HOBOKEN, N.J. – In a recent publication in the high impact journal Optics Letters, Svetlana Malinovskaya, Associate Professor of Physics at Stevens Institute of Technology, proposes to use femtosecond, chirped laser pulse trains to reduce decoherence. Controlling coherence can overcome current barriers in a variety of fields, from quantum computing to molecular selective bio-imaging.
Coherence is a natural phenomenon where molecules exist in a superposition of states. "In condensed phase, molecules interact with environment, for example, with water molecules. This interaction increases complexity of the energy distribution causing molecules to lose their quantum properties, such as coherence, faster than in the gas phase," Malinovskaya explained. "Loss of coherence is a problem in Raman microscopy, which is a prospective method for molecular identification and imaging. The molecules that are excited with a laser pulse lose their energy very fast. Sometimes this energy loss is on the same scale as the pulse duration, which negatively influences the Raman signal identifying the molecules."
In her recent publication in Optics Letters, "Prevention of decoherence by two femtosecond chirped pulse trains" (Vol. 33, Issue 19), Malinovskaya describes a method to counteract decoherence by using femtosecond chirped pulse trains. The key is to make the period of the pulse trains equal to the relaxation time of the vibrational energy of the target molecules. This way, you can selectively prepare the target molecules in the excited state and restore coherence periodically.
Recently, femtosecond pulse trains emitted from a mode-locked laser have been utilized to form the basis of the frequency comb spectroscopy. For contributions to the development of laser-based precision spectroscopy, including the optical frequency comb technique, the 2005 Nobel Prize was awarded in physics to John Hall, Theodor Hänsch and Roy Glauber. "Soon after, physicists have started to use pulse trains as a new way to control light and matter," Malinovsksya said. "Using the modulated laser pulse trains, we aim to affect predetermined properties of molecules. In addition to other achievements, we can now selectively address molecular vibrations of known frequency and optimize the Raman signal from them in the presence of decoherence."
One of the key applications of the pulse train manipulation lies in the biological imaging. Malinovskaya explained: "In order to get an image of a molecular specific structure one has to program the laser pulses to excite vibrations only in the predetermined molecular groups constituting target bio-compounds. No other methods allow one to see the difference in the structure built of, for example, saturated or unsaturated fats."
Malinovskaya performs her research within the Center for Control of Quantum Systems, which aims to engineer the quantum world, and manipulate nature at the quantum level. Together with another faculty member, Ting Yu, she studies applications in quantum computing and quantum information processing where coherence control is currently one of most challenging issues.
Optics Letters offers rapid dissemination of new results in all areas of optics with short, original, peer-reviewed communications. Articles accepted for publication in this journal are newsworthy to a substantial part of the optics community. This journal, published twice each month, is where readers look for the latest discoveries in optics.
Optics Letters is the most heavily cited journal in optics and photonics, based on "impact factor," or the number of citations compared to the number of papers published. This was announced by Thomson Reuters, the world's leading source of intelligent information for businesses and professionals in their 2007 Journal Citation Report.
To view the abstract, please visit http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-33-19-2245
About Stevens Institute of Technology
Founded in 1870, Stevens Institute of Technology is one of the leading technological universities in the world dedicated to learning and research. Through its broad-based curricula, nurturing of creative inventiveness, and cross disciplinary research, the Institute is at the forefront of global challenges in engineering, science, and technology management. Partnerships and collaboration between, and among, business, industry, government and other universities contribute to the enriched environment of the Institute. A new model for technology commercialization in academe, known as Technogenesis®, involves external partners in launching business enterprises to create broad opportunities and shared value. Stevens offers baccalaureates, master's and doctoral degrees in engineering, science, computer science and management, in addition to a baccalaureate degree in the humanities and liberal arts, and in business and technology. The university has a total enrollment of 2,150 undergraduate and 3,500 graduate students with about 250 full-time faculty. Stevens' graduate programs have attracted international participation from China, India, Southeast Asia, Europe and Latin America. Additional information may be obtained from its web page at www.stevens.edu.
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Optics Letters