Showing papers on "Quantum published in 1990"
TL;DR: In this paper, it was observed that the optical spectra of a nanometer-sized semiconductor crystallite are sensitive to size and the number of atoms in the crystallite.
Abstract: How can one understand the excited electronic states of a nanometer sized semiconductor crystallite, given that the crystallite structure is simply that of an excised fragment of the bulk lattice? This question is motivated by recent experiments on chemically synthesized "quantum crystallites," sometimes called "quantum dots," in which it is observed that the optical spectra are quite sensitive to size. For example, bulk crystalline CdSe is a semiconductor with an optical band gap at 690 nm, and continuous optical absorption at shorter wavelengths. However, 3540/~ diameter CdSe crystallites containing some 1500 atoms exhibit a series of discrete excited states with a lowest excited state at 530 nm (1-3). With increasing size, these states shift red and merge to form the optical absorption of the bulk crystal. Electron microscopy and Bragg X-ray scattering measurements show that these crystallites have the same structure and unit cell as the bulk semiconductor. Such changes have now been observed in the spectra of many different semiconductors. This phenomenon is a "quantum size effect" related to the development of the band structure with increasing crystallite size (4). Smaller crystallites behave like large molecules (e.g. polycyclic aromatic hydrocarbons) their spectroscopic and photophysical properties. They are true "clusters" that do not exhibit bulk semiconductor electronic properties. In this review
1,012 citations
TL;DR: In this paper, the statistical properties of quantum chaos are considered on the basis of the well-known model of a kicked rotator and the quasienergy spectrum and the structure of the eigenfunctions in the case of strong classical chaos.
605 citations
TL;DR: Current approaches for generating nanostructures of conducting materials are briefly reviewed, especially the use of three-dimensional crystalline superlattices as hosts for quantum-confined semiconductor atom arrays (such as quantum wires and dots) with controlled inter-quantum-structure tunneling.
Abstract: Nanoparticulate metals and semiconductors that have atomic arrangements at the interface of molecular clusters and "infinite" solid-state arrays of atoms have distinctive properties determined by the extent of confinement of highly delocalized valence electrons. At this interface, the total number of atoms and the geometrical disposition of each atom can be used to significantly modify the electronic and photonic response of the medium. In addition to teh novel inherent physical properties of the quantum-confined moieties, their "packaging" into nanocomposite bulk materials can be used to define the confinement surface states and environment, intercluster interactions, the quantum-confinement geometry, and the effective charge-carrier density of the bulk. Current approaches for generating nanostructures of conducting materials are briefly reviewed, especially the use of three-dimensional crystalline superlattices as hosts for quantum-confined semiconductor atom arrays (such as quantum wires and dots) with controlled inter-quantum-structure tunneling.
601 citations
TL;DR: A gedanken gadget based on an idea of Greenberger, Horne, and Zeilinger that provides a more powerful demonstration of quantum nonlocality than Bell's analysis of the Einstein-Podolsky-Rosen experiment is described in this article.
Abstract: A gedanken gadget is described, based on an idea of Greenberger, Horne, and Zeilinger, that provides a more powerful demonstration of quantum nonlocality than Bell’s analysis of the Einstein–Podolsky–Rosen experiment.
466 citations
TL;DR: It is proposed by which the quantum states of two light beams of different frequencies can be interchanged and it is possible to generate frequency-tunable squeezed light for spectroscopic applications.
Abstract: An experimental scheme is proposed by which the quantum states of two light beams of different frequencies can be interchanged. With this scheme it is possible to generate frequency-tunable squeezed light for spectroscopic applications.
342 citations
TL;DR: Cette representation est utile pour decrire la transition entre des phases ordonnees magnetiquement and dimerisees des antiferromagnetiques quantiques.
Abstract: We introduce a new representation of S=1/2 quantum spins in terms of bond operators. The bond operators create and annihilate singlet and triplet bonds between a pair of spins. The representation is useful in describing the transition between dimerized and magnetically ordered phases of quantum antiferromagnets. It is used to obtain a mean-field theory of the two-dimensional frustrated quantum Heisenberg antiferromagnets considered recently by Gelfand, Singh, and Huse. The method should also be useful in the analysis of random quantum antiferromagnets.
326 citations
TL;DR: The evolution of the atomic state in the resonant Jaynes-Cummings model (a two-level atom interacting with a single mode of the quantized radiation field) with the field initially in a coherent state is considered and it is shown that the atom is to a good approximation in a pure state in a middle of what has been traditionally called the "collapse region".
Abstract: The evolution of the atomic state in the resonant Jaynes-Cummings model (a two-level atom interacting with a single mode of the quantized radiation field) with the field initially in a coherent state is considered. It is shown that the atom is to a good approximation in a pure state in the middle of what has been traditionally called the "collapse region. This pure state exhibits no Rabi oscillations and is reached independently of the initial state of the atom. For most initial states a total or partial "collapse of the wave function" takes place early during the interaction, at the conventional collapse time, following which the state vector is recreated, over a longer time scale. PACS numbers: 42.50.— p, 03.65.— w, 42.52.+x The Jaynes-Cummings model' (JCM) is perhaps the simplest nontrivial example of two interacting quantum systems: a two-level atom and a single mode of the radiation field. In addition to its being exactly solvable, the physical system that it represents has recently become experimentally realizable with Rydberg atoms in high-Q microwave cavities. Comparison of the predictions of the model with those of its semiclassical version have served to identify a number of uniquely quantum properties of the electromagnetic field; indeed, the model displays some very interesting dynamics, and the differences with the semiclassical theory are both profound and unexpected. The JCM would also appear to be an excellent model with which to explore some of the more puzzling aspects of quantum mechanics, such as the possibility (or impossibility) to describe an interacting quantum system by a state vector undergoing unitary evolution; i.e., the socalled "collapse of the wave function. " In the semiclassical version, the atom interacting with the classical electromagnetic field may at all times be described by a state vector evolving unitarily. What happens, however, when it is recognized that the field is itself a quantum system (which leads inevitably to "entanglement" )? This is the question addressed in this Letter. It does not seem to have been addressed before in full generality, although entanglement in the JCM dynamics plays an essential role in a recent measurement-theory-related proposal of Scully and Walther, and preparation of a pure state of the field in the JCM has been the subject of several theoretical investigations and may be close to being achieved experimentally. The resonant JCM interaction Hamiltonian may be written as Ht = hg(~a&(b (a+ a'(b)(a ~ ), ' is a coupling constant (d is the atomic dipole matrix element for the transition, m is the transition frequency, and Vis the mode volume), ~a) and ~b) are the upper and lower atomic levels, respectively, and a and a are the annihilation and creation operators of the field mode, which in the semiclassical theory are simply replaced by c numbers. The solution to the Schrodinger equation for the atom initially in state y(0)).,&,~ =a~a)+ p b) and field initially in state ttt(0))fi iu g„-OC„n) is ~y(t)) = g [[aC„cos(gOn+1 t) — ipC„s+i l(gnawn +1 t)]~ a& +[ — iaC„~sin(gran t)+pC„cos(gran
299 citations
TL;DR: In this paper, the photon number distribution is shown to display unusual oscillations which are interpreted as interference in phase space, analogous to Franck-Condon oscillations in molecular spectra, and the possibility of detecting these oscillations is discussed, through the photodetection counting statistics of the displaced number states.
Abstract: Recent developments in quantum optics have led to new proposals to generate number states of the electromagnetic field using conditioned measurement techniques or the properties of atom-field interactions in microwave cavities in the micromaser. The number-state field prepared in such a way may be transformed by the action of a displacement operator; for the microwave micromaser state this could be implemented by the action of a classical current that drives the cavity field. We evaluate some properties of such displaced number states, especially their description in phase space. The photon number distribution is shown to display unusual oscillations, which are interpreted as interference in phase space, analogous to Franck-Condon oscillations in molecular spectra. The possibility of detecting these oscillations is discussed, through the photodetection counting statistics of the displaced number states. We show that the displaced-number-state quantum features are relatively robust when dissipation of the field energy is included.
286 citations
TL;DR: The existence of resistance fluctuations in experimentally realizable ballistic conductors due to scattering from geometric features is demonstrated and these systems provide a test of the ``random'' quantum behavior of classically chaotic systems.
Abstract: We demonstrate the existence of resistance fluctuations in experimentally realizable ballistic conductors due to scattering from geometric features. The magnetic-field and energy correlation functions are calculated both semiclassically and exactly numerically, and are found to have a scale determined by the underlying chaotic classical scattering. These systems provide a test of the ``random'' quantum behavior of classically chaotic systems.
285 citations
TL;DR: In this paper, a new formalism for determining energy eigenstates of spherical quantum dots and cylindrical quantum wires in the multiple-band envelope function approximation is described, based upon a reformulation of the K⋅P theory in a basis of eigen states of total angular momentum.
Abstract: We describe a new formalism for determining energy eigenstates of spherical quantum dots and cylindrical quantum wires in the multiple-band envelope-function approximation. The technique is based upon a reformulation of the K⋅P theory in a basis of eigenstates of total angular momentum. Stationary states are formed by mixing bulk energy eigenvectors and imposing matching conditions across the heterostructure interface, yielding dispersion relations for eigenenergies in quantum wires and quantum dots. The bound states are studied for the conduction band and the coupled light and heavy holes as a function of radius for the GaAs/AlxGa1-xAs quantum dot. Conduction-band–valence-band coupling is shown to be critical in a "type-II" InAs/GaSb quantum dot, which is studied here for the first time. Quantum-wire valence-subband dispersion and effective masses are determined for GaAs/AlxGa1-xAs wires of several radii. The masses are found to be independent of wire radius in an infinite-well model, but strongly dependent on wire radius for a finite well, in which the effective mass of the highest-energy valence subband is as low as 0.16m0. Implications of the band-coupling effects on optical matrix elements in quantum wires and dots are discussed.
250 citations
TL;DR: In this paper, a quantum mechanical formalism for the optimal control of physical observables of microsystems is developed, and three illustrative examples with a model Morse oscillator show that optimal pumping fields can be found to reach the physical objectives: selective excitations, steering a system to a specified state, and breaking a bond.
Abstract: A quantum mechanical formalism for the optimal control of physical observables of microsystems is developed. The computational procedure for numerical implementation is presented. Three illustrative examples with a model Morse oscillator show that optimal pumping fields can be found to reach the physical objectives: selective excitations, steering a system to a specified state, and breaking a bond.
TL;DR: In this paper, an elementary description of NMR is given and a general description of 2D spectroscopy and shift correlation spectroscopies are discussed. And the fundamental foundations of relaxation theory are presented.
Abstract: 1 Elementary description of NMR 2 Epitome of quantum mechanics 3 Spin and magnetic moment 4 Quantum statistical mechanics 5 Quantum description of NMR 6 Generalities on 2D spectroscopy 7 J Spectroscopy 8 Shift correlation spectroscopy 9 Multiple quantum coherence and applications 10 Fundamentals of relaxation theory
TL;DR: Observations of an electric-field threshold conduction and of related ac voltage (broad-band noise) generation in low-disorder two-dimensional electron systems in the extreme magnetic quantum limit are reported.
Abstract: We report observations of an electric-field threshold conduction and of related ac voltage (broad-band noise) generation in low-disorder two-dimensioanl electron systems in the extreme magnetic quantum limit. We interpret these phenomena as definitive evidence for formation of a pinned quantum Wigner crystal and determine its melting phase diagram from the disappearance of threshold and noise behavior at higher temperatures.
TL;DR: In this article, a semi-classical analysis of quantum noise is used to show that a judicious use of squeezed states allows one in principle to push the sensitivity beyond the standard quantum limit.
Abstract: Quantum noise limits the sensitivity of interferometric measurements. It is generally admitted that it leads to an ultimate sensitivity, the "standard quantum limit". Using a semi-classical analysis of quantum noise, we show that a judicious use of squeezed states allows one in principle to push the sensitivity beyond this limit. This general method could be applied to large-scale interferometers for gravitational wave detection.
TL;DR: A method to obtain a superposition of time evolutions of a quantum system which correspond to different Hamiltonians as well as to different periods of time is derived.
Abstract: A method to obtain a superposition of time evolutions of a quantum system which correspond to different Hamiltonians as well as to different periods of time is derived. Its application to amplification of an effect due to the action of weak forces is considered. A quantum time-translation machine based on the same principle, utilizing the gravitational field, is also considered.
TL;DR: In this paper, a linearized quantum theory of soliton squeezing and detection is presented, which reduces the quantum problem to a classical one, and an optimal homodyne detector is presented that suppresses the noise associated with the continuum and the uncertainties in position and momentum.
Abstract: A linearized quantum theory of soliton squeezing and detection is presented. The linearization reduces the quantum problem to a classical one. The classical formulation provides physical insight. It is shown that a quantized soliton exhibits uncertainties in photon number and phase, position (time), and momentum (frequency). Detectors for the measurement of all four operators are discussed. The squeezing of the soliton in the fiber is analyzed. An optimal homodyne detector for detection of the squeezing is presented that suppresses the noise associated with the continuum and the uncertainties in position and momentum.
TL;DR: In this paper, a wave function satisfying the Wheeler-DeWitt equation becomes an operator acting on a Wave Function of the many-universes system, in which Euclidean worm-holes join different Lorentzian universes.
Abstract: The contributed papers presented to the GR-12 workshop on “Quantum Cosmology and Baby Universes” have demonstrated the great interest in, and rapid development of, the field of quantum cosmology. In my view, there are at least three areas of active research at present. The first area can be defined as that of practical calculations. Here researchers are dealing with the basic quantum cosmological equation, which is the Wheeler-DeWitt equation. They try to classify all possible solutions to the Wheeler-DeWitt equation or seek a specific integration contour in order to select one particular wave function of generalize the simple minisuperspace models to more complicted cases, including various inhomogeneities, anisotropies, etc. The second area of research deals with the interpretational issues of quantum cosmology. There are still many questions about how to extract the observational consequences from a given cosmological wave function, the role of time in quantum cosmology, and how to reformulate the rules of quantum mechanics in such a way that they could be applicable to the single system which is our Universe. The third area of research is concerned with the so-called “third quantization” of gravity. In this approach a wave function satisfying the Wheeler-DeWitt equation becomes an operator acting on a Wave Function of the many-universes system. Within this approach one operates with Euclidean worm-holes joining different Lorentzian universes. This is, perhaps, one of the most fascinating, although not entirely clear, subjects considered recently.
01 Jan 1990
TL;DR: In this article, the authors propose a method to obtain a specified probability of a specified value of a given value in a physical quantity by measuring the distribution of the probability of the value.
Abstract: 1. The Problem of Control on the Quantum Level.- 1.1. Introduction.- 1.2. A Quantum Process as the Object of Control.- 1.3. Problems of Control in Different Descriptions.- 1.4. Obtaining a Prescribed Pure State or a State in its Vicinity.- 1.5. Control with the Aim of Obtaining a Specified Probability of a Given Pure State.- 1.6. Obtaining the Maximum (or Minimum) Probability of a Specified Value of a Physical Quantity.- 1.7. Obtaining a Desired Distribution of Probability Amplitudes for Values of Given Physical Quantities.- 1.8. Control of Quantum Averages and Moments of Physical Quantities.- 1.9. Control of the Distributions of Eigenvalues of Physical Quantities.- 1.10. Control of Operators of Physical Quantities.- 1.11. Measurement in Systems with Feedback.- 2. Controllability and Finite Control of Quantum Processes (Analytical Methods).- 2.1. Control of Pure States of Quantum Processes.- 2.2. Local Controllability in the Vicinity of a Pure State.- 2.3. Global Asymptotic Controllability of Pure States.- 2.4. Control of the Electron in a Rectangular Potential Well.- 2.5. Control of a Two-Spin System.- 2.6. Finite Control of a Particle Spin State.- 2.7. Control of Quantum Averages of Physical Quantities.- 2.8. Control of Coherent States of a One-Dimensional Quantum Oscillator by Means of an External Force.- 2.9. Control of a One-Dimensional Quantum Oscillator by Varying its Eigenfrequency.- 2.10. Obtaining a Specified Probability of a Given State of a Charged Particle by Means of an External Magnetic Field.- 2.11. Control of the State of a Free Particle by an External Force.- 2.12. Control of the Coefficients of Linear Differential Equations Impulse Control.- 2.13. Control of Magnetization.- 3. Controllability and Finite Control (Algebraic Methods).- 3.1. Algebraic Conditions for the Controllability of a Quantum Process.- 3.2. Control on the Motion Groups of Quantum Systems.- 3.3. The Structure of the Algebra of a Quantum System.- 3.4. The Accessible Set of Evolution Matrices.- 3.5. Designing Discrete Automata on Controlled Transitions of Quantum Systems.- 4. Optimal Control of Quantum-Mechanical Processes.- 4.1. General Formulation of the Control Problem for a Quantum Statistical Ensemble.- 4.2. Variational Control Problems.- 4.3. Necessary Conditions for an Extremum.- 4.4. Methods of Solving Boundary Value Optimization Problems.- 4.5. Methods of Direct Optimization on Unitary Groups.- 4.6. Maximization of the Probability of Observing a Given State of a Quantum System.- 5. Dynamical Systems with Stored Energy and Negative Susceptibility.- 5.1. The Effect of Negative Susceptibility of Dynamical Systems and its Applications.- 5.2. Synthesis of Bipolar Circuits with Negative Impedance and Negative Conductivity.- 5.3. Negative Susceptibility in Gyroscopically Related Systems.- 5.4. Transverse Susceptibility of a Rigid Dipole in an Inversely Directed Constant Field.- 5.5. Negative Susceptibility of a Parametrically Modulated Oscillator.- 5.6. Systems with Stored Energy.- 5.7. Static Susceptibility of Adiabatically Invariant Control Systems.- 5.8. Conditions for Negative Static Susceptibility in Quantum Systems.- 6. Negative Susceptibility in Parametrically Induced Magnetics.- 6.1. Induced Superdiamagnetism and its Application to Distributed Control.- 6.2. Superdiamagnetic States in Inversely Magnetized Ferromagnetic Media.- 6.3. Superdiamagnetism and Parametrically Stimulated Anomalous Gyrotropy.- 6.4. Low-Frequency Susceptibility of a Gyromagnetic Medium.- 6.5. Stability of Spin Waves in Longitudinal Pumping of Ferromagnetic Crystals.- 6.6. Applications.- Appendix 1. Mathematical Models of Quantum Processes.- Appendix 2. Controllability and Finite Control of Dynamical Systems.- A2.1. Controllability and Finite Control of Linear Finite-Dimensional Systems.- A2.2. Finite Control of Linear Distributed Systems.- A2.3. A New Differential Geometric Method of Solving the Problems of Finite Control of Non-Linear Finite-Dimensional Dynamical Systems.- Appendix 3. Continuous Media and Controlled Dynamical Systems (CDS's). The Maximum Principle for Substance Flow. The Laplacian of a CDS.- References.
TL;DR: Grâce a ce formalisme plus realiste, les calculs a la fois numeriques and analytiques, qui incluent entierement les effets quantiques and the effets a plusieurs corps, peuvent etre realises d'une maniere directe and avec un sens physique.
Abstract: The use of the lattice-space Weyl-Wigner formalism of the quantum dynamics of particles in solids, coupled with nonequilibrium Green's-function techniques, provides a rigorous and straightforward derivation of an exact integral form of the equation for a quantum distribution function in many-body quantum-transport theory. We show that with the present formalism more realistic calculations, both numerical (particularly, highly transient simulations) and analytical (fully gauge-invariant calculations), which include full quantum effects and many-body effects, can be carried out in a straightforward, elegant, and physically meaningful manner. This is demonstrated by new results based on a more-accurate numerical simulation procedure and novel applications in terms of ``quantum particle trajectories'' for resonant tunneling diodes, and by a straightforward and fully gauge-invariant formulation of the exact quantum-transport equation of a uniform electron-phonon scattering system in high electric fields, which, for the first time, do not involve any gradient expansion.
TL;DR: In this paper, the energy flow in high dimensional and highly quantum mechanical systems is modeled as coherent transport on a locally but weakly correlated random energy surface, which exhibits a sharp but continuous transition from local to global energy flow characterized by critical exponents.
Abstract: The quantum mechanics of energy flow in many‐dimensional Fermi resonant systems has several connections to the theory of Anderson localization in disordered solids. We argue that in high dimensional and highly quantum mechanical systems the energy flow can be modeled as coherent transport on a locally but weakly correlated random energy surface. This model exhibits a sharp but continuous transition from local to global energy flow characterized by critical exponents. Dephasing smears the transition and an interesting nonmonotonic dependence of energy flow rate on environmental coupling is predicted to occur near the transition.
TL;DR: In this article, the authors assume a model in which phase-breaking and dissipation are caused by the interaction of electrons with a reservoir of oscillators through a delta potential, leading to a kinetic equation with a simple physical interpretation.
Abstract: An important problem in quantum transport is to understand the role of dissipative processes. In this paper the author assume a model in which phase-breaking and dissipation are caused by the interaction of electrons with a reservoir of oscillators through a delta potential. In this model the self-energy is a delta function in space, leading to a kinetic equation with a simple physical interpretation. A novel treatment of the contacts is used to introduce the external current into the kinetic equation. One specializing to linear response the author obtains an integral equation that looks like the Buttiker formula (1961) extended to a continuous distribution of probes. The author show that this equation can be reduced to the usual Buttiker formula which involves only the actual physical probes. Dissipation modifies the transmission coefficients, and the author presents explicit expressions derived from this model. Also, in a homogeneous medium the integral equation reduces to the diffusion equation, it the electrochemical potential is assumed to vary slowly. This paper serves to establish a bridge between the quantum kinetic approach which rigorously accounts for the exclusion principle and the one-particle approach which is intuitively appealing.
01 Oct 1990
TL;DR: Corrections to the Schr\"odinger equation which arise from the quantization of the gravitational field are derived through an expansion of the full functional Wheeler-DeWitt equation with respect to powers of the Gravitational constant.
TL;DR: It is argued that potentially very accurate quantization of charge transport or electron current can be achieved, once these conditions are approximately satisfied.
Abstract: Here we give a critical examination of the possibility of realizing a quantum pump of electric charges. The physics is based on the theory of quantum adiabatic particle transport initially due to Thouless. We present theoretical guidelines on the experimental conditions for observing this phenomenon. We argue that potentially very accurate quantization of charge transport or electron current can be achieved, once these conditions are approximately satisfied. An example of experimental setup is outlined to demonstrate the practical possibilities. Some comments are also made on the scientific significance of such a quantum device.
TL;DR: In this paper, a quantum treatment of a double minimum system interacting with a heat bath is presented for the purpose of interpreting experimental data on transfer kinetics in condensed hydrogen-bonded systems.
Abstract: A quantum mechanical treatment of a double minimum system interacting with a heat bath is presented for the purpose of interpreting experimental data on transfer kinetics in condensed hydrogen‐bonded systems. The model describes the transfer motion in one or two dimensions. The heat bath is represented by a set of harmonic oscillators and the interaction by a term linear in the system coordinates and in the bath coordinates. Extending an earlier random field approach, the present treatment consistently accounts for the quantum nature of the total system. With crystalline benzoic acid dimer used as an example, the master equation for the populations of the energy levels of the hydrogen transfer motion is derived. Transition probabilities consistent with the principle of detailed balance are obtained, based on a representation with explicit off‐diagonal tunnel interactions for pairs of states localized on different sides of the barrier and with diagonal terms describing the rearrangement of the heat bath as a consequence of the tunneling motion. The activation of the double minimum transfer process with increasing temperature is related to the excitation of the local vibrations in the two potential wells.
01 Jan 1990
TL;DR: In this paper, a revised second edition on the "Quantum Theory of the Optical and Electronic Properties of Semiconductors" presents the basic elements needed to understand and engage in research in semiconductor physics.
Abstract: This revised second edition on the "Quantum Theory of the Optical and Electronic Properties of Semiconductors" presents the basic elements needed to understand and engage in research in semiconductor physics. In this revised second edition misprints are corrected and some new and more detailed material is added. In order to treat the valence-band structure of semiconductors, an introduction to the k.p. theory and the related description in terms of the Luttinger Hamiltonian is included. An introductory chapter on mesoscopic semiconductor structures discussing the modifications of the envelope function approximation caused by the spatial quantum confinement is also included. Many results are developed in parallel first for bulk material, and then for quasi-two-dimensional quantum wells, and for quasi-one-dimensional quantum wires. Semiconductor quantum dots are treated in a separate chapter. The discussion of time-dependent and coherent phenomena in semiconductors has been considerably extended by including a section dealing with the theoretical description of photon echoes in semiconductors. A new chapter on magneto-absorption has been added, in which magneto-excitons and magneto-plasmas in two-dimensional systems are discussed. The chapter on electron kinetics due to the interaction with longitudinal-optical phonons has been extended. The material is presented in sufficient detail for graduate students and researchers who have a general background in quantum mechanics, and is aimed at solid state physicists, engineers, materials and optical scientists.
TL;DR: A technique of canonical quantization in a general dispersive nonlinear dielectric medium is presented, which results in an expansion of the quantum Hamiltonian in terms of annihilation and creation operators corresponding to group-velocity photon-polariton excitations in the dielectrics.
Abstract: A technique of canonical quantization in a general dispersive nonlinear dielectric medium is presented. The medium can be inhomogeneous and anisotropic. The fields are expanded in a slowly varying envelope approximation to allow quantization. An arbitrary number of envelopes is included, assuming lossless propagation in each relevant frequency band. The resulting Lagrangian and Hamiltonian agree with known propagation equations and expressions for the dispersive energy. The central result of the theory is an expansion of the quantum Hamiltonian in terms of annihilation and creation operators corresponding to group-velocity photon-polariton excitations in the dielectric.
TL;DR: By presqueezing the signal port input, it is found that gain requirements of the back-action evader are much less demanding and the asymptotic behavior of the output is determined.
Abstract: We analyze a quantum nondemolition measurement scheme similar to that advocated by Song, Caves, and Yurke [Phys. Rev. A 41, 5261 (1990)] for generating superpositions of macroscopically distinct quantum states, but with the parametric amplifier and the back-action evader interchanged. We determine the asymptotic behavior of the output and obtain the conditions under which a superposition of two coherent states is approached. By presqueezing the signal port input, we find that gain requirements of the back-action evader are much less demanding.
TL;DR: A quantization procedure for treating the propagation of light is developed, which is particularly effective in a dispersive nonlinear medium characterized by its macroscopic linear and nonlinear polarizability.
Abstract: We develop a quantization procedure for treating the propagation of light. This formalism is particularly effective in a dispersive nonlinear medium characterized by its macroscopic linear and nonlinear polarizability. We demonstrate it by analyzing the propagation of light in a multimode degenerate parametric amplifier.
TL;DR: In this article, the authors present the modifications of the spontaneous radiation rate in a cavity and the shifts of energy levels, with an outline of a theoretical framework in which the experiments may be understood.
Abstract: Publisher Summary This chapter focuses on cavity quantum electrodynamics. It presents the modifications of the spontaneous radiation rate in a cavity and the shifts of energy levels. The chapter focuses on experimental work, with an outline of a theoretical framework in which the experiments may be understood. In the laboratory, the study of atoms in cavities is a relatively young field in which much of the effort is still aimed at elucidating the basic physical principles at work and demonstrating the elementary modifications of energies and the rates of an atom in a cavity. However, the ability to adjust the electromagnetic spectrum of the vacuum is leading into a remarkable new domain of quantum physics in which atoms can decay from the ground state to an excited state, radiative corrections can be far larger than fine structure, and electromagnetic fields can be prepared with an exact number of photons. This realm of physics is now known as “cavity quantum electrodynamics.”