Engineering of an all-heteronuclear 5-qubit NMR quantum computer.

The realization of an all-heteronuclear 5-qubit nuclear magnetic resonance quantum computer is reported, from the design and synthesis of a suitable molecule through the engineering of a prototype 6-channel probe head. Full control over the quantum computer is shown by a benchmark experiment.

Nuclear-magnetic-resonance quantum calculations of the Jones polynomial.

The repertoire of problems theoretically solvable by a quantum computer recently expanded to include the approximate evaluation of knot invariants, specifically the Jones polynomial. The experimental implementation of this evaluation, however, involves many known experimental challenges. Here we present experimental results for small-scale approximate evaluation of the Jones polynomial by nuclear magnetic resonance (NMR); in addition, we show how to escape from the limitations of NMR approaches that employ pseudopure states.

Exploring the limits of electron-nuclear polarization transfer efficiency in three-spin systems.

For three model systems, consisting of one electron spin and two nuclear spins, polarization transfer sequences were optimized using an optimal control based numerical algorithm. This makes it possible to explore the physical limits of achievable nuclear polarization enhancement in such systems. The resulting coherent and incoherent transfer schemes are analyzed and their efficiency is compared with standard DNP approaches.