A radical demonstration of quantum theory could see a bacterium suspended in an uncertain state similar to that famously endured by Schrödinger’s cat

Physicists have drawn up plans to put a living organism in two places at once in a radical demonstration of quantum theory.

The scientists aim to suspend a common microbe in an uncertain state similar to that endured by Schrödinger’s cat, which is portrayed in the Nobel laureate’s famous thought experiment as dead and alive at the same time.

But instead of harnessing the bizarre laws of the quantum world to hold a hapless bacterium in limbo, the uncertainty will centre on the bug’s geographical whereabouts.



“It is cool to put an organism in two different locations at the same time,” Tongcang Li of Purdue University, Indiana, told the Guardian.



“In many fairy tales, a fairy could be at two different locations or change locations instantly. This will be similar to that. Although it will be a microbe instead of a fairy,” he added. His team is working with Zhang-Qi Yin at the Centre for Quantum Information at Tsinghua University in Beijing.



The rules of quantum mechanics allow for objects to be in a “superposition” of two different states at once. The principle forms the bedrock of hopes to develop powerful quantum computers that can work on several problems simultaneously.

Erwin Schrödinger, one of the founding fathers of quantum theory, proposed his thought experiment in 1935. In it, a cat found itself in a closed box with a small radioactive source, a Geiger counter, a hammer and a small bottle of poison.

Schrodinger explained that if an atom of the radioactive source decayed, the Geiger counter would trigger a device to release the poison. In quantum mechanics, the state of the cat would then be “entangled” with the state of the radioactive material. In due course, the cat would be in a superposition of both alive and dead states.

“Although it has attracted enormous interest, no quantum superposition state of an organism has been realized. So we propose a straightforward approach to put a microbe into a superposition of two spatial states, that is, the microbe will be at two different positions at the same time,” Dr Li said.



“It will be the first experiment to put an organism into a quantum superposition state,” he added. Details of the study appear on a website where scientists post papers before they are published.



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.

