2011-2012
September
15 (Thursday) 4:35 pm
Speaker: Dr. Brian Arbic, Professor of Geological Sciences, University of Michigan
Title: Predicting the Maelstrom: The Physics of the Ocean
Abstract: I will briefly describe the highly-interdisciplinary and societally-relevant field of Earth and Environmental Sciences, and opportunities for graduate study in EES at University of Michigan. Then I will discuss my specific sub-discipline, physical oceanography, and the kinds of ocean-related problems I work on, all of which require a strong quantitative background in subjects such as physics, mathematics, and computer science.
Title: Predicting the Maelstrom: The Physics of the Ocean
Abstract: I will briefly describe the highly-interdisciplinary and societally-relevant field of Earth and Environmental Sciences, and opportunities for graduate study in EES at University of Michigan. Then I will discuss my specific sub-discipline, physical oceanography, and the kinds of ocean-related problems I work on, all of which require a strong quantitative background in subjects such as physics, mathematics, and computer science.
Location: Wright 201
October
13 (Thursday) 4:35 pm
Speaker: Dr. Harsh Mathur, Associate Professor of Physics, Case Western Reserve University
Title: Fractal analysis and drip paintings
Abstract: Are Jackson Pollock's drip paintings examples of fractals? Can such analysis authenticate paintings of disputed provenance?
Title: Fractal analysis and drip paintings
Abstract: Are Jackson Pollock's drip paintings examples of fractals? Can such analysis authenticate paintings of disputed provenance?
Location: Wright 201
November
30 (Wednesday) 4:35 pm
Speaker: Dr. Terrence Sheridan, Professor of Physics, Ohio Northern University
Title: Symmetry-breaking transitions in small Debye clusters
Abstract: We consider a cluster of n identical charged particles which repel each other through a Debye (i.e., a shielded Coulomb or Yukawa) potential and which are confined by a two-dimensional biharmonic well. In the strong-coupling regime, the particles' arrangement is determined by n, the Debye parameter, and the well anisotropy. For large anisotropies, the particles lie in a one-dimensional straight-line configuration. As the anisotropy is reduced, the cluster undergoes a structural transition to a two-dimensional configuration via the zigzag instability. In the opposite limit of an isotropic well, the ground state configuration is "circular". In particular, for n = 6, 7 or 8 particles, the isotropic configuration has a single particle in the center which is surrounded by the remaining n - 1 particles. Since the zigzag and isotropic configurations have different symmetries, a symmetry-breaking mechanism is required to make the structural transition between these states. We have determined this mechanism by experimentally characterizing dusty plasma clusters as the number of particles and the anisotropy are varied.
Title: Symmetry-breaking transitions in small Debye clusters
Abstract: We consider a cluster of n identical charged particles which repel each other through a Debye (i.e., a shielded Coulomb or Yukawa) potential and which are confined by a two-dimensional biharmonic well. In the strong-coupling regime, the particles' arrangement is determined by n, the Debye parameter, and the well anisotropy. For large anisotropies, the particles lie in a one-dimensional straight-line configuration. As the anisotropy is reduced, the cluster undergoes a structural transition to a two-dimensional configuration via the zigzag instability. In the opposite limit of an isotropic well, the ground state configuration is "circular". In particular, for n = 6, 7 or 8 particles, the isotropic configuration has a single particle in the center which is surrounded by the remaining n - 1 particles. Since the zigzag and isotropic configurations have different symmetries, a symmetry-breaking mechanism is required to make the structural transition between these states. We have determined this mechanism by experimentally characterizing dusty plasma clusters as the number of particles and the anisotropy are varied.
Location: Wright 201
April
5 (Thursday) 4:35 pm
Speaker: Dr. Cody C. Leary, Assistant Professor of Physics, The College of Wooster
Title: Measurement, control and collisions of photon spatial wavefunctions
Abstract: A single photon, or light particle, has four internal degrees of freedom. Two of these are related to the photon's energy and polarization, while the remaining two determine its spatial intensity distribution -- or wave function -- in the direction perpendicular to its motion. In this talk, various means of experimentally measuring and manipulating a photon's wave function will be discussed, including the measurement and sorting of a photon's wave function with respect to its parity properties, and the imparting of one quantum of orbital angular momentum to a single photon. These experimental achievements make it possible to prepare and "collide" two photons with distinct wave functions within an interferometric device, with the result that these distinguishable photons can be made to interact with one another via a phenomenon known as two-photon interference.
Title: Measurement, control and collisions of photon spatial wavefunctions
Abstract: A single photon, or light particle, has four internal degrees of freedom. Two of these are related to the photon's energy and polarization, while the remaining two determine its spatial intensity distribution -- or wave function -- in the direction perpendicular to its motion. In this talk, various means of experimentally measuring and manipulating a photon's wave function will be discussed, including the measurement and sorting of a photon's wave function with respect to its parity properties, and the imparting of one quantum of orbital angular momentum to a single photon. These experimental achievements make it possible to prepare and "collide" two photons with distinct wave functions within an interferometric device, with the result that these distinguishable photons can be made to interact with one another via a phenomenon known as two-photon interference.
Location: Wright 201
13 (Friday) 4:35 pm
Speaker: Sophia L. Chen, Honors Student in Physics, Oberlin College
Title: Frequency Comb Spectroscopy of Rubidium: Measuring Atomic Energies to High Precision
Abstract: Precision spectroscopy measurements have contributed significantly to our understanding of the fundamental structure of atoms. Here we present an experiment involving a new precision spectroscopic technique using a femtosecond optical frequency comb. A femtosecond optical frequency comb is an ultrashort, pulsed laser with tens of thousands of frequencies, equally spaced in frequency-space. These frequencies can be used to excite atoms to specific transitions. When the atoms decay, they emit light, and we can extract useful information about atomic structure from this light. The frequency comb is a versatile instrument that can avoid many of the experimental uncertainties that are associated with other spectroscopic techniques. In addition, the setup could be cheaply and easily altered to study different atoms or systems. In this experiment, we study this new technique of using an optical frequency comb for spectroscopy in order to learn more about the fundamental structure of atoms and their interaction with light.
Title: Frequency Comb Spectroscopy of Rubidium: Measuring Atomic Energies to High Precision
Abstract: Precision spectroscopy measurements have contributed significantly to our understanding of the fundamental structure of atoms. Here we present an experiment involving a new precision spectroscopic technique using a femtosecond optical frequency comb. A femtosecond optical frequency comb is an ultrashort, pulsed laser with tens of thousands of frequencies, equally spaced in frequency-space. These frequencies can be used to excite atoms to specific transitions. When the atoms decay, they emit light, and we can extract useful information about atomic structure from this light. The frequency comb is a versatile instrument that can avoid many of the experimental uncertainties that are associated with other spectroscopic techniques. In addition, the setup could be cheaply and easily altered to study different atoms or systems. In this experiment, we study this new technique of using an optical frequency comb for spectroscopy in order to learn more about the fundamental structure of atoms and their interaction with light.
Location: Wright 201
18 (Wednesday) 4:35 pm
Speaker: Joseph Galamba, Honors Student in Physics, Oberlin College
Title: The Hydrogen Molecule Ion and Dimensional Scaling
Title: The Hydrogen Molecule Ion and Dimensional Scaling
Abstract: Dimensional scaling is a technique that can provide insight into the mathematical nature of difficult problems. For example, the problem may be solvable exactly in closed form in a certain number of dimensions other than three due to the simplicity of the problem or some symmetry that is present that was lacking in three dimensions. In this talk, a dimensional scaling of the simplest of molecules to one dimension will be presented.
Location: Wright 201
23 (Monday) 4:35 pm
Speaker: Chris Pierce, Honors Student in Physics, Oberlin College
Title: Quantum Sieving of Hydrogen and Deuterium Gas in an Iron-Based, Metal-Organic Framework
Abstract: A great deal of interest has recently arisen surrounding the synthesis and characterization of nano-porous materials. Metal-organic frameworks, a novel class of nano-porous materials, have shown potential to resolve numerous industrial and environmental difficulties. They are constructed from metal oxide groups connected by organic linkers, creating a diverse set of highly adjustable materials with large internal surface areas and relatively high binding energies. They have been examined in conjunction with their ability to store hydrogen gas, for use in an efficient and lightweight hydrogen storage system for fuel cell cars. They have additionally shown properties which could potentially lead to selective capture of carbon dioxide from industrial flue gas and atmospheric mixtures. We examined the potential for use in the separation of hydrogen from its isotopologue, deuterium. Classically, deuterium and hydrogen would have identical binding energies confining them to the materials internal surface, however, a quantum effect resulting in the difference of the zero-point energies of the molecules, known as quantum sieving, allows for the existence of a subtle difference in their binding energies.
Title: Quantum Sieving of Hydrogen and Deuterium Gas in an Iron-Based, Metal-Organic Framework
Abstract: A great deal of interest has recently arisen surrounding the synthesis and characterization of nano-porous materials. Metal-organic frameworks, a novel class of nano-porous materials, have shown potential to resolve numerous industrial and environmental difficulties. They are constructed from metal oxide groups connected by organic linkers, creating a diverse set of highly adjustable materials with large internal surface areas and relatively high binding energies. They have been examined in conjunction with their ability to store hydrogen gas, for use in an efficient and lightweight hydrogen storage system for fuel cell cars. They have additionally shown properties which could potentially lead to selective capture of carbon dioxide from industrial flue gas and atmospheric mixtures. We examined the potential for use in the separation of hydrogen from its isotopologue, deuterium. Classically, deuterium and hydrogen would have identical binding energies confining them to the materials internal surface, however, a quantum effect resulting in the difference of the zero-point energies of the molecules, known as quantum sieving, allows for the existence of a subtle difference in their binding energies.
Location: Wright 201
27 (Friday) 4:35 pm
Speaker: Jacob Baron, Honors Student in Physics, Oberlin College
Title: Studying Atoms with a Laser Ruler: Spectroscopy of Lithium with an Optical Frequency Comb
Abstract: The development of the optical frequency comb over the past two decades has lead to unprecedented precision in the measurement of the frequencies of visible light. A frequency comb is produced by a laser of ultrashort pulses (~10 femtoseconds long). In frequency space, this corresponds to ~100 000 equally spaced frequencies. This can be thought of as hundreds of thousands of lasers in a single laser beam. The frequency comb is used in this experiment to calibrate the frequency of a single frequency diode laser to very high precision. In this way, we will measure energies of atomic lithium to fractional uncertainty of 10-12. A new measurement of the D lines of lithium will potentially resolve discrepancies between recent measurements and calculations. In this talk we will explain the techniques used in the experiment and present preliminary data.
Title: Studying Atoms with a Laser Ruler: Spectroscopy of Lithium with an Optical Frequency Comb
Abstract: The development of the optical frequency comb over the past two decades has lead to unprecedented precision in the measurement of the frequencies of visible light. A frequency comb is produced by a laser of ultrashort pulses (~10 femtoseconds long). In frequency space, this corresponds to ~100 000 equally spaced frequencies. This can be thought of as hundreds of thousands of lasers in a single laser beam. The frequency comb is used in this experiment to calibrate the frequency of a single frequency diode laser to very high precision. In this way, we will measure energies of atomic lithium to fractional uncertainty of 10-12. A new measurement of the D lines of lithium will potentially resolve discrepancies between recent measurements and calculations. In this talk we will explain the techniques used in the experiment and present preliminary data.
Location: Wright 201
Department of Physics and Astronomy Lecture Series speakers from past years.
