光子晶体中巨Lamb移位

对非均匀电磁系统中原子的Lamb移位导出一个普适的理论公式，发现对Lamb移位的主要贡献来自实光子的吸收和再辐射过程，这打破了自1947年以来一直被人们所认同的传统概念，即在均匀空间中，Lamb移位主要来自虚光子的吸收和再辐射过程．对光子晶体，文章作者预言了巨Lamb移位效应．对原子集合，进一步发现依赖位置的Lamb移位将使一个能级扩展成一个能带，就像原子气体中依赖速度的多普勒效应一样．     

Cooperative Lamb shift in an atomic vapor layer of nanometer thickness

We present an experimental measurement of the cooperative Lamb shift and the Lorentz shift using a nanothickness atomic vapor layer with tunable thickness and atomic density. The cooperative Lamb shift arises due to the exchange of virtual photons between identical atoms. The interference between the forward and backward propagating virtual fields is confirmed by the thickness dependence of the shift, which has a spatial frequency equal to twice that of the optical field. The demonstration of cooperative interactions in an easily scalable system opens the door to a new domain for nonlinear optics.     

Extra dimensions and atomic transition frequencies

New unification theories predict large extra dimensions （LEDs）. If that is the case, gravity would be stronger at short ranges than what Newtonian gravity predicts. LEDs could also have effects at atomic level. In this paper we propose a new method to constrain the size of ‘gravity-only’ LEDs by analysing how these LEDs modify the energy of the atomic transitions 1s-2s and 2s-2p （Lamb shift）, in the particular case of the hydrogen and muonium atoms. We estimate these effects by using Bethe＇s non-relativistic treatment of Lamb shift. In the particular case of three LEDs, which may be a candidate to explain the interaction mechanism of dark matter particles, we have found that current knowledge in atomic spectroscopy could constrain their sizes to less than 10 μm. Although our contributions do not reach the sensitivity given by SN1987a, they are still slightly better than recent constraints given by Inverse Square Law tests of the Eoet-Wash group at Washington University, which gave R3 〈 36.6 μm.     

Extra dimensions and atomic transition frequencies

New unification theories predict large extra dimensions (LEDs). If that is the case, gravity would be stronger at short ranges than what Newtonian gravity predicts. LEDs could also have effects at atomic level. In this paper we propose a new method to constrain the size of `gravity-only' LEDs by analysing how these LEDs modify the energy of the atomic transitions 1s--2s and 2s--2p (Lamb shift), in the particular case of the hydrogen and muonium atoms. We estimate these effects by using Bethe's non-relativistic treatment of Lamb shift. In the particular case of three LEDs, which may be a candidate to explain the interaction mechanism of dark matter particles, we have found that current knowledge in atomic spectroscopy could constrain their sizes to less than 10\,$\mu$m. Although our contributions do not reach the sensitivity given by SN1987a, they are still slightly better than recent constraints given by Inverse Square Law tests of the E\"{o}t--Wash group at Washington University, which gave $R_{3} < 36.6\,\mu$m.     

Lamb shift of laser-dressed atomic states

We discuss radiative corrections to an atomic two-level system subject to an intense driving laser field. It is shown that the Lamb shift of the laser-dressed states, which are the natural state basis of the combined atom-laser system, cannot be explained in terms of the Lamb shift received by the atomic bare states which is usually observed in spectroscopic experiments. In the final part, we propose an experimental scheme to measure these corrections based on the incoherent resonance fluorescence spectrum of the driven atom.     

The collective Lamb shift in nuclear γ-ray superradiance

The electromagnetic transitions of M?ssbauer nuclei provide almost ideal two-level systems to transfer quantum optical concepts into the regime of hard x-rays. If many identical atoms collectively interact with a resonant radiation field, one observes (quantum) optical properties that are strongly different from those of a single atom. The most prominent effect is the broadening of the resonance line known as collective enhancement, resulting from multiple scattering of real photons within the atomic ensemble. On the other hand, the exchange of virtual photons within the ensemble leads to a tiny energy shift of the resonance line, the collective Lamb shift, that remained experimentally elusive for a long time after its prediction. Here we illustrate how highly brilliant synchrotron radiation allows one to prepare superradiant states of excited M?ssbauer nuclei, an important condition for observation of the collective Lamb shift.     

真空中V型三能级原子的布居弛豫及其量子相干自发发射

本文研究了V型三能级原子与真空耦合构成光子-原子束缚态的布居弛豫及其量子相干现象,具体阐述了引起原子相干的必要条件、布居粒子数的交换过程、真空与原子耦合所产生的Lamb移动对自发发射光谱特性带来的影响.     

Two-loop Bethe-logarithm correction in hydrogenlike atoms

We calculate the two-loop Bethe logarithm correction to atomic energy levels in hydrogenlike systems. The two-loop Bethe logarithm is a low-energy quantum electrodynamic (QED) effect involving multiple summations over virtual excited atomic states. Although much smaller in absolute magnitude than the well-known one-loop Bethe logarithm, the two-loop analog is quite significant when compared to the current experimental accuracy of the 1S-2S transition: It contributes -8.19 and -0.84 kHz for the 1S and the 2S state, respectively. The two-loop Bethe logarithm has been the largest unknown correction to the hydrogen Lamb shift to date. Together with the ongoing measurement of the proton charge radius at the Paul Scherrer Institute, its calculation will bring theoretical and experimental accuracy for the Lamb shift in atomic hydrogen to the level of 10(-7).     

Update on nuclear structure effects in light muonic atoms

We present calculations of the nuclear structure corrections to the Lamb shift in light muonic atoms, using state-of-the-art nuclear potentials. We outline updated results on finite nucleon size contributions.     

Influence of Lamb Shift Parameter on Dissipative Dynamics of the Phase Damped Jaynes–Cummings Model with Gravity Under Markovian Approximation

In this paper, we study the dissipative dynamics of the phase damped Jaynes–Cummings model with gravity under Markovian approximation in the presence of the Lamb shift parameter. The model consists of a moving two-level atom simultaneously exposed to the gravitational field and a single-mode traveling radiation field in the presence of a phase damping mechanism. We first present the master equation for the reduced density operator of the system under Markovian approximation in terms of a Hamiltonian describing the atom-field interaction with gravity in the presence of Lamb-shift parameter. Then, by making use of the super-operator technique, we obtain an exact solution of the master equation. Assuming that initially the radiation field is prepared in a Glauber coherent state and the two-level atom is in the excited state, we investigate the influence of Lamb shift parameter on the temporal evolution of collapses and revivals of the atomic population inversion, atomic dipole squeezing and atomic momentum diffusion in the presence of phase damping.     

Exact two-loop vacuum polarization correction to the Lamb shift in hydrogenlike ions

We present a calculation scheme for the two-loop vacuum polarization correction of order to the Lamb shift of hydrogenlike high-Z atoms. The interaction with the external Coulomb field is taken into account to all orders in . By means of a modified potential approach the problem is reduced to the evaluation of effective one-loop vacuum polarization potentials. An expression for the energy shift is deduced within the framework of partial wave decomposition performing appropriate subtractions. Exact results for the two-loop vacuum polarization contribution to the Lamb shift of K- and L-shell electron states in hydrogenlike Lead and Uranium are presented. Received: 10 August 1997 / Revised: 31 October 1997 / Accepted: 18 November 1997     

The influence of nuclear structure on the Lamb shift in hydrogenlike heavy atoms

We evaluate and list the various contributions to the Lamb shift in hydrogenlike heavy atoms which arise from parameters describing shape, size and structure of the nucleus. We compare these contributions with those obtained from quantum electrodynamics. It is found that in heavy nuclei, nuclear contributions depending on experimental parameters and nuclear models are of the same size as QED contributions of order a². Therefore, in these systems the theoretical predictions for binding energies are limited by the exact knowledge of the nuclear parameters. In addition, we tabulate all corrections contributing to the 1s_1/2 Lamb shift in hydrogenlike Pb and U. This revised version was published online in August 2006 with corrections to the Cover Date.     

Cooperative single-photon subradiant states in a three-dimensional atomic array

We propose a complete superradiant and subradiant states that can be manipulated and prepared in a three-dimensional atomic array. These subradiant states can be realized by absorbing a single photon and imprinting the spatially-dependent phases on the atomic system. We find that the collective decay rates and associated cooperative Lamb shifts are highly dependent on the phases we manage to imprint, and the subradiant state of long lifetime can be found for various lattice spacings and atom numbers. We also investigate both optically thin and thick atomic arrays, which can serve for systematic studies of super- and sub-radiance. Our proposal offers an alternative scheme for quantum memory of light in a three-dimensional array of two-level atoms, which is applicable and potentially advantageous in quantum information processing.     

Maximal acceleration corrections to the Lamb shift of hydrogen,deuterium and He+

The maximal acceleration corrections to the Lamb shift of one-electron atoms are calculated in a nonrelativistic approximation. They are compatible with experimental results, are in particularly good agreement with the 2S2P Lamb shift in hydrogen and reduce by ∼ 50% the experiment-theory discrepancy for the 2S2P shift in He⁺.     

Complete Lamb-shift calculation to order α5 by applying the methods of non-relativistic quantum electrodynamics

Summary It is shown, for the first time to our knowledge, that the Lamb shift for the states of hydrogenic atoms can be almost completely calculated by applying the methods of non-relativistic quantum electrodynamics and without using the Dirac equation and the second quantization for the electron. By taking into account the spin-orbit interaction, the complete Lamb shift to order α⁵ is calculated for different hydrogenic states. The author of this paper has agreed to not receive the proofs for correction.     

Chirping in light emitted by an assembly of two-level atoms

It is shown quantum mechanically that Lamb shift in radiation emitted by an assembly of two-level atoms contained in a small volume and in high excitation is opposite to that for its weak excitation and to that for a single excited atom. This leads to chirping in emitted radiation.     

Relativistic and many-body effects in K, L, and M shell ionization energy for elements with and the determination of the 1s Lamb shift for heavy elements

We report on a calculation of K, L and M inner-shell ionization energy in atoms with atomic numbers in the range . Many-body effects are evaluated for all n =1, 2, and 3 hole states. Those include correlation and effects due to the auto-ionizing nature of the hole states (Auger shift). For high Z we add recent corrected nuclear polarization, and several second-order vacuum polarization corrections. K and L ionization energies are compared with experimental X-ray absorption edges measurements. Excellent agreement with rare gazes and metal vapor measurements is found. We also compare our calculations with X-ray transition energies for all K and L lines that involve K, L and M holes. Finally we use K X-ray lines to deduce an hydrogenlike 1 s Lamb shift for several heavy elements, with far better accuracy than has been obtained by direct measurements of hydrogenlike ions. Received: 25 February 1998 / Accepted: 31 March 1998     

Laser cooling force in noisy quadrature of squeezed light

The laser cooling of atoms is a result of the combined effect of Doppler shift, light shift and polarization gradient. These are the phenomena which generally introduce frequency shift and uncertainty. However, they combine gainfully in realizing laser cooling and trapping of the atoms. In this paper we discuss the laser cooling of atoms in the presence of the squeezed light with the decay of atomic dipole moment into noisy quadrature. We show that the higher decay rate of the atomic dipole moment into the noisy quadrature, which leads to decrease in the signal to noise ratio, may contribute in realizing larger cooling force vis-à-vis with coherent laser light.     

Master and Langevin equations for electromagnetic dissipation and decoherence of density matrices

We set up a forward - backward path integral for a point particle in a bath of photons to derive a master equation for the density matrix which describes electromagnetic dissipation and decoherence. We also derive the associated Langevin equation. As an application, we recalculate the Wigner-Weisskopf formula for the natural line width of an atomic state at zero temperature and find, in addition, the temperature broadening caused by the decoherence term. Our master equation also yields the correct Lamb shift of atomic levels. The two equations may have applications to dilute interstellar gases or to few-particle systems in cavities. Received 29 November 2000 and Received in final form 11 February 2001     

The shift of atomic ground state by a limited nonresonant moderately strong laser field

The shift of the atomic ground state due to the interaction with an external limited nonresonant laser field and vacuum fluctuation is calculated in resolvent formalism. The shift operator ¯R is taken to the fourth order of perturbation expansion. It is shown that the term which mixes these two interactions gives a slight correction to the total shift, which can be expressed by the Lamb shift of the excited state.