Research and Development of Multichannel Optical Memory and Photon Echo-Processor Based on the Optical Transient Processes in Extended Resonance Media Cooled by Laser Radiation
Tech Area / Field
- PHY-OPL/Optics and Lasers/Physics
8 Project completed
Senior Project Manager
Science and Production Center "State Institute of Applied Optics", Russia, Tatarstan, Kazan
- Russian Academy of Sciences / Kazan Physical-Technical Institute, Russia, Tatarstan, Kazan
- University of Kent at Canterbury / Schoool of Physical Sciences, UK, Canterbury\nInstitute fur Physik der Kondensieren Materie, Germany, Düsseldorf\nCNRS, France, Paris\nUniversity of Kent at Canterbury, UK, Canterbury\nLund Institute of Technology
- Department of Physics, Sweden, Lund\nJenoptik AG, Germany, Jena\nUS Naval Academy, USA, MD, Annapolis
Project summaryThe goal of project is the development and creation of photon-echo model sample based on crystals and lightguides doped by rare-earth ions.
Participants of presented project have got a sufficient experience during the fulfillment of project No.737 in the experimental and theoretical investigation of solid media by methods of photon echo and optical superradiance. Optical superradiance was first time observed in crystals doped by rare-earth ions. Fiber-optic setup is constructed for observation of photon echo using fiber-optic delay line and fiber-optic head for read out of graphic information from hard carrier. With that, fibers are used for read out of photon echo signals in helium cryostat. The principles of construction are investigated for optical transient image processor. In proposed project, we plan to use these results for creation of photon-echo processor model sample and basic research of construction principles for multichannel storage and processing of information.
Photon echo-processor is very perspective and principally novel device of storing and processing of information. Collaborators of project participants have already reached the density of information storage several Gbit/cm2 and rate of information processing several THz by order of magnitude (Ulf Elman, Stefan Kroell, Baezhu Zero, R. Krishna Mohan, Rene Nilssen, Mindzhen Tian. Division of Atomic Physics Lund Institute of Technology. Progress Report 1997-1988. B. Quantum electronics, quantum optics and solid state spectroscopy. B1. Time-domain optical data storage and processing. – Ed. By Joergen Larssen, Lund, Sweden). With that, our Sweden collaborators also use fiber-optic technique for amplification of photon echo signals. The combination of efforts would allow to create the model sample of all fiber-optic processor that would rise greatly the technological level of research. Additionally, the amplification of signals could be realized using superradiance effect observed by participants of ISTC project No. 737 in materials doped by rare earths. It should be added that indicated figures are not maximum ones in respect to density of information writing. It is known that 107 more separate spectral information channels can be stored within single diffraction limited spot that is to say writing density of existing compact disks can be essentially exceeded. The technologies of spectral multi-demultiplexers for fiber-optic communication lines based on the concave chirped gratings developed in SIAO could be used for this aim. Scheme of multi-demultiplexers with more narrow spectral width of separate channel must be developed in the course of this project fulfillment. These fiber-optic devices naturally fit to the fiber-optic scheme solution of proposed echo-processor. Practical application of such processors is limited however by the necessity to use helium cryostat to provide low temperature of working sample. Therefore in this project, it is supposed also to investigate for the first time the possibility to use laser cooling for reaching low temperature and vice versa to use photon echo for monitoring of working sample laser cooling. The lucky coincidence is that the most advantages in the laser cooling of solids are reached by other our collaborators from USA namely on fiber samples doped by rare earth elements that are also used for the observation of photon echo.
The advantages in laser cooling of gases are well known that were prized by awarding of Nobel prize in 1997 to S. Chu, C. Cohen-Tannoudji and Phillips. In large extent, these achievements became possible due to the investigations of Prof. V.S. Letokhov generalized in his monograph “Pressure of light upon atoms” (Moscow, Nauka, 1986).
Question arose about the performance of analogous experiments on solid samples. P. Pringsheim had shown already in 1929 that the perspective for radiation cooling is anti-stokes regime of absorbed radiation scattering. A. Kastler had recommended in 1950 to use rare earth ions for the solution of this problem since they have high quantum efficiency.
It was such solid medium Yb3+:ZBLANP (heavy metal-fluoride glass doped by trivalent ytterbium) that was used in 1995 in USA by workers of Los Alamos National Laboratory and University of West Florida R. Epstein, M. Buchwald, B. Edwards, T. Gosnell and С. Mungan when performing experiment on laser cooling. Further, they have continued their investigations and the last experimental result was cooling of optical fiber made with the same doped glass at 21˚ starting from room temperature. It was one of the representatives of this group of investigators, Prof. Carl Mungan who agreed to be collaborator on presented project.
The beginning of theoretical research of the problem of laser cooling of solids by participants of presented project S.N. Andrianov and V.V. Samartsev relates to 1996. They have published during the period of 1996-2000 approximately 15 papers and one monograph: S.N. Andrianov, V.V. Samartsev “Optical Superradiance and Laser Cooling of Solids”. Kazan: ed. by KSU, 1998. Advantages of Kazan group of investigators appeared to be highly appreciated in the recent review of C. Mungan and T. Gosnell “Laser cooling of solids” in the journal: Advances in Atomic, Molecular and Optical Physics, 40, 161-228, 1999. At the same time, there was pointed to the fact, that not only glasses can serve as perspective objects for such experiments but also crystals LaF3, Y2O3, YAlO3 doped by rare-earth ions. Lets note that it is these crystals, first of all LaF3:Pr3+ that are the objects of last experiments conducting in KPTI KSC RAS in the field of creation of optical echo-processors (see the book of A.A. Kalachev and V.V. Samartsev “Photon echo and its application”, Kazan: ed. by KSU, 1998). Therefore authors of present project have serious scientific experience and corresponding experimental technique for the solution of the problem of laser cooling of these crystals and also of optical fibers doped by rare-earth ions. Solution of this fundamental scientific problem along with transition to use in echo-processors of semiconductor lasers and lightguide technique will allow to make robust echo processor and to provide in perspective their efficient operation without cryogenic liquids and cryostats. The developments of department on integrated and fiber optics of SPC SIAO can promote this goal. All premises are created in it for realization of multi-demultiplexer based on the use of recent technological advantages on creation of diffraction gratings and obtaining monoblock construction for selection of separate spectral components within the inhomogeneously broadened absorption line.
It should be noted that photon echo-processor is the special case of quantum computer in its most general form (Benioff computer). Here the set of two-level atoms plays the role of Turing machine tape. The interaction of atoms with electromagnetic field fulfills the role of reading head and quantum evolution equations play the role of program that results in transformation of initial set of main states to the final set of main states via superposition states and one or another quantum computing takes place with that.
It is planned in project to realize the Fourier transform in real scale of time that will mean according to the theorem of Shor the possibility of factoring of large integers. For that, spectral multiplexing will be also used that will allow to carry out the calculation of various spectral components in separate spectral ranges.
The possibility to use superradiance effect will be studied theoretically and experimentally for the amplification of signals of optical processors, since self-correlation processes unite rare-earth ions in single macroscopic dipole. Results of these developments are seemed to be extremely important for the creation of quantum computers that will be analyzed in details in present project for the possibility of their creation. The point is that modern quantum computers in the Feynman-Deutsch scheme are supposed to built on the separate atoms – cubits. With that it is complicated to construct addressing scheme on writing and reading information on single atoms. Superradiance yields the possibility to treat macro-atom (macrocubit) in the form of quantum dot containing thousands of atoms. It makes feasible the construction of nano-scheme and quantum computer consisting of several such macro-atoms.
Attraction of specialists of SPC SIAO formally engaged in the development of weapons would allow giving them the work in the civil sphere that corresponds to goals of ISTC. Employees of the laboratory of nonlinear optics of Kazan Physical and Technical Institute of KSC of Russian Academy of Sciences will be close partners of these specialists.
The fulfillment of project is planned for three years.
During first year, equipment will be modernized for the realization of experiments of laser cooling of LaF3:Pr3+ crystal and all-round theoretical analysis will be carried out for the conditions of successful experiment performance both on mentioned crystal and in new crystals and optical fibers doped by rare-earth ions. The development of fiber-optic multiplexer with narrow spectral width of channels will be started that will yield the possibility to observe multichannel superradiance and long-lived photon echo by pision of inhomogeneous linewidth into spectral packets. The corresponding orders on lacking equipment and objects of study will be made.
During the second year of project fulfillment, the performance of experiments on LaF3:Pr3+ crystal and other crystals doped by rare-earth ions is planned. The search experiments will be performed in the third quarter of second year on laser cooling of optical fibers doped by rare-earth ions. Multi-demultiplexer with linewidth of channels Dl=1Å will be created. The Fourier transform will be also realized using photon echo that will serve as a proof of possibility to create quantum computers on the basis of photon echo. Multichannel superradiance will be investigated in the crystal doped by rare-earth ions. This will open possibility to create multicubit optical processor with essential value of signals at the input and output.
Experiments on laser cooling of solids will be continued in the two first quarters of the third year of project fulfillment. Then the model sample of multichannel photon echo-processor will be constructed where these objects will be used as information carrier. Besides, the possibilities and ways of creation of quantum computers will be investigated during all the third year of project fulfillment on the basis of conducted investigations.
The results of research are planned to use further at the creation with S. Kroll (Lund, Sweden) in the part of photon echo and C. Mungan (Pensacola, USA) in the part of laser cooling of all fiber-optic processor cooled by a laser.
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