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Quantum Electronics, IEEE Journal of

Issue 7 • Date July 1988

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Displaying Results 1 - 25 of 29
  • The two-photon Rydberg atom micromaser

    Page(s): 1323 - 1330
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    A Rydberg atom maser operated on a two-photon degenerate atomic transition is discussed. This device combines two interesting features: it is a quantum oscillator working on an intrinsically nonlinear effect and it is a micromaser, with only a few atoms and a few tens of photons at a time in the cavity. The reasons why Rydberg atom-superconducting cavity systems are well adapted for two-photon maser studies are discussed, and the main properties of the device are analyzed by comparing it to Rydberg masers operating on one-photon transitions.<> View full abstract»

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  • Physical interpretation of operator dynamics in the Jaynes-Cummings model

    Page(s): 1338 - 1345
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    By means of simple mathematical methods, typical properties of the quantum dynamics in the Jaynes-Cummings model are discussed. The methods used allow a clear physical interpretation in the sense of an ensemble average and permit an investigation of the influence of the initial photon distribution width on collapse and revivals. Results obtained by a more sophisticated treatment provide corrections which are on the order 1/√N0 for N0>>1 where N0 is the average photon number. The time evolution of the electric field strength and the photon distribution are also studied View full abstract»

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  • On spontaneous emission

    Page(s): 1346 - 1350
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    The problem of the spontaneous emission from a single excited two-level atom in the presence of N unexcited similar atoms is discussed. A formalism is presented for evaluation of the time-development operator (and thus the density matrix) which has certain desirable features for time-dependent problems in the area, e.g. of atom-field interactions, when the off-diagonal elements are large compared to the diagonal elements of the Hamiltonian. By use of this formalism, it is shown that the spontaneous emission from a single atom is often drastically altered in the presence of unexcited atoms with similar resonances. When the number of atoms present becomes very large relative to the number of modes of the electromagnetic field, the excited atom becomes trapped in its excited state View full abstract»

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  • Single-atom cavity-enhanced absorption. I. Photon statistics in the bad-cavity limit

    Page(s): 1351 - 1366
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    The photon statistics of the transmitted light from a driven cavity containing a single resonant two-level atom are studied in the bad-cavity limit. For weak driving fields, the second-order intensity correlation function shows novel nonclassical behavior due to the interference of the driving field and forward reradiation from the atom. This behavior is related to squeezing in the cavity transmission. A physical interpretation is given in terms of the reduced quantum state of the coupled atom-field system following photodetection View full abstract»

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  • Atomic resonance filters

    Page(s): 1266 - 1277
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    The atomic resonance filter (ARF) is an ultranarrowband (Q~105-106), large-acceptance-angle, isotropic optical filter. These features make the device ideally suited for applications in which weak laser signals are detected against a continuum background. The filter properties arise from the physical processes of absorption, emission, and internal energy conversion in atomic vapors. The characteristics of the ARF are described and the underlying physics that governs the operation is discussed. Representative examples of passive, active, and IR filters are presented. A metastable ARF that offers improved solar background-limited performance by filtering signals at Fraunhofer wavelengths is described View full abstract»

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  • Quantum theory of a one-dimensional optical cavity with output coupling. V. Spontaneous emission

    Page(s): 1367 - 1375
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    For pt.IV see J. Phys. Soc. Japan, vol.47, p.217-224 (1982). Spontaneous emission in a lossy one-dimensional cavity is analyzed under the perturbation approximation and the Wigner-Weisskopf approximation. The cavity loss due to output coupling is treated quantum mechanically by the use of a set of continuously distributed radiation modes. The enhancement and reduction factors in the spontaneous emission probability due to the presence of the cavity structure are derived. Interesting transients in spontaneous emission during a time of the order of the cavity decay time are predicted, which leads to an interpretation of the enhancement or the reduction in spontaneous emission in terms of feedback and self-interference effects. The detection of the emitted photon by a detector atom outside the cavity is also discussed View full abstract»

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  • Resonance fluorescence spectra of two driven two-level atoms

    Page(s): 1376 - 1382
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    A theoretical analysis is developed for the spectrum of the light scattered by two two-level atoms driven near resonance by an external coherent electromagnetic field. The atoms are assumed to relax to equilibrium with the driving field as a result of radiation damping. The explicit dependence of the coherent dipole-dipole interactions on the distance between the two atoms is taken into account. For the case of two two-level atoms with a fixed distance smaller than a wavelength, an analytical result for the resonance fluorescence line shape is obtained, and the result is compared to previous work View full abstract»

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  • Theory of output beam divergence in pulsed unstable resonators

    Page(s): 1302 - 1311
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    The evolution of the far-field pattern of pulsed large-Fresnel-number unstable resonators is analyzed. Both geometrical optic and physical optic descriptions are given as a function of the number of trips around the unstable resonator. The analysis determines apparent size and distance to the image of the spontaneous emission source, as seen from the output aperture by looking back through multiple passes of the resonator. It is shown that this image is not obstructed by intervening apertures. The output far-field pattern is predicted to be the pattern generated by the output aperture when illuminated by incoherent light from the image of the spontaneous emission source. Far-field intensity patterns are analyzed for square and circular apertures, and the beam quality of the output is determined View full abstract»

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  • Spontaneous excitation of atoms near a phase conjugating mirror

    Page(s): 1383 - 1387
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    It is shown by means of a semiclassical theory that the ground state of a localized collection of two-level atoms is unstable when the atomic sample is sufficiently close to a phase-conjugating mirror with high gain. Any small disturbance causes the atoms to become excited and begin fluorescing, the fluorescence taking the form of a sequence of superradiant pulses. Experiments to test this prediction seem possible View full abstract»

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  • Photon statistics and quantum jumps: the picture of the dressed atom radiative cascade

    Page(s): 1395 - 1402
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    The statistics of spontaneous photon emission times in single atom resonance fluorescence are investigated through the radiative cascade of the dressed atom. The delay function which gives the distribution of the delays between two successive emissions is calculated for a coherent as well as an incoherent laser excitation. For a two-level atom, various signals that reflect the fluorescence intensity (average value, photon counting, fluctuation spectrum, etc.) are reviewed by this method. For a three-level atom, this approach is applied to the analysis of the recently observed phenomenon of intermittent fluorescence and quantum jumps View full abstract»

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  • Semiclassical theory of multimode operation of a distributed feedback laser

    Page(s): 1248 - 1257
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    Nonlinear self-consistency equations, including for the first time the effects of mode competition, are derived for index and gain gratings. Additional terms to those contained in self-consistency equations for lasers with a conventional resonator are found. Approximate analytic solutions for single- and two-mode operation of distributed-feedback (DFB) lasers are obtained with the help of the energy theorem. The analysis includes nonvanishing end reflectors of DFB structure View full abstract»

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  • Filamentation in conventional double heterostructure and quantum well semiconductor lasers

    Page(s): 1297 - 1301
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    A wave-optical model is used to investigate filamentation of the optical field in conventional double heterostructure and quantum well semiconductor lasers. The field is propagated by the Crank-Nicholson method, and the gain model is based on a semiclassical laser theory that contains the effects of cross relaxation due to electron-electron and electron-phonon collisions. The model predicts that for broad-area devices, quantum well lasers are less affected by filamentation than conventional double heterostructure lasers View full abstract»

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  • Quantum jumps in a system of few trapped ions

    Page(s): 1413 - 1419
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    A theory of quantum jumps in a system of few trapped ions is formulated. The V configuration of the energy levels and incoherent pumping are assumed. The master equation is derived in terms of the SU(3) collective operators for the V system. Numerical results for the intensity-intensity correlations for up to five ions are presented. Analytical results for a system of two ions are derived separating out dynamics at two difference time scales and by eliminating adiabatically the fast variables. From the analytical results, the underlying three-state Markov process that can be used to characterize the quantum jumps in the two-ion system is identified. Probability distributions for various off-on time intervals are presented View full abstract»

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  • Correspondence principles: the relationship between classical trajectories and quantum spectral

    Page(s): 1445 - 1452
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    The general correspondence principle specifies a relationship between wave functions and families of trajectories. For bounded systems with regular trajectories, this general correspondence principle leads to the principle of quantization of action. The general principle also leads to a correspondence principle for finite-resolution spectra: oscillation in the average density of states, or in the average oscillator strength as a function of energy, are connected to periodic or to closed orbits. This principle holds independently or whether classical trajectories are orderly or chaotic View full abstract»

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  • Theory and experiments on the power modulation of CO2 lasers

    Page(s): 1289 - 1296
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    The operation of a pulsed transverse flow CO2 laser system with RF excitation is studied theoretically by computer simulation. The calculations are supported by experimental results which confirm that the pulse repetition frequency of the system is restricted by the time delay between the electric and the laser pulse and by relaxation oscillations. The time delay is roughly inversely proportional to the gas pressure and not very sensitive to variations of the CO2 fraction and the output coupling of laser radiation. A pulse repetition frequency over some 30 kHz can be attained only if the excitation pulse period is equal to the delay time, but this operation condition is very sensitive to changes of the duty cycle. The calculations show that full modulation depth should be attainable up to a repetition frequency of 360 kHz View full abstract»

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  • Bistability in the radiation pressure on two-level atoms in a ring cavity

    Page(s): 1388 - 1394
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    A simple model for the interaction of a beam of two-level atoms with a running radiation model in a ring cavity is formulated. The occurrence of optical bistability significantly affects the radiation pressure force on atoms. Hysteresis effects are predicted for the transverse component of atomic velocity which couples with the electric field View full abstract»

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  • Quantum jump statistics for two-atom systems

    Page(s): 1403 - 1412
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    The quantum jump statistics in the fluorescence intensity from two three-level atoms is studied. A rate-equation description valid for strong driving fields is derived, and a partial analysis of quantum jump statistics which goes beyond the strong-excitation limit is presented. As the main result, it is shown that collective effects, such as unusual intensity levels and double quantum jumps, can occur in two-atom systems. However, their observation requires that the atoms be localized within a wavelength of light View full abstract»

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  • Operating characteristics of single-quantum-well AlGaAs/GaAs high-power lasers

    Page(s): 1258 - 1265
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    The operating characteristics of six types of graded-index separate confinement heterostructure single-quantum-well wide-stripe lasers grown by metalorganic chemical vapor deposition are reported. The lasers exhibited intrinsic mode losses as low as 3 cm-1 and internal quantum efficiencies near unity. Measured differential gain coefficients range from 3.7 to 6.5 cm/A, and extrapolated transparency current densities range from 54 to 145 A/cm2. These wide-stripe lasers are typically multilongitudinal mode and exhibit narrowing of the gain envelope and lateral far-field pattern as the cavity length increases. The high value of T0(>200 K) at long cavity lengths in conjunction with the low current density permits junction-side-up operation to CW optical powers of 0.5-0.7 W/facet, at which level catastrophic facet damage occurs on the uncoated devices. A maximum power conversion efficiency of 57% was measured on the laser structure exhibiting the lowest threshold current View full abstract»

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  • FIR emissions from a laser cavity having a zig-zag axis

    Page(s): 1231 - 1234
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    FIR emissions in three directions from a FIR NH3 laser cavity having a zig-zag axis were observed when radiation from a pump CO 2 laser with multiple or single modes was linearly injected into the cavity. The temporal variation and Fabry-Perot interferogram of these emissions showed that the FIR zig-zag emission is dominated by a laser process due to a population inversion, while the other forward and backward emissions are due to a Raman process View full abstract»

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  • Numerical analysis of the feedback regimes for a single-mode semiconductor laser with external feedback

    Page(s): 1242 - 1247
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    The effect of external feedback on a single-mode semiconductor laser is estimated by a numerical solution of the nonlinear rate equations. The analysis yields an excellent description of published experimental results. It is found that the lasing mode with the minimum linewidth is most stable rather than the mode with minimum threshold gain. The transition to the coherence-collapse regime is of particular interest. It usually occurs for feedback fractions ≈10-4, but it can be shifted to considerably larger feedback levels either by increasing the emitted optical power or the laser length or by decreasing the linewidth enhancement factor α View full abstract»

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  • Hydrogen atom in monochromatic field: chaos and dynamical photonic localization

    Page(s): 1420 - 1444
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    The quantum localization phenomenon that strongly limits any quantum process of diffusive ionization that may be started in systems subjected to a periodic perturbation is discussed. In the case of a highly excited hydrogen atom in a monochromatic field, this phenomenon is theoretically analyzed by reducing the dynamics to appropriate mappings. It is shown that if the field strength is less than a so-called delocalization border, the distribution over unperturbed levels is exponential in the number of absorbed photons and the corresponding localization length is determined. Using the mapping description, it is shown that the excitation process occurring in a two-dimensional atom proceeds essentially along the same lines as in the one-dimensional model. These predictions are supported by results of numerical simulation, and the possibility of their experimental verification is discussed View full abstract»

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  • Quantum collapse and revival of Rydberg atoms in cavities of arbitrary Q at finite temperature

    Page(s): 1331 - 1337
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    Numerical calculations on the Jaynes-Cummings model in a cavity of arbitrary Q at finite temperature, using the master equation approach, are discussed. Effects due to mismatch of the atomic transition frequency and cavity mode frequency are included. Results relate to recent experiments on 85Rb Rydberg atoms View full abstract»

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  • Small systems: when does thermodynamics apply?

    Page(s): 1320 - 1322
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    The validity of using temperature to describe quantitatively the state of excitation of an isolated nucleus is examined. The problem arises because of the small number of particles in a nucleus. As a consequence, it is possible to construct a heat bath and so fix the temperature. Another definition is used that leads to an uncertainty in the measured temperature which tends to zero as the number of particles in the system increases. The emphasis is on the nuclear problem but it is presumed that similar considerations apply to other small isolated systems such as single molecules, atomic clusters containing two to several hundred atoms, helium droplets, etc View full abstract»

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  • Quantum resonances and strong field ionization

    Page(s): 1453 - 1460
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    The phenomenon of subthreshold ionization of quantum systems in an intense monochromatic field is discussed. A particularly simple system exhibiting this phenomenon is studied both analytically and numerically. The spectral properties of the quasi-energy-operator of the system are emphasized. The notion of doorway states is defined, and their importance in the mechanism of ionization is shown. The relationship between the quantum and the corresponding classical motion is emphasized. The quantum analog of the classical nonlinear resonance is recognized in the structure of some eigenfunctions of the Floquet operator. The aim of this research is twofold: reliable quantum estimates are sought to predict the onset of subthreshold ionization, which cannot be obtained from standard perturbation theory; and a precise theoretical framework is a necessary requirement in discussing the existence of chaos in the quantum mechanics of these systems View full abstract»

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  • Mode analysis of a dielectric-loaded Raman-type free-electron laser

    Page(s): 1235 - 1241
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    The Raman-type free-electron laser consists of a relativistic electron beam contained in a dielectric-induced parallel plate waveguide and an array of permanent magnets for the wiggler. Under the influence of the periodic magnetostatic field, the coupling between the scattered electromagnetic wave of the TE mode (positive-energy wave) and the electron plasma wave of the TM mode (negative-energy wave) is investigated in detail. The following results are obtained. First, when a dielectric sheet is loaded on the waveguide, the maximum growth rate and the oscillation frequency can be greater than those for the vacuum Raman-type free-electron laser. Second, by choosing proper values for the relative permittivity of the dielectric sheet and the ratio of the beam guide, the beam energy can be greatly lowered without degrading the oscillation characteristics. Third, the growth rate decays exponentially with the oscillation frequency kept almost constant as the beam-dielectric gap increases View full abstract»

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Aims & Scope

The IEEE Journal of Quantum Electronics is dedicated to the publication of manuscripts reporting novel experimental or theoretical results in the broad field of the science and technology of quantum electronics..

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Meet Our Editors

Editor-in-Chief
Aaron R. Hawkins
Brigham Young University