Lasing Without Inversion in He and He-like Ions in XUV and X-Ray Regions

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This project is to demonstrate Lasing Without Inversion (LWI) in extreme vacuum ultraviolet (XUV) and X-ray regions. The basis for the project is the recently developed theory of LWI in He atoms at 58 nm and in He-like ions of triply ionized B at 6.1 nm, as transient lasing in a three-level system. The important features of LWI are the coherent control in the XUV and X-ray, and that lasing wavelengths rapidly decrease with increasing Z. Such lasing has common features with Dicke super-radiance, and, hence, can yield strong XUV and X-ray lasing. The quantum coherence phenomenon in atomic and radiation physics has led to many interesting and unexpected consequences. For example, an atomic ensemble prepared in a coherent superposition of states will yield self-induced transparency, photon echo, and coherent Raman beats. By preparing an atomic system in a coherent superposition of states, under certain conditions it is possible for atomic coherence to cancel absorption but not emission, which is the basis for LWI. Frequently, this is accomplished in three- or four-level atomic systems in which there are coherent routes for absorption that can destructively interfere, thus leading to the cancellation of absorption. A small population in the excited state of the system can lead to net gain. Previous LWI studies have been limited primarily to the visible and infrared regions of the spectrum. This is the fist attempt to produce lasing in the XUV and X-ray regions, which are difficult to generate, via LWI. Achieving the proposed LWI for XUV and farther extending it to the X-ray region would provide an excellent "tool" for researchers who need portable, inexpensive coherent XUV and X-ray devices.Ths research will provide an excellent opportunity for teaching and training of graduate students, and also for very advanced undergraduate students. Several of our former graduate students are already accomplished scientists and administrative leaders in the areas of basic laser and plasma theory, experiments, applications of lasers and plasma physics, as well as in computer simulations of experiments and laser applications.