共查询到20条相似文献,搜索用时 31 毫秒
1.
Christopher King 《Communications in Mathematical Physics》1994,165(3):569-594
We consider a model Hamiltonian derived from the interaction of an atom with a non-relativistic massless quantized field. The model atom has two states, and the interaction is linear in the field operator. We do not make the rotating wave approximation and there is no infrared cutoff. We prove that the excited state of the atom with no photons present decays at an approximately exponential rate in accordance with the predictions of time dependent perturbation theory. The proof requires some analyticity and regularity assumptions on the interaction between atom and field. These imply in particular that the interaction goes to zero at least as fast ask
2, ask0, wherek is the photon momentum. 相似文献
2.
Stability of coulomb systems with magnetic fields 总被引:1,自引:0,他引:1
The ground state energy of an atom in the presence of an external magnetic filedB (with the electron spin-field interaction included) can be arbitrarity negative whenB is arbitrarily large. We inquire whether stability can be restored by adding the self energy of the field, B
2. For a hydrogenic like atom we prove that there is a critical nuclear charge,z
c
, such that the atom is stable forz<z
c
and unstable forz>z
c
.Work partically supported by U.S. National Scinece Foundation grant DMS-8405264 during the author's stay at the Institute for Advanced Study, Princeton, NJ, USAWork partially supported by U.S. National Science Foundation grant PHY-8116101-A03Work partially supported by U.S. and Swiss National Science Foundation Cooperative Science Program INT-8503858. Current address: Institut f. Mathematik, FU Berlin, Arnimallee 3, D-1000 Berlin 33 相似文献
3.
V. Ernst 《Zeitschrift für Physik B Condensed Matter》1976,23(1):103-111
The interaction of a two level atom with many photons in a continuum of modes is investigated on the base of a Weisskopf-Wigner theory of infinite order. Special emphasis is given to the problem whether a given uncertainty in the number of incident photons has observable effects upon the atom. This refers in particular to the special uncertainty related to the Poisson distribution of photons in a fully coherent state. It is shown that, if at all, the photon number uncertainty can only shift the atomic levels. These shifts are of the order of magnitude of the 2S
1/2–2P
1/2 level separation by Lambschifts. In an approximation in which these level shifts are omitted the photon number uncertainty has no effects upon the atom: The atom interacts simultaneously withall n-photon components of the incident beam, but inindependent interaction processes taking place in orthogonal Hilbert-spaces. Arguments are given to justify the mentioned approximation, a variant of the usual rotating wave approximation. This approximation reduces the Weisskopf-Wigner theory of infinite order to an infinite set of Weisskopf-Wigner theories of finite, lowest order. The latter govern the independent processes mentioned. 相似文献
4.
N. L. Manakov A. V. Merem’yanin 《Journal of Experimental and Theoretical Physics》1997,84(6):1080-1089
Using the electric dipole approximation, we present, in invariant form, the cross section of an arbitrary three-photon transition
between the discrete states of an atom with total angular momenta J
i and J
f. The cross section contains scalar and mixed products of the photon polarization vectors, and invariant atomic parameters
dependent only on the photon frequencies. We determine the number of independent atomic parameters at fixed values of J
i and J
f and obtain their explicit expressions in terms of the reduced composite dipole matrix elements. The polarization dependence
of the cross sections is expressed in terms of the degrees l and ξ of linear and circular photon polarizations. We analyze the phenomenon of dissipation-induced circular dichroism in three-photon
processes, i.e., the difference Δ of the cross sections for opposite signs of the degree of circular polarization of all the
photons. We study in detail the case of two identical photons and the phenomenon of elliptical dichroism, when Δ∼lξ holds and dichroism occurs only when the photons are elliptically polarized, with 0<|ξ|<1. Finally, we discuss the dissipation-induced effects of atom polarization in three-photon processes involving linearly
polarized or unpolarized photons.
Zh. éksp. Teor. Fiz. 111, 1984–2000 (June 1997) 相似文献
5.
Xian-Ming Qin Zhao-Xian Yu Zhi-Yong Jiao Bing-Hao Xie 《International Journal of Theoretical Physics》2009,48(4):1098-1103
By using the Lewis-Riesenfeld invariant theory, we have studied the dynamical phase and the geometric phase in a two energy
level k-photon Jaynes-Cummings model with imaginary photon process. We find that the geometric phase in a cycle case is independent
of the frequency of the photon field, the coupling coefficient between photons and atoms, and the atom transition frequency.
We predict the physical effect of the geometric phase in the imaginary photon process may be measured. 相似文献
6.
Eckehard W. Mielke 《General Relativity and Gravitation》1977,8(3):175-196
The familiar wormhole model of geometrodynamics is extended to allow for knotted embeddings of the initial hypersurface. It is shown that topology change is not only a means to modify the connectivity of the space, but also the knot invariants of its embedding. In a probabilistic framework the process of wormhole scattering can be expressed by creation and annihilation operators acting on the wave function of quantum geometrodynamics. Implications concerning Wheeler's exciton model of elementary particles, thef-gravity approach to hadronic matter, and interrelations with Jehle's flux quantization program are discussed.Work supported by a grant of the Studienstiftung des deutschen Volkes and in part by National Science Foundation grant No. GP 30799 X to Princeton University. 相似文献
7.
Zhao-Xian Yu Bing-Hao Xie Shuo Jin Zhi-Yong Jiao 《International Journal of Theoretical Physics》2008,47(10):2690-2696
By using the Lewis–Riesenfeld invariant theory, we have studied the dynamical and the geometric phases in a generalized time-dependent
k-photon Λ-type Jaynes–Cummings model. It is found that, different from the dynamical phases, the geometric phases in a cycle
case are independent of the photon numbers, the frequency of the photon field, the coupling coefficient between photons and
atoms, and the atom transition frequency. 相似文献
8.
It is proved that a nucleus of chargeZ can bind at mostZ+O(Z
a) electrons, witha=47/56.Partially supported by a NSF grant at Princeton UniversitySupported by a Sloan Foundation Dissertation Fellowship at Princeton University 相似文献
9.
A strong resonant interaction of a two-level atom with a dielectric microsphere is studied on the basis of quantum electrodynamics.
The initial condition considered is one in which the atom is initially excited and the resonant mode of the microsphere has
been excited by a single photon. The spectrum of two emitted photons depends strongly on the method used to excite the microsphere,
i.e., on the spatial distribution of the photon energy. The most characteristic feature of the two-photon fluorescence spectrum
is a strong energy correlation of the emitted photons. This correlation is expressed in the fact that the energies of the
emitted photons are related by the equation of an ellipse (ω+ω
2−2ω
vA
)2+3(ω
1−ω
2)2= 4Ω
Rabi
2
. The relation between the results obtained and the predictions of the theory of dressed states is discussed.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 3, 192–197 (10 August 1999) 相似文献
10.
Ira Herbst Jacob Sachach Møller Erik Skibsted 《Communications in Mathematical Physics》1996,174(3):509-535
We prove asymptotic completeness for short- and long-rangeN-body Stark Hamiltonians with local singularities of at most Coulomb type. Our results include the usual models for atoms and molecules.Research partially supported by NSF grant DMS 9307147. 相似文献
11.
We consider a particle system coupled to the quantized electromagnetic or phonon field. Assuming that the coupling is small enough and that Fermi’s Golden Rule is satisfied, we prove asymptotic completeness for Rayleigh scattering on the states for which the expectation of either the photon/phonon number operator or an operator testing the photon/phonon infrared behaviour is uniformly bounded on corresponding dense sets. By extending a recent result of De Roeck and Kupiainen in a straightforward way, we show that the second of these conditions is satisfied for the spin-boson model. 相似文献
12.
The feasibility of resonance transfer of quantum information from one double-level atom to another that is at an arbitrary distance from the former one has been proved. Symmetric and antisymmetric combinations of the wave functions of individual atoms are considered. When taking into account the interatomic dipole–dipole interaction, a certain energy corresponds to each wave function. A solution has been found to a system of equations for the amplitudes of the probability that a resonance photon will be absorbed by one of the system atoms, and it has been shown that the interaction of the system with actual photons has the result that the wave function of the final state of the system can be represented as a linear combination of the functions < 00|, < 0n|, and < n0| corresponding to the ground and excited states of individual atoms. The amplitude of the probability of each of these states depends on the interatomic distance and on the parameters of the action of actual photons on atoms. Three types of solution to the system of equations have been investigated for the resonance and nonresonance absorption of photons and different interatomic distances. It has been shown that when atoms are at an infinite distance from one another, so that there is no dipole–dipole interaction of atoms, quantum information can be transferred from one atom to another with a characteristic time considerably shorter than the time it takes for a photon to cover the interatomic distance. This effect is referred to as the effect of quantum teleportation in a system of resonance atoms. 相似文献
13.
A version of the one-dimensional Rayleigh gas is considered: a point particle of massM (molecule), confined to the unit interval [0,1], is surrounded by an infinite ideal gas of point particles of mass 1 (atoms). The molecule interacts with the atoms and with the walls via elastic collision. Central limit theorems are proved for a wide class of additive functionals of this system (e.g. the number of collisions with the walls and the total length of the molecular path).Research partially supported by the Hungarian National Foundation for Scientific Research, grant No. 819/1 相似文献
14.
G. Rodrigo H. Czyż J.H. Kühn M. Szopa 《The European Physical Journal C - Particles and Fields》2002,24(1):71-82
Electron–positron annihilation into hadrons plus an energetic photon from initial state radiation allows the hadronic cross-section
to be measured over a wide range of energies. The full next-to-leading order QED corrections for the cross-section for annihilation into a real tagged photon and a virtual photon converting into hadrons are calculated where the tagged photon
is radiated off the initial electron or positron. This includes virtual and soft photon corrections to the process and the emission of two real hard photons: . A Monte Carlo generator has been constructed, which incorporates these corrections and simulates the production of two charged
pions or muons plus one or two photons. Predictions are presented for centre-of-mass energies between 1 and 10 GeV, corresponding
to the energies of DANE, CLEO-C and B-meson factories.
Received: 14 December 2001 / Published online: 5 April 2002 相似文献
15.
For the standard model of QED with static nuclei, nonrelativistic electrons and an ultraviolet cutoff, a new simple proof
of absence of excited eigenstates with energies above the groundstate energy and below the ionization threshold of an atom
is presented. Our proof is based on a multi-scale virial argument and exploits the fact that, in perturbation theory, excited
atomic states decay by emission of one or two photons. Our arguments do not require an infrared cutoff (or regularization)
and are applicable for all energies above the groundstate energy, except in a small (α-dependent) interval around the ionization threshold.
also at IHES, Bures-sur-Yvette. 相似文献
16.
I.F. Ginzburg U.D. Jentschura V.G. Serbo 《The European Physical Journal C - Particles and Fields》2008,54(2):267-276
Delbrück scattering is the elastic scattering of a photon in the Coulomb field of a nucleus via a virtual electron loop. The
contribution of this virtual subprocess to the emission of a photon in the collision of ultra-relativistic nuclei, Z1Z2→Z1Z2γ, is considered. We identify the incoming virtual photon as being generated by one of the relativistic nuclei involved in
the binary collision and the scattered photon as being emitted in the process. The energy and angular distributions of the
photons are calculated. The discussed process has no infrared divergence. The total cross section obtained is 14 barn for
Au–Au collisions at the RHIC collider and 50 barn for Pb–Pb collisions at the LHC collider. These cross sections are considerably
larger than those for ordinary tree-level nuclear bremsstrahlung in the considered photon energy range, me⪡Eγ⪡meγ, where γ is the Lorentz factor of the nucleus. Finally, photon emission in electron–nucleus collisions, eZ→eZγ, is discussed
in the context of the eRHIC option. 相似文献
17.
A. N. Khopersky A. M. Nadolinsky K. Kh. Ikoeva O. A. Khoroshavina 《Optics and Spectroscopy》2012,112(1):44-49
Using the Zn atom as an example, beyond the scopes of the impulse approximation and the incoherent scattering-function approximation,
we study the absolute value and the shape of the double differential nonresonance Compton scattering cross section of an X-ray
photon by an atom with the core of the d symmetry. We take into account the effects of radial relaxation of shells in the field of core vacancies and of elastic (Thomson
and Rayleigh) scattering. Calculation results have a predictive character and, for the incident photon energies of 14.93 and
22.10 keV and the scattering angles of 141° and 133°, agree well with experimentally determined values of the differential
Compton scattering cross section. 相似文献
18.
This paper solves the problem of the interaction of an electron and positron via the field of soft and hard photons with emission
or absorption of a real photon. The interaction is interpreted as a third-order QED effect in the coordinate representation.
The role of intermediate states with positive and negative frequencies is studied. A general expression is derived for the
matrix elements of the operator of the effective electron-positron interaction energy for different types of quantum transitions.
The expression makes it possible to calculate the probabilities of the corresponding transitions in the nonrelativistic approximation.
Electric dipole transitions in the positronium atom accompanied by emission (absorption) of an optical photon are investigated.
Two-particle wave functions of the positronium atom are used to introduce the concept of polarization fields inside the positronium
atom. It is found that the polarization fields depend on the coordinates and time and on the choice of the pair of states
between which a quantum transition with emission or absorption of a photon takes place.
Zh. éksp. Teor. Fiz. 113, 471–488 (February 1998) 相似文献
19.
The effect of the specific anisotropy of the environment on the dynamics of a resonantly fluorescing atom is analyzed in a one-dimensional model. The environmental anisotropy, which is manifested as different spectral selectivities of the absorption of spontaneous photons emitted by the atom in different directions, results in the anisotropy of the photon emission rate giving rise to a nonzero recoil force on the atom. The effect under optimal conditions can reach one-quarter of the recoil momentum per single photon emission. This force is directed toward the weaker spectral selectivity.
相似文献20.
We calculated the photon path distribution (PPD) in a scattering medium based on a theoretical analysis, which utilizes the relationship between the photon intensity and photon pathlength. This PPD is defined by local photon pathlengths for photons having total pathlengths of l between the light input points and detection points. The PPD of photons that consist of the impulse response at time t (= l/c) was calculated for a 2-D model. Precise analysis of photon migration in the scattering medium is essential in order to carry out image reconstruction of diffuse optical tomography (DOT). We show the PPD at time t (the total pathlength l = ct) and demonstrate its effectiveness. Our method for describing photon migration is intuitive and allows finding weight functions in DOT. 相似文献