Techniques for using chirped fields to reconfigure a medium that stores spectral features

Abstract

Techniques for reconfiguring spectral features stored in a medium based on a two-state atomic system with transition dipole moment μ includes causing a chirp to pass into the medium. The chirp includes a monochromatic frequency that varies in time by a chirp rate κ over a frequency band BR during a time interval TR. The amplitude AR of the chirp is constant over BR and equal to AR=(hbar / μπ)√{square root over ((κ ln [2 / ε]))}, The term hbar is reduced 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. For ε<<1, the atomic-state populations in the two states are inverted. For ε=1, prior atomic-state populations are erased, with final populations equal in the two states, regardless of populations before erasure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit of Provisional Appln. 60 / 699,477, filed Jul. 15, 2005, the entire contents of which are hereby incorporated by reference as if fully set forth herein, under 35 U.S.C. §119(e).STATEMENT OF GOVERNMENTAL INTEREST [0002] This invention was made with Government support under Contract Nos. MDA-972-03-1-0002 awarded by the Defense Advanced Research Projects Agency and NRO-DII-000-03-C-0312 awarded by the National Reconnaissance Office. The Government has certain rights in the invention.BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates to configuring a medium with a two-state atomic system that stores spectra at electromagnetic frequencies, and, in particular, to the use of a chirped field to erase or invert spectra already stored in the medium. [0005] 2. Description of the Related Art [0006] Information processing based on optical analog signal processing promises ...

AI Technical Summary

Benefits of technology

[0019] Techniques are provided for reconfiguring spectral features in a medium using a chirped electromagnetic field. These techniques allow for erasure or inversion or both and enable faster OCT and NMR processing as well as adjustable integrated absorption of a material in selectable frequency bands and selectable spatial portions of the medium.

[0031] In various embodiments, these population reconfiguration techniques enable a medium to be erased and reused in a shorter time than population decay, even when the stored spectrum is unknown.

Problems solved by technology

A disadvantage of this approach is that decay is typically exponential and requires waiting very long times, compared to desirable processing rates, to effectively return the population to the ground state.

A disadvantage of this approach is that it takes substantial energy.

Another disadvantage is that it takes a long time to decay to a desired population distribution, even to equal populations in both states.

A disadvantage of this approach is that the spectral content already stored in the medium must be known well.

Another disadvantage is that perfect cancellation is not possible due to non-linearities and population decay.

However, no publication known to applicants has addressed inversion of frequency-dependent populations; publications have only addressed uniform populations.

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