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.

A novel low-E field coil to minimize heating of biological samples in solid-state multinuclear NMR experiments.

A novel coil, called Z coil, is presented. Its function is to reduce the strong thermal effects produced by rf heating at high frequencies. The results obtained at 500MHz in a 50 microl sample prove that the Z coil can cope with salt concentrations that are one order of magnitude higher than in traditional solenoidal coils. The evaluation of the rf field is performed by numerical analysis based on first principles and by carrying out rf field measurements. Reduction of rf heating is probed with a DMPC/DHPC membrane prepared in buffers of increasing salt concentrations. The intricate correlation that exists between the magnetic and electric field is presented. It is demonstrated that, in a multiply tuned traditional MAS coil, the rf electric field E(1) cannot be reduced without altering the rf magnetic field. Since the detailed distribution differs when changing the coil geometry, a comparison involving the following three distinct designs is discussed: (1) a regular coil of 5.5 turns, (2) a variable pitch coil with the same number of turns, (3) the new Z coil structure. For each of these coils loaded with samples of different salt concentrations, the nutation fields obtained at a certain power level provide a basis to discuss the impact of the dielectric and conductive losses on the rf efficiency.