The second day of the “Quantum Boot Camp” was much lighter on talks. The only speaker was Ray Laflamme from the Institute for Quantum Computing in Waterloo, who gave a nice introduction to quantum technologies. While he did spend a bit of time at the start going through Shor’s algorithm for factoring numbers (following up a discussion from Wednesday), he mostly focused on ways to use quantum physics to improve sensors of technological interest.

So, for example, he talked about how efforts to develop techniques for error-correcting codes in liquid state NMR quantum computing led to the development of better sensors for drilling oil wells. The techniques needed to protect against inhomogeneities during information processing also help pick out small signals when doing NMR of rocks outside a potential oil well, to help determine the composition and porosity of the rock. It’s a nice example of indirect benefits of basic research. He also talked about using nitrogen vacancies in diamond for magnetic sensing, another very promising application of quantum effects to problems that aren’t the factoring of large numbers. Ray also brought items to pass around: a chip with some superconducting qubits on it, and a small piece of artificial diamond with NV centers. Those were a big hit.

In the afternoon, we got a tour of the quantum optics labs at KTH, from Mohamed Bourennane, who had the group do a Bell’s Inequality test with down-converted photons. The lasers and detectors were all set up, but he had visitors change the detector settings to do the necessary measurements; the tour group I was part of got close to the maximum possible violation of the local hidden variable limit (2.7 out of 2.828…), so quantum worked really well for us.

The last session of the day was a fairly wide-ranging discussion of issues with communicating quantum mechanics to the general public, which mostly talked about whether people who wrte about quantum over-emphasize the weirder aspects. The problem, of course, is that weirdness sells, and it’s hard to find the right balance between mentioning enough of the exotic aspects to draw people in without being gratuitously confusing. At one point, I felt compelled to channel Matt Leifer and speak up for the importance of thinking about quantum interpretations (on the grounds that particular views of what’s “really” going on with the math can be helpful in suggesting particular lines of experiment that wouldn’t seem productive to people favoring a different interpretation). So if reality felt a little wobbly yesterday afternoon, that’s probably my fault…

We didn’t come up with any foolproof solutions, alas, but it was a fun discussion. My talk is the middle of three today, so I’m likely to be a bit distracted for the morning session. Especially since I just thought of a joke I need to add to my slides…