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Nonlinear and Quantum Optics at X-Ray Wavelengths

Final Report Summary - XRAYQUN (Nonlinear and Quantum Optics at X-Ray Wavelengths)

The main goals of the Marie Curie career integration grant with the acronym “XRAYQUN” were to initiate a quantum and nonlinear at x-ray wavelengths research program in Dr. Sharon Shwartz’s new laboratory at Bar Ilan university and to demonstrate fundamental quantum and nonlinear effects it this regime.
The fields of quantum optics and nonlinear optics at x-ray wavelengths are new emerging fields that offer many exciting new opportunities, which now become possible mainly due to the recent and expected improvements in the x-ray sources. It is important to note that the physical description of nonlinear and quantum effects in the hard x-ray regime have unique features that are substantially different from those associated with nonlinear and quantum processes commonly observed in the optical regime of the spectrum. Indeed, recently, the number of works associated with nonlinear and quantum effects in the x-ray regime, is growing rapidly with many new publications. My group has contributed and led several of the state of the art experiments in the field, and theoretical publications of our group have described and analyzed new effects with x-rays.
The ongoing program is focused on the development of methodology for novel experiments performed at x-ray free-electron lasers and synchrotron facilities and on the establishment of system and techniques for the measurements of nonlinear and quantum effects at x-ray wavelengths in our laboratory.
The central objectives of the proposal are :1) The study of second harmonic generation at x-ray wavelengths in its own right and for applications to the measurement of the temporal structure of the x-ray free-electron laser. 2) Experiments on parametric down-conversion from x-ray to long wavelengths. 3) The demonstration entanglement based effects with x-ray photons

During the first two years of the projects we have developed electronics and mechanics for x-ray coincidence measurements. This equipment is essential for experiments aiming at the demonstration of quantum effects in our laboratory at the large facilities. The equipment has been used in several experiments including the improvement of the signal-to-noise in x-ray parametric down-conversion, in our experiments on quantum ghost imaging, and in our experiments on parametric down conversion of x-rays into visible radiation.
We installed and commissioned an x-ray diffraction system in our laboratory and trained students to perform experiments with it. We have developed a technique for high energy-resolution measurements of the effect of parametric down-conversion of x-rays into ultraviolet radiation in our laboratory.
In addition, my group has shown improvement of almost three orders of magnitude in the measurement of x-ray pairs for the demonstration of quantum effects with x-rays. We have shown theoretically a new nonlinear technique for the measurement of x-rays ultrashort pulses.
In the last two years my group has used the developments of the first two years to demonstrate several fundamental effects. We have conducted experiments in my laboratory and at several x-ray free-electrons laser and storage ring based synchrotron facilities. We have developed the methodology for the measurements of entangled x-ray photons and for the measurements of extremely non-degenerate parametric down-conversion. This progress has led to the results we have accomplished during the project.

The main achievements include the first observation of x-ray parametric down conversion into the visible regime, the first observation of collective effects with x-ray parametric down conversion (both led to papers published in Physical Review Letters).
My group has contributed to the development of a new emerging imaging technique that utilize correlation measurements and known as ghost imaging with x-rays.
More recently, we have demonstrated the effect of quantum imaging with x-rays. This is the first observation of effects that rely on quantum statistics with x-rays and pave the way for conducting advanced experiments in the field of quantum x-ray optics.

Since the beginning of the CIG grant I have published 15 papers in refereed journals (I am the corresponding author), and gave 13 invited talks. My students presented another 5 talks at international conferences.

My group has grown from one graduate student at the beginning of the program to 8 graduate students (4 MSc and 4 PhD), and one engineer, who supports the technical aspects of our experiments and trains new students. We have a fully functional laboratory that supports our experiments. Two PhD and 3 MSC students have been graduated. One of them is now a postdoc at Stanford.

“XRAYQUN” has been very fruitful and the achievements are beyond the initially anticipated. It opens many new possibilities for research with x-rays. I anticipate further advanced experiments on fundamental aspects of quantum effects that will shed new light on old debates and major challenges. The ability to observe extreme non-degenerate parametric down conversion of x-rays is expected to open new possibilities for applications for multidimensional metrology methods that combine spectroscopic and structural information on the atomic scale. These methods will advance the study of new physical effects and has the potential to promote the solution for unsolved challenges in solid-state physics.