To test the principle, the researchers created a simple two-state bit: a single microscopic silica bead held in a ‘light trap’ by a laser beam. The trap contains two ‘valleys’ where the particle can rest, one representing a 1 and the other a 0. It could jump between the two if the energy ‘hill’ separating them is not too high. The researchers could control this height by changing the power of the laser, and could ‘tilt’ the two valleys to tip the bead into one of them by moving the physical cell containing the bead slightly out of the laser’s focus. By monitoring the position and speed of the particle during a cycle of switching and resetting the bit, they could calculate how much energy was dissipated (abstract http://www.nature.com/nature/journal/v483/n7388/full/nature10872.html). The results safeguard one of the most cherished principles of physical science: the second law of thermodynamics.
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