Vector Potential Versus Field Intensity

Fried, Z.

doi:10.1103/physreva.8.2835

Cited by 56 publications

(12 citation statements)

References 8 publications

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“…A striking contrast is that the classical analysis of Smeenk posits an initial velocity v of the photoelectron that is parallel to the electric field direction, whereas the relativistic quantum analysis presented herein predicts an initial photoelectron velocity that arises from a circular motion around the residual ion and is thus perpendicular to the electric field. This is a contrast in gauge-dependent physical interpretations rivaling that found by Lamb [4] in his strongly gauge-dependent calculation of the line-shape associated with a Lamb-shift calculation, a dilemma resolved by Fried [5].…”

Section: Introductionmentioning

confidence: 89%

“…Lamb was disturbed by this seeming violation of gauge invariance, but succeeding authors seized on the Lamb result as evidence of an inherent superiority of the length gauge. The dilemma was resolved by Fried [5], who showed that, in the velocity gauge, all intermediate states are important, even states in the continuum. The two gauges were found to be equivalent after all, despite the major gauge-dependent difference in physical interpretations attributable to the relative contributions of intermediate states.…”

Section: Gauge Dependence Of Physical Interpretationsmentioning

confidence: 99%

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Relativistic effects in nonrelativistic ionization

Reiss

2013

Phys. Rev. A

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Phys. Rev. Lett. 106, 193002 (2011)] in atomic ionization by circularly polarized light are readily explained by the relativistic strong-field approximation (RSFA). The physical picture that emerges is determined by linear and angular momentum properties of the photons required for ionization, and it is largely independent of the atom being ionized. Radiation pressure follows from linear momenta carried by photons, and the angular momenta of the photons require the photoelectron to be in a circular orbit around the remnant ion. Two special features of the Smeenk et al. experiments are highlighted by the analysis. One is that this is the first verification of true relativistic effects in ionization. The other is that the circular trajectory picture from the RSFA analysis directly contradicts the physical picture that emerges from the length gauge. This is an exceptionally striking example of gauge-dependent differences in physical interpretations. Nevertheless, the distribution of momentum found by the Smeenk et al. experiments is accurately predicted by the RSFA. Results herein provide a universal theory to which the analysis of Titi and Drake [A. S. Titi and G. W. F. Drake, Phys. Rev. A 85, 041404(R) (2012)] represents an approximation. The physical properties of ionization by circularly polarized light also cast doubt on some predictions of rescattering theory.

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Section: Introductionmentioning

confidence: 89%

Section: Gauge Dependence Of Physical Interpretationsmentioning

confidence: 99%

Relativistic effects in nonrelativistic ionization

Reiss

2013

Phys. Rev. A

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“…Transition matrix elements on-energy-shell are gauge invariant, the matrix element of the two photon resonant transition 2s → 1s being a particular example. This has been amply verified with semi-classical treatments when complete sets of intermediate states are used [6,20,21]. On the other hand lineshape formulas including radiation damping will not in general produce the same results in each gauge [20,22].…”

Section: The Lamb Line In Hydrogenmentioning

confidence: 99%

On the gauge of the natural lineshape

Stokes¹

2013

J. Phys. B: At. Mol. Opt. Phys.

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We use a general formulation of nonrelativistic quantum electrodynamics in which the gauge freedom is carried by the arbitrary transverse component of the the Green's function for the divergence operator to calculate the natural lineshape of spontaneous emission, thus discerning the full dependence of the result on the choice of gauge. We also use a representation of the Hamiltonian in which the virtual field associated with the atomic ground state is explicitly absent. We consider two processes by which the atom is excited; the first is resonant absorption of incident radiation with a sharp line. This treatment is then adapted to derive a resonance fluorescence rate associated with the Lamb line in atomic hydrogen. Second we consider the atom's excitation due to irradiation with a laser pulse treated semi-classically. An experiment could be used to reveal which of the calculated lineshape distributions is closest to the measured one. This would provide an answer to a question of fundamental importance; how does one best describe atom-radiation interactions with the canonical formalism? arXiv:1306.3348v1 [quant-ph]

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“…For example, the JCM predicts that there is no atom-photon entanglement within the ground state, while the ground state of the QRM is highly entangled within the ultrastrong-coupling regime [26]. It was noted sometime ago in the context of scattering theory that retaining only a subset of states raises the prospect of gauge non-invariance [27][28][29][30][31][32][33][34][35]. Yet, when the coupling is weak it possible to elicit gauge-invariance through systematically accounting for the effects of the truncation [36], and the choice of gauge has no practical implications for the qualitative physical conclusions.…”

Section: Introductionmentioning

confidence: 99%

Gauge ambiguities imply Jaynes-Cummings physics remains valid in ultrastrong coupling QED

2019

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Ultrastrong-coupling between two-level systems and radiation is important for both fundamental and applied quantum electrodynamics (QED). Such regimes are identified by the breakdown of the rotating-wave approximation, which applied to the quantum Rabi model (QRM) yields the apparently less fundamental Jaynes-Cummings model (JCM). We show that when truncating the material system to two levels, each gauge gives a different description whose predictions vary significantly for ultrastrong-coupling. QRMs are obtained through specific gauge choices, but so too is a JCM without needing the rotating-wave approximation. Analysing a circuit QED setup, we find that this JCM provides more accurate predictions than the QRM for the ground state, and often for the first excited state as well. Thus, Jaynes-Cummings physics is not restricted to light-matter coupling below the ultrastrong limit. Among the many implications is that the system’s ground state is not necessarily highly entangled, which is usually considered a hallmark of ultrastrong-coupling.

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Vector Potential Versus Field Intensity

Cited by 56 publications

References 8 publications

Relativistic effects in nonrelativistic ionization

Relativistic effects in nonrelativistic ionization

On the gauge of the natural lineshape

Gauge ambiguities imply Jaynes-Cummings physics remains valid in ultrastrong coupling QED

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