This year’s Nobel Prize in Physics was awarded to Serge Haroche and David Wineland for their work in the experimental measurement of quantum systems. The official announcement might make the area of their work seem rather vague and a cursory glance at the two laureate’s work could lead someone to believe that this award was for work in a similar, but somewhat unrelated area. This is most certainly not the case. The work of Haroche and Wineland has enabled experimental investigation of quantum computing. The field of quantum computing was itself postulated in 1982 by another Nobel physics laureate, Richard Feynman, and has the potential to change the way we think about computing and the processing of information.
Dr. Haroche’s groundbreaking work, published in 1996, showed experimentally that quantum systems “leaked” information to their environment, which was heralded as the explanation for wavefunction collapse, and the implications for that decoherence on the measurement of the quantum state. To simplify it, think back to the classic gedaken experiment about Schrodinger’s cat. In this experiment, the animal’s survival is predicated on the decay of a single atom, which is a quantum event. We then say that the animal must be in a superposition of the two states labelled “alive” and “dead.” Quantum decoherence is the process by which the observed wave function collapses into a classical state, or in the cat-model, how the system falls back into the cat being either alive or dead. Haroche’s key paper (Phys. Rev. Lett. 77, 4887) provided key insight into this process of measurement and posited that quantum decoherence is the boundary between classical and quantum behavior that is reached when the quantum system interacts with its environment.
Dr. Wineland, both a Rabi Award and National Medal of Science winner, used quantum systems of trapped ions to perform computations, pulling together and building on the Nobel prize winning work of Wolfgang Paul (ion trapping, 1989), Steven Chu, Claude Cohen-Tannoudji, and William Phillips (laser cooling of atoms, 1997) and Haroche’s work to show that entangled quantum systems could be made to process information and then that the processed information could be retrieved reliably. While quantum computing is in a relative infancy, Wineland’s early work in the area also enabled more precise atomic clocks and made the global positioning system possible.