Peter Lambropoulos

University of Crete | UOC · Department of Physics, Heraklion, Crete 71110

We report on the existence of exceptional points (EPs) in single-resonance autoionization and provide analytical expressions for their positions in parameter space, in terms of the Fano asymmetry parameter. We additionally propose a reliable method for the experimental determination of EPs, based solely on information about their ionization probabi...

We provide a quantitative evaluation of non-Markovianity (NM) for an XX chain of interacting qubits with one end coupled to a reservoir. The NM of several non-Markovian spectral densities is assessed in terms of various quantum state distance (QSD) measures. Our approach is based on the construction of the density matrix of the open chain, without...

We report on the existence of exceptional points (EPs) in single-resonance autoionization and provide analytical expressions for their positions in parameter space, in terms of the Fano asymmetry parameter. We additionally propose a reliable method for the experimental determination of EPs, based solely on information about their ionization probabi...

We provide a quantitative evaluation of the degree of non-Markovianity (DNM) for an XX chain of interacting qubits with one end coupled to a reservoir. The DNM is assessed in terms of various quantum state distance (QSD) measures and various cases of non-Markovian spectral densities. Our approach is based on the construction of the density matrix o...

Diagonalization of the effective Hamiltonian describing an open quantum system is the usual method of tracking its exceptional points (EPs). Although such a method is successful for tracking EPs in Markovian systems, it may be problematic in non-Markovian systems where a closed expression of the effective Hamiltonian describing the open system may...

Diagonalization of the effective Hamiltonian describing an open quantum system is the usual method of tracking its exceptional points. Although, such a method is successful for tracking EPs in Markovian systems, it may be problematic in non-Markovian systems where a closed expression of the effective Hamiltonian describing the open system may not e...

In this work we provide a recursive method of calculating the wave function of an XX spin chain coupled at both ends to non-Markovian reservoirs with arbitrary spectral density. The method is based on the appropriate handling of the time-dependent Schrödinger's equations of motion in Laplace space and leads to closed-form solutions of the transform...

In this work we provide a recursive method of calculating the wavefunction of a XX spin chain coupled at both ends to non-Markovian reservoirs with arbitrary spectral density. The method is based on the appropriate handling of the time-dependent Schrodinger's equations of motion in Laplace space and leads to closed form solutions of the transformed...

In this work, we study the steady-state entanglement between two qubits interacting asymmetrically with a common non-Markovian environment. Depending on the initial two-qubit state, the asymmetry in the couplings between each qubit and the non-Markovian environment may lead to enhanced entanglement in the steady state of the system, measured in ter...

In this work we study the steady state entanglement between two qubits interacting asymetrically with a common non-Markovian environment. Depending on the initial two-qubit state, the asymmetry in the couplings between each qubit and the non-Markovian environment may lead to enhanced entanglement in the steady state of the system, measured in terms...

In this work, we consider a “Λ-type” three-level system where the first transition is driven by a radiation field initially prepared in a squeezed coherent state, while the second one by a weak probe field. If the squeezed field is sufficiently strong to cause Stark splitting of the states it connects, such a splitting can be monitored through the...

In this work we study the production of electron-positron pairs from vacuum in presence of a field resulting from the collision of two counter-propagating FEL beams that undergo Gaussian amplitude fluctuations. Our work aims to the extension of previous works based on the standing wave hypothesis, by including the inherent stochastic amplitude fluc...

In this work we study the production of electron-positron pairs from vacuum in presence of a field resulting from the collision of two counter-propagating FEL beams that undergo Gaussian amplitude fluctuations. Our work aims to the extension of previous works based on the standing wave hypothesis, by including the inherent stochastic amplitude fluc...

Through a quantitative analysis of an atomic transition driven strongly by quantized electromagnetic fields of various quantum states, we explore the role of quantum fluctuations on the behavior of the system. The emphasis is on fields with super-Poissonian statistics manifested in photon bunching, with the case of squeezed vacuum radiation serving...

Through a quantitative analysis of an atomic transition driven strongly by quantized electromagnetic fields of various quantum states, we explore the role of quantum fluctuations on the behavior of the system. The emphasis is on fields with super-Poissonian statistics manifested in photon bunching, with the case of squeezed vacuum radiation serving...

We report on the experimental observation of a strong-field dressing of an autoionizing two-electron state in helium with intense extreme-ultraviolet laser pulses from a free-electron laser. The asymmetric Fano line shape of this transition is spectrally resolved, and we observe modifications of the resonance asymmetry structure for increasing free...

We report on the experimental observation of strong-field dressing of an autoionizing two-electron state in helium with intense extreme-ultraviolet laser pulses from a free-electron laser. The asymmetric Fano line shape of this transition is spectrally resolved, and we observe modifications of the resonance asymmetry structure for increasing free-e...

In this paper, we extend the results of an earlier paper [G. Mouloudakis and P. Lambropoulos, Phys. Rev. A 97, 053413 (2018)] in which we had demonstrated the limitations of the notion of nonresonant multiphoton ionization, in the exploration of photon statistics effects in nonlinear processes. Through the quantitative analysis of specific realisti...

In this paper, we extend the results of an earlier paper in which we had demonstrated the limitations of the notion of non-resonant multiphoton ionization, in the exploration of photon statistics effects in non-linear processes. Through the quantitative analysis of specific realistic processes, we provide the connection to conditions of intensity a...

We propose a protocol for state transfer and entanglement generation between two distant spin qubits (sender and receiver) that have different energies. The two qubits are permanently coupled to a far-off-resonant spin chain, and the qubit of the sender is driven by an external field, which provides the energy required to bridge the energy gap betw...

We propose a protocol for state transfer and entanglement generation between two distant spin qubits (sender and receiver) that have different energies. The two qubits are permanently coupled to a far off-resonant spin-chain, and the qubit of the sender is driven by an external field, which provides the energy required to bridge the energy gap betw...

We propose a protocol for state transfer and entanglement generation between two distant spin qubits (sender and receiver) that have different energies. The two qubits are permanently coupled to a far off-resonant spin-chain, and the qubit of the sender is driven by an external field, which provides the energy required to bridge the energy gap betw...

We present a detailed analysis of the effects of photon statistics on multi-photon ionization. Through a detailed study of the role of intermediate states, we evaluate the conditions under which the premise of non-resonant processes is valid. The limitations of its validity are manifested in the dependence of the process on the stochastic propertie...

We have examined the profile of an isolated autoionizing resonance driven by a pulse of short duration and moderately strong field. The analysis has been based on stochastic differential equations governing the time evolution of the density matrix under a stochastic field. Having focused our quantitative analysis on the $2s2p({}^1P)$ resonance of H...

The excitation of a resonance embedded in a continuum by intense radiation requires a theoretical description beyond the transition probability per unit time. This implies a time-dependent formulation incorporating all features of the radiation source, such as pulse temporal shape and duration, as well as stochastic properties, for pulses other tha...

In a combined experimental and theoretical study we have investigated the ionization of atomic argon upon irradiation with intense soft-x-ray pulses of 105 eV photon energy from the free-electron laser FLASH. The measured ion yields show charge states up to Ar7+. The comparison with the theoretical study of the underlying photoionization dynamics h...

We analyze the performance of two quantum-state-transfer Hamiltonians in the presence of diagonal and off-diagonal disorders, and in terms of different measures. The first Hamiltonian pertains to a fully engineered chain, and the second to a chain with modified boundary couplings. The task is to find which Hamiltonian is the most robust to given le...

In a combined experimental and theoretical study we have investigated the ionization of atomic argon upon irradiation with intense soft-x-ray pulses of 105 eV photon energy from the free-electron laser FLASH. The measured ion yields show charge states up to Ar$^{7+}$. The comparison with the theoretical study of the underlying photoionization dynam...

We provide a detailed quantitative study of the possible role of a small admixture of harmonics on resonant two-photon ionization. The motivation comes from the occasional presence of 2nd and 3rd harmonics in FEL radiation. We obtain the dependence of ionic yields on the intensity of the fundamental, the percentage of 2nd harmonic and the detuning...

We demonstrate the capabilities of time-dependent density functional theory (TDDFT) for strong-field, short wavelength (soft X-ray) physics, as compared to a formalism based on rate equations. We find that TDDFT provides a very good description of the total and individual ionization yields for Ne and Ar atoms exposed to strong laser pulses. We asse...

We present a rather elaborate theoretical model describing the dynamics of Neon under radiation of photon energies $\sim 93$ eV and pulse duration in the range of 15 fs, within the framework of Lowest non-vanishing Order of Perturbation Theory (LOPT), cast in terms of rate equations. Our model includes sequential as well as direct multiple ionizati...

We review the main aspects of multiple photoionization processes in atoms exposed to intense, short wavelength radiation. The main focus is the theoretical framework for the description of such processes as well as the conditions under which direct multiphoton multiple ionization processes can dominate over the sequential ones. We discuss in detail...

We present calculations on the multiple ionization of argon at the photon energy 123 eV and pulse duration 50 fs. At that photon energy, it is possible to drive the two-photon resonant Auger transition 2p → 4p, whose lifetime is 5.5 fs, much shorter than the pulse duration. The excitation of a 2p electron to the 4p state thus creates a hole which d...

Motivated by recent experiments pertaining to the interaction of weak SASE-free-electron-laser (FEL) pulses with atoms and molecules, we investigate the conditions under which such interactions can be described in the framework of a simple phase-diffusion model with decorrelated atom–field dynamics. The nature of the fluctuations that are inevitabl...

We explore the three-photon triple ionization from the ground state of Li with short wavelength free electron lasers. We calculate and discuss the cross sections used in the relevant rate equations and the dependence of the ion yields on laser intensity and pulse duration. In addition to the three-photon 3e ejection we also discuss two- and three-p...

We study the effects of field fluctuations on the total yields of Auger electrons, obtained in the excitation of neutral atoms to a core-excited state by means of short-wavelength free-electron-laser pulses. Beginning with a self-contained analysis of the statistical properties of fluctuating free-electron-laser pulses, we analyse separately and in...

The influence of an intense optical laser on the electronic relaxation of the 3d–5p resonance in atomic Kr has been studied experimentally and theoretically. The resonance profile undergoes a strong modification, observed as a shift and a broadening of the excitation spectrum, as a function of the optical intensity. The theoretical treatment of the...

The interaction between Ps and a strong laser pulse of short duration is studied. Substantial population is deposited in excited states under few photon excitation. The possible usefulness as a source of excited Ps to spectroscopy and the formation of antihydrogen is discussed. Finally, photoelectron energy spectra are calculated.

We examine the conditions under which multiple ionization of xenon, under strong radiation of photon energy 93 eV and pulse duration 10 fs, leading up to Xe21 + can be observed. Through a set of rate equations, we show that the dominant sequential channels are sufficient for and consistent with the observed ionic species. Addressing the possible ro...

We discuss the passage-time statistics of superradiant light pulses generated during the scattering of laser light from an elongated atomic Bose-Einstein condensate. Focusing on the early-stage of the phenomenon, we analyze the corresponding probability distributions and their scaling behaviour with respect to the threshold photon number and the co...

We address the concept of direct multiphoton multiple ionization in atoms exposed to intense, short wavelength radiation and explore the conditions under which such processes dominate over the sequential. Their contribution is shown to be quite robust, even under intensity fluctuations and interaction volume integration, and reasonable agreement wi...

We investigate the dynamics of matter and optical waves at the early stage of superradiant Rayleigh scattering from Bose-Einstein Condensates. Our analysis is within a spatially dependent quantum model which is capable of providing analytic solutions for the operators of interest. The predictions of the present model are compared to the predictions...

Two-photon excitation of a single-photon forbidden Auger resonance has been observed and investigated using the intense extreme ultraviolet radiation from the free electron laser in Hamburg. At the wavelength 26.9 nm (46 eV) two photons promoted a 3d core electron to the outer 4d shell. The subsequent Auger decay, as well as several nonlinear above...

We present a theoretical study of a two-photon single-colour and two-colour excitation of ground-state krypton atoms to the final 3d−15/24d autoionising states.

We investigate the coherence properties of pairs of counter-propagating atomic clouds, produced in superradiant Rayleigh scattering off atomic condensates. It is shown that these clouds exhibit long-range spatial coherence and strong nonclassical density cross-correlations, which make this scheme a promising candidate for the production of highly d...

We study the merging of two independent Bose-Einstein condensates with arbitrary initial phase difference, in the framework of a one-dimensional time-dependent Gross-Pitaevskii model. The role of the initial phase difference in the process is discussed, and various types of phase-sensitive excitations are identified. Comment: 19 Pages, 7 figures

We examine the speed and fidelity of several protocols for state or single excitation transfer in finite spin chains subject to diagonal and off-diagonal disorder. We find that, for a given chain length and maximal achievable inter-spin exchange (XY) coupling strength, the optimal static spin-coupling protocol, implementing the fastest state transf...

We present a theoretical interpretation of recent experimental results on multiphoton multiple ionization of xenon by soft-x-ray radiation of photon energy approximately 93 eV and intensity up to 10(16) W/cm2 [A. A Sorokin, Phys. Rev. Lett. 99, 213002 (2007)]. The data are interpreted within multiphoton perturbation theory, taking into account the...

In view of recent papers on two-photon double ionization of helium, pertaining to a perceived anomaly in the behavior of the sequential process and its influence on the direct process, as well as the dependence of both on the laser pulse duration, we show that upon the proper formulation, the sequential is well defined and free of divergence, and t...

We present a theoretical analysis of multiphoton ionization of xenon pertaining to experimental data obtained by free electron laser (FEL) radiation of photon energy 12.7 eV by Wabnitz et al. Phys. Rev. Lett. 94 023001 (2005)]. Taking also into consideration previous related theoretical information by Santra and Greene Phys. Rev. A 70 053401 (2004)...

We present photoelectron angular distributions resulting from the two-photon direct double ionization of helium, under XUV radiation, by solving the time-dependent (TD) Schrödinger equation. The helium TD wavefunction is expanded in terms of fully correlated multichannel states normalized with incoming-wave boundary conditions. The present study fo...

We present an attempt at the theoretical interpretation of recent experimental results on multiphoton ionization of neon by photons of energies 38.4 and 42.8 eV at the free electron laser facility [ A. A. Sorokin et al. Phys. Rev. A 75 051402 (2007)]. Although, given the photon energies, the intensities employed place the process within the regime...

We investigate aspects of the dynamics of a continuous atom-laser scheme based on the merging of independently formed atomic condensates. Our theoretical analysis covers the Markovian as well as the non-Markovian operational regimes, and is based on a semiclassical (mean-field) two-mode model. The role of the relative phase between the two condensa...

We present the theory of photoelectron energy spectra in two-electron atoms strongly driven by a field near resonance with the ionic core. We show that the unavoidable simultaneous excitation of the atomic resonance transition and the ever present a.c. Stark shifts leads to rich structure in the spectrum not predictable by simplified models. We pre...

We investigate the dynamics of a continuous atom laser based on the merging of independently formed atomic condensates. In a first attempt to understand the dynamics of the system, we consider two independent elongated Bose-Einstein condensates which approach each other and focus on intermediate inter-trap distances so that a two-mode model is well...

We present non-perturbative time-dependent calculations of single and double ionization of helium, under XUV radiation of photon energy ranging from 40 to 45 eV, through the direct propagation of the time-dependent Schrödinger equation. The time-dependent wavefunction of the atom under the field is expanded in terms of correlated multichannel state...

We present theoretical results on the spin-polarization of photoelectrons ejected in the process of single-, two-, and three-photon ionization of xenon by circularly polarized radiation. In all cases, we find significant spin-polarization at a series of photon frequency ranges together with substantial cross-sections. The results are analysed an...

We present photoelectron angular distributions (PAD) in two-photon double ionization of helium for photon energies in the range of 45 eV, where the direct double ejection is unequivocally distinguishable from the sequential. Through an approach that allows us to explore the role of correlation, we obtain conditions under which the two electrons...

This book is an introduction to the two closely related subjects of quantum optics and quantum information. Essentially, the physical aspects of quantum information processing have now become an integral part of quantum optics. The book gives a simple, self-contained introduction to both subjects, while illustrating the physical principles of quant...

In this closing chapter of the book, we dwell upon various schemes for the physical implementation of quantum computation. We begin with an outline of the necessary requirements on physical systems for implementing quantum information processing. We then describe a simple model system in which basic quantum gates between Rydberg atoms and microwave...

Computation is data processing. Computers process the input data, following a certain set of instructions called program, to proceed toward the result of computation contained in the output data. One distinguishes analog and digital computation. In analog computation, the computer basically imitates the physical process being simulated. In digital...

We turn now to the description of the building blocks of quantum information theory. We introduce the quantum analog of the bit—qubit, single- and multiple-qubit logic gates and quantum circuits performing information processing. Any introduction to quantum information theory would be incomplete if it did not contain a discussion on the peculiar pr...

In this chapter, after a brief outline of the physics of an one-electron atom, we discuss its interaction with an external electromagnetic field. In particular, we focus on a two-level atom interacting with a near-resonant monochromatic (single-frequency) field which can be treated classically in the case of a strong coherent field produced by a la...

Having summarized the fundamental notions of quantum theory in Chap. 1, here we employ the classical Maxwell equations to quantize the electromagnetic field in vacuum. We then consider various quantum states of the field, followed by the discussion of the photon measurement and the information that it can yield. In the last section of this chapter,...

In this chapter, we consider several illustrative examples of weak field propagation in atomic media. We derive the coupled evolution equations for the field and the atoms, which in general should be solved self consistently. Physically, depending on the amplitude and the pulse shape, the field interacts with the atoms in a certain linear or nonlin...

The dynamics of a small system coupled to a large reservoir can be described using several different formalisms developed in the previous chapter and illustrated with the system of a two-level atom in the open radiation field. Here we adapt this general theory to a system represented by a single-mode cavity field coupled to a reservoir of harmonic...

In this chapter, we begin with the general derivation of the so-called master equation, which is the equation of motion for the reduced density operator for a small system interacting with a large system, or a reservoir, having infinitely many densely spaced energy levels. We then describe an alternative approach to the same problem, based on the q...

In this chapter, after an outline of the general principles of operation of a quantum computer, we present several representative quantum algorithms for data processing and error correction. As we will see, these quantum algorithms can outperform their classical counterparts. The material here also serves to motivate the discussion in the next chap...

We present a quantitative theory with detailed calculations pertaining to multiphoton ionization of helium under moderately strong uv radiation of photon energy 13 eV. Employing both, the nonperturbative solution of the time-dependent Schrödinger equation, as well as perturbation theory, we obtain detailed results for all processes expected to be o...

In view of recent developments in the production of high intensity and subpicosecond pulse duration, XUV radiation sources, we discuss a number of novel photoabsorption processes that are expected to provide windows into a variety of hitherto unexplored territory of atomic and molecular structure, involving highly excited states embedded in multipl...

A Comment on the Letter by Yasuo Nabekawa et al., Phys. Rev. Lett. 94, 043001 (2005). The authors of the Letter offer a Reply.

We consider the dynamics of a single electron in a chain of tunnel coupled quantum dots, exploring the formal analogies of this system with some of the laser-driven multilevel atomic or molecular systems studied by Bruce W. Shore and collaborators over the last 30 years. In particular, we describe two regimes for achieving complete coherent transfe...

http://deepblue.lib.umich.edu/bitstream/2027.42/21262/2/rl2137.0001.001.pdf http://deepblue.lib.umich.edu/bitstream/2027.42/21262/1/rl2137.0001.001.txt

http://deepblue.lib.umich.edu/bitstream/2027.42/21265/2/rl2140.0001.001.pdf http://deepblue.lib.umich.edu/bitstream/2027.42/21265/1/rl2140.0001.001.txt

In this work we present theoretical ionization yields of helium for photon energies where direct two-photon double electron ejection is allowed. We explore the photon energies and the laser peak intensities of the xuv pulse where the direct double ionization of helium is expected to dominate over the sequential channel. This is achieved with the se...

Without Abstract

We present calculations on the dynamics of two-photon ionization of sodium involving core excited autoionizing states in the presence of two-colour radiation fields. We calculate the total ionization probability, the line shapes, and their dependence on the intensity of the laser. The atomic parameters (Rabi frequencies and ac-Stark shifts) are cal...

In anticipation of upcoming two-photon double ionization of atoms and particularly Helium, under strong short wavelength radiation sources (45 eV), we present quantitative signatures of direct two-photon double ejection, in the photoelectron spectrum (PES) and the peak power dependence, that can be employed in the interpretation of related data. We...

A Comment on the Letter by A. Nazarkin, R. Netz, and R. Sauerbrey, Phys. Rev. Lett. 92, 043002 (2004)PRLTAO0031-900710.1103/PhysRevLett.92.043002. The authors of the Letter offer a Reply.

DOI:https://doi.org/10.1103/PhysRevA.70.059903

We discuss the dynamics of doubly resonant ionization in helium involving the strong coupling of two doubly excited autoionizing resonances, under the influence of XUV radiation of short duration (DESY FEL) and a synchronized optical laser. We explore the possibility of using the photoelectron spectra to extract information about the pulse shape of...

We study the coherent dynamics of one- and two-electron transport in a linear array of tunnel-coupled quantum dots. We find that this system exhibits a rich variety of coherent phenomena, ranging from electron wavepacket propagation and interference to two-particle bonding and entanglement. Our studies, apart from their relevance to the exploration...

We study the quantum Zeno effect in the case of indirect measurement, where the detector does not interact directly with the unstable system. Expanding on the model of Koshino and Shimizu [Phys. Rev. Lett., 92, 030401, (2004)] we consider a realistic Hamiltonian for the detector with a finite bandwidth. We also take explicitly into account the posi...

In view of recent experimental developments and interest, we evaluate the possibility of measuring the absolute phase of a short laser pulse via the asymmetry in the angular distribution of the electron emission. On the basis of quantitative calculations of the ionization of Cs, we demonstrate that the asymmetry is directly related to the initial p...

The European Physical Society (EPS) is a not for profit association whose members include 41 National Physical Societies in Europe, individuals from all fields of physics, and European research institutions. As a learned society, the EPS engages in activities that strengthen ties among the physicists in Europe. As a federation of National Physical...

We present a computational approach to the outcoupling in a simple one-dimensional atom laser model, the objective being to circumvent mathematical difficulties arising from the breakdown of the Born and Markov approximations. The approach relies on the discretization of the continuum representing the reservoir of output modes, which allows the tre...

We present theoretical results on the single-photon ionization of magnesium and two-photon double ejection on the two-electron system of helium. In the case of magnesium, partial multichannel cross-section are presented through our ab initio approach, already applied to the helium single and double photoionization [Lambropoulos, P., Maragakis, P.,...

We present an ab initio calculation of multiphoton double ionization in atomic magnesium, the first of its type in an atom with a complex core, showing that direct correlated double electron ejection can be studied through analysis of the photoelectron energy spectrum, using currently or upcoming extreme-ultraviolet radiation sources.

In this paper we report the theoretical results obtained for partial ionization yields and the above-threshold ionization (ATI) spectra of magnesium in a Ti: sapphire laser field (804 nm) in the range of short pulse duration (20-120 fs). Ionization yield, with linearly polarized light for a 120 fs laser pulse, is obtained as a function of the peak...

We present calculations, based on the solution of the time-dependent Schrödinger equation for the hydrogen atom in a discrete basis demonstrating the possibility of extracting the phase profile of a harmonic through its interference with the fundamental. We examine two aspects of the interference: the generated harmonic radiation and the photoelect...

We present detailed calculations for one- and two-photon above-threshold detachment (ATD) cross-sections of the negative positronium ion Ps - ( e + e - e - ), below the threshold of Ps(n = 2), using a configuration interaction (CI) method on a B splines basis. Both the one- and two-photon detachment cross-sections have a form similar to the corresp...

Calculations of intense field (around 1016 W/cm2) single- and double-ionization processes in helium at XUV wavelengths are presented. The laser wavelength is chosen near the | 2s2p 1 P autoionization structure and the dynamics are explored. Single and double ionization yields, as well as the photoelectron energy spectrum for photon energies around...

We present a consistent second order perturbation theory for the lowest-lying condensed modes of very small, weakly-interacting Bose-Einstein condensates in terms of bare particle eigenstates in a harmonic trap. After presenting our general approach, we focus on explicit expressions for a simple three-level system, mainly in order to discuss the an...

In free space, where the vacuum mode density varies relatively slowly in the spectral region of an atomic transition, an atom's real-field and vacuum interactions are effectively decoupled. Consequently, spontaneous decay and the Lamb shift are, for all practical purposes, independent of any real-field atomic perturbation. However, in a colored vac...

We study the behaviour of two closely spaced two-level atoms near-resonantly coupled to the edge of a photonic band-gap continuum. The problem is solved by means of the discretization technique, while a four-level configuration is adopted for the interpretation of the numerical results. The role of the dipole-dipole interaction in the enhancement o...

An ab initio investigation of the excitation of an H(2) resonance, coupled to ionization and dissociation continua, was performed. The excitation occurs via a one- and a three-photon path where both fields have a variable but well-defined phase relation. While both continuum yields show an oscillatory behavior as the phase is varied, a pronounced p...

We extend recent work on the discretization of photonic continua. A two-level atom is coupled to a photonic bandgap reservoir, which we model by a large number of discrete modes. The atom is also coupled to a defect mode inside the gap, which acts as a photon source that can pump the atom. Propagating the wavefunction of the system, we obtain resul...

Taking as the point of departure a frequently used experimental detection scheme, we present a derivation of the analytical expressions of the line shapes in partial decay channels pertaining to photoexcitation of triply excited hollow states in atomic lithium with subsequent autoionization into a specific doubly excited state in the singly charged...

It is shown that a process for producing totally polarized electrons proposed by Fargo and Walker (1973) can also be obtained as a special case in three-photon ionization of an alkali atom. No dependence of the radial matrix elements on the total angular momentum is necessary, nor is it assumed.