Stephen R. Leone, Ph.D. - US grants

0128826
Leone

This two-year award for US-France collaboration in experimental physical chemistry and quantum information science involves researchers and students at the University of Colorado and the Aime Cotton Laboratory in Orsay, France. Stephen R. Leone in the US and Christian Jurgen in France lead this collaboration of experimentalists and theorists. The objective of their combined efforts is to investigate Rydberg molecular packets of complex sodium or lithium compounds (dimers) or nobelium as potential sources for quantum information. The US group will assemble and prepare molecular wave packets with ultrafast pulsed lasers in order to construct coherent superpositions of states. Pairs of superposition states, called qubits, will then be used to investigate algorithms proposed for quantum information science. The French investigators will provide the theoretical expertise to identify the states involved and to interpret the complex wave packet dynamics.

This collaboration advances understanding of research in laser control of chemical reactions and molecular spectroscopy. The new knowledge will be used in quantum information science, optical communications, and femtosecond laser optics. The collaboration advances research training of graduate students and provides them with opportunities to establish international partnerships early in their careers.

This award represents the US side of parallel proposals to the NSF and the CNRS. NSF will cover travel funds and living expenses for the US investigator, postdoctoral researcher and students. The CNRS will support visits by French researchers and students to the United States.

In this ITR-Small project funded by the Chemistry Division, Stephen Leone of the University of California-Berkeley will investigate single and multiple qubit operations on pairs of superposition states formed among rotational, vibrational, and electronic degrees of freedom in diatomic molecules. Using multiple pulse sequences from ultrafast lasers, phase and amplitude pulse shaping, and evolutionary algorithms, optimal pulses will be determined for single qubit transformations in molecules, such as Z-gates and Hadamard transformations. The work is further extended to multiple qubit operations such as controlled-Z and swap gates. Lithium dimers will be used as the molecular system for these studies. The experiments in this project will address for the first time the use of molecular rotational states as a motional control qubit for controlled transformations of an electronic qubit.

This project focuses on exploring logic gates that may be useful for constructing a quantum computer. In the course of this research students will receive training in quantum mechanics and the use of ultrafast lasers and pulse shaping. Since these areas are already of great relevance to optical communications and optical computing efforts, the students will experience the integration of basic science and its applications in advanced information technology applications. In addition, what is learned from molecular systems may enable the formation of qutrits (three-level systems) and multi-qubits (superpositions of many levels at a time) that will broaden thinking about potential algorithms for quantum information processing. This research has other possible applications to areas such as quantum cryptography and code-breaking, information storage and retrieval, and faster processing with quantum computing. Fields affected include fiber optic communications, information transmission, and data encryption.

This is a NER proposal for a specific one-year trial to (1) characterize single ZnO nanowire laser structures using spatially-resolved confocal microscopy detection, and (2) to introduce pump - stimulated emission dump probing to study stimulated emission processes of single nanowire laser configurations. The requisite morphologies of ZnO nanowires have been produced and synthetic refinement will be performed to obtain the best quality crystalline patterns of multiple nanowires. Laser and confocal optical microscopy tools that are available in this laboratory will be used to optically excite ZnO single nanowire laser media and to detect spectrally and spatially resolved stimulated emission. These include novel ultrafast pump-dump experiments with a Ti:sapphire femtosecond laser. The fundamental science of the exciton-exciton scattering mechanism to produce stimulated emission in crystalline nanowires and the transition to an electron-hole plasma stimulated emission mechanism will be explored. These studies are designed to develop new confocal microscopy methods to interrogate nanowire laser devices, with the specific ability to explore a single device at a time. Single molecule spectroscopy experiments have revealed a number of intriguing aspects of individual molecular environments over the last few years. These studies are intended to transfer this remarkable type of investigation to the study of single nanowire lasers and stimulated emission.

This project addresses polymer photoresist processing through infrared near field optical micros-copy (IR NSOM) and Coherent Anti-Stokes Raman Spectroscopy (CARS) microscopy. These methods permit access to latent images in the polymer film at various stages in the photoresist processing. A key aspect is to probe the films spatially and chemically through observations of chemically modified vibrational bands within the polymer films. The project involves an active collaboration with scientists at IBM Almaden, William Hinsberg and Frances Houle, who also provide deep ultraviolet, chemically amplified polymer photoresists tailored to special require-ments of the experiments. The project involves experiments to probe line dimensions, acid diffu-sion, the influence of vapor uptake, and other deep UV polymer lithographic chemistries.

The project addresses fundamental research issues associated with electronic/photonic materials having technological relevance. Broader impacts of this work to society are that new methods of measuring line dimensions and for following chemical processes are developed to address ultra-small feature sizes. The results of these studies assist industry in making less expensive and more powerful tools for society. Through the active collaboration with William Hinsberg and Frances Houle at IBM on this particular project, students learn essential teamwork skills and how to be responsive to additional challenges and deadlines outside the academic environment. Students are trained in a variety of important technologies, including lasers, optics, photoresist chemistry, and nanoscale measurements.

This IGERT Program is in nanoscale science and engineering at the University of California, Berkeley. The key scientific goals and intellectual merit of this IGERT program address three important themes of this field: nanostructure synthesis and processing of novel functional devices and systems, nanoscale characterization, and modeling. Each of these is designed to facilitate the integration of nanostructures into engineered systems. Students selected for this program will focus on one of five research sub-areas: nanoelectronics, nanophotonics, nanobiology, nanomagnetics, and nanomechanics. They will master core courses offered across several disciplines and multiple departments. Students will carry out their Ph.D. research under the joint supervision of two advisors from both engineering and the physical sciences, and they will receive additional practical training through cross-laboratory investigations within and outside of the labs of IGERT faculty.

A national and international internship program will contribute to the broader impacts of this program and constitute an integral part of the IGERT educational experience. Students may elect to complete their internship either in an industrial or national laboratory, or they can choose to work at institutions abroad with several of which we already have established close contacts. An array of services at the university will be utilized for the recruitment of a diverse student body, with much-anticipated success. Women and underrepresented minority groups will be recruited actively. We also plan to complement the IGERT program with the National Consortium for Graduate Degrees for Minorities in Engineering (the GEM Program) and the National Physical Sciences Consortium. Role models and mentors are key to the successful recruitment and retention of women and minorities. Our strong group of faculty and industrial mentors will provide crucial guidance to our graduate fellows. Outreach programs to engage students from underrepresented groups in local high schools will be implemented. They include After-School Science Workshops and Summer High- School Internships in Nanoscience and Engineering. The faculty comprising the IGERT program are committed to leadership and participation in outreach and educational activities that will foster knowledge and appreciation of nanoscience and engineering in the community and nationally.

UC Berkeley is in the unique position of having an unusual combination of resources committed to nanoscale science and engineering. Significantly, the Chancellor of UC Berkeley has identified nanoscience and nanoengineering as one of the top three research priorities on campus and has made an institutional commitment to focus research resources on areas that will be critical in the upcoming nanoengineering revolution. This program will find its specific intellectual merit in the establishment a new kind of graduate education at Berkeley in a research area that is unprecedented in its impact across disciplines. The interdisciplinary IGERT curriculum will allow to establish innovative educational concepts to prepare qualified graduate students at the University of California, Berkeley, for the future demands of this rapidly expanding field. This traineeship program spans nine graduate programs in three colleges, each with its own unique approaches to and robust research capabilities in nanoscale science and engineering. The lasting impact of this project will not be limited to the scientific achievements that will make an important contribution towards the building, understanding, and controlling of engineered objects on the nanometer length scale. Equally important will be a paradigm shift in graduate education, especially in Engineering education at Berkeley that is expected to have long-lasting impact beyond the scope of this program.

IGERT is an NSF-wide program intended to meet the challenges of educating U.S. Ph.D. scientists and engineers with the interdisciplinary background, deep knowledge in a chosen discipline, and the technical, professional, and personal skills needed for the career demands of the future. The program is intended to catalyze a cultural change in graduate education by establishing innovative new models for graduate education and training in a fertile environment for collaborative research that transcends traditional disciplinary boundaries. In this sixth year of the program, awards are being made to institutions for programs that collectively span the areas of science and engineering supported by NSF.

In this award, funded by the Experimental Physical Chemistry Program of the Chemistry Division, Prof. Stephen R. Leone of the University of California - Berkeley and his graduate and undergraduate research students will investigate the use of coherent control methods with tailored ultrafast laser pulses to manipulate chemical events. Studies will range from rotational heating and cooling of simple diatomic systems to the control of the photodissociation of polyatomic molecules. The ultimate goal of the research is to learn of ways in which coherent control may be used to achieve exquisite control chemical dynamics. The information gleaned from these studies is expected to have broad impact on a variety of technologies including fiber optic telecommunications, quantum information, encryption, and data storage and transfer.

In addition to the broader impacts of the proposed research, Prof. Leone will continue in his efforts at educating young scientists at all levels - from high school through postdoctoral level. He will also work on developing curricular materials for undergraduate physical chemistry students.

In this project funded by the Chemical Structure Dynamics and Mechanism-A (CSDM-A) program of the Chemistry Division, Professor Stephen Leone of the University of California Berkeley is using innovative laser techniques to investigate the behavior of molecules at the shortest possible time. The experiments detect fast molecular changes on timescales down to hundreds of attoseconds (1 attosecond is one billionth of a billionth of a second). Such measurements have only become possible in the last 15 years due to new methods for producing attosecond light pulses with lasers. Because electrons move so rapidly, their motion (electron dynamics) becomes central to the molecular processes under investigation. This research measures fast electron motion, such as when charges redistribute or periodically change in molecules, or electrons hop as the structure of the molecule transforms. To accomplish this, Professor Leone produces two laser pulses, one to excite the molecules and one delayed in time to measure the molecular response, analogous to a starting pistol and a stopwatch in a race. These experiments use numerous optical technologies to obtain the required short pulses and accurate time delays. The benefits to society are anticipated from the development of measurement capabilities that push the boundaries of time using tools that require precision stability. These techniques are important as the dimensions of devices decrease and performance speeds of storage media and computational tools increase. The students engaged in this project are learning an array of techniques and principles relevant for high technology professions, including laser technology, electronics, and computing.

Attosecond time-resolved measurements represent a new way to probe chemical dynamics on timescales short enough to separate electron dynamics from nuclear motion. Electron dynamics such as electron correlation and electronic superposition states play a central role in chemical processes on these short timescales, as does the breakdown of the separability of timescales between electrons and nuclei (Born Oppenheimer). To study these phenomena, an experimental laboratory based on the production of isolated attosecond pulses in the extreme ultraviolet (XUV) spectral range is employed. The chemical systems involve measurements of few-femtosecond and subfemtosecond (attosecond) time dynamics of electronic superpositions, dissociation processes, and passage through curve crossings or conical intersections of electronically excited molecules. The students involved in this attosecond measurement-based project are gaining experience in a variety of areas that are emerging in high tech industry. These include, for example, carrier-envelope-phase stabilized lasers, interferometric control of light, core level spectroscopy principles, x-ray optical programming, electron spectrometers, and rate equation approaches to predict ionization, orbital occupancy, and alignment.

With this award from the award from the Major Research Instrumentation (MRI) and the Chemistry Research Instrumentation (CRIF) Programs, Professor Stephen Leone from the University of California Berkeley and colleagues Daniel Neumark, Roger Falcone and Feng Wang have developed an attosecond spectrometer system to measure fast processes when electrons are excited in materials containing carbon. This is a benchtop laboratory system with a laser source generating pulses in an energy range called the carbon K-edge. When electrons are excited by this laser pulse, the dynamic process that result (molecular fragmentation, or rearrangement of other electrons) are observed. These processes can be very fast, on an attosecond time scale (10 to the minus 18 seconds). The processes are probed with such time-scale pulses of light as they occur. Initial experiments have demonstrated the operational proof-of-principle. Applications will proceed on various carbon-containing materials. In the long term, progress will allow new measurements and basic knowledge to be generated on electronic properties of materials, electronics and biological systems. In the process of building this system students interact with expert builders helping in the formation of the new generation of instrument builders.

The award addresses the development of a laser system and apparatus that can produce high order harmonics and isolated attosecond pulses up to and through the carbon K edge (300 eV). A robust system is built that can perform dynamical attosecond experiments at the carbon K edge on a daily basis. The proposal is aimed at enhancing research and education at all levels, especially to (a) develop robust attosecond pulses, (b) study charge migration in molecules, (c) explore photodissociation dynamics and isomerization in prototype systems, (d) study electronic coherences and (e) analyze solid state and many-body charge state dynamics.