lectrical charge is the key to modern computing. We can generate, detect, and control current with accuracy and precision. As we contemplate a world of quantum computing, it's important to note researchers have not really coalesced around an equivalent basic architecture. Each architecture we've looked at has a set of disadvantages that are sufficient to keep all the other architectures alive despite their problems.
This is true for optical quantum computers. They require single photons, and sources that generate single photons kind of... well, suck. Ideally, what we want is a device that generates single photons on demand. To put not too fine a point on it, at the press of a button, we want an electrical current to reliably generate a single photon. And, while we haven't had it, it's exactly what a group of researchers from Germany is now claiming to have accomplished.
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