Further Feats (and Frustrations) of Quantum Mechanics

Charles Day

When Eric Cornell and Carl Wieman made the first Bose–Einstein condensate from a gas of cold rubidium-87 atoms in 1995, I was excited and impressed. Conceptually, BECs are simple enough to have been included in my undergraduate quantum mechanics course. But making one—what a feat!

H. T. Flint

Frank Boldt, Peter Salamon, Karl Heinz Hoffmann

We discuss fastest effectively adiabatic transitions (FEATs) for a collection of noninteracting harmonic oscillators with shared controllable real frequencies. The construction of such transitions is presented for given initial and final equilibrium states, and the dependence of the minimum time control on the interval of achievable frequencies is discussed. While the FEAT times and associated FEAT processes are important in their own right as optimal controls, the FEAT time is an added feature which provides a measure of the quality of a shortcut to adiabaticity (STA). The FEAT time is evaluated for a previously reported experiment, wherein a cloud of Rb atoms is cooled following a STA recipe that took about twice as long as the FEAT speed limit, a time efficiency of 50%.

Josef Honerkamp

Miya Knights

This paper presents a different kind of computer that will exploit the peculiarities of the quantum world to accomplish number-crunching feats that are currently impossible. The principles by which a quantum computer would work are quite different from those governing today's classical computers. Despite current processor and memory designs already having to take quantum mechanical effects into account, quantum computing is something far stranger.