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Full-Text Articles in Physics
Controlling The Ratchet Effect For Cold Atoms, Anatole Kenfack, Jiangbin Gong, Arjendu K. Pattanayak
Controlling The Ratchet Effect For Cold Atoms, Anatole Kenfack, Jiangbin Gong, Arjendu K. Pattanayak
Faculty Work
Low-order quantum resonances manifested by directed currents have been realized with cold atoms. Here we show that by increasing the strength of an experimentally achievable delta-kicking ratchet potential, quantum resonances of a very high order may naturally emerge and can induce larger ratchet currents than low-order resonances, with the underlying classical limit being fully chaotic. The results offer a means of controlling quantum transport of cold atoms.
Beating The Spin-Down Limit On Gravitational Wave Emission From The Crab Pulsar, Ligo Scientific Collaboration, Nelson Christensen,
Beating The Spin-Down Limit On Gravitational Wave Emission From The Crab Pulsar, Ligo Scientific Collaboration, Nelson Christensen,
Faculty Work
We present direct upper limits on gravitational wave emission from the Crab pulsar using data from the first nine months of the fifth science run of the Laser Interferometer Gravitational-wave Observatory (LIGO). These limits are based on two searches. In the first we assume that the gravitational wave emission follows the observed radio timing, giving an upper limit on gravitational wave emission that beats indirect limits inferred from the spin-down and braking index of the pulsar and the energetics of the nebula. In the second we allow for a small mismatch between the gravitational and radio signal frequencies and interpret …
Arecibo Hi Absorption Measurements Of Pulsars And The Electron Density At Intermediate Longitudes In The First Galactic Quadrant, J. M. Weisberg, S. Stanimirovic, K. Xilouris, A. Hedden,, A. De La Fuente, S. B. Anderson, F. A. Jenet
Arecibo Hi Absorption Measurements Of Pulsars And The Electron Density At Intermediate Longitudes In The First Galactic Quadrant, J. M. Weisberg, S. Stanimirovic, K. Xilouris, A. Hedden,, A. De La Fuente, S. B. Anderson, F. A. Jenet
Faculty Work
We have used the Arecibo telescope to measure the H i absorption spectra of eight pulsars. We show how kinematic distance measurements depend on the values of the Galactic constants R0 and 0, and we select our preferred current values from the literature. We then derive kinematic distances for the low-latitude pulsars in our sample and electron densities along their lines of sight. We combine these measurements with all others in the inner Galactic plane visible from Arecibo to study the electron density in this region.
Nonmonotonicity In The Quantum-Classical Transition: Chaos Induced By Quantum Effects, Arie Kapulkin, Arjendu K. Pattanayak
Nonmonotonicity In The Quantum-Classical Transition: Chaos Induced By Quantum Effects, Arie Kapulkin, Arjendu K. Pattanayak
Faculty Work
The classical-quantum transition for chaotic systems is understood to be accompanied by the suppression of chaotic effects as the relative h is increased. We show evidence to the contrary in the behavior of the quantum trajectory dynamics of a dissipative quantum chaotic system, the double-well Duffing oscillator. The classical limit in the case considered has regular behavior, but as the effective h is increased we see chaotic behavior. This chaos then disappears deeper into the quantum regime, which means that the quantum-classical transition in this case is nonmonotonic in h.
A Simple Model For Pulse Profiles From Precessing Pulsars, With Special Application To Relativistic Binary Psr B1913+16, Timothy Clifton, Joel M. Weisberg
A Simple Model For Pulse Profiles From Precessing Pulsars, With Special Application To Relativistic Binary Psr B1913+16, Timothy Clifton, Joel M. Weisberg
Faculty Work
We study the observable pulse profiles that can be generated from precessing pulsars. A novel coordinate system is defined to aid visualization of the observing geometry. Using this system we explore the different families of profiles that can be generated by simple, circularly symmetric beam shapes. An attempt is then made to fit our model to the observations of relativistic binary PSR B1913+16. It is found that while qualitatively similar pulse profiles can be produced, this minimal model is insufficient for an accurate match to the observational data. Consequently, we confirm that the emission beam of PSR B1913+16 must deviate …