BOUND-STATES AND TRANSMISSION ANTIRESONANCES IN PARABOLICALLY CONFINED CROSS STRUCTURES - INFLUENCE OF WEAK MAGNETIC-FIELDS

The ballistic conductance through a device consisting of quantum wires , to which two stubs are attached laterally, is calculated assuming pa rabolic confining potentials of frequencies omega(w) for the wires and omega(s) for the stubs. As a function of the ratio omega(w)/omega(s) the conductance shows nearly periodic minima associated with quasiboun d states forming in the stubbed region. Applying a magnetic field B no rmal to the plane of the device changes the symmetry of the wave funct ions with respect to the center of the wires and leads to new quasibou nd states in the stubs. The presence of the magnetic field can also le ad to a second kind of state, trapped mainly in the wires by the corne rs of the confining potentials, that yields conductance minima as well . In either case, these bound states form for weak B and strong confin ing frequencies and thus are nor edge states. Finally, we show experim ental evidence for the presence of these quasibound states.