title: Coherent population trapping in two-electron three-level systems with aligned spins.
abstract: The possibility of coherent population trapping in two electron states with aligned spins (orthosystem) is evidenced. From the analysis of a three-level atomic system containing two electrons, and driven by the two laser fields needed for coherent population trapping, a conceptually new kind of dark state appears. The properties of this trapping are physically interpreted in terms of a dark hole, instead of a dark two-electron state. This technique, among many other applications, offers the possibility of measuring, with subnatural resolution, some superposition-state matrix elements of the electron-electron correlation that due to their time dependent nature are inaccessible by standard measuring procedures.
authors.affiliation: Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Mompart
authors.forename: Ramon
authors.initials: R
authors.lastname: Corbalan
authors.forename: Luis
authors.initials: L
authors.lastname: Roso