Quantum Interface Between Gamma-Photons - Nuclear Ensembles
The elementary particles or "quanta" of light have a wavelength of about 500 nanometers (less than 20 millionths of an inch). The study of the interaction of these photons with the electrons inside atoms led to development of devices such as lasers, atomic clocks, supersensitive miniature magnetometers, etc. The goal of the present project is to extend these studies to photons of much shorter wavelengths: 10,000 to 100,000 times shorter. These photons, invisible to the naked eye, begin to enter the regime where they are known as "gamma-photons" or "gamma-rays." Rather than interacting with the electrons inside atoms, these high energy photons interact with the nucleus of the atom. Some of the reasons gamma-photons might be better than conventional (optical) photons for applications is that they can be detected more easily, they can be focused to much smaller spots (ultimately limited by the wavelength of the photon), and they can in principle help process information more quickly because of their higher frequencies. A problem is that they are currently very difficult and expensive to produce and hard to control precisely because conventional optical lenses and mirrors do not work at such short wavelengths. This work seeks to advance the development of compact ("table-top") sources of highly controlled gamma-photons, both through experiments and theoretical work. In effect, this work seeks to extend the field of "quantum optics" to wavelengths approaching the gamma-ray regime. If successful, the work may find applications in the areas of quantum information science, spectroscopy, microscopy, metrology, and sensors. The proposed joint theoretical and experimental research program will provide training for graduate and undergraduate students in the emerging field of the experimental and theoretical quantum gamma-optics as well as in the related (and more general) experimental techniques, analytical methods, and numerical modeling. The project is focused on the experimental and theoretical development of methods to coherently control the interaction of gamma-photons with nuclear ensembles via the variation of the resonant frequency of the nuclear transition in the laboratory reference frame. This variation is achieved via the Doppler shift associated with precisely vibrating the solid through which the photon passes. This is used in conjunction with a source of heralded single photons provided by the essentially simultaneous emission of two photons at 122 keV and 14.4 keV via the natural radioactive decay of Cobalt-57. The advantages of nuclear transitions over electronic transitions is that they have narrow, lifetime-broadened spectral linewidths in bulk solids at room temperature (due to the large mass and small size of nucleons, shielding from the environment, and recoilless absorption due to the Mossbauer effect). This results in orders-of-magnitude stronger interaction of the photons with the nuclear ensemble. Progress has been limited, however, by the absence of bright coherent sources and high finesse resonators in the desired short wavelength range. The present work is based on the lead scientist''s recent realization of a table-top source of ultra-short photon sources in the 14.4 keV range with coherent properties, as well as the demonstration of efficient control of single gamma-photon waveforms (F. Vagizov et al., Nature, vol. 508| 3 April 2014, p. 80). The technical and fundamental limitations of the technique as presently developed will be explored and new techniques for the production of short intense pulses and single gamma-photon shaping will be developed. Applications for the controlled single-photon waveforms will be explored in the areas of quantum information science.