Okay, this is WAY above my pay grade, but I’ve been sent articles on this by several authors, including an explanation at the Guardian. It’s a description by two theoretical physicists of an experiment that uses quantum superposition to put a bacterium in two places at the same time. They plan to collaborate with experimentalists to actually carry it out. Here’s what the Guardian says about it:
The researchers plan to build on the work of others at the University of Colorado who showed in 2013 that a tiny, vibrating aluminium membrane could be placed in a superposition of states.
“We propose to simply put a small microbe on top of the aluminum membrane. The microbe will also be in a superposition state when the aluminum membrane is in a superposition state. The principle is quite simple,” Dr Li said.
The researchers plan to go one step further in a second experiment that would entangle the position of the microbe with the spin of an electron inside it. “The purpose of the second experiment is to make the system useful. It can be used to detect defects of DNA and proteins in a microbe, and image the microbe with single electron spin sensitivity,” Dr Li said.
Li said he hoped to conduct the experiment, but that leading scientists in the field had laboratories better equipped to take the project on, and that he hoped to collaborate with them. “If the top group in quantum electromechanics want to focus on doing this experiment, I think a microbe could be put into a superposition state in three years,” he said.
The experiment is proposed in a paper by Tongcang Li and Zhang-Qi Yin (full pdf here) placed at ArXiv before publication. The abstract:
Schrödinger’s thought experiment to prepare a cat in a superposition of both alive and dead states reveals profound consequences of quantum mechanics and has attracted enormous interests. Here we propose a straightforward method to create quantum superposition states of a living microorganism by putting a small bacterium on top of an electromechanical oscillator. Our proposal is based on recent developments that the center-of-mass oscillation of a 15-μm-diameter aluminium membrane has been cooled to its quantum ground state [Nature 475, 359 (2011)], and entangled with a microwave field [Science, 342, 710 (2013)]. A microorganism with a mass much smaller than the mass of the electromechanical membrane will not significantly affect the quality factor of the membrane and can be cooled to the quantum ground state together with the membrane. Quantum superposition and teleportation of its center-of-mass motion state can be realized with the help of superconducting microwave circuits. More importantly, the internal states of a microorganism, such as the electron spin of a glycine radical, can be prepared in a quantum superposition state and entangled with its center-of-mass motion. Our proposal can be realized with state-of-art technologies. The proposed setup is also a quantum-limited magnetic resonance force microscope (MRFM) that not only can detect the existence of an electron spin, but also can coherently manipulate and detect the quantum state of the spin.
And here’s the diagram of the experiment from the paper:
Because this is all beyond my ken, I asked Official Website Physicist™ Sean Carroll for a comment on the feasibility of the experiment. (Note that Sean is giving the famous Gifford Lectures next year and has an intriguing Book on Everything coming out next May). His take:
As far as Schrödinger’s microbe is concerned — there’s no problem in principle, though I am quite dubious in practice. Quantum mechanics says that things can be in superpositions of different locations, and everything in the world (including bacteria) is governed by the rules of quantum mechanics, so it’s certainly conceivable.The problem is that to count as a “superposition” you need to keep the system unentangled from the rest of the world — once the thing interacts with the environment, the superposition branches the whole wave function of the universe (the phenomenon known as “decoherence”). That’s why we can’t even imagine doing it for real cats; they’re always breathing and radiating heat and so forth, thereby interacting with their environments. It seems to me that the same would be true for a bacterium, or anything else that we would qualify as “alive” — unless you were talking about very short time periods indeed. (I’d be much less skeptical if it were a freeze-dried bacterium.) Note that the paper is a theoretical proposal, not an experimental result.
