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We investigate microwave background anisotropies in the presence of primordial magnetic fields. We show that a homogeneous field with fixed direction can amplify vector perturbations. We calculate the correlations of $\delta T/T$ explicitly and show that a large scale coherent field induces correlations between $a_{\ell-1,m}$ and $a_{\ell+1,m}$. We discuss constraints on amplitude and spectrum of a primordial magnetic field imposed by observations of CMB anisotropies., Comment: 18 page LaTeX file, 4 postscript figs. included, submitted to PRD

The theoretical basis of coherent field imaging technique (also called the Fourier telescopy) is reconsidered. The limitations of the technique principle are analyzed by defining the measured object and deriving rigorously mathematical expressions. The reconstructed image of the technique ineluctably contains the gradient information about the object; as a result the technique cannot acquire the reflectivity of the object exactly. The computer simulation verifies the conclusion. Based on the conclusion, the reconstructed image of the technique can be evaluated and three-dimensional coherent field imaging technique may be developed.

A new method of path averaging for waves propagating in a random dilute system of identical scatterers is developed. The scattering matrix of such a system is calculated. The method systematically takes into account repeating scatterings on the same scatterer and effects of correlations. Results obtained show the significant influence of new effects on the extinction of a coherent field and are valid in both the diffusive and localized regimes., 11 pages, RevTex

The free-induction decay (FID) after saturation by a laser radiation pulse of finite duration is studied for systems with spectral diffusion. The exact solution of the FID signal shape has been obtained in the framework of a model of noncorrelated spectral exchange. The analysis accounts for the finite duration of the saturating field and is valid at an arbitrary value of the spectral exchange rate and amplitude of the coherent field. An exact expression for the FID signal is derived in the weak-external-field limit. A self-consistent explanation of the experimental field dependence of the FID rate [A. Szabo and T. Muramoto, Phys. Rev. A 39, 3992 (1989)] is obtained using a model of slow noncorrelated spectral diffusion.

A study of the spectral shifts of a well-known type of partially coherent field, namely, one formed by Gaussian Schell model beams, propagating beyond an optical system reveals that there are no shifts in the geometric-image plane, whereas the greatest (blue) shift occurs in the back focal plane. These results are relevant for spectroradiometric measurements.

A simple method is presented for generating multicomponent Schrodinger cat states through resonant atom-field interactions. In the scheme n two-level atoms, initially in ground states, are sent through a resonant cavity filled with a strong coherent field sequentially. Then state-selective measurements are performed on the atoms. The detections of the atoms in ground states collapse the cavity field onto a superposition of 2n coherent states. This is the first way for producing superpositions of many coherent states through resonant atom-field interaction.

David Ackerly and Russ Monson took on a daunting task in organizing the symposium that led to this collection of papers: identifying a representative set of studies of plant function that together might point the way to a coherent field of evolutionary inquiry into plant functional biology. In their introduction to this proceedings, Ackerly and Monson speak of "waking the sleeping giant"--the study of the evolutionary foundations of plant function. This is indeed a potentially coherent and exciting field of inquiry and perhaps the best hope for rejuvenation of the study of plants as whole organisms. It is interesting that although the main lines of inquiry fell into place rather quickly after Darwin's publication of the Origin of Species, the field has yet to come into sharp focus. The deep roots of the science are perhaps nowhere more apparent than in the work of A. E W. Schimper, a leading figure in late 19th-century botanical studies. In the foreword to the English translation of Schimper's 1898 Pflanzen-Geographie aufphysiologischer Grundlage, Percy Groom at Oxford outlines Schimper's surprisingly modern approach to his work on the nature of plant adaptation

We analyze the inversionless gain in a three-level ladder system by replacing the usual coherent coupling field with an incoherent field. Surprisingly, it is found that one can obtain inversionless amplification of a weak probe even in the absence of a coherent field in the model. We conclude that gain is determined by the ensemble average of the product of the two-photon coherence and the ``effective Rabi frequency'' of the field. Thus, even though the incoherent pump reduces the two-photon coherence, gain can be restored by choosing sufficiently high strengths of the incoherent field.

Publisher Summary This chapter reviews the abundance and distribution of symbiotic micro-organisms, both in symbiosis and in isolation, and to explore the processes which may underlie the observed patterns. The chapter also illustrates the dearth of basic information on the ecology of most endosymbiotic micro-organisms. Only infrequently have ecological principles been used to explore the biology of these organisms, and their ecology has not, to date, developed into a coherent field of research. The technical advances relate to the intractability of most symbiotic micro-organisms to traditional methods in microbiology, which require isolation into axenic culture for identification and study. Symbiotic microorganisms are either unculturable, or they lose their symbiotic characteristics when isolated from the association. Much of this difficulty has been circumvented by the advent of molecular methods, especially those using PCR-technology, which provide a basis to study the abundance and diversity of micro-organisms in natural habitats, in principle without any recourse to axenic cultivation.

In this paper we investigate the phase and coherence properties of the field in the nonresonant Jaynes-Cummings model. We find the phase distribution to be split into four separate asymmetrically peaked functions. We also find, in the large-detuning limit, that the coherence properties of an originally coherent field occur periodically. We conclude that the phase formalism of Pegg and Barnett [Europhys. Lett. 6, 483 (1988)] and the coherence theory of Glauber [Phys. Rev. 130, 2529 (1963)] are complementary.

Solid-state ionic materials have been extensively developed and applications of solid electrolytes as well as insertion compounds have begun to converge into a coherent field during the last 10 years. Various designs of working devices are outlined in this chapter with the emphasis on all solid-state configurations. The large number of references reflects the great interest of researchers in energy storage devices, sensors, and optical and other electrochemical applications of solid-state ionics. For most types it is mentioned whether they are commercially available, items of intense current development, or one of the hot new research items.

We propose a scheme for the test of nonlocality with atom-field entanglement. An atom is sent through a cavity filled with a coherent field with a small amplitude. The dispersive interaction leads to atom-field entanglement. Then the field is driven by a classical current. The Bell inequality can be tested by the joint measurement of the parity of the field and the atomic state.

Hadron production consists traditionally of two main channels in the intermediate-pT region at RHIC and LHC energies: parton coalescence/recombination and jet fragmentation. We have studied a new channel, namely hadron production connected to the appearance of strong time-dependent coherent field in heavy ion collisions. In the momentum window of 5 GeV/c

In this paper, we investigate the entropy squeezing of a two-level atom interacting with a quantum field prepared initially in the Glauber–Lachs state by using the Jaynes–Cummings model. We explore the effects of increasing the intensity of the thermal field over a fixed intensity of the coherent field on the entropy squeezing of the atom. We show that increasing the number of thermal photons in the coherent field has a destructive effect on the entropy squeezing of the atom.

The vacuum Rabi splitting may be observed with population-trapping techniques. The trapped population has a lifetime much greater than the natural lifetime of the atomic transition; as a result, vacuum Rabi splittings that are much smaller than the natural lifetime may be observed. A condition for lasing without inversion in this system without any externally injected coherent field or coherence is stated.

It is shown that, in the paraxial approximation, the intensity distribution produced throughout the space by a partially coherent field depends only on certain projection integrals of the cross spectral density. These projections, in turn, can be recovered from knowledge of the spatial distribution of the optical intensity. This result can enlighten the recently evidentiated fact that two fields in different states of coherence can give rise to the same intensity everywhere. Some examples are discussed.

Recently several mechanisms have been proposed for achieving laser action without population inversion.1,2 Some of these mechanisms depend on interference effects arising from different pathways while others make use of additional pumping by coherent fields.3 In this work we study the fairly standard laser model. However we assume that the excited state of the laser transition is coupled to a high lying state with a coherent field. We show that under suitable conditions such a pumping scheme can produce gain on the laser transition even if there is no inversion among the bare states of the atom.

A numerical quantum dynamics of molecular aggregates interacting with a single-mode quantized field, i.e., coherent field, is performed. The phase properties of photons and the information entropy of aggregates are investigated to elucidate the differences in the features of collapse-revival phenomena between dimer and trimers.

We extend the concept of the degree of paraxiality, introduced recently for monochromatic fields, to the domain of stochastic fields. As an example we analytically evaluate the degree of paraxiality for a broad class of model stochastic fields, the Gaussian Schell-model fields, without and with truncation and twist phase. The dependence of the degree of paraxiality on the size and the state of coherence of the source as well as on the truncation parameter and the magnitude of twist phase is analyzed by a number of numerical examples.

Nonclassical properties of a two-mode field initially in an SU(2) coherent state resonantly interacting with a three-level Λ-type atom are investigated by means of the quantum theory and numerical calculations. The dependence of the nonclassical properties on the total photon number of the two-mode, the partition parameter and the coupling constant is discussed for three cases: (1) no state-selective atomic measurement; (2) direct state-selective atomic measurement; and (3) state-selective atomic measurement after the application of a classical field. The results indicate that when the total photon number of the two-mode is increased or the state-selective measurement is performed on the atom, the difference squeezing of two-mode is distinctly enhanced; and when the partition parameter is decreased or the state-selective measurement is performed on the atom after the application of a classical field, the average intensity of the sub-Poisson statistic distribution of mode a is reduced and that of mode b is enhanced; when the total photon number of the two modes is increased or the direct state-selective measurement is performed on the atom, the anti-correlation character between the two modes is preserved, but the average intensity of the anti-correlation is reduced; and when the direct state-selective measurement is performed on the atom, the Cauchy-Schwartz inequality is violated.

A four-level system driven by two coherent fields is considered. It is shown that in the presence of an incoherent pumping the absorption and dispersion properties of the medium can be changed. We find that the probe absorption or amplification can be achieved depending on the intensity of a coherent field and an incoherent pumping.

For a time‐harmonic source in a stratified waveguide, the acoustic field can be approximated by a coherent sum of modes propagating in range. In range‐dependent waveguides, the phase contribution from mode n is the product of a range‐dependent wave number kn(r) and range. At any given range, kn is dependent on water depth and the depth‐dependent geoacoustic parameters of both the water column and the seabed. To exploit these relationships, inversion algorithms have been developed for estimating range‐dependent seabed properties from the acoustic field measured on synthetic aperture horizontal arrays. These methods are based on inferring information about the waveguide environment by extracting information contained in the phase of the acoustic signal as a function of range. In this talk we examine the individual contributions to the total phase from each of the propagating modes based on changes in depth, sediment sound speed, and water column properties. Sensitivity of individual modes to each of these c...

A two-level atom drvien by a strong classical field interacts with a single-mode light field, and the interaction between the atom and the light field can turn into an effective anti-Jaynes-Cummings model under the conditions of strong driving and large detuning. In this paper, we mainly study the two-mode entangled coherent light field in this model, in which one mode of the entangled coherent light field interacts with a two-level atom driven by a strong classical field. During the evolution of the total system, we make a selective measurement on the atom. Through tuning the evolution time and the parameter of the coherent field, we can easily control the quantum statistical properties of the other mode of the entangled light fields and generate the expected non-classical light field in a longer interaction time and a wider region of coherent parameter.

Perception of reverberant sound field changes with a sound source distance (SSD). This article describes SSD perception in a coherent region close to the sound source in the reverberation field. We performed listening tests for SSD perception and loudness of speech and carried out transfer functions analysis using a reverberant room. We confirm that both SSD perception and loudness are correlated to the standard deviation of the magnitude frequency response of the transfer function in the coherent region. That is SSD erception and loudness increase as SSD becomes long in the coherent region. However loudness decreases in an incoherent region. Consequently, we surmise SSD perception in the coherent region might be due to increase in loudness.

We prove that in the absence of phase singularities, a generalized Schell model partially coherent field is fully defined by its intensity in three planes. We discuss the implications of this result for the problem of characterizing wave fields.

On the basis of the irradiance-moments formalism, four matrices are proposed whose elements, defined for any partially coherent field, are closely related with the second-order measurable parameters handled in the ISO standard 11146. These matrices are shown to exhibit a number of properties concerning the orientation of the transverse profile of a partially coherent beam. This behavior is described by the rotation of the principal axes of the field around its propagation axis. In addition, these matrices provide information about the spatial structure of the field (beam spread product and orbital part of the angular momentum). A new overall parameter is introduced in terms of the above matrices, which remains invariant under rotation of the Cartesian coordinate axes and upon propagation through rotationally-symmetric first-order optical systems.

We propose a method to test Bohr complemetarity with cavity QED techniques. It involves an atomic beam passing through two Ramsey zones and a nonresonant cavity initially filled with a strong coherent field. In the absence of the cavity field the probability of finding the atom in a definite state exhibits interference. Due to the dispersive atom-field interaction the paths by which the atom reach the definite state are remarked and thus the interference is destroyed. The associated quantum eraser is also presented.

The evolution of the field (atomic) entropy in a system of a quasi_Λ_type fourlevel atom interacting with an uncoupled two_mode coherent field is investigated. The effects of initial atomic state, the initial mean photon number and the splitting of the atomic energy levels on the entropy are discussed. The system reduces to that of a twolevel or threelevel atom interacting with a singlemode coherent field in special cases.

In this paper, the interactions between a two-level atom and a coherent field with a time-varying frequency have been studied. The two typical cases, in which the frequency of the field varies with time in the form of sine or impulse, have been considered. It is found that the collapse and revival phenomena of the atomic population inversion will disappear as the frequency changing with time in sine form; and the frequency varying in impulse form can lead to some new collapses and new revivals in the evolution of the atomic population inversion.

The properties of super‐resolution and stability in time‐reversal focusing of an acoustic wave are investigated using perturbation theory in a finite scattering medium with weak sound‐speed fluctuations. Although super‐resolution is obscured by weak scattering of the coherent field, the incoherent field still shows time‐reversal enhanced focusing and the analytically tractable results may provide physical insight into time‐reversal in stronger scattering media. Using first‐order perturbation theory, the correlation scales of focused time‐reversed field are defined by the scales of the fluctuations in the medium, the scale of effective aperture of the time‐reversal array due to scattering and boundary conditions, the bandwidth of the system, and the array geometry. In this weak scattering example analytic expressions for the first and second moments of the time‐reversal Green’s function operator are found and provide physical insight into the mechanism of time‐reversal focusing and the role of bandwidth in super‐resolution and stability. Numerical simulation using discrete point scatterers are performed to compare with the analytic results and to investigate the transitional behavior of time‐reversal focusing from weak to stronger scattering.

Physical mechanisms by which responses at the difference frequency can arise from targets insonified by sources radiating at two distinct primary frequencies, as found in ultrasound‐stimulated vibro‐acoustic spectrography, Fatemi and Greenleaf [Science 280 (1998)], are described from first principles using coherent field theory. Three specific mechanisms are investigated. These are (1) nonlinear interactions at the difference frequency in the primary fields co‐linearly scattered from the object, (2) linear scattering by the object of nonlinear evanescent waves incident on the object at the difference frequency due to interference of noncolinear primary incident waves, (3) the linear scattering of propagating nonlinear waves incident on the object from co‐linear primary waves. The relative amplitude of waves from these various mechanisms will be investigated and shown to vary with the target’s size, shape, acoustic properties as well as the measurement geometry.

By considering the detuning and the initial atomic coherence,a general expression of distance between density operators of arbitrary initial states (reference states) is obtained. The emphasize is put on the influence of detuning on the evolution in the interaction of a two-level atom of arbitrary initial states with the coherent field. The results show that the distance between density operators is obviously dependent on the value of detuning.

Clinical immunology is not a traditional medical specialty at all. Clinical immunology is an intellectual territory divided into tiny bits among pulmonologists, neurologists, oncologists, nephrologists, pediatricians, dermatologists, rheumatologists, clinical laboratory directors, allergists, nutritionists, hematologists, ophthalmologists who have a special interest in the anterior chamber, and many more, all intensely concerned. Each clinical specialty takes over a small piece of the territory for elaborate development, and it is a daunting task for any editor to bring the little pieces back together. Even in a 2250-page book in two heavy volumes, edited carefully by experts, it is not possible to bring unity to this awkward field. Clinical scholars may consider limiting their close study to the more coherent field of basic immunology. Clever readers will compare this text to William E. Paul's shorter and simplerFundamental Immunology(Raven Press, 1993), which originates in the same research centers and draws on many of

Recent papers have shown that there are different coherent and partially coherent fields that may have identical intensity distributions throughout space. On the other hand, the well-known transport-of-intensity equation allows the phase of a coherent field to be recovered from intensity measurements, and the solution is widely held to be unique. A discussion is given on the recovery of the structure of both coherent and partially coherent fields from intensity measurements, and we reconcile the uniqueness question by showing that the transport-of-intensity equation has a unique solution for the phase only if the intensity distribution has no zeros.

Presents an analysis of the moire fringe self images of two gratings of slightly different spatial periods. The illuminating field is spatially partially coherent and homogeneous. The existence is shown of critical coherence field structures which reduce the visibility of the fringes when self imaging conditions are satisfied.

We study the spectrum of squeezing in the light transmitted by a system of two-level atoms in an optical cavity driven by a coherent field, as recently observed by Kimble and collaborators. Our analysis does not introduce any restriction on the detuning parameters or on the relative order of magnitude of the atomic and cavity relaxation rates. Using the dressed-mode formalism, we derive explicit analytic expressions for the spectrum of squeezing and for the second-order intensity correlation function. We describe how the spectrum depends on the various parameters of the system; this study provides general indications on how to optimize the conditions to observe squeezing in optical bistability. A special attention is devoted to the changes of the spectrum under variation of the detuning parameters or of the ratio of cavity to atomic-damping rate. In all cases, the changes are continuous and smooth, with quantitative variations in the level of squeezing. This indicates the existence of a single avenue to squeezing in this system. The bad-cavity direction is identified as especially conventient to obtain a significant amount of squeezing.

If the energy of a molecule coupled to the quantised radiation field is made an extremum with respect to products of arbitrary molecular states and coherent field states, then there results a nonlinear Schrodinger equation for the molecule from which bounds for the energy contribution of the A2-term are derived. It is shown in what sense this contribution can be expected to be small under rather general circumstances.

The contribution to the index of refraction which arises from the penetration of two-level alien atoms into an interacting medium is obtained from the self-consistent mean field theory developed earlier, and its implications about the self-focusing, self-defocusing, and anomalous dispersion of a coherent field are discussed.

Every partially coherent field of illumination may be associated with a collection of generalized pencils of rays which, in turn, furnish a representation of the wave field. The hybrid Wolf function which represents the radiant energy of a thin pencil is shown to be a real, but not necessarily positive definite quantity. Such generalized pencils are used to represent certain familiar interferograms and recognize elementary results.

The dynamic response of the inversion in a two-level atom to single-mode squeezed states of the radiation field is examined. Depending on the direction of squeezing, an increase or decrease in the collapse time is demonstrated. A number of additional departures from the response of the atom to a coherent field are noted. In particular, for certain squeezed states the response of the atom is similar to that expected for chaotic radiation.

We derive the semiclassical equations governing the response of a solid-state monochromatic laser with saturable absorber driven by an external coherent field. The behavior of the emitted field intensity versus either the driving field intensity or the pump parameter of the amplifying atoms displays the same qualitative behavior. Three possible situations can appear, depending on the values taken by the relevant parameters: for a given external field intensity or pump parameter there can be one, two or three stable values of the emitted field intensity. In this way we have an example of a system which displays mono-, bi- or tristability.

After 20 years of decline, US corporations need leaders who will set coherent field strategies in a return to the basics.

The theoretical scheme developed in Parts I to III is related to equations which exactly describe the multiple scattering problem. This procedure exhibits that the hitherto investigated simple variant is restricted to uncorrelated scatterers and that it rests on the same approximation idea as a previously developed medium approach to the coherent field. The neglect of fluctuations which is characteristic for a medium theory can be seen explicitly. The basic integral representation is generalized by the inclusion of pair correlations. The generalized representation is determined uniquely and forms the starting point for a generalized wave theory of diffusion. Die in den Teilen I bis III entwickelte Theorie wird zu Gleichungen in Beziehung gesetzt, die das Vielfachstreuproblem exakt beschreiben. Dabei wird deutlich, das die bisherige einfache Variante auf unkorrelierte Streuer begrenzt ist und auf den gleichen Naherungsvoraussetzungen wie eine fruher entwickelte Mediumstheorie des koharenten Feldes beruht. Die fur die Mediumsbeschreibung charakteristische Vernachlassigung von Fluktuationen wird explizit sichtbar. Die grundlegende Integraldarstellung wird durch Einbeziehung von Paarkorrelationen verallgemeinert. Die verallgemeinerte Form wird genau bestimmt. Sie bildet den Ausgangspunkt fur eine verallgemeinerte Wellentheorie der Diffusion.

A method for calculation matrix-elements of the density operator for the superposition of two electromagnetic fields from the matrix-elements of the two components is developed. In the special case of superposition of a stationary coherent field and a stationary chaotic field results are compared with Peřina's results.

The effects of incoherent feeding and decay on a coherently driven two-level system are investigated using density-matrix techniques. A closed-form solution that includes the effects of relaxation and spontaneous emission between the two levels is obtained for cases in which the sample size is both small and large compared to the wavelength of the coherent field. The formalism developed herein is somewhat more general than the original approach of Bloch, Bloembergen, Purcell, Pound, and Redfield, insofar as it is applicable to cases where the trace of density matrix is not constant in time. As such, several new phenomena are predicted. Specifically, the steady-state solutions reveal that under appropriate conditions a significant off-resonance coherent component can be maintained indefinitely by the combination of driving field and incoherent feeding. We term this effect "kinetic coherence" and develop its formalism for both optical and radio-frequency fields.

Some general properties of optical fields with specular cross-spectral density functions are established. A practical method for generating a field with specular cross-spectral density function starting from any partially coherent field is examined. The results are analysed with reference to several common models of optical fields.

An angular spectrum of plane waves is used to represent a partially coherent field in a diffracting aperture. The concepts of a characteristic coherence angle and of a characteristic diffraction angle are then used to investigate the behaviour of the diffracted radiation. A simple formalism allows the diffraction pattern to be accurately determined.

For a disordered system of point-like scatterers the density of states is calculated in two ways: firstly as usual with the Green's function method and then based on a general relation between the density of states and the normal “particle” density. This density is determined in two steps: firstly its coherent part as the absolutely squared coherent field and secondly its incoherent part as the solution of a classical transport problem. Velocity and mean free path of the incoherent radiation are identical with the corresponding quantities of the coherent field. This opens the way to get information on the transport behaviour of the disordered material if only the properties of the coherent field are known. Fur ein System ungeordneter Punktstreuer wird die Zustandsdichte auf zwei Wegen berechnet: zunaohst wie ublich aus der Greenschen Funktion und dann aus einem allgemein-gultigen Zusammenhang zwischen Zustandsdichte und raumlicher Dichte. Diese wird in zwei Stufen bestimmt: zuerst der koharente Anteil als Absolutquadrat des koharenten Feldes, danach der inkoharente Anteil als Losung eines klassischen Transportproblems. Die der in koharenten Strahlung zugeordnete Geschwindigkeit und freie Weglange stimmen mit den entsprechenden Grosen des koharenten Feldes uberein. Dadurch ergibt sich die Moglichkeit, aus den Eigenschaften dieses Feldes unmittelbar auf das Transportverhalten des Materials zu schliesen.

Starting from the multiple scattering hierarchy the low-density solution for point-like scatterers is constructed. A given scatterer interacts with itself via the medium consisting of all the other scatterers. All pair effects are neglected. A new and simple result has been found for the attenuation of the wave by elastic scattering. The damping mechanism in the total reflection regime represents an unsolved problem. The relation of the results obtained to the behaviour of ultracold neutrons is discussed. Ausgehend von den Hierarchiegleichungen der Vielfachstreuung wird die Losung fur kleine Dichten der als punktartig angenommenen Streuzentren konstruiert. Dabei wechselwirkt jeder Streuer mit sich selbst durch die Vermittlung des von allen anderen Streuern gebildeten Mediums. Alle Paareffekte werden vernachlassigt. Fur die durch elastische Streuung bewirkte Dampfung der Welle wurde ein neues und einfaches Ergebnis gefunden. Der Dampfungsmechanismus im Totalreflexionsbereich stellt ein ungelostes Problem dar. Die Beziehungen der erhaltenen Resultate zum Verhalten ultrakalter Neutronen werden diskutiert.