Published online by Cambridge University Press: 01 January 2022
A recent attempt to compute a (recursion-theoretic) noncomputable function using the quantum adiabatic algorithm is criticized and found wanting. Quantum algorithms may outperform classical algorithms in some cases, but so far they retain the classical (recursion-theoretic) notion of computability. A speculation is then offered as to where the putative power of quantum computers may come from.
We thank Itamar Pitowsky, Bill Unruh, Bill Demopoulos, Michael Dickson, and an anonymous referee for helpful comments. We also thank Andrew Hodges for an extensive discussion. Earlier versions of this paper were presented in the European Science Foundation Workshop on Quantum Information (Sardegna, September 2004), the Sigma Club Seminar (London School of Economics, March 2005), and the European Congress for Analytic Philosophy Workshop on Quantum Information (Lisbon, August 2005) and the Foundations of Physics Seminar at the University of Maryland (College Park, October 2005). Hagar is grateful for financial support from the Alexander von Humboldt Foundation, the Federal Ministry of Education and Research, and the Program for the Investment in the Future (ZIP) of the German Government through a Sofja Kovalevskaja Award. Korolev is grateful for financial support from the University of British Columbia Li Tze Fong Memorial Fellowship.