Quantum mechanics describes the world of the invisibly small, from subatomic particles at the tiniest scale, to complex molecules at the largest. On the other hand, our everyday, macro-scale world is governed by classical laws of nature, with none of the strangeness and often contradictory nature of the quantum realm. But where exactly is the dividing line between the quantum and classical worlds, and does it make sense to talk of such a discontinuity?
To test for quantum behaviour in relatively large and complex entities, physicists in Germany and Spain are using the principles behind the thought experiment known as Schrödinger’s cat on objects composed of as many as a billion atoms, including the ’flu virus. In particular, the researchers are looking to determine whether such macroscale objects can exist in more than one physical state at a time (superposition), or be connected with each other even when separated in space (entanglement).
Oriol Romero-Isart and his colleagues say that their study of the quantum properties of viruses could help in understanding the role of life and consciousness in quantum mechanics, and no doubt vice versa. In recent years the study of consciousness has moved beyond the often abstract and academic philosophy of mind, and now takes in psychology, neuroscience, artificial intelligence, and quantum physics and chemistry.
The latest work is at an early stage, and in their New Journal of Physics article Romero-Isart and his fellow theoretical physicists describe a method for manipulating small living organisms such as viruses into superposed and entangled quantum states. The biggest challenge will be to extend the proposed technique to objects larger than the wavelength of light used to probe them:
“This would permit us to bring larger and more complex living organisms to the quantum realm, for instance, the Tardigrade, which have a size ranging from 100 μm to 1.5 mm and is known to survive for several days in open space.”
Further reading: Oriol Romero-Isart et al., “Toward quantum superposition of living organisms”, New Journal of Physics 12, 033015 (2010)