He researches decoherence, physics of quantum and classical information, non-equilibrium dynamics of defect generation, and
astrophysics. He is also the co-author, along with
William Wootters and
Dennis Dieks, of a proof stating that a single
quantum cannot be cloned (see the
no-cloning theorem). He also coined the terms
einselection and
quantum discord. Zurek with his colleague
Tom W. B. Kibble pioneered a paradigmatic framework for understanding defect generation in non-equilibrium processes, particularly, for understanding topological defects generated when a second-order phase transition point is crossed at a finite rate. The paradigm covers phenomena of enormous varieties and scales, ranging from structure formation in the early Universe to vortex generation in
superfluids. The key mechanism of critical defect generation is known as the
Kibble–Zurek mechanism, and the resulting scaling laws known as the
Kibble–Zurek scaling laws. He pointed out the fundamental role of environment in determining a set of special basis states immune to environmental decoherence (
pointer basis) which defines a classical measuring apparatus unambiguously. His work on decoherence paves a way towards the understanding of emergence of the classical world from the quantum mechanical one, getting rid of ad hoc demarcations between the two, like the one imposed by
Niels Bohr in the famous
Copenhagen interpretation of
quantum mechanics. The underlying mechanism proposed and developed by Zurek and his collaborators is known as
quantum Darwinism. His work also has a lot of potential benefit to the emerging field of
quantum computing. He is a pioneer in information physics, edited an influential book on "Complexity, Entropy and the Physics of Information", and spearheaded the efforts that finally exorcised
Maxwell's demon. Zurek showed that the demon can extract energy from its environment for "free" as long as it (a) is able to find structure in the environment, and (b) is able to compress this pattern (whereas the remaining code is more succinct than the brute-force description of the structure). In this way the demon can exploit thermal fluctuations. However, he showed that in thermodynamic equilibrium (the most likely state of the environment), the demon can at best break even, even if the information about the environment is compressed. As a result of his exploration, Zurek suggested redefining
entropy and distinguishing between two parts: the part that we already know about the environment (measured in
Kolmogorov complexity), and, conditioned on our knowledge, the remaining uncertainty (measured in
Shannon entropy). ==Honors==