Physics of life: The dawn of quantum biology (hat tip to Steve Kurtz)
The key to practical quantum computing and high-efficiency solar cells may lie in the messy green world outside the physics lab.
On the face of it, quantum effects and living organisms seem to occupy utterly different realms. The former are usually observed only on the nanometre scale, surrounded by hard vacuum, ultra-low temperatures and a tightly controlled laboratory environment. The latter inhabit a macroscopic world that is warm, messy and anything but controlled. A quantum phenomenon such as 'coherence', in which the wave patterns of every part of a system stay in step, wouldn't last a microsecond in the tumultuous realm of the cell.
Or so everyone thought. But discoveries in recent years suggest that nature knows a few tricks that physicists don't: coherent quantum processes may well be ubiquitous in the natural world.
Robert Blankenship, a photosynthesis researcher at Washington University in St Louis, Missouri, and a co-author with Fleming on the C. tepidium paper, admits to some scepticism. "My sense is that there may well be a few cases, like the ones we know about already, where these effects are important," he says, "but that many, if not most, biological systems will not utilize quantum effects like these." But Scholes believes that there are grounds for optimism, given a suitably broad definition of quantum biology. "I do think there are other examples in biology where an understanding at the quantum-mechanical level will help us to appreciate more deeply how the process works," he says.
Quantum coherence in photosynthesis seems to be beneficial to the organisms using it. But did their ability to exploit quantum effects evolve through natural selection? Or is quantum coherence just an accidental side effect of the way certain molecules are structured? "There is a lot of speculation about the evolutionary question, and a lot of misunderstanding," says Scholes, who is far from sure about the answer. "We cannot tell if this effect in photosynthesis is selected for, nor if there is the option not to use coherence to move the electronic energy. There are no data available at all even to address the question."