James Clerk Maxwell created a thought experiment in which he came up with a way in which the Second Law of Thermodynamics could be violated – hypothetically, of course. The experiment was dubbed Maxwell’s demon. The idea was that a demon would be opening and shutting a door, allowing faster-moving atoms through, while stopping slower-moving ones.
Now, the experiment isn’t exactly Maxwell’s demon, but it’s close enough as scientists have created a set of optical tweezers out of lasers which they are using to remove rubidium-87 atoms from a cloud and are then shifting the atoms between the tweezers. The scientists in question feel that the experiment will prove useful to developing quantum computers.
To be able to grab the individual atoms they had to slow them down, which they did by cooling a cloud of rubidium-87 atoms to nearly absolute 0. A laser beam was then directed through an optical splitter, where the application of RF waves to a deflector are used to control the angle and number of the resulting beams. The RF emissions are then pulsed and panned to control the laser beams at a microsecond level.
The process was described as being similar to rubbing a comb against wool to charge it up with static electricity and then using it to pick up small bits of paper. The exact same thing happens with the laser beams and the atoms, with the latter being attracted to the former.
The relevancy of the experiment to quantum computers is that the ability to manipulate atoms allows for the induction of quantum gates. Quantum computing will necessitate the retention of quantum gates for quite a fair bit longer than a few seconds, but it’s a definite starting point.
Currently, the majority of quantum computing research has relied on the use of ions for the creation of quantum gates because they can be manipulated using electromagnetism. However, ions pose a problem that you can’t create a dense array using them since like charges repel and unlike charges will result in compounds that have no charge and can no longer be manipulated, which is why they chose to use rubidium-87 atoms, which are more likely to lead to the creation of many persistent quantum gates.