Authors:John B. Boffard; Chun C. Lin; Amy E. Wendt Abstract: Publication date: Available online 7 June 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): John B. Boffard, Chun C. Lin, Amy E. Wendt Natural and human-produced plasmas cover a vast parameter space with a rich array of properties that bear on science and engineering problems spanning many disciplines. A property common to all plasmas is their glow, in which information about plasma conditions is encoded. Photon emission, for many plasma conditions, results primarily from electron-impact excitation, and the emission spectrum thus contains embedded information about the distribution (often nonequilibrium) of electron energies in the plasma. With knowledge of the magnitudes and energy dependence of the optical emission cross sections for various emission lines, it is possible to use measurements of the plasma glow to extract the energy distribution of the plasma electrons. In this chapter we discuss the fundamental principles of electron-impact excitation of atoms (mainly illustrated with argon) and experimental results that are relevant to plasma applications. Plasma emission models which link the cross sections to the observable plasma glow measurements are described. With the aid of a radiation model that includes the excitation cross sections of ground-state and metastable argon atoms, the observed plasma spectra enable the characterization of nonequilibrium electron energy distributions. Individual features of the energy dependence of the cross sections for exciting the various radiating levels are exploited to develop diagnostics to address anomalous distributions of high-energy electrons (i.e., distributions with either an excess or reduced number of high-energy electrons) that can occur in different types of plasmas. Because electron collisions also govern other important plasma mechanisms, such as ionization and electron-driven chemistry, noninvasive optical diagnostic tools to measure energy distributions are of great interest.

Authors:Hélène Perrin; Barry M. Garraway Abstract: Publication date: Available online 17 May 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Hélène Perrin, Barry M. Garraway In this chapter we review the field of radio frequency dressed atom trapping. We emphasize the role of adiabatic potentials and give simple but generic models of electromagnetic fields that currently produce traps for atoms at microkelvin temperatures and below. This chapter aims to be didactic and starts with general descriptions of the essential ingredients of adiabaticity and magnetic resonance. As examples of adiabatic potentials we pay attention to radio frequency dressing in both the quadrupole trap and the Ioffe–Pritchard trap. We include a description of the effect of different choices of radio frequency polarization and orientations or alignment. We describe how the adiabatic potentials, formed from radio frequency fields, can themselves be probed and manipulated with additional radio frequency fields including multiphoton-effects. We include a description of time-averaged adiabatic potentials. Practical issues for the construction of radio frequency adiabatic potentials are addressed including noise, harmonics, and beyond rotating wave approximation effects.

Authors:Sebastian G. Hofer; Klemens Hammerer Abstract: Publication date: Available online 15 May 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Sebastian G. Hofer, Klemens Hammerer In this chapter we aim at bringing together the fields of quantum control theory and quantum optomechanics, exploring the prospects of entanglement-enhanced quantum control of these systems. We first analyze in detail how the radiation pressure interaction can be used to generate entanglement between a mechanical mode and the electromagnetic field, both in continuous-wave and pulsed regimes, and introduce an optomechanical teleportation scheme to transfer an arbitrary quantum state from a traveling-wave light pulse onto the mechanical system. Making use of continuous measurement and optimal control theory, we then show how similar schemes can be implemented in a time-continuous regime; analyzed protocols include optimal optomechanical feedback cooling, time-continuous teleportation, and time-continuous entanglement swapping. Finally we discuss the implementation of a Kalman filter for an optomechanical system, representing an important first step toward the experimental realization of the discussed protocols. Additionally, elementary aspects of quantum stochastic calculus and quantum control theory are given in comprehensive appendices.

Authors:Matthias Meister; Stefan Arnold; Daniela Moll; Michael Eckart; Endre Kajari; Maxim A. Efremov; Reinhold Walser; Wolfgang P. Schleich Abstract: Publication date: Available online 15 May 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Matthias Meister, Stefan Arnold, Daniela Moll, Michael Eckart, Endre Kajari, Maxim A. Efremov, Reinhold Walser, Wolfgang P. Schleich Quantum sensors based on matter-wave interferometry are promising candidates for high-precision gravimetry and inertial sensing in space. The favorable sources for the coherent matter waves in these devices are Bose–Einstein condensates. A reliable prediction of their dynamics, which is governed by the Gross–Pitaevskii equation, requires suitable analytical and numerical methods, which take into account the center-of-mass motion of the condensate, its rotation, and its spatial expansion by many orders of magnitude. In this chapter, we present an efficient way to study their dynamics in time-dependent rotating traps that meet this objective. Both an approximate analytical solution for condensates in the Thomas–Fermi regime and dedicated numerical simulations on a variable adapted grid are discussed. We contrast and relate our approach to previous alternative methods and provide further results, such as analytical expressions for the one- and two-dimensional spatial density distributions and the momentum distribution in the long-time limit that are of immediate interest to experimentalists working in this field of research.

Authors:Marina Radulaski; Kevin A. Fischer; Jelena Vučković Abstract: Publication date: Available online 12 May 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Marina Radulaski, Kevin A. Fischer, Jelena Vučković In this chapter, we present the state of the art in the generation of nonclassical states of light using semiconductor cavity quantum electrodynamics (QED) platforms. Our focus is on the photon blockade effects that enable the generation of indistinguishable photon streams with high purity and efficiency. Starting with the leading platform of InGaAs quantum dots in optical nanocavities, we review the physics of a single quantum emitter strongly coupled to a cavity. Furthermore, we propose a complete model for photon blockade and tunneling in III–V quantum dot-cavity QED systems. Turning toward quantum emitters with small inhomogeneous broadening, we propose a direction for novel experiments for nonclassical light generation based on group-IV color-center systems. We present a model of a multiemitter cavity QED platform, which features richer dressed-states ladder structures, and show how it can offer opportunities for studying new regimes of high-quality photon blockade.

Authors:Hebin Li; Steven T. Cundiff Abstract: Publication date: Available online 9 May 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Hebin Li, Steven T. Cundiff Optical two-dimensional coherent spectroscopy has been developed as a new method over the last 20 years. It probes the structure and dynamics of materials by exciting them with a sequence of phase-coherent pulses and recording their response as two or more delays are varied. It excels at determining if resonances are coupled, overcoming the effects of inhomogeneous broadening and disentangling congested resonances by spreading them in two dimensions. In this chapter, we review the use of two-dimensional coherent spectroscopy to probe electronic transitions in atomic vapors and semiconductor heterostructures. The atomic vapors provide an ideal model system to test the technique. At the same time, it provides unexpected results that arise from interactions between atoms in the vapor. In semiconductor quantum wells, the two-dimensional coherent spectra reveal the importance of many-body interactions in the nonlinear optical response. It also provides unique insight into the role of interactions in double-quantum wells.

Authors:Ilya I. Fabrikant; Samuel Eden; Nigel J. Mason; Juraj Fedor Abstract: Publication date: Available online 24 April 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Ilya I. Fabrikant, Samuel Eden, Nigel J. Mason, Juraj Fedor Dissociative electron attachment (DEA) processes occur in many important applied contexts, particularly gas discharges, plasmas, biological systems, and astrophysical environments. In this review, we survey the basic physics of DEA and the progress that has been made during past 14 years since the last important review on DEA (Hotop et al., Adv. At. Mol. Opt. Phys. 49, 86). This progress includes studies of DEA to simple diatomic and polyatomic molecules with high energy resolution revealing vibrational Feshbach resonances and threshold structures, studies of angular distribution of the fragmentation products allowing analysis of the symmetries of the resonances involved, and theoretical developments in investigating the dynamics of nuclear motion in DEA processes. Particular attention is paid to recent advances in DEA to biological molecules as the process is important for understanding radiation damage. Recent progress in understanding electron attachment to van der Waals clusters and the influence of cluster environments on DEA is also reviewed. The review concludes with a forward look and suggestions for new research directions.

Authors:Pablo Solano; Jeffrey A. Grover; Jonathan E. Hoffman; Sylvain Ravets; Fredrik K. Fatemi; Luis A. Orozco; Steven L. Rolston Abstract: Publication date: Available online 24 April 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Pablo Solano, Jeffrey A. Grover, Jonathan E. Hoffman, Sylvain Ravets, Fredrik K. Fatemi, Luis A. Orozco, Steven L. Rolston The development of optical nanofibers (ONFs) and the study and control of their optical properties when coupling atoms to their electromagnetic modes has opened new possibilities for their use in quantum optics and quantum information science. These ONFs offer tight optical mode confinement (less than the wavelength of light) and diffraction-free propagation. The small cross section of the transverse field allows probing of linear and nonlinear spectroscopic features of atoms with exquisitely low power. The cooperativity—the figure of merit in many quantum optics and quantum information systems—tends to be large even for a single atom in the mode of an ONF, as it is proportional to the ratio of the atomic cross section to the electromagnetic mode cross section. ONFs offer a natural bus for information and for inter-atomic coupling through the tightly confined modes, which opens the possibility of one-dimensional many-body physics and interesting quantum interconnection applications. The presence of the ONF modifies the vacuum field, affecting the spontaneous emission rates of atoms in its vicinity. The high gradients in the radial intensity naturally provide the potential for trapping atoms around the ONF, allowing the creation of one-dimensional arrays of atoms. The same radial gradient in the transverse direction of the field is responsible for the existence of a large longitudinal component that introduces the possibility of spin–orbit coupling of the light and the atom, enabling the exploration of chiral quantum optics.

Authors:Alessia Allevi; Maria Bondani Abstract: Publication date: Available online 28 March 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Alessia Allevi, Maria Bondani In this review we present the main results of some experimental investigations that we performed in the last 10 years on optical twin-beam states. We explore twin-beam statistical properties and spatio-spectral coherence in different intensity regimes, from the mesoscopic to the macroscopic domain, also including pump depletion. We also characterize the quantum nature of the mesoscopic twin-beam states in terms of different nonclassicality criteria, all of them written for detected photons and demonstrate the generation of sub-Poissonian non-Gaussian states by conditional operations. Finally, we address a ghost-imaging protocol implemented with twin-beam states in the macroscopic regime.

Authors:Michael Schulz Abstract: Publication date: Available online 27 February 2017 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Michael Schulz The reaction dynamics in simple atomic systems have been studied extensively in order to address the fundamentally important, but yet unsolved few-body problem. For the description of electron impact-induced reactions theory has made remarkable progress over the last decade. However, describing the reaction dynamics for the same processes induced by ion impact proved to be much more challenging. Surprising discrepancies between experiment and theory were found even for cases which were considered to be “easy” for theory. Only a few years ago an important step toward a resolution of this puzzle was made when strong experimental indications were reported that measured cross sections can sensitively depend on the projectile coherence properties, while theory usually assumes that the projectile beam is always coherent. Owing to the much larger de Broglie wavelength electron projectiles tend to be much more coherent relative to the target dimension, which results in much better agreement between experiment and theory. In this chapter, recent studies on the effect of the projectile coherence properties on the reaction dynamics are reviewed.

Authors:Murray Pohl Abstract: Publication date: 2016 Source:Advances In Atomic, Molecular, and Optical Physics, Volume 65 Author(s): C. Murray, T. Pohl Coupling light to ensembles of strongly interacting particles has emerged as a promising route toward achieving few photon nonlinearities. One specific way to implement this kind of nonlinearity is to interface light with highly excited atomic Rydberg states by means of electromagnetically induced transparency, an approach which allows freely propagating photons to acquire synthetic interactions of hitherto unprecedented strength. Here, we present an overview of this rapidly developing field, from classical effects to quantum manifestations of the nonlocal nonlinearities emerging in such systems. With an emphasis on underlying theoretical concepts, we describe the many experimental breakthroughs so far demonstrated and discuss potential applications looming on the horizon.

Abstract: Publication date: Available online 18 May 2016 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): R. Côté Ultracold atomic samples doped with charged particles is a nascent field marrying two usually well-separated fields, namely trapped ions and ultracold atoms. Since the original proposals over 15 years ago, the initially slow pace has given way to rapid progress. In this chapter, we review some of the concepts relevant to this hybrid field, ranging from resonant charge transfer to the effect of isotope shifts, and the role of hyperfine and Zeeman interactions in obtaining Feshbach resonances allowing control of the scattering processes taking place. The next frontier, charges in a Bose–Einstein condensate, is also introduced and discussed.

Authors:Jason A.C.; Gallas Abstract: Publication date: Available online 10 March 2016 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Jason A.C. Gallas The CO2 laser is a complex dynamical system that has been investigated extensively both experimentally and through numerical simulations. As a result, a number of models exist for this laser, famed for providing satisfactory agreement between numerical and experimental observations. But the laser involves a large number of freely tunable control parameters whose impact on its performance and stability is not known in detail. The spontaneous emergence and organization of laser stability phases are also poorly understood. Here, we review recent progress in the classification of laser spiking, periodic or nonperiodic self-pulsations, predicted for CO2 lasers with modulated parameters and with feedback, instantaneous or delayed. The unfolding of spiking is classified with the help of numerically obtained high-resolution stability charts for experimentally accessible control parameters. Such stability charts display novel regular and irregular features, suggesting that the laser control parameter planes harbor remarkable symmetries not yet accounted for theoretically but which are experimentally within reach. High-resolution stability charts put stringent tests on the reliability and accuracy of current models in forecasting laser dynamics.

Authors:E. Arimondo; D. Ciampini; C. Rizzo Pages: 1 - 66 Abstract: Publication date: Available online 20 April 2016 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): E. Arimondo, D. Ciampini, C. Rizzo This chapter provides an overview of the action of magnetic fields on diluted media constituted by simple systems as natural atoms (such as neutral atoms, electrons, and ions) and artificial atoms with similar magnetic field response (such as semiconductor quantum dots and electron vacancies). In those media the interactions between the components of the medium play a limited role with respect to the magnetic energy of the components, while the very large precision achieved in spectroscopic measurements allows the determination of very tiny magnetic interactions. The precise quantum control of the interaction between a laser system and atoms is a key element of those measurements. Modification of atomic structures by the presence of magnetic fields has a very rich history dating back to the very birth of quantum mechanics. However, the motivations for studying those structures have also changed significantly as time progressed. The review covers latest findings and future prospects in a variety of magnetic property investigations, from the determination of atomic g-factors for relativistic correction and quantum-electrodynamics tests or of diamagnetic interactions, to the measurement of magnetic fields.

Authors:W.P. Menzel; D.C. Tobin; H.E. Revercomb Pages: 193 - 264 Abstract: Publication date: Available online 13 May 2016 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): W.P. Menzel, D.C. Tobin, H.E. Revercomb Remote sensing of the earth and its atmosphere in the infrared spectrum has become a mainstay in environmental monitoring for weather and climate. From the start of occasional rocket-borne camera pictures, to the first global measurements of outgoing longwave infrared radiation, to global day and night visible and infrared picture mosaics, to complementary hourly full earth disk visible and infrared measurements, to full spectral (visible, near infrared, infrared, and microwave) global measurements of the earth surface and atmosphere, it is a history of continuing improvement in environmental remote sensing capabilities. Snapshots and mosaics gave way to seamless global coverage in wavelengths from half microns to hundreds of GHz. This chapter gives a brief history of the evolution of meteorological satellite sensors in polar and geostationary orbit, explores the characteristics of radiative transfer through the atmosphere (with a focus on infrared radiation that is dominated by CO2, H2O, and O3 molecular interactions), notes where high spectral resolution infrared measurements have improved absorption and radiative transfer calculations, and gives some examples of applications with high spectral resolution infrared measurements.

Authors:A.P. Mills Pages: 265 - 290 Abstract: Publication date: Available online 9 May 2016 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): A.P. Mills This chapter reviews the steps required to capture and accumulate copious numbers of low-energy positrons, and to form positronium (Ps) atoms at low energies. We then relate the few results that have so far been achieved using large pulses of positrons at high densities, include observing Ps–Ps spin exchange quenching, formation and optical excitation of the Ps2 molecule, and production of a fully spin-polarized ensemble of Ps via Ps–Ps spin exchange quenching. In addition there are many ongoing experiments that are benefiting from the availability of large positron pulses at lower densities, including studying antihydrogen, doing optical spectroscopy on Ps and its negative ion (Michishio et al., 2015) with pulsed lasers, and eventually for measuring Ps free fall in Earth's gravitational field. Meanwhile a number of interesting possibilities involving positron–positron and Ps–Ps interactions are on the horizon, including forming Ps Bose–Einstein condensates and dense collections of positrons having a nonnegligible positronic Fermi energy. In particular, collecting positrons at high density on a tungsten tip from which they would be field emitted could be the basis for a valuable single-molecule positron microscope suggested by Platzman (Barbiellini and Platzman, 2006; Mills and Platzman, 2001), in which the damage that would ordinarily be sustained by a molecule is mitigated by the rapid transfer of the molecular excitations to the metallic surface.

Authors:M.S. Pindzola; J. Colgan; F. Robicheaux; T.G. Lee; M.F. Ciappina; M. Foster; J.A. Ludlow; Sh.A. Abdel-Naby Pages: 291 - 319 Abstract: Publication date: Available online 11 March 2016 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): M.S. Pindzola, J. Colgan, F. Robicheaux, T.G. Lee, M.F. Ciappina, M. Foster, J.A. Ludlow, Sh.A. Abdel-Naby We review the application of the time-dependent close-coupling method to the study of ion-impact ionization of atoms and molecules. Ionization cross sections are presented for bare ion, antiproton, and neutron collisions with light atoms and molecules.

Authors:T.G. Walker; M.S. Larsen Pages: 373 - 401 Abstract: Publication date: Available online 17 May 2016 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): T.G. Walker, M.S. Larsen We present the basic theory governing spin-exchange-pumped nuclear magnetic resonance (NMR) gyros. We review the physics of spin-exchange collisions and relaxation as they pertain to precision NMR. We present a simple model of operation as an NMR oscillator and use it to analyze the dynamic response and noise properties of the oscillator. We discuss the primary systematic errors (differential alkali fields, quadrupole shifts, and offset drifts) that limit the bias stability, and discuss methods to minimize them. We give with a brief overview of a practical implementation and performance of an NMR gyro built by Northrop Grumman Corporation and conclude with some comments about future prospects.

Authors:Stephan Abstract: Publication date: Available online 4 August 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Stephan Kümmel In this chapter, the Kohn–Sham variant of the self-interaction correction, i.e., SIC with one global multiplicative potential that is the same for all orbitals, is discussed. Two concepts of unifying the SIC with the optimized effective potential approach are reviewed. The strengths that Kohn–Sham SIC develops in particular in the time-dependent regime, e.g., in describing charge-transfer and optical excitations, are highlighted. Kohn–Sham SIC emerges as one of the density functional theory approaches that allows for tackling the long-standing problem of describing long-range charge-transfer phenomena correctly.

Authors:John P. Perdew; Adrienn Ruzsinszky; Jianwei Sun; Mark R. Pederson Pages: 1 - 14 Abstract: Publication date: Available online 22 July 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): John P. Perdew, Adrienn Ruzsinszky, Jianwei Sun, Mark R. Pederson Popular local, semilocal, and hybrid density functional approximations to the exchange-correlation energy of a many-electron ground state make a one-electron self-interaction error which can be removed by its orbital-by-orbital subtraction from the total energy, as proposed by Perdew and Zunger in 1981. This makes the functional exact for all one-electron ground states, but it does much more as well: It greatly improves the description of negative ions, the dissociation curves of radical molecules and of all heteronuclear molecules, the barrier heights for chemical reactions, charge-transfer energies, etc. PZ SIC even led to the later discovery of an exact property, the derivative discontinuity of the energy. It is also used to understand strong correlation, which is beyond the reach of semilocal approximations. The paradox of SIC is that equilibrium properties of molecules and solids, including atomization energies and equilibrium geometries, are at best only slightly improved and more typically worsened by it, especially as we pass from local to semilocal and hybrid functionals which by themselves provide a ladder of increasing accuracy for these equilibrium properties. The reason for this puzzling ambivalence remains unknown. In this speculative chapter, we suggest that the problem arises because the uncorrected functionals provide an inadequate description of compact but noded one-electron orbital densities. We suggest that a meta-generalized gradient approximation designed to satisfy a tight lower bound on the exchange energy of a one-electron density could resolve the paradox, providing after self-interaction correction the first practical “density functional theory of almost everything.”

Authors:Koblar Alan Jackson Pages: 15 - 27 Abstract: Publication date: Available online 27 June 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Koblar Jackson The application of the self-interaction correction to the local density functional theory to the problem of transition metal defects in alkali-halide crystals is reviewed. The computational machinery involves a number of approximations that are based on the localized, atomic-like nature of the charge distributions in these systems. These allow the detailed calculation of the variationally correct local orbitals to be circumvented and a much more computationally convenient approach to determining the defect and host crystal orbitals to be used. Results are presented for the NaCl:Cu+ and LiCl:Ag+ impurity systems.

Authors:Anna Pertsova; Carlo Maria Canali; Mark R. Pederson; Ivan Rungger; Stefano Sanvito Pages: 29 - 86 Abstract: Publication date: Available online 21 July 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Anna Pertsova, Carlo M. Canali, Mark R. Pederson, Ivan Rungger, Stefano Sanvito While spintronics often investigates striking collective spin effects in large systems, a very important research direction deals with spin-dependent phenomena in nanostructures, reaching the extreme of a single spin confined in a quantum dot, in a molecule, or localized on an impurity or dopant. The issue considered in this chapter involves taking this extreme to the nanoscale and the quest to use first-principles methods to predict and control the behavior of a few “spins” (down to 1 spin) when they are placed in an interesting environment. Particular interest is on environments for which addressing these systems with external fields and/or electric or spin currents is possible. The realization of such systems, including those that consist of a core of a few transition-metal (TM) atoms carrying a spin, connected and exchanged-coupled through bridging oxo-ligands has been due to work by many experimental researchers at the interface of atomic, molecular and condensed matter physics. This chapter addresses computational problems associated with understanding the behaviors of nano- and molecular-scale spin systems and reports on how the computational complexity increases when such systems are used for elements of electron transport devices. Especially for cases where these elements are attached to substrates with electronegativities that are very different than the molecule, or for coulomb blockade systems, or for cases where the spin-ordering within the molecules is weakly antiferromagnetic, the delocalization error in DFT is particularly problematic and one which requires solutions, such as self-interaction corrections, to move forward. We highlight the intersecting fields of spin-ordered nanoscale molecular magnets, electron transport, and coulomb blockade and highlight cases where self-interaction corrected methodologies can improve our predictive power in this emerging field.

Authors:Phuong Mai Dinh; Paul-Gerhard Reinhard; Eric Suraud; Marc Vincendon Pages: 87 - 103 Abstract: Publication date: Available online 21 July 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): P.M. Dinh, P.-G. Reinhard, E. Suraud, M. Vincendon In this chapter, we discuss a two-set self-interaction correction (SIC) approach for time-dependent solutions of the equation. The approach simultaneously updates two equivalent set of orbitals that, respectively, represent the localizing set which lead to a minimum of the SIC energy and the diagonalizing or propagating set which are expected to coincide with ionizable states for static calculations and physical states for time-dependent calculations. We show that the relationship between the localizing set and the diagonalizing/propagating set is the same regardless of whether the time-independent or time-dependent formulation is considered. Our fast and reliable scheme for solving the computationally obnoxious symmetry condition is then applied to several molecular problems which include the N 2 dimer, atoms, small covalent molecules, and the Na5 cluster. In addition to consideration of the orbital-by-orbital SIC associated with the original formulation of Perdew and Zunger, we demonstrate that the average-density SIC can lead to very good agreement with experiment in finite systems, as long as one type of bonding (either covalent or metallic) is concerned. A comparison of LDA, ADSIC, and SIC eigenvalues to experiment is provided, showing that the ADSIC method, which exhibits a lower degree of orbital dependence than SIC, further can improve the agreement between theory and experiment for small enough systems but that for the medically interesting case of Na–water complexes which mix metallic and covalent bounds, or for large or periodic arrays of atoms, the orbital-by-orbital SIC performs better.

Authors:Nicolas Poilvert; Giovanni Borghi; Ngoc Linh Nguyen; Nathan Daniel Keilbart; Kevin Wang; Ismaila Dabo Pages: 105 - 127 Abstract: Publication date: Available online 13 August 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Nicolas Poilvert, Giovanni Borghi, Ngoc Linh Nguyen, Nathan Keilbart, Kevin Wang, Ismaila Dabo Self-interaction is a central problem for the accuracy of density-functional approximations in describing the electronic structure of atoms and molecules. In this work, we discuss the different types of self-interaction errors commonly encountered in density-functional calculations, providing precise definitions for each of them. Based upon these definitions, we derive an orbital-dependent density-functional method, called the Koopmans-compliant approach, which simultaneously corrects the different self-interaction errors, by enforcing piecewise linearity with respect to fractional particle counts and by imposing the correct asymptotic behavior of the one-electron potential in approximate energy functionals. We illustrate the very good performance of this new method in predicting the electronic properties of atoms and molecules, while preserving or improving the prediction of total energies and equilibrium geometries. These results highlight the accuracy and efficiency of Koopmans-compliant functionals as an attractive solution to the self-interaction problem.

Authors:Nikitas Gidopoulos; Nektarios N.N. Lathiotakis Pages: 129 - 142 Abstract: Publication date: Available online 21 July 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): N.I. Gidopoulos, N.N. Lathiotakis In this chapter, we discuss a method to alleviate self-interaction (SI) errors from the approximate Kohn–Sham potential, but without altering the corresponding approximate exchange and correlation energy, which still remains contaminated with SIs. In particular, we aim to correct the asymptotic behavior—at large distances—of the potential, by enforcing two subsidiary conditions. These conditions are incorporated with the help of the optimized effective potential method. This method is applied to molecules, using LDA or approximate exchange and correlation functionals from Reduced Density Matrix Functional Theory. The resulting ionization energies of this constrained approach, as compared to LDA, are significantly improved and much closer to experiment.

Authors:Mark R. Pederson; Tunna Baruah Pages: 153 - 180 Abstract: Publication date: Available online 23 July 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Mark R. Pederson, Tunna Baruah In this chapter, we suggest a recent modification to the self-interaction correction, which allows one to recast the self-interaction correction into a form that is explicitly invariant to unitary transformations and which is also size extensive. In addition to restoring unitary invariance and a correct asymptotic potential the formulation seems to provide classical electronic positions, or descriptors, which seem to be in accord with Lewis structures. By explicitly introducing the constraint of unitary invariance, it has been found that the accuracy of binding energies in simple molecules is improved compared to the uncorrected density functional. The improvement in bonding energies seems to be especially pronounced for systems containing pi bonds. Further as for the case of the original self-interaction corrected formulation, the results show that the improvement of the occupied-orbital eigenvalues, based on comparison to experimental ionization potentials, is retained in this formulation. This chapter includes a discussion of recent results on small molecules and a complete derivation of the equations required to calculate the positions of the Fermi-orbital descriptors. In addition to molecules that are clearly composed of single, double, and triple bonds, we provide an example on the benzene molecule that yields orbitals that adequately describe the resonant character of this system.

Authors:Duncan G. Steel Pages: 181 - 222 Abstract: Publication date: Available online 4 August 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): Duncan G. Steel This chapter reviews primarily the evolution of the understanding of coherent optical interactions and spectroscopy in semiconductor quantum dots. The work begins by a brief review of the dominance of complex many-body interactions in higher dimensional materials and then proceeds to examine the behavior in quantum dots. The work reviews the knowledge extracted using frequency domain spectroscopy techniques, which has provided considerable insight into the physics of these systems. The results show that quantum confinement suppresses the kind of many-body physics seen in bulk material and allows the optical interaction to be well described by two or few state energy-level diagrams and the master equations using the density matrix. Numerous examples of classical atomic behavior are reviewed including Rabi oscillations, coherent population trapping, and the Mollow absorption spectrum. The chapter also discusses how these structures can be used as a platform for possible applications to quantum information sciences. Finally, the chapter concludes by examining the role of the hyperfine interaction. Unlike atomic systems with one nucleus, quantum dot excitons involve of order 104 nuclei. The hyperfine interaction is the origin of decoherence of the spin doublet ground state in a negatively charged quantum dot. However, the optical studies have shown an unexpected coupling between the exciton and the nuclei that leads to freezing of the nuclear fluctuations.

Authors:Michael S. Murillo; Scott D. Bergeson Pages: 223 - 271 Abstract: Publication date: Available online 16 June 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): M.S. Murillo , S.D. Bergeson Ultracold neutral plasmas (UNPs) are plasmas generated through a rapid photoionization process of a laser-cooled atomic gas. Because of the very low initial ionic temperature (T i(0) ∼mK), UNPs are extremely strongly coupled. Following the formation of correlations, UNPs settle into a coupling regime with Γ ∼ 1, where Γ is the usual Coulomb coupling parameter. The observation of a wider range of plasma phenomena requires experimental control over the details of this process. We describe the generation and diagnosis of UNPs in the strongly coupled plasma regime with Γ ≥ 1 using calcium in a magneto-optical trap. We discuss four avenues to achieve such couplings, including the use of electron screening, multiple ionization to higher ionization states, Rydberg atom dynamics, and direct laser-cooling of the ions. Electron screening mitigates the initial Coulomb repulsion, but also impacts the final effective coupling. We illustrate this by calculating the structural properties of UNPs for different strengths of electron screening for typical values of Γ. Molecular dynamics (MD) simulations are used to reveal the dynamical impacts of electron screening, and show that the final Γ is readily increased whereas the effective coupling remains of order unity. Similarly, we perform MD for a double ionization process in which the second ionization is timed carefully to correspond to a minimum in the time evolution of g(r,t). In addition to their intrinsic interest, UNPs can provide a platform for exploring basic plasma physics relevant to a wide range of seemingly disparate plasmas, including fusion-class plasmas.

Authors:Swati Singh; Yiwen Chu; Mikhail Lukin; Susanne Yelin Pages: 273 - 327 Abstract: Publication date: Available online 26 July 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): S. Singh, Y. Chu, M.D. Lukin, S.F. Yelin We describe and analyze a method for controlling nuclear spin environment of atom-like quantum emitters in the solid state. The method makes use of laser manipulation of an electronic spin transition via coherent population trapping. Specifically, we present a detailed description of the nuclear spin dynamics and its interplay with the optical excitation of the electronic spin of nitrogen-vacancy color centers in diamond. We introduce a simple model of this process that allows us to study both optimal cooling parameters for nuclear spins and optimal information transfer between the optical measurement of the electron and the nuclear bath dynamics. This allows us to investigate the statistical properties of the nuclear spin bath. Potential applications to quantum information processing and quantum metrology are possible.

Authors:David Gelbwaser-Klimovsky; Wolfgang Niedenzu; Gershon Kurizki Pages: 329 - 407 Abstract: Publication date: Available online 19 August 2015 Source:Advances In Atomic, Molecular, and Optical Physics Author(s): David Gelbwaser-Klimovsky, Wolfgang Niedenzu, Gershon Kurizki In this review, the debated rapport between thermodynamics and quantum mechanics is addressed in the framework of the theory of periodically driven/controlled quantum-thermodynamic machines. The basic model studied here is that of a two-level system (TLS), whose energy is periodically modulated while the system is coupled to thermal baths. When the modulation interval is short compared to the bath memory time, the system–bath correlations are affected, thereby causing cooling or heating of the TLS, depending on the interval. In steady state, a periodically modulated TLS coupled to two distinct baths constitutes the simplest quantum heat machine (QHM) that may operate as either an engine or a refrigerator, depending on the modulation rate. We find their efficiency and power-output bounds and the conditions for attaining these bounds. An extension of this model to multilevel systems shows that the QHM power output can be boosted by the multilevel degeneracy. These results are used to scrutinize basic thermodynamic principles: (i) externally driven/modulated QHMs may attain the Carnot efficiency bound, but when the driving is done by a quantum device (piston), the efficiency strongly depends on its initial quantum state. Such dependence has been unknown thus far. (ii) The refrigeration rate effected by QHMs does not vanish as the temperature approaches absolute zero for certain quantized baths, e.g., magnons, thus challenging Nernst's unattainability principle. (iii) System–bath correlations allow more work extraction under periodic control than that expected from the Szilard–Landauer principle, provided the period is in the non-Markovian domain. Thus, dynamically controlled QHMs may benefit from hitherto unexploited thermodynamic resources.