Quantum control by selective population of dressed states using intense chirped femtosecond laser pulses

The physical mechanism of strong field quantum control using chirped femtosecond laser pulses is investigated. Dressed state control is exerted by making explicit use of the temporal phase changes of the pulse. In our experiment, the dressed state population is mapped by photoelectron spectra from simultaneous excitation and ionization of potassium atoms as a function of the chirp parameter. We show that chirped pulses can be used to selectively steer ground state atoms temporarily into a single dressed state realizing transient Selective Population of Dressed States (SPODS).