Retarded Interaction of Radiation Field and Symmetry Violation of Time Reversal in the High order Stimulated Radiation and Absorption Processes of Light
It is proved that when the retarded effect (or multiple moment effect) of radiation fields is taken into account, the high order stimulated radiation and stimulated absorption probabilities of light are not the same so that time reversal symmetry would be violated, though the total Hamiltonian of electromagnetic interaction is still unchanged under time reversal. The reason to cause time reversal symmetry violation is that certain filial or partial transitive processes of bounding state atoms are forbidden or can not be achieved actually due to the law of energy conservation, the asymmetric actions of effective transition operators before and after time reversal, as well as the special states of atoms themselves. These restrictions would cause the symmetry violation of time reversal of other filial or partial transition processes which can be actualized really. The symmetry violation is also relative to the initial state asymmetries of bounding atoms before and after time reversal. For the electromagnetic interaction between non-bounding state atoms and radiation field, there is no this kind of symmetry violation of time reversal. In this way, the current formula of light stimulated radiation and absorption parameters with time reversal symmetry should be revised. The influence of time reversal symmetry violation on the foundational theory of laser is also discussed and the phenomena of non-population inversion and non-radiation transition can also be explained well. In this way, a more reliable foundation can be established for the theories of laser and nonlinear optics in which non-equilibrium processes are involved.
It is proved that when the retarded effect (or multiple moment effect) of radiation fields is taken into account, the high order stimulated radiation and stimulated absorption probabilities of light are not the same so that time reversal symmetry would be violated, though the total Hamiltonian of electromagnetic interaction is still unchanged under time reversal. The reason to cause time reversal symmetry violation is that certain filial or partial transitive processes of bounding state atoms are forbidden or can not be achieved actually due to the law of energy conservation, the asymmetric actions of effective transition operators before and after time reversal, as well as the special states of atoms themselves. These restrictions would cause the symmetry violation of time reversal of other filial or partial transition processes which can be actualized really. The symmetry violation is also relative to the initial state asymmetries of bounding atoms before and after time reversal. For the electromagnetic interaction between non-bounding state atoms and radiation field, there is no this kind of symmetry violation of time reversal. In this way, the current formula of light stimulated radiation and absorption parameters with time reversal symmetry should be revised. The influence of time reversal symmetry violation on the foundational theory of laser is also discussed and the phenomena of non-population inversion and non-radiation transition can also be explained well. In this way, a more reliable foundation can be established for the theories of laser and nonlinear optics in which non-equilibrium processes are involved.
Electromagnetic Radiation 20time reversal, for the motion equations of quantum mechanics and the Hamiltonian of electromagnetic interaction are unchanged under time reversal.However, most processes related to laser and nonlinear optics are actually high nonequilibrium ones.As we known that time reversal symmetry will generally be violated in non-equilibrium processes.It is proved in this paper that after the retarded effect of radiation fields is taken into account, the time reversal symmetry will be violated in light's high order stimulated radiation and absorption processes with ml lm BB , although the Hamiltonian of electromagnetic interaction is still unchanged under time reversal.The transition probability of third order process is calculated and the revised formula of nonlinear optics polarizability is deduced in this paper.Many phenomena of time reversal symmetry violation in non-linear optics just as sum frequency, double frequency, different frequencies, double stable states, self-focusing and self-defocusing, echo phenomena, as well as optical self-transparence and self absorptions and so on are analyzed.The reason to cause symmetry violation is that some filial or partial transition processes of bounding state atoms are forbidden or can't be achieved due to the law of energy conservation.These restrictions can cause the symmetry violation of time reversal of other partial transition processes which can be actualized really.These realizable filial or partial processes which violate time reversal symmetry generally are just the practically observed physical processes.The symmetry violation is also relative to the initial state's asymmetries of bounding atoms before and after time reversal.For the electromagnetic interaction between non-bounding atoms and radiation fields, there is no this kind of symmetry violation of time reversal.For example, in the experiments of particle physics in accelerators, we can not observe the symmetry violation of time reversal.At last, the influences of symmetry violation of time reversal on the foundation theory of laser and non-equilibrium statistical physics are discussed.The phenomena of producing laser without the reversion of particle population and transition without radiation can be well explained.The result indicates that the irreversibility of evolution processes of macrosystems originates from the irreversibility of micro-processes.The irreversibility paradox can be eliminated thoroughly.By introducing retarded electromagnetic interaction, the forces between classical changed particles are not conservative ones.Based on them, we can establish the revised Liouville equation which is irreversible under time reversal.In this way, we can lay a really rational dynamic foundation for classical non-equilibrium statistical mechanics. The transition probability of the first order processFor simplification, we consider an atom with an electron in its external layer.Electron's mass is , charge is q .When there is no external interaction, the Hamiltonian and the wave function of electron are individually 2 2 0 ˆ2 HU r m 1 0 n Et n en (1) www.intechopen.comRetarded Electromagnetic Interaction and Symmetry Violation of Time Reversal in High Order Stimulated Radiation and Absorption Processes of Lights as Well as Nonlinear Optics ... 21 After external electromagnetic field is introduced, the interaction Hamiltonian is 2 2 2 ˆˆ ˆ2 qq HA pA q c c How to reference In order to correctly reference this scholarly work, feel free to copy and paste the following: Mei Xiaochun (2012).Retarded Electromagnetic Interaction and Symmetry Violation of Time Reversal in High Order Stimulated Radiation and Absorption Processes of Lights as well as Nonlinear Optics -Influence on Fundamental Theory of Laser and Non-Equilibrium Statistical Physi, Electromagnetic Radiation, Prof. S. O.
The stimulated radiation and absorption theory of light based on low order linear interaction is considered symmetrical in time reversal processes at present. It is provided in the paper that after high order nonlinear interaction between radiation fields and charged particles is considered, time reversal symmetry in the stimulated radiation and absorption processes would be violated. Based on revised theory, the non-equilibrium and nonlinear phenomena just as generation of laser, amplification of non-population inversion, self-induced transparency and self-induced absorption can be explained more rationally. Other nonlinear processes light such as multiple frequency, sum frequency and difference frequency, double stationary state, self-focusing and self-defocusing, double and multi-photon absorption, stimulated Raman and Brillouim scatterings, photon echo and so on are also enumerated and analyzed in the paper. The results show that most processes of nonlinear optics are violated time reversal symmetry obviously.
Radiation can change the energy state of matter via three optical processes: spontaneous emission, absorption and stimulated emission. In spontaneous emission, an excited atomic or molecular state decays to a lower energy state with the emission of a photon of energy equal to the difference in the quantum state energies. Photon absorption is the reverse process, with a photon causing excitation from a lower to an excited quantum state. Stimulated emission was first proposed by Einstein in a paper published in 1917. He attempted to balance spontaneous emission and photon absorption, but could not get the correct balance without the postulated process of stimulated emission (see Section 4.2). With stimulated emission, an excited quantum state is stimulated to decay to a lower quantum state by an impinging photon. The existing photon survives with another identical photon being created (so that energy is conserved). The rates at which radiative transitions occur can be calculated using quantum mechanics. The time-dependent Schrodinger equation is used with the system wavefunction comprising time-varying linear combinations of the two wavefunctions for the lower and upper quantum states. In semi-classical treatments, an atom is treated quantum mechanically with the radiation field treated classically. There is a perturbation in energy associated with, say, the electric field of the radiation interacting with the electric dipole of the atom, though other interactions can be significant if the electric dipole interaction energy is small. In absorption, for example, a differential equation representing the change in ‘weighting’ of the wavefunction from the lower to upper state is obtained. A ‘time constant’ for the speed of change represents the rate of the radiative process. We examine the quantum mechanical nature of radiation absorption in Section 10.1 before discussing (Section 10.3) another important parameter arising with radiative transitions between discrete bound quantum states: the lineshape function. Quantum Theory of the Atom–Radiation Interaction An expression for the Einstein B-coefficient for photo-absorption is derived using quantum mechanics in this section. Einstein determined the detailed balance relationship between the rates of spontaneous emission, photo-absorption and stimulated emission when light interacts with an atom by considering an atomic system of two energy levels which are in equilibrium with a black-body radiation field. We use a semi-classical treatment where the atom is treated quantum mechanically and the radiation field is treated as a classical oscillating electric field.
Radiative transitions When a system changes its energy as the result of the emission or the absorption of a photon, it is said to undergo radiative transition. There are three kinds of radiative transition. In the presence of an electromagnetic field the system can absorb a photon, so that its energy is raised to a higher level. If the system is initially in a state other than the ground state, it can emit a photon and so shed energy. This can happen without the presence of any external electromagnetic field, in which case a spontaneous emission is said to occur. On the other hand, if the excited system is placed in an electromagnetic field that varies in time with the appropriate frequency, the probability that it will emit a photon can be greatly enhanced. In this case the emission process is known as stimulated emission . Stimulated emission is the basis of maser and laser action, which we describe in this chapter. First, we construct a simple model that allows us to investigate how the internal structure of a quantum system changes as the result of a radiative transition. Although the model is very simple, it will allow us to understand the main features of the proper, more exact treatment. We shall deal mainly with absorption and stimulated emission, the two types of radiative transition where there is an external electromagnetic field.
The basic phenomena of interaction between atoms and e.m. fields can be discussed in some detail without the need of a detailed model of the atom. Absorption and stimulated emission of radiation can be explained satisfactorily by the theory, where a classical electromagnetic wave provides a time-dependent perturbation to the energy of the atomic electrons. Laser radiation appears to a very good approximation to be a classical travelling wave of well-defined amplitude and phase. The radiation produced by a continuous laser is a good approximation to a coherent state. For conventional sources of radiation, the interaction energy is small compared with the energy an electron possesses by virtue of the attraction to the atomic nucleus, so perturbation theory produces quite acceptable results. The quantum mechanical analogy to the distortion of the classical charge cloud is given by the writing down of a general state function for the system, Ψ.
An attempt is made to present a consistent detailed theory of optical phenomena, based on the suggestion recently made by the author in collaboration with Bohr and Kramers. This suggestion is that atoms are radiating or absorbing continuously, during their stationary states, and that transitions influence radiation only in terminating the radiation characteristic of the old state, and substituting that of the new. The atoms, on the other hand, are supposed not to change their energy while radiating, but to change it discontinuously on transition. This necessitates giving up the detailed application of the conservation of energy in interaction between atoms and radiation. In the present paper, an additional suggestion is made, namely that resonance radiation is to be identified with the radiation carried out by the spherical wavelets which, by their interference with the external field, also produce absorption. This is practically a return to the classical picture of resonance radiation. Statement of the theory consists formally of two parts: the description of the behavior of atoms, and of radiation, when the two interact. The first involves the statement of the probabilities of transition of atoms, and is taken without change from Einstein. The probability of interruption of coherent vibrations is also discussed. The second requires the specification of the fields emitted by atoms in any steady state under the influence of any external field. These consist of spherical wavelets of the frequencies of the various quantum lines which the atom can emit or absorb in the stationary state in which it is. For emission frequencies, wavelets are emitted even in the absence of an external field; for absorption frequencies, external fields induce wavelets, similar to the wavelets of linearly bound electrons in electron theory, which on the one hand interfere with the external field to produce the phenomena of dispersion, etc., and on the other carry out the resonance radiation in all directions. Detailed descriptions of these fields are given. In a discussion of the theory, it is first shown that the assumptions which have been made about the field satisfy the correspondence principle, in that for large quantum numbers the field aproaches that which would be emitted classically on account of the interaction of an external field and a multiply periodic atom. On the other hand, it is shown that the field has a character essentially like that of classical electron theory, which is known to be in general agreement with experiments. Next, the energy and momentum relations at interaction of atoms and light are investigated, and it is shown that, although these quantities are not precisely conserved, still the assumptions as to atomic and radiation processes have been so made that they are conserved on an average over a great number of atomic processes. Finally the spectral resolution of emitted and absorbed radiation is considered; the theory gives a minimum breadth for the lines, depending on the finite length of wave trains resulting from the finite life in stationary states, and it is shown that Kirchhoff's law is obeyed, the emission and absorption lines being of the same breadth. By way of illustration, specific application of the theory is made to the simple examples of emission of light by bombardment of electrons at the resonance potential, resonance radiation, its quenching by presence of foreign gases, absorption, scattering, and disperison.