AMO Physics meet chips.
I recently had the pleasure of attending a small workshop on the topic of doing atomic physics on chip-scale apparatus. The presentations and discussions were very interesting, but unfortunately do not lend themselves to a blog report for a couple of reasons. This kind of get-together discusses ongoing projects, some or all of which are not-ready-for-primetime, i.e. things haven’t been written up and published, so I wouldn’t be at liberty to discuss details, and a lot of the really cool stuff was shown in the pictures, some of which also haven’t been published. So while I can’t go into certain details, I can give an overview, and provide some links to representative work that has been published or is otherwise available to the public.
There’s quite a bit of physics that is described as being “tabletop” physics — in part to distinguish it from the physics that requires large collaborations and trips to an accelerator lab, or access to a big telescope or a satellite, etc. However, “tabletop” in atomic physics usually refers to an optical table, which can be a behemoth — an 8′ x 4′ table can weigh 1000 lbs or more. Add to that the requisite optics, optomechanics, vacuum systems and the support electronics, and you still have quite a lot of equipment, and it’s not going to be very portable.
As I had mentioned before, research layouts tend to be bigger than they strictly need to be, in order to provide some flexibility, and you can transition to more compact layouts if you have just one application in mind. If you take the concept a little further, and start thinking of the possibility that you might want an AMO experiment (e.g. a MOT or BEC, or trapped ions) to be applied to some specific problem, and require portability, you have to shrink not only the laser system, but the trap, and everything mentioned above — the vacuum pumps, power supplies and control electronics. Fortunately, a lot of this is coupled: if the trapping volume is decreased you don’t need as much pumping capacity or laser power, so your power demand is also smaller. If you can survive the decrease in signal, you can still go pretty good measurements, though new challenges tend to crop up working close to surfaces rather than far away. Instead of using general-purpose power supplies and electronics, you use devices specifically built for the application. You mount components together, rather than spaced apart, and use fibers rather than mirrors to transport light.