25 results on '"Bart H. McGuyer"'
Search Results
2. Flat-Panel Mechanical Beam Steerable Array Antennas With In-Plane Rotations: Theory, Design and Low-Cost Implementation
- Author
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Eric Booen, Srishti Saraswat, Hamid Bolandhemmat, Qi Tang, Curt Von Badinski, Farbod Tabatabai, Theunissen Wilhelmus Hendrikus, and Bart H. McGuyer
- Subjects
Aperture ,Computer science ,Acoustics ,mechanical systems ,TK5101-6720 ,Space (mathematics) ,Communications system ,low earth orbit satellites ,Flat panel ,high altitude platform ,Mechanism (engineering) ,In plane ,Feature (computer vision) ,Beam steering ,design-to-cost ,Telecommunication ,Physics::Accelerator Physics ,flat-panel ,Beam (structure) - Abstract
We present a compact, flat-panel phased-array antenna design that beam steers using only mechanical in-plane rotations. We explain the steering mechanism and characterize the beam analytically and numerically. Measurements of two prototype antennas for different frequencies validate the concept and modeling. The prototype designs are described in detail and feature added phase-offset control of the array elements in the aperture layout. Potential applications include low-cost and low-power flat-panel user terminals for the next generation of aerial and space communication systems.
- Published
- 2021
3. Symmetry and Voltmeters
- Author
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Bart H. McGuyer
- Subjects
Physics ,Electromotive force ,Physics - Physics Education ,General Physics and Astronomy ,FOS: Physical sciences ,Computer Science::Human-Computer Interaction ,Computer Science::Digital Libraries ,Symmetry (physics) ,Physics::Popular Physics ,Voltmeter ,Physics Education (physics.ed-ph) ,Quantum mechanics ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics - Abstract
Letter to the Editor that explains a popular demonstration with voltmeters and electromotive force using symmetry., 1 page
- Published
- 2021
4. Diet Soda and Liquid Nitrogen
- Author
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Bart H. McGuyer, Justin M. Brown, and Hoan B. Dang
- Subjects
business.product_category ,Chemistry ,fungi ,Physics - Physics Education ,FOS: Physical sciences ,General Physics and Astronomy ,food and beverages ,Liquid nitrogen ,biochemical phenomena, metabolism, and nutrition ,equipment and supplies ,Physics Education (physics.ed-ph) ,Immersion (virtual reality) ,Bottle ,bacteria ,business ,Nuclear chemistry - Abstract
Letter to the Editor about how the diet soda and Mentos reaction can be produced by the direct immersion of a plastic soda bottle in liquid nitrogen., 1 page
- Published
- 2021
5. Frequency-dependent capacitors using paper
- Author
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Bart H. McGuyer
- Subjects
Materials science ,business.industry ,Physics - Physics Education ,General Physics and Astronomy ,FOS: Physical sciences ,Dielectric ,Capacitance ,law.invention ,Capacitor ,Simple (abstract algebra) ,law ,Physics Education (physics.ed-ph) ,Optoelectronics ,business - Abstract
Measurements of capacitors made with paper sheets reveal a significant decrease in capacitance with increasing frequency from 10 to 100,000 Hz, offering a simple demonstration of complex dielectric phenomena using common equipment., 3 pages, 2 figures
- Published
- 2021
6. Experimental and theoretical investigation of the crossover from the ultracold to the quasiclassical regime of photodissociation
- Author
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Chih-Hsi Lee, Mickey McDonald, Tanya Zelevinsky, I. Majewska, Robert Moszynski, Stanimir Kondov, and Bart H. McGuyer
- Subjects
Chemical Physics (physics.chem-ph) ,Physics ,Quantum Physics ,010304 chemical physics ,Atomic Physics (physics.atom-ph) ,Photodissociation ,FOS: Physical sciences ,Semiclassical physics ,01 natural sciences ,7. Clean energy ,Diatomic molecule ,WKB approximation ,Physics - Atomic Physics ,Quantum state ,Physics - Chemical Physics ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,Physics::Atomic Physics ,Physics::Chemical Physics ,Atomic physics ,Quantum Physics (quant-ph) ,010306 general physics ,Quantum statistical mechanics ,Quantum ,Identical particles - Abstract
At ultralow energies, atoms and molecules undergo collisions and reactions that are best described in terms of quantum mechanical wave functions. In contrast, at higher energies these processes can be understood quasiclassically. Here, we investigate the crossover from the quantum mechanical to the quasiclassical regime both experimentally and theoretically for photodissociation of ultracold diatomic strontium molecules. This basic reaction is carried out with a full control of quantum states for the molecules and their photofragments. The photofragment angular distributions are imaged, and calculated using a quantum mechanical model as well as the WKB and a semiclassical approximation that are explicitly compared across a range of photofragment energies. The reaction process is shown to converge to its high-energy (axial recoil) limit when the energy exceeds the height of any reaction barriers. This phenomenon is quantitatively investigated for two-channel photodissociation using intuitive parameters for the channel amplitude and phase. While the axial recoil limit is generally found to be well described by a commonly used quasiclassical model, we find that when the photofragments are identical particles, their bosonic or fermionic quantum statistics can cause this model to fail, requiring a quantum mechanical treatment even at high energies., 13 pages, 6 figures
- Published
- 2018
7. Low-Dose-Rate Cobalt-60 Testing Results for Kaman KD-5100 Differential Inductive Position Measuring Systems
- Author
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Slaven Moro, Bart H. McGuyer, and Randall Milanowski
- Subjects
Radiation testing ,Materials science ,Position (vector) ,System of measurement ,Absorbed dose ,Radiochemistry ,Low dose rate ,Cobalt-60 - Abstract
We report 60Co gamma radiation testing of a Kaman KD-5100 position measuring system to a total ionizing dose of 10 kRad(Si) at a rate of 5 mRad(Si)/s.
- Published
- 2018
8. Control of Ultracold Photodissociation with Magnetic Fields
- Author
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Bart H. McGuyer, Tanya Zelevinsky, I. Majewska, Stanimir Kondov, Mickey McDonald, Robert Moszynski, and Chih-Hsi Lee
- Subjects
Chemical Physics (physics.chem-ph) ,Physics ,Quantum Physics ,010304 chemical physics ,Atomic Physics (physics.atom-ph) ,Photodissociation ,FOS: Physical sciences ,General Physics and Astronomy ,7. Clean energy ,01 natural sciences ,Diatomic molecule ,Quantum chemistry ,Physics - Atomic Physics ,Magnetic field ,Physics - Chemical Physics ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,Molecule ,Physics::Atomic Physics ,Physics::Chemical Physics ,Atomic physics ,Quantum Physics (quant-ph) ,010306 general physics ,Quantum - Abstract
Photodissociation of a molecule produces a spatial distribution of photofragments determined by the molecular structure and the characteristics of the dissociating light. Performing this basic chemical reaction at ultracold temperatures allows its quantum mechanical features to dominate. In this regime, weak applied fields can be used to control the reaction. Here, we photodissociate ultracold diatomic strontium in magnetic fields below 10 G and observe striking changes in photofragment angular distributions. The observations are in excellent qualitative agreement with a multichannel quantum chemistry model that includes nonadiabatic effects and predicts strong mixing of partial waves in the photofragment energy continuum. The experiment is enabled by precise quantum-state control of the molecules., 8 pages, 3 figures
- Published
- 2018
9. Proton Testing Results for Kaman KD-5100 Differential Inductive Position Measuring Systems
- Author
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Randall Milanowski, Bert Vermeire, Slaven Moro, Bart H. McGuyer, and Norman Hall
- Subjects
Physics ,Optics ,Proton ,business.industry ,Absorbed dose ,System of measurement ,mental disorders ,business ,psychological phenomena and processes ,Laser beams - Abstract
We report proton testing of a position measuring system, the Kaman KD-5100, with applications including mirror positioning for laser beam control. We measure a device response likely due to total ionizing dose and/or displacement damage.
- Published
- 2017
10. A broadband chip-scale optical frequency synthesizer at 2.7 × 10−16 relative uncertainty
- Author
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Chee Wei Wong, Jinghui Yang, Bart H. McGuyer, Dim-Lee Kwong, Tanya Zelevinsky, Shu-Wei Huang, and Mingbin Yu
- Subjects
Optical fiber ,chip-scale ,Attosecond ,Astronomy ,Physics::Optics ,01 natural sciences ,law.invention ,010309 optics ,Frequency comb ,Optics ,law ,Optical frequency comb ,0103 physical sciences ,Broadband ,Fiber Optic Technology ,Physics::Atomic Physics ,010306 general physics ,Research Articles ,Physics ,Multidisciplinary ,business.industry ,Spectrum Analysis ,SciAdv r-articles ,Equipment Design ,Laser ,Metrology ,Femtosecond ,Telecommunications ,astronomical spectrography ,business ,Microwave ,precision spectroscopy ,coherent communications ,Research Article - Abstract
Frequency stabilization to 0.3 parts per quadrillion is demonstrated on chip, opening new frontiers in precision metrology., Optical frequency combs—coherent light sources that connect optical frequencies with microwave oscillations—have become the enabling tool for precision spectroscopy, optical clockwork, and attosecond physics over the past decades. Current benchmark systems are self-referenced femtosecond mode-locked lasers, but Kerr nonlinear dynamics in high-Q solid-state microresonators has recently demonstrated promising features as alternative platforms. The advance not only fosters studies of chip-scale frequency metrology but also extends the realm of optical frequency combs. We report the full stabilization of chip-scale optical frequency combs. The microcomb’s two degrees of freedom, one of the comb lines and the native 18-GHz comb spacing, are simultaneously phase-locked to known optical and microwave references. Active comb spacing stabilization improves long-term stability by six orders of magnitude, reaching a record instrument-limited residual instability of 3.6mHz/τ. Comparing 46 nitride frequency comb lines with a fiber laser frequency comb, we demonstrate the unprecedented microcomb tooth-to-tooth relative frequency uncertainty down to 50 mHz and 2.7 × 10−16, heralding novel solid-state applications in precision spectroscopy, coherent communications, and astronomical spectrography.
- Published
- 2016
11. Bichromatically-pumped coherent Kerr frequency combs with controllable repetition rates
- Author
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Chee Wei Wong, Tanya Zelevinsky, Bart H. McGuyer, Dim-Lee Kwong, Guo-Qiang Lo, Mingbin Yu, Shu-Wei Huang, Mickey McDonald, and Jinghui Yang
- Subjects
Condensed Matter::Quantum Gases ,Physics ,Repetition (rhetorical device) ,business.industry ,Physics::Optics ,01 natural sciences ,010309 optics ,Frequency divider ,Optics ,0103 physical sciences ,Coherent states ,Physics::Atomic Physics ,010306 general physics ,business ,Noise (radio) - Abstract
We study the coherent comb formation by a bichromatic pump and detail noise state transitions by detuning the seeding. We also show comb spacing in a coherent state can be tuned by 40 MHz. The work paves a way towards coherently tunable comb oscillator for chip-scale RF-optical frequency division and clockworks.
- Published
- 2016
12. Photodissociation of ultracold diatomic strontium molecules with quantum state control
- Author
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Robert Moszynski, Chih-Hsi Lee, F. Apfelbeck, I. Majewska, Tanya Zelevinsky, Bart H. McGuyer, and Mickey McDonald
- Subjects
Physics ,Quantum Physics ,Multidisciplinary ,Atomic Physics (physics.atom-ph) ,Photodissociation ,FOS: Physical sciences ,01 natural sciences ,Diatomic molecule ,Quantum chemistry ,010305 fluids & plasmas ,Physics - Atomic Physics ,13. Climate action ,Quantum state ,Excited state ,0103 physical sciences ,Matter wave ,Atomic physics ,010306 general physics ,Quantum Physics (quant-ph) ,Quantum ,Quantum tunnelling - Abstract
The photodissociation of 88Sr2 molecules is examined at ultracold temperatures with a high degree of control, and a wealth of quantum effects such as barrier tunnelling, matter—wave interference of reaction products and forbidden pathways are observed Chemistry is beginning to benefit from the advances made by atomic physicists working with ultracold molecules. In particular, reaching the quantum regime and looking at basic chemical processes in this regime could yield rich insights into the basic building blocks of chemistry. Here, Tanya Zelevinsky and colleagues look at the photodissociation of ultracold 88Sr2 molecules and cleanly observe a wealth of quantum effects, including barrier tunnelling, matter–wave interference of reaction products and forbidden reaction pathways. The high level of control may allow for high-precision measurement of important quantities, such as long-range molecular potentials, in the future. Chemical reactions at ultracold temperatures are expected to be dominated by quantum mechanical effects. Although progress towards ultracold chemistry has been made through atomic photoassociation1, Feshbach resonances2 and bimolecular collisions3, these approaches have been limited by imperfect quantum state selectivity. In particular, attaining complete control of the ground or excited continuum quantum states has remained a challenge. Here we achieve this control using photodissociation, an approach that encodes a wealth of information in the angular distribution of outgoing fragments. By photodissociating ultracold 88Sr2 molecules with full control of the low-energy continuum, we access the quantum regime of ultracold chemistry, observing resonant and nonresonant barrier tunnelling, matter–wave interference of reaction products and forbidden reaction pathways. Our results illustrate the failure of the traditional quasiclassical model of photodissociation4,5,6,7 and instead are accurately described by a quantum mechanical model8,9. The experimental ability to produce well-defined quantum continuum states at low energies will enable high-precision studies of long-range molecular potentials for which accurate quantum chemistry models are unavailable, and may serve as a source of entangled states and coherent matter waves for a wide range of experiments in quantum optics10,11.
- Published
- 2015
13. Note: Investigation of a Marx generator imitating a Tesla transformer
- Author
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Bart H. McGuyer
- Subjects
010302 applied physics ,Physics ,Tesla coil ,Physics - Instrumentation and Detectors ,business.industry ,Pulse generator ,Electrical engineering ,FOS: Physical sciences ,Instrumentation and Detectors (physics.ins-det) ,02 engineering and technology ,Spark gap ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Marx generator ,law.invention ,law ,0103 physical sciences ,0210 nano-technology ,business ,Transformer ,Instrumentation - Abstract
A compact Marx generator was built to mimic a spark-gap Tesla transformer. The generator produced radio-frequency pulses of up to $\pm$200 kV and $\pm$15 A with a frequency between 110 to 280 kHz at a repetition rate of 120 Hz. The generator tolerated larger circuit-parameter perturbations than is expected for conventional Tesla transformers. Possible applications include research on the control and laser guiding of spark discharges., Comment: 9 pages, 11 figures, includes supplementary material (but not supplementary video)
- Published
- 2018
14. Control of Optical Transitions with Magnetic Fields in Weakly Bound Molecules
- Author
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Robert Moszynski, Wojciech Skomorowski, Geoffrey Z. Iwata, Bart H. McGuyer, Mickey McDonald, and Tanya Zelevinsky
- Subjects
Physics ,Quantum Physics ,Optical lattice ,Atomic Physics (physics.atom-ph) ,FOS: Physical sciences ,General Physics and Astronomy ,Nanotechnology ,Quantum chemistry ,Diatomic molecule ,Molecular physics ,Physics - Atomic Physics ,3. Good health ,Magnetic field ,Quantization (physics) ,Ab initio quantum chemistry methods ,Excited state ,Molecule ,Quantum Physics (quant-ph) - Abstract
In weakly bound diatomic molecules, energy levels are closely spaced and thus more susceptible to mixing by magnetic fields than in the constituent atoms. We use this effect to control the strengths of forbidden optical transitions in $^{88}$Sr$_2$ over 5 orders of magnitude with modest fields by taking advantage of the intercombination-line threshold. The physics behind this remarkable tunability is accurately explained with both a simple model and quantum chemistry calculations, and suggests new possibilities for molecular clocks. We show how mixed quantization in an optical lattice can simplify molecular spectroscopy. Furthermore, our observation of formerly inaccessible $f$-parity excited states offers an avenue for improving theoretical models of divalent-atom dimers., 8 pages, 4 figures
- Published
- 2015
15. High-precision spectroscopy of ultracold molecules in an optical lattice
- Author
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Tanya Zelevinsky, Andrew T. Grier, Marco G. Tarallo, F. Apfelbeck, Bart H. McGuyer, Geoffrey Z. Iwata, and Mickey McDonald
- Subjects
Chemical Physics (physics.chem-ph) ,Physics ,Optical lattice ,Quantum Physics ,Atomic Physics (physics.atom-ph) ,Binding energy ,FOS: Physical sciences ,General Physics and Astronomy ,Molecular physics ,3. Good health ,Physics - Atomic Physics ,Quantum state ,Coherent control ,Lattice (order) ,Physics - Chemical Physics ,Ultracold neutrons ,Molecule ,Quantum Physics (quant-ph) ,Spectroscopy - Abstract
The study of ultracold molecules tightly trapped in an optical lattice can expand the frontier of precision measurement and spectroscopy, and provide a deeper insight into molecular and fundamental physics. Here we create, probe, and image microkelvin $^{88}$Sr$_2$ molecules in a lattice, and demonstrate precise measurements of molecular parameters as well as coherent control of molecular quantum states using optical fields. We discuss the sensitivity of the system to dimensional effects, a new bound-to-continuum spectroscopy technique for highly accurate binding energy measurements, and prospects for new physics with this rich experimental system., 12 pages, 4 figures
- Published
- 2015
16. Thermometry via Light Shifts in Optical Lattices
- Author
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Bart H. McGuyer, Tanya Zelevinsky, Geoffrey Z. Iwata, and Mickey McDonald
- Subjects
Condensed Matter::Quantum Gases ,Optical lattice ,Quantum Physics ,Materials science ,Atomic Physics (physics.atom-ph) ,business.industry ,Anharmonicity ,FOS: Physical sciences ,General Physics and Astronomy ,Molecular physics ,Physics - Atomic Physics ,Optics ,Light Shift ,Quantum Gases (cond-mat.quant-gas) ,Lattice (order) ,Thermal ,Molecule ,Quantum Physics (quant-ph) ,business ,Condensed Matter - Quantum Gases - Abstract
For atoms or molecules in optical lattices, conventional thermometry methods are often unsuitable due to low particle numbers or a lack of cycling transitions. However, a differential spectroscopic light shift can map temperature onto the line shape with a low sensitivity to trap anharmonicity. We study narrow molecular transitions to demonstrate precise frequency-based lattice thermometry, as well as carrier cooling. This approach should be applicable down to nanokelvin temperatures. We also discuss how the thermal light shift can affect the accuracy of optical lattice clocks., 7 pages, 4 figures. Final version
- Published
- 2014
17. Precise study of asymptotic physics with subradiant ultracold molecules
- Author
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Bart H. McGuyer, Robert Moszynski, Wojciech Skomorowski, Tanya Zelevinsky, Marco G. Tarallo, Mickey McDonald, and Geoffrey Z. Iwata
- Subjects
Physics ,Quantum Physics ,Atomic Physics (physics.atom-ph) ,General Physics and Astronomy ,FOS: Physical sciences ,Weak interaction ,Quantum chemistry ,Homonuclear molecule ,Physics - Atomic Physics ,Bond length ,Excited state ,Molecule ,Atomic physics ,Spectroscopy ,Quantum Physics (quant-ph) ,Quantum - Abstract
Weakly bound molecules have physical properties without atomic analogues, even as the bond length approaches dissociation. In particular, the internal symmetries of homonuclear diatomic molecules result in formation of two-body superradiant and subradiant excited states. While superradiance has been demonstrated in a variety of systems, subradiance is more elusive due to the inherently weak interaction with the environment. Here we characterize the properties of deeply subradiant molecular states with intrinsic quality factors exceeding $10^{13}$ via precise optical spectroscopy with the longest molecule-light coherent interaction times to date. We find that two competing effects limit the lifetimes of the subradiant molecules, with different asymptotic behaviors. The first is radiative decay via weak magnetic-dipole and electric-quadrupole interactions. We prove that its rate increases quadratically with the bond length, confirming quantum mechanical predictions. The second is nonradiative decay through weak gyroscopic predissociation, with a rate proportional to the vibrational mode spacing and sensitive to short-range physics. This work bridges the gap between atomic and molecular metrology based on lattice-clock techniques, yielding new understanding of long-range interatomic interactions and placing ultracold molecules at the forefront of precision measurements., 12 pages, 6 figures
- Published
- 2014
18. Hyperfine-frequency shifts of alkali-metal atoms during long-range collisions
- Author
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Bart H. McGuyer
- Subjects
Condensed Matter::Quantum Gases ,Physics ,Range (particle radiation) ,Atomic Physics (physics.atom-ph) ,FOS: Physical sciences ,Alkali metal ,Atomic and Molecular Physics, and Optics ,Physics - Atomic Physics ,symbols.namesake ,Electric field ,Atom ,Physics::Atomic and Molecular Clusters ,symbols ,Molecule ,Physics::Atomic Physics ,van der Waals force ,Atomic physics ,Spin (physics) ,Hyperfine structure - Abstract
Collisions with chemically inert atoms or molecules change the hyperfine coupling of an alkali-metal atom through the hyperfine-shift interaction. This interaction is responsible for the pressure shifts of the microwave resonances of alkali-metal atoms in buffer gases, is an important spin interaction in alkali-metal--noble-gas van der Waals molecules, and is anticipated to enable the magnetoassociation of ultracold molecules such as RbSr. An improved estimate is presented for the long-range asymptote of this interaction for Na, K, Rb, and Cs. To test the results, the change in hyperfine coupling due to a static electric field is estimated and reasonable agreement is found., 5 pages
- Published
- 2013
19. Spin-velocity correlations of optically pumped atoms
- Author
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Robert Marsland, William Happer, Bart H. McGuyer, and Ben A. Olsen
- Subjects
Physics ,Cusp (singularity) ,Statistical Mechanics (cond-mat.stat-mech) ,Atomic Physics (physics.atom-ph) ,Plane (geometry) ,Relaxation (NMR) ,FOS: Physical sciences ,Space (mathematics) ,Atomic and Molecular Physics, and Optics ,Computational physics ,Magnetic field ,Physics - Atomic Physics ,Optical pumping ,Adaptive optics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Condensed Matter - Statistical Mechanics ,Spin-½ - Abstract
We present efficient theoretical tools for describing the optical pumping of atoms by light propagating at arbitrary directions with respect to an external magnetic field, at buffer-gas pressures that are small enough for velocity-selective optical pumping (VSOP) but large enough to cause substantial collisional relaxation of the velocities and the spin. These are the conditions for the sodium atoms at an altitude of about 100 km that are used as guidestars for adaptive optics in modern ground-based telescopes to correct for aberrations due to atmospheric turbulence. We use spin and velocity relaxation modes to describe the distribution of atoms in spin space (including both populations and coherences) and velocity space. Cusp kernels are used to describe velocity-changing collisions. Optical pumping operators are represented as a sum of poles in the complex velocity plane. Signals simulated with these methods are in excellent agreement with previous experiments and with preliminary experiments in our laboratory., 17 pages, 8 figures
- Published
- 2013
20. Collision Kernels from Velocity-Selective Optical Pumping with Magnetic Depolarization
- Author
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I. K. Kominis, William Happer, Bart H. McGuyer, Robert Marsland, and Tejal Bhamre
- Subjects
Cusp (singularity) ,Physics ,business.industry ,Atomic Physics (physics.atom-ph) ,chemistry.chemical_element ,FOS: Physical sciences ,Physics::Optics ,Atomic and Molecular Physics, and Optics ,Computational physics ,Physics - Atomic Physics ,Optical pumping ,Transverse plane ,Earth's magnetic field ,Optics ,chemistry ,Precession ,business ,Adaptive optics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Helium ,Spin-½ - Abstract
We experimentally demonstrate how magnetic depolarization of velocity-selective optical pumping can be used to single out the collisional cusp kernel best describing spin and velocity relaxing collisions between potassium atoms and low pressure helium. The range of pressures and transverse fields used simulate the novel optical pumping regime pertinent to sodium guidestars employed in adaptive optics. We measure the precession of spin-velocity modes under the application of transverse magnetic fields, simulating the natural configuration of mesospheric sodium optical pumping in the geomagnetic field. We also provide a full theoretical account of the experimental data using the recently developed cusp kernels, which realistically quantify velocity damping collisions in this novel optical pumping regime. A single cusp kernel with a sharpness $s=13\pm 2$ provides a global fit to the K-He data., 5 pages, 3 figures
- Published
- 2013
21. Simple method of light-shift suppression in optical pumping systems
- Author
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William Happer, Y.-Y. Jau, and Bart H. McGuyer
- Subjects
Physics ,Physics and Astronomy (miscellaneous) ,business.industry ,Atomic Physics (physics.atom-ph) ,Resonance ,FOS: Physical sciences ,Laser ,Atomic clock ,law.invention ,Physics - Atomic Physics ,Optical pumping ,Optics ,Light Shift ,law ,Radio frequency ,Physics::Atomic Physics ,Atomic physics ,business ,Frequency modulation ,Microwave - Abstract
We report a simple method to suppress the light shift in optical pumping systems. This method uses only frequency modulation of a radio frequency or microwave source, which is used to excite an atomic resonance, to simultaneously lock the source frequency to the atomic resonance and lock the pumping light frequency to suppress the light shift. We experimentally validate the method in a vapor-cell atomic clock and verify the results through numerical simulation. This technique can be applied to many optical pumping systems that experience light shifts. It is especially useful for atomic frequency standards because it improves long-term performance, reduces the influence of the laser, and requires less equipment than previous methods., Comment: 4 pages, 5 figures
- Published
- 2013
- Full Text
- View/download PDF
22. Cusp Kernels for Velocity-Changing Collisions
- Author
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Ben A. Olsen, Bart H. McGuyer, Robert Marsland, and William Happer
- Subjects
Cusp (singularity) ,Physics ,Distribution (mathematics) ,Atomic Physics (physics.atom-ph) ,Mathematical analysis ,FOS: Physical sciences ,General Physics and Astronomy ,Single parameter ,Kernel (category theory) ,Physics - Atomic Physics - Abstract
We introduce an analytical kernel, the "cusp" kernel, to model the effects of velocity-changing collisions on optically pumped atoms in low-pressure buffer gases. Like the widely used Keilson-Storer kernel [J. Keilson and J. E. Storer, Q. Appl. Math. 10, 243 (1952)], cusp kernels are characterized by a single parameter and preserve a Maxwellian velocity distribution. Cusp kernels and their superpositions are more useful than Keilson-Storer kernels, because they are more similar to real kernels inferred from measurements or theory and are easier to invert to find steady-state velocity distributions., 4 pages, 2 figures
- Published
- 2012
23. Nonlinear pressure shifts of alkali-metal atoms in Xenon
- Author
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Bart H. McGuyer, William Happer, Tian Xia, and Yuan-Yu Jau
- Subjects
Physics ,Buffer gas ,chemistry.chemical_element ,Alkali metal ,Rubidium ,symbols.namesake ,Xenon ,chemistry ,Caesium ,symbols ,Molecule ,Atomic physics ,van der Waals force ,Hyperfine structure - Abstract
We demonstrate that the microwave resonant frequencies of ground-state 87Rb and 133Cs atoms have a nonlinear dependence on the pressure of the buffer gas Xe. Surprisingly, though the frequency shifts of Rb and Cs in the heavy noble gases Ar, Kr, and Xe are all negative, the nonlinearity in Xe is of the opposite sign to the nonlinearities in Ar and Kr. This discrepancy suggests that the frequency shifts due to alkali-noble van der Waals molecules in Xe are opposite in sign to the those in Ar and Kr. The nonlinearity in Xe shows a reproducible deviation from a simple model used to describe the shifts in Ar and Kr, which suggests that the spin-rotation interaction plays a significant role in the frequency shifts due to molecules. No nonlinearities were observed with the gases He and N 2 , as expected, and also Ne to within experimental error, which suggests that molecules do not form in Ne. Additionally, we present improved measurements of the shifts of Rb in Ar and Kr and of Rb and Cs in He and N 2 .
- Published
- 2011
24. Temperature-insensitive laser frequency locking near absorption lines
- Author
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William Happer, Natalie Kostinski, Robert Marsland, Bart H. McGuyer, and Ben A. Olsen
- Subjects
Materials science ,Absorption spectroscopy ,Magnetic circular dichroism ,business.industry ,Physics::Optics ,Dichroic glass ,Laser ,Spectral line ,law.invention ,symbols.namesake ,Optics ,Mode-locking ,law ,Faraday effect ,symbols ,Physics::Atomic Physics ,business ,Absorption (electromagnetic radiation) ,Instrumentation - Abstract
Combined magnetically induced circular dichroism and Faraday rotation of an atomic vapor are used to develop a variant of the dichroic atomic vapor laser lock that eliminates lock sensitivity to temperature fluctuations of the cell. Operating conditions that eliminate first-order sensitivity to temperature fluctuations can be determined by low-frequency temperature modulation. This temperature-insensitive gyrotropic laser lock can be accurately understood with a simple model, that is in excellent agreement with observations in potassium vapor at laser frequencies in a 2 GHz range about the 770.1 nm absorption line. The methods can be readily adapted for other absorption lines.
- Published
- 2011
25. Paul Drude's Prediction of Nonreciprocal Mutual Inductance for Tesla Transformers
- Author
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Bart H. McGuyer
- Subjects
Electrical Impedance ,Tesla coil ,lcsh:Medicine ,Inductor ,Resonance ,Electronic Circuits ,law.invention ,Electromagnetism ,Electricity ,law ,Periodic Waves ,Solenoids ,lcsh:Science ,Transformer ,Physics ,Traveling Waves ,Conservation of energy ,Multidisciplinary ,business.industry ,lcsh:R ,Electrical engineering ,Voltage ,Equipment Design ,Models, Theoretical ,Resonance Frequency ,Inductance ,Electric power transmission ,Electrical network ,Physical Sciences ,Waves ,Interdisciplinary Physics ,Engineering and Technology ,Equivalent circuit ,lcsh:Q ,Electronics ,Wave Propagation ,business ,Algorithms ,Electrical Engineering ,Research Article ,Electrical Circuits - Abstract
Inductors, transmission lines, and Tesla transformers have been modeled with lumped-element equivalent circuits for over a century. In a well-known paper from 1904, Paul Drude predicts that the mutual inductance for an unloaded Tesla transformer should be nonreciprocal. This historical curiosity is mostly forgotten today, perhaps because it appears incorrect. However, Drude's prediction is shown to be correct for the conditions treated, demonstrating the importance of constraints in deriving equivalent circuits for distributed systems. The predicted nonreciprocity is not fundamental, but instead is an artifact of the misrepresentation of energy by an equivalent circuit. The application to modern equivalent circuits is discussed.
- Published
- 2014
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