussian or near Gaussian wavepackets.

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