On time as a quantum-physical observable quantity

1999 ◽  
Author(s):  
V. S. Olkhovsky
Keyword(s):  
Observable Quantity ◽  
Physical Observable

scholarly journals Enhanced avionic sensing based on Wigner’s cusp anomalies

2021 ◽  
Vol 7 (23) ◽  
pp. eabg8118
Author(s):  
Rodion Kononchuk ◽  
Joshua Feinberg ◽  
Joseph Knee ◽  
Tsampikos Kottos
Keyword(s):  
Cross Section ◽  
Linear Response ◽  
Nuclear Reactions ◽  
Exceptional Point ◽  
Small Perturbations ◽  
Differential Scattering Cross Section ◽  
Sensing Applications ◽  
Physical Observable ◽  
Resonant Systems ◽  
Square Root Singularity

Typical sensors detect small perturbations by measuring their effects on a physical observable, using a linear response principle (LRP). It turns out that once LRP is abandoned, new opportunities emerge. A prominent example is resonant systems operating near Nth-order exceptional point degeneracies (EPDs) where a small perturbation ε ≪ 1 activates an inherent sublinear response ∼εN≫ε in resonant splitting. Here, we propose an alternative sublinear optomechanical sensing scheme that is rooted in Wigner’s cusp anomalies (WCAs), first discussed in the framework of nuclear reactions: a frequency-dependent square-root singularity of the differential scattering cross section around the energy threshold of a newly opened channel, which we use to amplify small perturbations. WCA hypersensitivity can be applied in a variety of sensing applications, besides optomechanical accelerometry discussed in this paper. Our WCA platforms are compact, do not require a judicious arrangement of active elements (unlike EPD platforms), and, if chosen, can be cavity free.

scholarly journals Teaching kinetic energy as an observable quantity

2019 ◽  
Vol 54 (4) ◽  
pp. 045003
Author(s):  
Bruno Hartmann ◽  
Burkhard Priemer
Keyword(s):  
Kinetic Energy ◽  
Observable Quantity

scholarly journals THE ANAPOLE MOMENT IN SCALAR QUANTUM ELECTRODYNAMICS

2010 ◽  
Vol 25 (37) ◽  
pp. 3145-3150 ◽  
Author(s):  
A. BASHIR ◽  
Y. CONCHA-SÁNCHEZ ◽  
M. E. TEJEDA-YEOMANS ◽  
J. J. TOSCANO
Keyword(s):  
Quantum Electrodynamics ◽  
Scalar Particle ◽  
Charged Scalar ◽  
Current Conservation ◽  
Anapole Moment ◽  
Effective Lagrangian ◽  
Physical Observable ◽  
Scalar Quantum ◽  
Charged Scalar Particle ◽  
Shell Particles

The anapole moment of a massless charged scalar particle is studied in a model-independent fashion, using the effective Lagrangian technique, as well as radiatively within the context of scalar quantum electrodynamics (SQED). It is shown that this gauge structure is characterized by a non-renormalizable interaction, which is radiatively generated at one-loop. It is found that the resulting anapole moment for off-shell particles, though free of ultraviolet divergences, is gauge dependent and thus it is not a physical observable. We also study some of its kinematical limits. In particular, it is shown that its value comes out to be zero when the photon is on-shell and the momenta squared of the incoming and outgoing scalars are equal. It is a stronger statement than it being zero for all particles being on-shell which is required by the current conservation.

scholarly journals Definitions, Summary, and Some Issues

2002 ◽  
Vol 12 ◽  
pp. 179-181
Author(s):  
Peter S. Conti
Keyword(s):  
Spectral Type ◽  
Massive Star ◽  
Massive Stars ◽  
Mass Star ◽  
Mass Limit ◽  
Physical Processes ◽  
Intermediate Mass ◽  
Observable Quantity ◽  
Low Mass ◽  
Final Evolution

This Joint Discussion has been titled Massive Star Birth. Perhaps it is appropriate here to define what we mean by a massive star. The very word massive suggests we consider aminimummassMbelow which one would speak of low (or intermediate) mass evolution, and above which is the realm of massive stars. It is natural to take this mass limit as that in which a (single) star will end its life as a supernova: 8M⊙. This corresponds to a (minimum) luminosityLof a few × 103L⊙, a (minimum)Teff of 20000 K, and a ZAMS spectral type of about B1.5V. Note that this mass division refers to the final evolution of a star, and might well have nothing to do with difference in physical processes between massive and low mass starbirth. For example, the minimumTeff for a star to produce an UCHII region, a readily observable quantity, corresponds to aTeffcloser to 30000 K and a mass of 15M⊙.

scholarly journals Remarks on an Anomalous Triple Gauge Boson Couplings

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Patricio Gaete ◽  
J. A. Helayël-Neto ◽  
L. P. R. Ospedal
Keyword(s):  
Gauge Boson ◽  
Wilson Loop ◽  
Higgs Mechanism ◽  
Linear Potential ◽  
Gauge Invariant ◽  
Physical Observable ◽  
The Standard Model ◽  
Electroweak Sector ◽  
Path Dependent ◽  
Gauge Boson Couplings

We address the effect of an anomalous triple gauge boson couplings on a physical observable for the electroweak sector of the Standard Model, when the S U 2 L ⊗ U 1 Y symmetry is spontaneously broken by the Higgs mechanism to U 1 e m . Our calculation is done within the framework of the gauge-invariant, but path-dependent variable formalism is an alternative to the Wilson loop approach. Our result shows that the interaction energy is the sum of a Yukawa and a linear potential, leading to the confinement of static probe charges. The point we wish to emphasize, however, is that the anomalous triple gauge boson couplings ( Z γ γ ) contributes to the confinement for distances on the intranuclear scale.

SCALING, VORONOI TESSELLATION, AND KJMA: THE DISTRIBUTION FUNCTION IN THIN SOLID FILMS

2010 ◽  
Vol 09 (01n02) ◽  
pp. 1-18 ◽  
Author(s):  
M. TOMELLINI ◽  
M. FANFONI
Keyword(s):  
Distribution Function ◽  
Film Growth ◽  
Voronoi Tessellation ◽  
Size Distribution Function ◽  
Solid Surfaces ◽  
Diffusional Growth ◽  
Scaling Properties ◽  
Solid Films ◽  
Mathematical Demonstration ◽  
Physical Observable

Among several aspects concerning the growth of thin films on solid surfaces, we focus our discussion on the physical observable known as the island size distribution function (SDF). Since this is a subject large enough to require a full review, even a whole book, we have limited our survey to the scaling properties of the distribution function and to some of its possible shapes. In particular, we discuss the fast and slow nucleation processes in diffusional growth and the KJMA (Kolmogorov–Johnson–Mehl–Avrami) distributions. Space has been given to the mathematical demonstration of the principal equations, in order to render the paper usable also to neophytes of thin film growth. Experimental particle (SDFs) are also reported and discussed.

scholarly journals Measurement of the spin of the M87 black hole from its observed twisted light

2019 ◽  
Vol 492 (1) ◽  
pp. L22-L27 ◽  
Author(s):  
Fabrizio Tamburini ◽  
Bo Thidé ◽  
Massimo Della Valle
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Observational Evidence ◽  
Rotation Parameter ◽  
Intensity Data ◽  
Wavefront Reconstruction ◽  
Recovery Techniques ◽  
Physical Observable ◽  
Twisted Light ◽  
Radio Intensity

ABSTRACT We present the first observational evidence that light propagating near a rotating black hole is twisted in phase and carries orbital angular momentum (OAM). This physical observable allows a direct measurement of the rotation of the black hole. We extracted the OAM spectra from the radio intensity data collected by the Event Horizon Telescope from around the black hole M87* by using wavefront reconstruction and phase recovery techniques and from the visibility amplitude and phase maps. This method is robust and complementary to black hole shadow circularity analyses. It shows that the M87* rotates clockwise with an estimated rotation parameter a = 0.90 ± 0.05 with an $\sim 95{{\ \rm per\ cent}}$ confidence level (c.l.) and an inclination i = 17° ± 2°, equivalent to a magnetic arrested disc with an inclination i = 163° ± 2°. From our analysis, we conclude that, within a 6σ c.l., the M87* is rotating.

scholarly journals Cathode ray oscillography of gas adsorption phenomena I-A method for measuring high-velocity approach to certain physical and chemical equilibria

1935 ◽  
Vol 151 (873) ◽  
pp. 296-307 ◽  
Author(s):  
M. C. Johnson ◽  
F. A. Vick ◽  
Samuel Walter Johnson Smith
Keyword(s):  
Essential Feature ◽  
Chemical Change ◽  
Optical Methods ◽  
Gas Content ◽  
Time Lags ◽  
Low Velocity ◽  
True Rate ◽  
Reaction Velocity ◽  
Observable Quantity ◽  
Physical And Chemical

The essential feature of many experiments on adsorption, evaporation, surface diffusion, and surface chemistry consists of observing a progress towards equilibrium after altering A the pressure of gas which has access to a solid, or B the temperature of a solid exposed to gas or gas mixture. But such observations only become adequate for investigating probabilities of transition between the relevant physical and chemical states if the true rate of approach to equilibrium is not obscured or distorted by time lags in the experimental methods employed. If the term "reaction velocity" be generalized to include rate of simple phase change, owing to the similarity of the latter to chemical change in its thermodynamic treatment, then the limits to accessible range of such velocity are set by the following: ( a ) the maximum rate at which A or B can be made to stimulate reaction, ( b ) the rate at which resulting energy exchanges affect some observable quantity chosen as indicator, and ( c ) the rate at which the indicator can record itself. Such limitations become serious in the study of reactions occurring in interfacial layers of monomolecular thickness. These present uniquely simple kinetics owing to the elimination of transmission delays in the actual reaction, since all the atoms may be exposed simultaneously to any agency of change; but reaction velocity becomes for that reason so large, in the interesting cases where intrinsic probabilities of transition are not extremely small, that detailed investigation by ordinary means becomes impossible. The difficulty is most acute when the solid surface is reduced to the dimensions of a filament capable of high-temperature flashing, to obey modern needs of reproducible cleanliness; the gas content is then so minute that all optical methods are inapplicable and no micromanometric or thermal observation can keep pace with the reaction. Time constants for the faster of these would seem essentially inaccessible except electron emission from a surface offers an observable quantity indicative of the state of surface layers, and responding instantaneously to any reactions which modify that state. Such thermionic acid photoelectric emission has not hitherto been combined with fast enough recording to take full advantage of this rapidity of response; Langmuir and others have used auxiliary vapours to avoid temperature ranges in which gas reaction would be rapid, while Oliphant and Moon, and Evans, have used mechanical oscillography for alkali ions only, whose behaviour is important in a low-velocity range. The extension which we here put forward, to phenomena rapid enough to justify introducing a cathode ray oscillographic technique, requires firstly certain improvements in the timing, etc., controls of such instruments not needed for their normal use; secondly, it requires theoretical and experimental determinations of the limits imposed on observable velocity by the time taken in attaining pressure equilibria and thermal and electrical steady state, and by the speed of photography. These requirements in establishing the method for rapid surface processes are completed in Part I, in relation to the two standard way A and B of initiating reaction by pressure and temperature. The conclusions are exhibited in photographic examples from phenomena well known but previously inaccessible to exact analysis, before proceeding, Part II, to apply them in the solution of particular problems.

scholarly journals NanoSQUIDs: Basics & recent advances

2017 ◽  
Vol 2 (8) ◽  
Author(s):  
Maria José Martínez-Pérez ◽  
Dieter Koelle
Keyword(s):  
Magnetic Nanoparticles ◽  
Magnetic Flux ◽  
Quantum Interference ◽  
Quantum Coherence ◽  
Particle Characterization ◽  
Physical Observable ◽  
Macroscopic Quantum Coherence ◽  
Scanning Squid ◽  
Electric Signals ◽  
Magnetic States

Abstract Superconducting Quantum Interference Devices (SQUIDs) are one of the most popular devices in superconducting electronics. They combine the Josephson effect with the quantization of magnetic flux in superconductors. This gives rise to one of the most beautiful manifestations of macroscopic quantum coherence in the solid state. In addition, SQUIDs are extremely sensitive sensors allowing us to transduce magnetic flux into measurable electric signals. As a consequence, any physical observable that can be converted into magnetic flux, e.g., current, magnetization, magnetic field or position, becomes easily accessible to SQUID sensors. In the late 1980s it became clear that downsizing the dimensions of SQUIDs to the nanometric scale would encompass an enormous increase of their sensitivity to localized tiny magnetic signals. Indeed, nanoSQUIDs opened the way to the investigation of, e.g., individual magnetic nanoparticles or surface magnetic states with unprecedented sensitivities. The purpose of this chapter is to present a detailed survey of microscopic and nanoscopic SQUID sensors. We will start by discussing the principle of operation of SQUIDs, placing the emphasis on their application as ultrasensitive detectors for small localized magnetic signals. We will continue by reviewing a number of existing devices based on different kinds of Josephson junctions and materials, focusing on their advantages and drawbacks. The last sections are left for applications of nanoSQUIDs in the fields of scanning SQUID microscopy and magnetic particle characterization, placing special stress on the investigation of individual magnetic nanoparticles.

scholarly journals Twisted light, a new tool for general relativity and beyond — Revealing the properties of rotating black holes with the vorticity of light —

2021 ◽  
Author(s):  
F. Tamburini ◽  
F. Feleppa ◽  
B. Thidé
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Gravitational Lensing ◽  
Compact Object ◽  
Additional Tool ◽  
Physical Observable ◽  
Rotating Black Holes

We describe and present the first observational evidence that light propagating near a rotating black hole is twisted in phase and carries orbital angular momentum. The novel use of this physical observable as an additional tool for the previously known techniques of gravitational lensing allows us to directly measure, for the first time, the spin parameter of a black hole. With the additional information encoded in the orbital angular momentum, not only can we reveal the actual rotation of the compact object, but we can also use rotating black holes as probes to test general relativity.

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