Time-frequency bases for BB84 protocol

The bases traditionally used for quantum key distribution (QKD) are a 0 or pi/2 polarization or alternatively a 0 or pi/2 phase measured by interferometry. We introduce a new set of bases, i.e. pulses sent in either a frequency or time basis if the pulses are assumed to be transform limited. In addition it is discussed how this scheme can be easily generalized from a binary to an N-dimensional system, i.e., to ``quNdits.'' Optimal pulse distribution and the chances for eavesdropping are discussed.