A quantum computer is a serious piece of hardware. My colleagues and I build quantum computers from superconducting systems, quantum dots, lasers operating on nonlinear crystals, and the like. Although the part of a quantum computer that actually performs the calculation is too small to be seen even under a microscope, the apparatus used to address and control the quantum computer typically takes up an entire laboratory full of equipment. In order to keep their sensitive components shielded from the environment, many quantum computers have to operate at very low temperatures, sometimes a few thousandths of a degree above absolute zero.
So in the spring of 2007 when the New York Times reported that green sulphur-breathing bacteria were performing quantum computations during photosynthesis, my colleagues and I laughed. We thought it was the most crackpot idea we had heard in a long time. Closer examination of the paper, published in Nature, however, showed that something decidedly non-crackpot was going on.
It's not easy being quantum. Credit: Santiago Ron/Flickr, under a Creative Commons license.
Photosynthesis converts light from the Sun into chemically useful energy inside cells. In photosynthesis, particles of light called photons are absorbed by light-sensitive molecules called chromophores (“light ...