Patent ID: 7307781

Claim:
A method for erasing spectral features stored in a medium based on a two-state atomic system having a transition dipole moment of μ, in which an atom transitions between a first state and a second state, comprising the step of causing a chirped electromagnetic field to pass into the medium: varying a monochromatic frequency of the chirped electromagnetic field in time by a chirp rate κ over an erasure frequency band of bandwidth B E during an erasure time interval T E ; wherein an amplitude A E of the electromagnetic field oscillations in the chirped electromagnetic field over the erasure frequency band is substantively constant and substantively specified by an equation of form A E =( h bar/μπ)√{square root over ((κ ln 2))}, in which hbar is Plank's constant, ln is a natural logarithm function, and π is a ratio of a circumference of a circle to a diameter of the circle, whereby substantively fifty percent of the two-state atomic system responsive in the erasure frequency band exposed to the chirped electromagnetic field is in the first state after erasure regardless of a percentage in the first state before erasure.