119488774
Quantum fluctuations of radiation pressure
Quantum fluctuations of electromagnetic radiation pressure are discussed. We use an approach based on the quantum stress tensor to calculate the fluctuations in velocity and position of a mirror subjected to electromagnetic radiation. Our approach reveals that radiation pressure fluctuations in the case of a coherent state are due to a cross term between vacuum and state dependent terms in a stress tensor operator product. Thus observation of these fluctuations would entail experimental confirmation of this cross term. We first analyze the pressure fluctuations on a single, perfectly reflecting mirror, and then study the case of an interferometer. This involves a study of the effects of multiple bounces in one arm, as well as the correlations of the pressure fluctuations between arms of the interferometer. In all cases, our results are consistent with those previously obtained by Caves using different methods. We argue that the agreement between the different methods supports the reality of the cross term and justifies the methods used in its evaluation.
124998001
Nonequilibrium backreaction on a moving charge and mirror in quantum fields
119118161
Quantum noise in the mirror-field system: A field theoretic approach
Abstract We revisit the quantum noise problem in the mirror–field system by a field-theoretic approach. Here a perfectly reflecting mirror is illuminated by a single-mode coherent state of the massless scalar field. The associated radiation pressure is described by a surface integral of the stress-tensor of the field. The read-out field is measured by a monopole detector, from which the effective distance between the detector and mirror can be obtained. In the slow-motion limit of the mirror, this field-theoretic approach allows to identify various sources of quantum noise that all in all leads to uncertainty of the read-out measurement. In addition to well-known sources from shot noise and radiation pressure fluctuations, a new source of noise is found from field fluctuations modified by the mirror’s displacement. Correlation between different sources of noise can be established in the read-out measurement as the consequence of interference between the incident field and the field reflected off the mirror. In the case of negative correlation, we found that the uncertainty can be lowered than the value predicted by the standard quantum limit. Since the particle-number approach is often used in quantum optics, we compared results obtained by both approaches and examine its validity. We also derive a Langevin equation that describes the stochastic dynamics of the mirror. The underlying fluctuation–dissipation relation is briefly mentioned. Finally we discuss the backreaction induced by the radiation pressure. It will alter the mean displacement of the mirror, but we argue this backreaction can be ignored for a slowly moving mirror.
53600200
Nonequilibrium dynamics of moving mirrors in quantum fields : Influence functional and the Langevin equation
We employ the Schwinger-Keldysh formalism to study the nonequilibrium dynamics of the mirror with perfect reflection moving in a quantum field. In the case where the mirror undergoes the small displacement, the coarse-grained effective action is obtained by integrating out the quantum field with the method of influence functional. The semiclassical Langevin equation is derived, and is found to involve two levels of backreaction effects on the dynamics of mirrors: radiation reaction induced by the motion of the mirror and backreaction dissipation arising from fluctuations in quantum field via a fluctuation-dissipation relation. Although the corresponding theorem of fluctuation and dissipation for the case with the small mirror's displacement is of model independence, the study from the first principles derivation shows that the theorem is also independent of the regulators introduced to deal with short-distance divergences from the quantum field. Thus, when the method of regularization is introduced to compute the dissipation and fluctuation effects, this theorem must be fulfilled as the results are obtained by taking the short-distance limit in the end of calculations. The backreaction effects from vacuum fluctuations on moving mirrors are found to be hardly detected while those effects from thermal fluctuations may be detectable.
119185780
Quantum Stress Tensor Fluctuations of a Conformal Field and Inflationary Cosmology
We discuss the additional perturbation introduced during inflation by quantum stress tensor fluctuations of a conformally invariant field such as the photon. We consider both a kinematical model, which deals only with the expansion fluctuations of geodesics, and a dynamical model which treats the coupling of the stress tensor fluctuations to a scalar inflaton. In neither model do we find any growth at late times, in accordance with a theorem due to Weinberg. What we find instead is a correction which becomes larger the earlier one starts inflation. This correction is non-Gaussian and highly scale dependent, so the absence of such effects from the observed power spectra may imply a constraint on the total duration of inflation. We discuss different views about the validity of perturbation theory at very early times during which currently observable modes are trans-Planckian.
119279483
Gravity Waves from Quantum Stress Tensor Fluctuations in Inflation
We consider the effects of the quantum stress tensor fluctuations of a conformal field in generating gravity waves in inflationary models. We find a non-scale invariant, non-Gaussian contribution which depends upon the total expansion factor between an initial time and the end of inflation. This spectrum of gravity wave perturbations is an illustration of a negative power spectrum, which is possible in quantum field theory. We discuss possible choices for the initial conditions. If the initial time is taken to be sufficiently early, the fluctuating gravity waves are potentially observable both in the CMB radiation and in gravity wave detectors, and could offer a probe of transplanckian physics. The fact that they have not yet been observed might be used to constrain the duration and energy scale of inflation.
43335620
The Universal Fermi Interaction and the Conserved Vector Current in Beta Decay
The theoretical formulation of the (V-- A) fermi interac tion is shown. The requirements of the continuity equatio of the electromagnetic current are discussed in order to lead to the formulation of the conserved vector current theory and the unique properties arising from it. The present status of the question of equality between the vector coupling constant g/sub v/ of beta decay and the Fermi constant g/sub u/ of mu decay is examined. Four types of experiments to test the CVC hypothesis are discussed. (auth) O H21308 A procedure was developed for measuring photoneutron yields from targets of grent thickness by the method of induced activity. The dependence of the photoneutron yields on the electron energy, on /sup 16/O nuclei over an energy range of 19 to 66 Mev, and on /sup 63/Cu nuclei over an energy range of 13 to 50 Mev was investigated. The electron beam from a linear accelerator was monitored by means of a secondary emission monitor. The measured values of the photoneutron yields agree with the data of others; they proved to be haif the calculated values obtained by means of the Belenky-Tamm equilibrium spectrum. (auth)
121147087
The Angular Correlation of Scattered Annihilation Radiation
120491282
Accessibility of the stochastic gravitational wave background from magnetars to the interferometric gravitational wave detectors
92250019
Isotopic Variations of the Nuclear Charge Distribution in Nd
It is well established that the optical isotope shifts for pairs of isotopes with 88 and 90 neutrons in 60Nd, 62Sm and 63Eu are anomalously large.(1) This is directly related to a change in the neutron-shell configuration. The sudden onset of permanent deformation occurs at a neutron number of 90, as predicted by the nuclear model of Nilsson. It is the increase in nuclear deformation, coupled with the usual increase in nuclear volume, that gives origin to such anomalous isotope shifts.
119651030
Mass and magnetic moment of the antiproton by the exotic atom method
Abstract Precision determinations of the mass and magnetic moment of the antiproton were made by the exotic atom method. Antiprotons were stopped in lead or uranium targets. De-excitation X-rays from the antiprotonic atoms were viewed by a high resolution Ge (Li) detector. Six principal transitions of the pPb spectrum (16 → 15 to 11 → 10) were analyzed to deduce a value of the antiproton mass. The fine structure splittings of the 11 → 10 and 12 → 11 transitions of pPb and pU were used to determine a value of the antiproton magnetic moment. Our computed values of the energy eigenvalues of the ( n , l , j ) levels included corrections due to vacuum polarization and higher order radiative terms, electron screening, nuclear finite size and nuclear polarization. In the case of the pU data, an additional shift due to the dynamic E2 mixing of nuclear rotational levels with antiprotonic orbital levels was included. Noncircular transitions were included in the analysis of the data. The values obtained for the antiproton mass and magnetic moment, 938.179±0.058 MeV and − 2.791±0.021 nuclear magnetons, respectively, are compared with the corresponding quantities pertaining to the proton, 938.2796 ± 0.0027 MeV and +2.793 nuclear magnetons, respectively (error 1.1 × 10 −6 nuclear magnetons).