SORDOR pulses: expansion of the Böhlen-Bodenhausen scheme for low-power broadband magnetic resonance

Controlling NMR spin systems for quantum computation

Nuclear magnetic resonance is arguably both the best available quantum technology for implementing simple quantum computing experiments and the worst technology for building large scale quantum computers that has ever been seriously put forward. After a few years of rapid growth, leading to an implementation of Shor's quantum factoring algorithm in a seven-spin system, the field started to reach its natural limits and further progress became challenging. Rather than pursuing more complex algorithms on larger systems, interest has now largely moved into developing techniques for the precise and efficient manipulation of spin states with the aim of developing methods that can be applied in other more scalable technologies and within conventional NMR. However, the user friendliness of NMR implementations means that they remain popular for proof-of-principle demonstrations of simple quantum information protocols.

Analytical solution for the inverting pulses with constant adiabaticity

The exact solution was found for inverting pulses with constant adiabaticity for spin ½. The analytical relationship between the time-varying frequency of the microwave resonant field (or RF field in the case of NMR) and its amplitude time dependence such that the adiabaticity parameter remains constant for the single isochromat throughout the pulse is found. Comparison with EPR (hyperbolic tangent)-(hyperbolic secant) pulse method was carried out. On the basis of the analytical solution the pulses with different dependences of the microwave field amplitude conserving the constant adiabaticity have been constructed. The pulses exhibit rather sharp inversion selectivity that can be used in the field of EPR, NMR and MRI.