Quantum Zeno Effect - Significance To Cognitive Science

Significance To Cognitive Science

The quantum Zeno effect (with its own controversies related to the problem of measurement) is becoming a central concept in the exploration of controversial theories of quantum mind consciousness within the discipline of cognitive science. In his book Mindful Universe (2007), Henry Stapp claims that the mind holds the brain in a superposition of states using the quantum Zeno effect. He advances that this phenomenon is the principal method by which the conscious can effect change, a possible solution to the mind-body dichotomy. Stapp and co-workers do not claim finality of their theory, but only:

The new framework, unlike its classic-physics-based predecessor, is erected directly upon, and is compatible with, the prevailing principles of physics.

Needless to say, such conjectures have their opponents, serving perhaps to create more furor, rather than less, for example, see Bourget. Recent work criticizes Stapp's model in two aspects: (1) The mind in Stapp's model does not have its own wavefunction or density matrix, but nevertheless can act upon the brain using projection operators. Such usage is not compatible with standard quantum mechanics because one can attach any number of ghostly minds to any point in space that act upon physical quantum systems with any projection operators. Therefore Stapp's model does not build upon "the prevailing principles of physics", but negates them. (2) Stapp's claim that quantum Zeno effect is robust against environmental decoherence directly contradicts a basic theorem in quantum information theory according to which acting with projection operators upon the density matrix of a quantum system can never decrease the Von Neumann entropy of the system, but can only increase it. Indeed, already in 1993 it was shown by M. J. Gagen and colleagues that the quantum Zeno effect is easily destroyed by noise and that a two-level system becomes a "random telegraph", i.e. the evolution of the system is not suppressed as required for quantum Zeno effect, instead the system jumps randomly between the two states.

A summary of the situation is provided by Davies:

There have been many claims that quantum mechanics plays a key role in the origin and/or operation of biological organisms, beyond merely providing the basis for the shapes and sizes of biological molecules and their chemical affinities.…The case for quantum biology remains one of “not proven.” There are many suggestive experiments and lines of argument indicating that some biological functions operate close to, or within, the quantum regime, but as yet no clear-cut example has been presented of non-trivial quantum effects at work in a key biological process.

The significance of the Zeno effect in determining the rate of quantum decoherence in biological systems remains unknown.