119426946
Fluctuations of quantum radiation pressure in dissipative fluid
Abstract Using the generalized Langevin equations involving the stress tensor approach, we study the dynamics of a perfectly reflecting mirror which is exposed to the electromagnetic radiation pressure by a laser beam in a fluid at finite temperature. Based on the fluctuation–dissipation theorem, the minimum uncertainty of the mirror's position measurement from both quantum and thermal noises effects including the photon counting error in the laser interferometer is obtained in the small time limit as compared with the “standard quantum limit”. The result of the large time behavior of fluctuations of the mirror's velocity in a dissipative environment can be applied to the laser interferometer of the ground-based gravitational wave detector.
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.
119162976
Smearing effect due to the spread of a probe particle on the Brownian motion near a perfectly reflecting boundary
Quantum fluctuations of electromagnetic vacuum are investigated in a half-space bounded by a perfectly reflecting plate by introducing a probe described by a charged wave-packet distribution in time-direction. The wave-packet distribution of the probe enables one to investigate the smearing effect upon the measured vacuum fluctuations caused by the quantum nature of the probe particle. It is shown that the wave-packet spread of the probe particle significantly influences the measured velocity dispersion of the probe. In particular, the asymptotic late-time behavior of its $z$-component, $ $, for the wave-packet case is quite different from the test point-particle case ($z$ is the coordinate normal to the plate). The result for the wave-packet is $ \sim 1/\t^2$ in the late time ($\t$ is the measuring time), in stead of the reported late-time behavior $ \sim 1/z^2$ for a point-particle probe. This result can be quite significant for further investigations on the measurement of vacuum fluctuations.
14403021
Fluctuations of the Hawking flux
The fluctuations of the flux radiated by an evaporating black hole will be discussed. Two approaches to this problem will be adopted. In the first, the squared flux operator is defined by normal ordering. In this case, both the mean flux and the mean squared flux are well defined local quantites. It is shown that the flux undergoes large fluctuations on a time scale of the order of the black hole's mass. Thus the semiclassical theory of gravity, in which a classical gravitational field is coupled to the expectation value of the stress tensor, breaks down below this time scale. In the second approach, one does not attempt to give meaning to the squared flux as a local quantity, but only as a time-averaged quantity. In both approaches, the mean squared mass minus the square of the mean mass grows linearly in time, but four times as fast in the second approach as in the first.
117773621
Quantum Stress Tensor Fluctuations and their Physical Effects
We summarize several aspects of recent work on quantum stress tensor fluctuations and their role in driving fluctuations of the gravitational field. The role of correlations and anticorrelations is emphasized. We begin with a review of the properties of the stress tensor correlation function. We next consider some illuminating examples of non‐gravitational effects of stress tensors fluctuations, specifically fluctuations of the Casimir force and radiation pressure fluctuations. We next discuss passive fluctuations of spacetime geometry and some of their operational signatures. These include luminosity fluctuations, line broadening, and angular blurring of a source viewed through a fluctuating gravitational field. Finally, we discuss the possible role of quantum stress tensor fluctuations in the early universe, especially in inflation. The fluctuations of the expansion of a congruence of comoving geodesics grows during the inflationary era, due to non‐cancellation of anticorrelations that would have occurr...
15106810
Stress Tensor Fluctuations and Passive Quantum Gravity
The quantum fluctuations of the stress tensor of a quantum field are discussed, as are the resulting space-time metric fluctuations. Passive quantum gravity is an approximation in which gravity is not directly quantized, but fluctuations of the space-time geometry are driven by stress tensor fluctuations. We discuss a decomposition of the stress tensor correlation function into three parts, and consider the physical implications of each part. The operational significance of metric fluctuations and the possible limits of validity of semiclassical gravity are discussed.
122242130
Collision quenching of the metastable 2S state of muonic hydrogen and the muonic helium ion
121147087
The Angular Correlation of Scattered Annihilation Radiation
118400125
The Discovery of the Parity Violation in Weak Interactions and Its Recent Developments
This address was presented by Chien-ShiungWu as the Nishina Memorial Lecture at the University of Tokyo, March 31, 1983
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)
100539642
SPIN DETERMINATION OF SUPERDEFORMED BANDS IN HG-189 AND HG-190
The superdeformed bands in 189Hg and 190Hg are investigated. The spin value of the lowest levels observed in 189Hg (fed by 366.0 keV) is assigned to be 31/2 and that of 190Hg (fed by 360.0 keV) is 15, rather than the previously proposed value 14.