太赫兹电磁场照射下量子线中的纳米电子力

研究两端连接电子库的量子线在太赫兹(THz)电磁场横向辐射下的电子力学问题. 在自由电子近似下求得了弹道区二能级电子波函数解析表达式,发现电子概率在两个能态间随线轴坐标作Rabi振荡, 其幅度与外场强度和频率有关. 利用热力学统计算符方法并利用波函数计算出了传导电子对量子线中张力贡献的大小. 其计算结果可表示成与外场无关和与外场有关的两部分之和,前者与已有的实验观测和理论计算结果一致, 而与外场参量有关的部分可用量子相干理论解释. 关键词： 量子线 THz电磁场 纳米电子力     

A rigorous uncertainty relation (Cauchy Inequality) for an electromagnetic field in quantum superpositions of coherent states and in a two-photon coherent state

It is shown that the Heisenberg uncertainty relation (or soft uncertainty relation) determined by the commutation properties of operators of electromagnetic field quadratures differs significantly from the Robertson–Schrödinger uncertainty relation (or rigorous uncertainty relation) determined by the quantum correlation properties of field quadratures. In the case of field quantum states, for which mutually noncommuting field operators are quantum-statistically independent or their quantum central correlation moment is zero, the rigorous uncertainty relation makes it possible to measure simultaneously and exactly the observables corresponding to both operators or measure exactly the observable of one of the operators at a finite measurement uncertainty for the other observable. The significant difference between the rigorous and soft uncertainty relations for quantum superpositions of coherent states and the two-photon coherent state of electromagnetic field (which is a state with minimum uncertainty, according to the rigorous uncertainty relation) is analyzed.     

Excited hydrogenic atom in a strong low-frequency electromagnetic field

The multiphoton ionization of a bound electron state which is twofold degenerate with respect to its orbital angular momentum is considered in a quasiclassical approximation. It is shown that the ionization probability increases strongly in an intense electromagnetic field, in which nonresonant mixing of the levels forming the degenerate state is significant, in comparison to the case described by the Keldysh formula. It is also shown that such degeneracy leads to a sharp increase in the intensity of the radiation scattered by the bound electron, and the high-frequency cutoff of the emission spectrum is shifted to higher frequencies. Zh. Tekh. Fiz. 69, 15–20 (August 1999)     

Influence of local relief on a low-frequency electromagnetic field

Leningrad State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 1, pp. 17–21, January, 1990.     

Ionization of atoms in strong low-frequency electromagnetic field

The ionization of atoms in a low-frequency linearly polarized electromagnetic field (the photon energy is much lower than the ionization potential of an atom) is considered under new conditions, in which the Coulomb interaction of an electron with the atomic core in the final state of the continuum cannot be considered in perturbation theory in the interaction of the electron with the electromagnetic field. The field is assumed to be much weaker that the atomic field. In these conditions, the classical motion of the electron in the final state of the continuum becomes chaotic (so-called dynamic chaos). Using the well-known Chirikov method of averaging over chaotic variations of the phase of motion, the problem can be reduced to non-linear diffusion on the energy scale. We calculate the classical electron energy in the final state, which is averaged over fast chaotic oscillations and takes into account both the Coulomb field and the electromagnetic field. This energy is used to calculate the probability of ionization from the ground state of the atom to a lower-lying state in the continuum using the Landau-Dykhne approximation (to exponential accuracy). This ionization probability noticeably depends on the field frequency. Upon a decrease in frequency, a transition to the well-known tunnel ionization limit with a probability independent of the field frequency is considered.     

Beta decay in a strong electromagnetic field. II

A study is made of the probability and spin-angle correlations of 3 decay in a strong electromagnetic field consisting of a superposition of a magnetic field and a plane monochromatic wave propagating in the direction of the magnetic field. The cases of a weakly varying wave field and cyclotron resonance, which is possible in such a system, are studied.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 88–92, January, 1981.We are grateful to Professor I. M. Ternov and V. R. Khalilov for helpful discussions and assistance.     

Ionization of a molecular hydrogen ion by a strong low-frequency electromagnetic field of laser radiation

Simple analytical expressions are obtained for the energy and angular distributions of outgoing electrons in ionization of a molecular hydrogen ion by a strong low-frequency electromagnetic field as well as for the ionization probabilities per unit time. The cases of linear and circular polarization of the laser radiation are studied. It is shown that in contrast to the case of the ionization of atoms oscillations appear in the energy spectra of the photoelectrons as a function of their kinetic energy. The well-known limits for the tunneling ionization probabilities for the hydrogen atom by a strong low-frequency alternating field are obtained in the case of large internuclear separations. Zh. é ksp. Teor. Fiz. 113, 583–592 (February 1998)     

Two-photon cooperative decay in a cavity in the presence of a thermalized electromagnetic field

We study the cooperative two-photon spontaneous decay of an excited atomic system in a microcavity whose size is of the order of several wavelengths of atomic radiation. We show that a thermalized electromagnetic field in the microcavity strongly affects the two-photon cooperative spontaneous emission of radiation. The increase in the rate of spontaneous cooperative decay is due to the presence of a small number of thermalized photons in a microcavity mode. At low temperatures, the two-photon absorption probability is found to be a linear function of the two-photon flux, and photon superbunching is observed. Zh. éksp. Teor. Fiz. 115, 1153–1167 (April 1999)     

A massive photon in a strong magnetic field: Generation and decay channels

The conditions for the formation of an effective photon mass in a strong magnetic field are considered. It is shown that massless photons are sterile. The channels γ* → e⁺e⁻ and γ* → v_iv_i for the decay of a massive photon and their possible contribution to the mechanism of energy losses by collapsing astrophysical objects are discussed. Moscow State Industrial University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 35–39, February, 1997.     

Neutrino decay of an axion in an external electromagnetic field

Switching on an external electromagnetic field opens a neutrino decay channel of a hypothetical pseudoscalar particle, an axion, which plays an important role in modern field theory. We obtain exact expressions in the one-loop approximation for the probability of the decay into a massless neutrino in a crossed fieldF and study the asymptotic behavior by the nature of the parameter . Moscow State Industrial University, Moscow. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 42, No. 2, pp. 8–12, February, 1999.     

Quasiclassical coherent trajectory states of a spinless relativistic particle in an arbitrary electromagnetic field

Approximate (quasiclassical) solutions of the Klein-Gordon equation for a charge in an arbitrary electromagnetic field are constructed. One of the decisive properties of these solutions is that the average quantum-mechanical values of the coordinates and momenta in these states are the exact solutions of the classical relativistic Hamiltonian equations.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 48–50, April, 1982.     

变频率光场与二能级原子的相互作用：双光子过程

研究了二能级原子与单模电磁场相互作用时的双光子过程,主要考虑了在相干态初始条件下场频率发生变化时的情况,讨论了场频率随时间作正弦缓慢变化对原子布居数反转、光场压缩与原子压缩等特性的影响.结果显示,场频率的改变将使得原子布居数反转的崩塌回复周期增大,回复值减小,而光场及原子压缩效应减弱. 关键词： 布居数反转 光场压缩 原子压缩 双光子过程     

Phonons in a magnon superfluid and symmetry-breaking field

Recent experiments [1,2] on the measurement of the spectrum of the Goldstone collective mode of a coherently precessing state in ³He-B are discussed using the presentation of the coherent-spin precession in terms of the Bose-Einstein condensation of magnons. The mass in the spectrum of the Goldstone boson—a phonon in the superfluid magnon liquid—is induced by the symmetry-breaking field, which is played by the RF magnetic field. The text was submitted by the author in English.     

Derivation of cooperative-dynamic equations for an ensemble of three-level atoms in a coherent electromagnetic field

Equations for the density matrix of three-level atoms interacting collectively with a two-mode radiation field are derived for level schemes of three types within the framework of a formalism with secondary quantization of the electromagnetic field. Saint Peterburg State Technical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 20–23, February, 1997.     

Quasienergy pseudopotential method in the theory of interaction of a coherent electromagnetic field with matter

We formulate the quasienergy pseudopotential methods, allowing us to study the behavior of the electronic structure of a material in a coherent electromagnetic field. We show that after canonical transformation, we can look for the solution to the nonsteady-state Schrödinger equation in a basis of wave functions from extended Hubert space, substituting the quasienergy pseudopotential for the true nonsteady-state electronic potential. We prove that the familiar compensation theorem remains valid even in this case.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 33–37, February, 1992.