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Search Results: 1 - 10 of 418823 matches for " R. F. O'Connell "
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Gravito-Magnetism in one-body and two-body systems: Theory and Experiments
R. F. O'Connell
Physics , 2008,
Abstract: We survey theoretical and experimental/observational results on general-relativistic spin (rotation) effects in binary systems. A detailed discussion is given of the two-body Kepler problem and its first post-Newtonian generalization, including spin effects. Spin effects result from gravitational spin-orbit and spin-spin interactions (analogous to the corresponding case in quantum electrodynamics) and these effects are shown to manifest themselves in two ways: (a) precession of the spinning bodies per se and (b) precession of the orbit (which is further broke down into precessions of the argument of the periastron, the longitude of the ascending node and the inclination of the orbit). We also note the ambiguity that arises from use of the terminology frame-dragging, de Sitter precession and Lense-Thirring precession, in contrast to the unambiguous reference to spin-orbit and spin-spin precessions. Turning to one-body experiments, we discuss the recent results of the GP-B experiment, the Ciufolini-Pavlis Lageos experiment and lunar-laser ranging measurements (which actually involve three bodies). Two-body systems inevitably involve astronomical observations and we survey results obtained from the first binary pulsar system, a more recently discovered binary system and, finally, the highly significant discovery of a double-pulsar binary system.
Radiation Reaction: General approach and applications, especially to electrodynamics
R. F. O'Connell
Physics , 2012, DOI: 10.1080/00107514.2012.688563
Abstract: Radiation reaction (but, more generally, fluctuations and dissipation) occurs when a system interacts with a heat bath, a particular case being the interaction of an electron with the radiation field. We have developed a general theory for the case of a quantum particle in a general potential (but, in more detail, an oscillator potential) coupled to an arbitrary heat bath at arbitrary temperature, and in an external time-dependent $c$-number field. The results may be applied to a large variety of problems in physics but we concentrate by showing in detail the application to the blackbody radiation heat bath, giving an exact result for radiation reaction problem which has no unsatisfactory features such as the runaway solutions associated with the Abraham-Lorentz theory. In addition, we show how atomic energy and free energy shifts due to temperature may be calculated. Finally, we give a brief review of applications to Josephson junctions, quantum statistical mechanics, mesoscopic physics, quantum information, noise in gravitational wave detectors, Unruh radiation and the violation of the quantum regression theorem
Two oscillators in a common heat bath
R. F. O'Connell
Physics , 2013,
Abstract: We show that the case of two oscillators in a common heat bath cannot be reduced to an effective one body problem. In addition, there is an interaction between the oscillators, even at zero temperature, due to the fluctuations caused in both oscillators by the zero-point oscillations of the electromagnetic field.
Charge Effects on Gravitational Wave Detectors
R. F. O'Connell
Physics , 2001, DOI: 10.1016/S0375-9601(01)00207-9
Abstract: We show that the mean-square displacement of a charged oscillator due to the zero point oscillations of the radiation field is unique in the sense that it is very sensitive to the value of the bare mass of the charge. Thus, a controlled experiment using gravitational wave detectors could lead to a determination of the electron bare mass and shed some light on quantum electrodynamic theory. We also speculate that the irregular signals of non-gravitational origin often observed in gravitational wave bar detectors could be caused by stray charges and that such charges could also adversely affect LIGO and other such detectors
Wigner Distribution Function Approach to Dissipative Problems in Quantum Mechanics with emphasis on Decoherence and Measurement Theory
R. F. O'Connell
Physics , 2003, DOI: 10.1088/1464-4266/5/3/369
Abstract: We first review the usefulness of the Wigner distribution functions (WDF), associated with Lindblad and pre-master equations, for analyzing a host of problems in Quantum Optics where dissipation plays a major role, an arena where weak coupling and long-time approximations are valid. However, we also show their limitations for the discussion of decoherence, which is generally a short-time phenomenon with decay rates typically much smaller than typical dissipative decay rates. We discuss two approaches to the problem both of which use a quantum Langevin equation (QLE) as a starting-point: (a) use of a reduced WDF but in the context of an exact master equation (b) use of a WDF for the complete system corresponding to entanglement at all times.
Decoherence in Nanostructures and Quantum Systems
R. F. O'Connell
Physics , 2003, DOI: 10.1016/S1386-9477(03)00294-7
Abstract: Decoherence phenomena are pervasive in the arena of nanostructures but perhaps even more so in the study of the fundamentals of quantum mechanics and quantum computation. Since there has been little overlap between the studies in both arenas, this is an attempt to bridge the gap. Topics stressed include (a) wave packet spreading in a dissipative environment, a key element in all arenas, (b) the definition of a quantitative measure of decoherence, (c) the near zero and zero temperature limit, and (d) the key role played by initial conditions: system and environment entangled at all times so that one must use the density matrix (or Wigner distribution) for the complete system or initially decoupled system and environment so that use of a reduced density matrix or reduced Wigner distribution is feasible. Our approach utilizes generalized quantum Langevin equations and Wigner distributions.
The Equation of Motion of an Electron
R. F. O'Connell
Physics , 2003, DOI: 10.1016/S0375-9601(03)00849-1
Abstract: The claim by Rohrlich that the Abraham-Lorentz-Dirac equation is not the correct equation for a classical point charge is shown to be incorrect and it is pointed out that the equation which he proposes is the equation {\underline{derived}} by Ford and O'Connell for a charge with structure. The quantum-mechanical case is also discussed.
Proposed New Test of Spin Effects in General Relativity
R. F. O'Connell
Physics , 2004, DOI: 10.1103/PhysRevLett.93.081103
Abstract: The recent discovery of a double-pulsar PSR J0737-3039A/B provides an opportunity of unequivocally observing, for the first time, spin effects in general relativity. Existing efforts involve detection of the precession of the spinning body itself. However, for a close binary system, spin effects on the orbit may also be discernable. Not only do they add to the advance of the periastron (by an amount which is small compared to the conventional contribution) but they also give rise to a precession of the orbit about the spin direction. The measurement of such an effect would also give information on the moment of inertia of pulsars.
Rotation and Spin in Physics
R. F. O'Connell
Physics , 2010, DOI: 10.1007/978-90-481-3735-0_14
Abstract: We delineate the role of rotation and spin in physics, discussing in order Newtonian classical physics, special relativity, quantum mechanics, quantum electrodynamics and general relativity. In the latter case, we discuss the generalization of the Kepler formula to post-Newtonian order $(c^{-2}$) including spin effects and two-body effects. Experiments which verify the theoretical results for general relativistic spin-orbit effects are discussed as well as efforts being made to verify the spin-spin effects.
The Wigner Distribution
R. F. O'Connell
Physics , 2010,
Abstract: In contrast to classical physics, the language of quantum mechanics involves operators and wave functions (or, more generally, density operators). However, in 1932, Wigner formulated quantum mechanics in terms of a distribution function $W(q,p)$, the marginals of which yield the correct quantum probabilities for $q$ and $p$ separately \cite{wigner}. Its usefulness stems from the fact that it provides a re-expression of quantum mechanics in terms of classical concepts so that quantum mechanical expectation values are now expressed as averages over phase-space distribution functions. In other words, statistical information is transferred from the density operator to a quasi-classical (distribution) function.
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