Biomedical subjects

Dieter Suter

Publications and source records attributed to Dieter Suter.

5 recordsLinked to original sources

PubMed2006

Reduced decoherence in large quantum registers.

Among the biggest obstacles for building larger (and thus more powerful) quantum-information processors is decoherence, the decay of quantum-information by the coupling between the quantum register and its environment. Procedures for reducing decoherence processes will be essential for successful operation of larger quantum processors. We study model quantum registers consisting of up to 4900 qubits and measure their decay as a function of the register size. We demonstrate that appropriate sequences of qubit rotations reduce the coupling between system and environment for all sizes of the quantum register, thus preserving the quantum-information 50 times longer than without decoupling.

Journal Article↗

PubMed2006

Adding salt to an aqueous solution of t-butanol: is hydrophobic association enhanced or reduced?

Recent neutron scattering experiments on aqueous salt solutions of amphiphilic t-butanol by Bowron and Finney [Phys. Rev. Lett. 89, 215508 (2002); J. Chem. Phys. 118, 8357 (2003)] suggest the formation of t-butanol pairs, bridged by a chloride ion via O-H...Cl- hydrogen bonds, leading to a reduced number of intermolecular hydrophobic butanol-butanol contacts. Here we present a joint experimental/theoretical study on the same system, using a combination of molecular dynamics (MD) simulations and nuclear magnetic relaxation measurements. Both MD simulation and experiment clearly support the more classical scenario of an enhanced number of hydrophobic contacts in the presence of salt, as it would be expected for purely hydrophobic solutes. [T. Ghosh et al., J. Phys. Chem. B 107, 612 (2003)]. Although our conclusions arrive at a structurally completely distinct scenario, the molecular dynamics simulation results are within the experimental error bars of the Bowron and Finney data.

Journal Article↗

PubMed2004

Scaling of decoherence in wide NMR quantum registers.

Among the most important parameters for the usefulness of quantum computers are the size of the quantum register and the decoherence time for the quantum information. The decoherence time is expected to get shorter with the number of correlated qubits, but experimental data are only available for small numbers of qubits. Solid-state nuclear magnetic resonance allows one to correlate large numbers of qubits (several hundred) and measure their decoherence rates. We use a modified magnetic dipole-dipole interaction to correlate the proton spins in a solid sample and observe the decay of the resulting highly correlated states. By systematically varying the number of correlated spins, we measure the increase of the decoherence rate with the size of the quantum register.

Journal Article↗

PubMed2004

Pulsed optically detected NMR of single GaAs/AlGaAs quantum wells.

While nuclear magnetic resonance (NMR) is one of the most important experimental tools for the analysis of bulk materials, the low sensitivity of conventional NMR makes it unsuitable for the investigation of small structures. We introduce an experimental scheme that makes NMR spectra of single, nanometer-sized quantum wells possible with excellent sensitivity and selectivity while avoiding the spectral broadening associated with some alternative techniques. The scheme combines optical pumping and pulsed radiofrequency excitation of the nuclei with time-resolved detection of the free induction decay through the polarization of the photoluminescence.

Aluminum Compounds↗

PubMed2002

Trends and random fluctuations in athletics.

Improvements in the results of athletic competitions are often considered to stem from better training and equipment, but elements of chance are always present in athletics and these also contribute. Here we distinguish between these two effects by estimating the range into which athletic records would have fallen in the absence of systematic progress and then comparing this with actual performance results. We find that only 4 out of 22 disciplines have shown a systematic improvement, and that annual best results worldwide show saturation in some disciplines.

Germany↗