Unitary control in quantum ensembles: maximizing signal intensity in coherent spectroscopy
Experiments in coherent magnetic resonance, microwave, and optical spectroscopy control quantum-mechanical ensembles by guiding them from initial states toward target states by unitary transformation. Often, the coherences detected as signals are represented by a non-Hermitian operator. Hence, spectroscopic experiments, such as those used in nuclear magnetic resonance, correspond to unitary transformations between operators that in general are not Hermitian. A gradient-based systematic procedure for optimizing these transformations is described that finds the largest projection of a transformed initial operator onto the target operator and, thus, the maximum spectroscopic signal. This method can also be used in applied mathematics and control theory.
Glaser
SJ
S. J. Glaser, O. Schedletzky, C. Griesinger, Institut fur Organische Chemie, J. W. Goethe-Universitat, Marie-Curie-Strasse 11, D-60439 Frankfurt, Germany. T. Schulte-Herbruggen, Laboratorium fur Physikalische Chemie, ETH Zentrum, CH-809.
Schulte-Herbruggen
T
Sieveking
M
Schedletzky
O
Nielsen
NC
Sorensen
OW
Griesinger
C