The usual interpretation of the quantum theory is self-consistent, but it involves an assumption that cannot be tested experimentally, viz., that the most complete possible specification of an individual system is in terms of a wave function that determines only probable results of actual measurement processes. The term ‘ontological interpretation’ is sometimes applied to Bohm’s approach, as he set out to tackle the ontological problems of conventional quantum theory. However, the ontological interpretations are strikingly different. In the many worlds view, the differing branches are simultaneously and equally real, whereas Bohm’s inactive channels remain as unmanifested potentialities, with steadily declining likelihoods as more and more irreversible process (like measurement) pile up along the manifest branch. Bohm’s theory serves to illuminate some of the more interesting aspects of quantum theory (its contextuality and nonlocal nature) and demonstrates what is at stake from an ontological point of view.
We analyse the track of an α-particle passing through a cloud chamber using the Bohm theory and show that the resulting classical track has its origins in the quantum Zeno effect. By assuming the ionised gas molecules reveal the positions of the α-particle on its trajectory and using these positions in a short time propagator technique developed by de Gosson, we show it is the failure of the quantum potential to develop quickly enough that leads to the appearance of the classical trajectory. Bohm and Hiley have already argued that it is this failure of the quantum potential to develop appropriately that prevents an Auger electron from undergoing a transition if continuously watched. This allows us to conclude that, in general, it is the suppression of the quantum potential that accounts for the quantum Zeno effect.
A tenet of time-resolved spectroscopy is "faster laser pulses for shorter timescales". Here, we suggest turning this paradigm around, and slowing down the system dynamics via repeated measurements, to do spectroscopy on longer timescales. This is the principle of the quantum Zeno effect. We exemplify our approach with the Auger process, and find that repeated measurements increase the core-hole lifetime, redistribute the kinetic energy of Auger electrons, and alter entanglement formation. We further provide an explicit experimental protocol for atomic Li, to make our proposal concrete.
We discuss a formal and physical connection between the Bohm quantum potential and the scalar mode of the Aharonov-Bohm extension of electrodynamics. The analysis is motivated by the effective non-relativistic bosonic model recently proposed by Minotti and Modanese, in which the electromagnetic field is coupled to a conserved current while the field equations contain an additional source term. In the Madelung representation
ψ=Rexp(iθ/ℏ), the Bohm quantum potential $ Q_B=-\frac{\hbar^2}{2m}\frac{\nabla^2 R}{R} $ is determined by the relative curvature
∇2R/R of the amplitude profile
R. In the same bosonic model, the scalar electromagnetic mode
S=∂μAμ is sourced by the extra-current
I=∂μjμ, which contains the density-weighted electromagnetic combination
∇⋅(R2A). Thus
QB does not act as a direct source of
S; rather, the two quantities probe different differential aspects of the same amplitude profile:
QB is sensitive to the relative curvature of
R, whereas the source of
S is sensitive to its density and gradient content through
R2 and
∇R. We show that, once boundary and normalization data are fixed, this observation may be written as a mediated functional dependence of
S on
QB through
R. We also clarify the physical status of
QB: although it is state-dependent and should not be interpreted as an autonomous external potential, its density-weighted integral gives the amplitude-gradient energy, equivalently a Fisher-information contribution. This makes
QB a compact diagnostic of quantum pressure, rigidity, and inhomogeneity of a bosonic condensate. The resulting link with
S is therefore best understood as a structural relation between the order-parameter amplitude profile of the condensate and the scalar sector of the extended electromagnetic theory.
In this work the Auger electron spectroscopy (AES) sputter depth profiling technique for binary solids has been discussed and exemplified by its application to reveal composition profiles generated in Ni(0.7)Mo(0.3) by pre-bombardment with Ar(+)-ions of 1 through 5 keV. Two element-specific. surface-sensitive Auger transitions are employed to monitor the surface composition. The Linear correlation between the Auger intensities provides the relative sensitivity factor for the quantification of AES data. A model proposed by Ho and co-workers is reformulated for the conversion of the measured temporal variation of surface concentration C(s)(t) into the original composition profile C(x). Radiation-enhanced diffusion caused by high-energy ion bombardment turns sputter depth profiling into an underdetermined inverse problem. On the other hand, experiments show that the strong preferential sputtering effect accompanying low-energy sputter may veil the detail of the composition profiles. An intermediate energy between about 100 and 300 eV is found to be optimum for the purpose of sputter depth profiling. (C) 2000 published by Elsevier Science B.V. All rights reserved.