Scientific American reveals how some strange research is bringing the weirdness of the subatomic world – where things can be (more or less) in two places at once – into living systems:
No one has ever witnessed a star, a planet or a cat in superposition or a state of quantum entanglement. But ever since quantum theory’s initial formulation in the early 20th century, scientists have wondered where exactly the microscopic and macroscopic worlds cross over. Just how big can the quantum realm be, and could it ever be big enough for its weirdest aspects to intimately, clearly influence living things? Across the past two decades the emergent field of quantum biology has sought answers for such questions, proposing and performing experiments on living organisms that could probe the limits of quantum theory.
So a new paper from a group at the University of Oxford is now raising some eyebrows for its claims of the successful entanglement of bacteria with photons—particles of light. Led by the quantum physicist Chiara Marletto and published in October in the Journal of Physics Communications, the study is an analysis of an experiment conducted in 2016 by David Coles from the University of Sheffield and his colleagues. In that experiment Coles and company sequestered several hundred photosynthetic green sulfur bacteria between two mirrors, progressively shrinking the gap between the mirrors down to a few hundred nanometers—less than the width of a human hair. By bouncing white light between the mirrors, the researchers hoped to cause the photosynthetic molecules within the bacteria to couple—or interact—with the cavity, essentially meaning the bacteria would continuously absorb, emit and reabsorb the bouncing photons. The experiment was successful; up to six bacteria did appear to couple in this manner.
Marletto and her colleagues argue the bacteria did more than just couple with the cavity, though. In their analysis they demonstrate the energy signature produced in the experiment could be consistent with the bacteria’s photosynthetic systems becoming entangled with the light inside the cavity. In essence, it appears certain photons were simultaneously hitting and missing photosynthetic molecules within the bacteria—a hallmark of entanglement.
According to study co-author Tristan Farrow, also of Oxford, this is the first time such an effect has been glimpsed in a living organism. “It certainly is key to demonstrating that we are some way toward the idea of a ‘Schrödinger’s bacterium,’ if you will,” he says. And it hints at another potential instance of naturally emerging quantum biology: Green sulfur bacteria reside in the deep ocean where the scarcity of life-giving light might even spur quantum-mechanical evolutionary adaptations to boost photosynthesis.