Control landscapes for observable preparation with open quantum systems

A quantum control landscape is defined as a function(al) of the system control variables that are to be optimized, and it was introduced to understand the successes in quantum control experiments. This paper explores the control landscape for observable preparation under the circumstance where the environment has an influence on the quantum system to be controlled. Provided that the open system is fully controllable, the analysis proves that there are no false traps to be encountered on the way to finding the absolute landscape maximum. This provides theoretical support for the observed ease of obtaining high quality controls in the laboratory, and opens up perspectives to develop more efficient quantum control algorithms.