Tyler Shendruk | Fulcrum Staff
QUANTUM MECHANICS IS the strange, alien world of the atomically small. Particles are waves, waves are particles—nothing is what it seems. Even if you take it one step at a time, there’s no certainty. And no matter how far you run, you stay entangled with those you were close to.
Good thing life isn’t like that.
Jacob Krich was recently hired by the University of Ottawa as a researcher of high-efficiency photovoltaics and as an assistant professor in the physics department. Krich studies the ways both organic and inorganic materials can convert light into electricity. He’s a theoretical physicist who is dedicated to working on the world’s energy problem and discovering new sources of renewable energy. One place where humanity could learn a thing or two is how cellular life makes use of quantum mechanics.
Green sulfur bacteria dwell in the dark depths of the ocean. Little light leaks to the ocean floor, so these cells live a poor life, only dividing once every year or so (happy, well-fed E. coli double every 40–50 minutes). Extreme poverty demands extreme efficiency, and green sulfur bacteria evolved to be adept at photosynthesis.
Green sulfur bacteria could be the poster child for quantum biology. A couple of years ago, it was discovered that the chlorophyll structure that acts as the wire between the cell’s little light-antenna and its reaction centre are quantum mechanically coherent.
Quantum coherence is a weird thing. It lets one single photon delocalize. The photon ripples through the chlorophyll wire, taking multiple paths simultaneously (rather than taking one single route, which might be slower or more costly); therefore, the green sulfur bacteria don’t lose time or energy.
But Krich isn’t so sure that there’s an electronic quantum coherence at all.
The early experiments saw oscillations, which are the hallmarks of quantum coherence, but Krich points out that they might not be electrical coherence: they could be the quantum mechanical equivalent to vibrations.
Present experiments can’t tell the difference. Wanting to determine once and for all whether quantum effects are important, Krich proposed an experiment that can discriminate between the two. After being blasted with an extremely short laser pulse, the chlorophyll wire will re-emit light. If the colour of that light is constant and unchanging, then the coherence is electrical; but if it varies, then the coherence is vibrational. Krich says that an experimentalist who can make fast enough laser pulses could immediately tell the difference.
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