Showing papers on "Stark effect published in 2007"
TL;DR: In this article, the fine structure of the neutral exciton in a single self-assembled InGaAs quantum dot is investigated under the effect of a lateral electric field, showing that the electric field strongly affects the exciton fine-structure splitting due to active manipulation of the single particle wave functions.
Abstract: The fine structure of the neutral exciton in a single self-assembled InGaAs quantum dot is investigated under the effect of a lateral electric field. Stark shifts up to 1.5meV, an increase in linewidth, and a decrease in photoluminescence intensity were observed due to the electric field. The authors show that the lateral electric field strongly affects the exciton fine-structure splitting due to active manipulation of the single particle wave functions. Remarkably, the splitting can be tuned over large values and through zero.
186 citations
TL;DR: High resolution laser Stark excitation of np (60
Abstract: High resolution laser Stark excitation of np (60
146 citations
TL;DR: In this article, the binding energy of a hydrogenic donor impurity in a rectangular parallelepiped-shaped quantum dot (QD) in the framework of effective mass envelope function theory using the plane wave basis was calculated.
Abstract: We calculate the binding energy of a hydrogenic donor impurity in a rectangular parallelepiped-shaped quantum dot (QD) in the framework of effective-mass envelope-function theory using the plane wave basis. The variation of the binding energy with edge length, position of the impurity, and external electric field is studied in detail. A finite potential model is adopted in our calculations. Compared with the infinite potential model [C. I. Mendoza et al., Phys. Rev. B 71, 075330 (2005)], the following results are found: (1) if the impurity is located in the interior of the QD, our results give a smaller binding energy than the infinite potential model; (2) the binding energies are more sensitively dependent on the applied electric field in the finite potential model; (3) the infinite potential model cannot give correct results for a small QD edge length for any location of the impurity in the QD; (4) some degeneracy is lifted when the dot is no longer cubic.
144 citations
IBM1
TL;DR: In this paper, the optical properties of carbon nanotubes in an external static electric field directed along the tube axis were analyzed and it was shown that the phonon-assisted mechanism dominates the dissociation rate in electro-optical devices due to the hot optical phonons.
Abstract: We calculate the optical properties of carbon nanotubes in an external static electric field directed along the tube axis. We predict strong Franz-Keldysh oscillations in the first and second band-to-band absorption peaks, quadratic Stark effect of the first two excitons, and the field dependence of the bound exciton ionization rate for a wide range of tube chiralities. We find that the phonon-assisted mechanism dominates the dissociation rate in electro-optical devices due to the hot optical phonons. We predict a quadratic dependence of the Sommerfeld factor on the electric field and its increase up to 2000% at the critical field of the full exciton dissociation.
140 citations
TL;DR: This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control, required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work.
Abstract: The Stark shift of the hyperfine coupling constant is investigated for a P donor in Si far below the ionization regime in the presence of interfaces using tight-binding and band minima basis approaches and compared to the recent precision measurements. In contrast with previous effective mass-based results, the quadratic Stark coefficient obtained from both theories agrees closely with the experiments. It is also shown that there is a significant linear Stark effect for an impurity near the interface, whereas, far from the interface, the quadratic Stark effect dominates. This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control. Such precise control of single donor spin states is required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work.
121 citations
TL;DR: A new absolute frequency measurement of the Cs 6s-8s two-photon transition measured using frequency comb spectroscopy is reported, and it is shown that the AC Stark shift of the transition is determined by the average rather than the much larger peak intensity.
Abstract: We report a new absolute frequency measurement of the Cs 6s-8s two-photon transition measured using frequency comb spectroscopy. The fractional frequency uncertainty is 5x10(-11), a factor of 6 better than previous results. The comb is derived from a stabilized picosecond laser and referenced to an octave-spanning femtosecond frequency comb. The relative merits of picosecond-based frequency combs are discussed, and it is shown that the AC Stark shift of the transition is determined by the average rather than the much larger peak intensity.
91 citations
TL;DR: In this paper, the quantum-confined Stark effect of excitonic states in self-assembled (In,Ga)As∕GaAs quantum dots was studied by microphotoluminescence spectroscopy.
Abstract: The quantum-confined Stark effect of excitonic states in self-assembled (In,Ga)As∕GaAs quantum dots was studied by microphotoluminescence spectroscopy. A similar Stark-shift behavior for excitons, biexcitons, and a charged state was observed. Investigations suggest the absence of a permanent dipole moment in the lateral quantum dot plane. Values of the polarizability could be derived for all the investigated states. Furthermore, high-resolution Fabry-Perot interferometry was applied to resolve the excitonic fine structure splitting and to investigate the influence of a lateral electric field. For a single dot, the splitting could be tuned to zero, thus affording the possibility to create electrically controlled entangled photon pairs.
87 citations
TL;DR: In this article, the spatial evolution of the aluminum plasma produced by the fundamental (1064 nm), second (532 nm) and third (355 nm) harmonics of a Q-switched pulsed Nd:YAG laser was studied.
Abstract: In the present work, we have studied the spatial evolution of the aluminum plasma produced by the fundamental (1064 nm), second (532 nm) and third (355 nm) harmonics of a Q-switched pulsed Nd:YAG laser. The experimentally observed line profiles of neutral aluminum have been used to extract the excitation temperature using Boltzmann plot method whereas the electron number density has been determined from the Stark broadened profiles. Besides we have studied the variation of excitation temperature and electron number density as a function of laser irradiance at atmospheric pressure. In addition, we have performed quantitative analysis of photon absorption and vapor ionization mechanism at three laser wavelengths and estimated the inverse bremsstrahlung (IB) absorption and photoionization (PI) coefficients. The validity of the assumption of local thermodynamic equilibrium is discussed in the light of the experimental results.
83 citations
TL;DR: In this paper, a spectroscopic method of diagnosis based on the Stark broadening of emission lines to determine the electron density and temperature in atmospheric-pressure plasmas was discussed.
Abstract: The aim of this work is to analyse and discuss a spectroscopic method of diagnosis based on the Stark broadening of emission lines to determine the electron density and temperature in atmospheric-pressure plasmas. Usually, when the electron temperature is previously known, the Stark broadening of certain spectral lines spontaneously emitted by the plasma is used to determine the electron density in a rapid and inexpensive way. However, comparing two or more broadening of lines can allow us to diagnose the electron density and temperature simultaneously. To carry out this cross-point method, we must know the Stark broadening dependence on the electron temperature and density for different lines. In this work we have used the first three Balmer series hydrogen lines, whose Stark broadenings were calculated by means of a recent micro-field model existing in the bibliography. The experimental study was made in argon and hydrogen plasma flames. The plasmas were produced at 2.45 GHz by an axial injection torch, which can operate at atmospheric pressure under different experimental conditions to produce appropriate plasmas in 'open air'. The flame produced in this way is a two-temperature plasma, so it is not in local thermodynamic equilibrium. Moreover, by means of the Boltzmann-plot modified with the p−6 law, we found for the hydrogen plasma that most of the observable atomic states were ruled by the excitation–saturation balance. With this method we could also determine the electron temperature.
82 citations
TL;DR: In this article, the relativistic all-order method was used to calculate the electric-dipole matrix elements in alkali-metal atoms. And the resulting matrix elements were used for the high-precision calculation of frequency-dependent polarizabilities of the excited states of alkali metal atoms.
Abstract: Extensive calculations of the electric-dipole matrix elements in alkali-metal atoms are conducted using the relativistic all-order method. This approach is a linearized version of the coupled-cluster method, which sums infinite sets of many-body perturbation theory terms. All allowed transitions between the lowest ns, np{sub 1/2}, np{sub 3/2} states and a large number of excited states are considered in these calculations and their accuracy is evaluated. The resulting electric-dipole matrix elements are used for the high-precision calculation of frequency-dependent polarizabilities of the excited states of alkali-metal atoms. We find 'magic' wavelengths in alkali-metal atoms for which the ns and np{sub 1/2} and np{sub 3/2} atomic levels have the same ac Stark shifts, which facilitates state-insensitive optical cooling and trapping.
80 citations
TL;DR: In this article, an electrically driven ∼1.3μm single-photon source with InAs quantum dots within a planar cavity light-emitting diode is demonstrated.
Abstract: An electrically driven ∼1.3μm single-photon source is demonstrated. The source contains InAs quantum dots within a planar cavity light-emitting diode. Electroluminescence (EL) spectra show clear emission lines and from time resolved EL we estimate a primary decay time of ∼1ns. Time-varying Stark shifts are studied and proposed for truncating the emission in jitter-sensitive applications (optimization for 2ns detector gate width demonstrated) and for relaxing excitation pulse-length requirements. A correlation measurement demonstrates suppression of multiphoton emission to below 28% of the Poissonian level before correction for detector dark counts, suggesting g(2)(0)∼0.19 for the source itself.
TL;DR: From simulated annealing, the molecular conformations in the most stable insertion sites and the orientations of the transition dipole moments are derived and an unambiguous structures for the two principal spectroscopic sites are proposed.
Abstract: We present a spectroscopic study of the properties of the two principal insertion sites (at 785.1 and 794.3 nm) of single dibenzoterrylene molecules in anthracene single crystals at cryogenic temperatures. We measured the temperature dependence of the line width, the orientation of the transition dipole moments, and the Stark effect. We performed molecular dynamics simulations, which show that one dibenzoterrylene molecule preferably replaces three anthracene molecules. From simulated annealing, we derive the molecular conformations in the most stable insertion sites and the orientations of the transition dipole moments. The good agreement between the spectroscopic results and the simulations allows us to propose unambiguous structures for the two principal spectroscopic sites.
Book•
25 Apr 2007TL;DR: The Wigner-Eckart Theorem for SO(3) Coupled Tensor Operators and Tensor operators has been used for coupling and uncoupling of Angular Momenta.
Abstract: BASIC FACTS OF NUCLEI Nucleons The Isotropic Harmonic Oscillator Magic Nuclei Numbers Nuclear Pairing Interactions Nuclear Spin of Nuclei Ground States NOTES ON THE QUANTUM THEORY OF ANGULAR MOMENTUM Coupling and Uncoupling of Angular Momenta The 3j-Symbols The 6j-Symbols The 9j-Symbols Tensor Operators The Wigner-Eckart Theorem for SO(3) Coupled Tensor Operators Some Special 3nj-Symbols The Zeeman Effect: Weak-Field Case Exercises INTERACTIONS IN ONE- AND TWO-ELECTRON SYSTEMS States of Two-Electron Systems The Central Field Approximation Coulomb Interaction in Two-Electron Systems Coulomb Matrix Elements for the f 2 Electron Configuration The Spin-Orbit Interaction Spin-Orbit Matrices for f 2 Intermediate Coupling Exercises COUPLING SCHEMES OF ANGULAR MOMENTA Notes on jj-coupling J1j-coupling NdI and NdII Energy Levels and j1j-Coupling J1j-coupling in GdIII Levels of 4 f 7 (8 S 7/2 )6p J1l-coupling Exercises FINE AND MAGNETIC HYPERFINE STRUCTURE Intermediate Coupling, g-Factors, and g-Sum Rule Fine Structure in Alkali Atoms and Zeeman Effect Introductory Remarks on Magnetic Hyperfine Structure Magnetic Hyperfine Structure Exercises MAGNETIC DIPOLE AND ELECTRIC QUADRUPOLE HYPERFINE STRUCTURES Magnetic Hyperfine Structure in the JMJ IMI Basis Zeeman Effect in the JIFMF and JMJ IMI MF Bases Example of a J = 1/2 Electronic Level Example of Electric Quadrupole Hyperfine Structure Exercises INTENSITIES OF ELECTRONIC TRANSITIONS Electric Dipole Transitions in Atoms Ratio of the Line Strengths for the D Lines of Alkali Atoms Line Strengths for Many-Electron Atoms Relative Line Strengths in LS-coupling Relative Line Strengths for Hyperfine Levels Relative Line Strengths for the D2 Transitions of Effective Operators and Perturbation Theory The Quadratic Stark Effect in Atoms Example of HYPERFINE INTERACTIONS AND LASER COOLING Motion and Temperature Some Basic Quantum Results Absorption and Emission of Photons Laser Cooling Magneto-Optical Traps IONS IN CRYSTALS Crystal Field Splittings Data on the Finite Groups O ~ S4 and C3v ~ S3 Data on the Finite Groups for Ho3+ Ions in LiY F4 Crystals The Crystal Field Expansion Point Group Symmetry Restrictions An Octahedral Crystal Field Identification of the Octahedral States for 3 F3 Influence of the Trigonal C3v Crystal Field SOME ASPECTS OF CRYSTAL FIELD THEORY Selection Rules for Transitions in Ions in a Crystal Field of S4 Point Symmetry Crystal Field Quantum Numbers Intensities of Transitions and Effective Operators for Ions in Crystals A Simplified Crystal Field Calculation The MAPLE Program HYPERFINE INTERACTIONS IN CRYSTALS: Pr3+ IN OCTAHEDRAL FIELD Matrix Elements of Magnetic Dipole Hyperfine Interactions An Octahedral Crystal Field Octahedral Magnetic Hyperfine Matrix Elements MAGNETIC INTERACTIONS IN f-ELECTRON SYSTEMS The f N Electron Configurations Calculation of the Free Ion Energy Levels of Sm I The Zeeman Effect in Sm I (Without Nuclear Spin Effects) The Zeeman Effect in Sm I, Including Nuclear Spin Some MAPLE Zeeman Effect Programs Zeeman Matrices in a | JMJ IMI MF Basis MAGNETIC HYPERFINE INTERACTIONS IN LANTHANIDES Magnetic Hyperfine Matrix Elements in JMJ IMJ Coupling Magnetic Hyperfine Matrix Elements for the 7F J = 0, 1 Levels Combined Magnetic and Hyperfine Fields in Sm I Combined Magnetic Hyperfine and Crystal Fields Other Physical Mechanisms and Higher Order Corrections Exercises ELECTRIC QUADRUPOLE HYPERFINE INTERACTIONS Derivation of a Tensorial Form of HEQ ELECTRIC QUADRUPOLE HYPERFINE STRUCTURE IN CRYSTALS Explicit Calculation of Elliott's Term Spin-Orbit Interaction Between 7F0 and the Lowest 5D0 THE ELECTRIC MULTIPOLE COUPLING MECHANISM IN CRYSTALS Configuration Interaction Mechanisms Excitations from the 4f N Shell Exercises ELECTRIC DIPOLE fâ f TRANSITIONS Judd-Ofelt Theory of fâ f Intensities Double-Perturbation Theory Third-Order Effective Operators Radial Integrals and Perturbed Function Approach Other Contributions RELATIVISTIC EFFECTS Relativistic Crystal Field Theory Relativistic fâ f Transitions in Crystal Fields Effective Operators of Relativistic fâ f Theory Parameterization Schemes of f Spectra MAGNETIC DIPOLE TRANSITIONS IN CRYSTALS Polarization of Light and Transitions Selection Rules for Transitions in Crystals The Oscillator Strengths for the 7F00 â 7F1M Transitions Intermediate Coupling and 5D1 â 7F0 Transitions Oscillator Strengths for the 5D1 â 7F1 Magnetic Dipole Transitions J-Mixing and "Intensity Borrowing" Perturbation Approach and Higher-Order Contributions Exercises HYPERFINE-INDUCED TRANSITIONS The Electron Configurations (2s2p) and (2p2) in N IV Ions Nuclear Magnetic Dipole Hyperfine Matrix Elements in (2s2p) The Mapleâ ¢ Procedures Used to Calculate the Hyperfine Matrix Elements Hyperfine Induced fâ f Transitions Nuclear Magnetic Hyperfine Contributions Electric Multipole Hyperfine Contributions Summary Intrashell Interactions NUMERICAL ANALYSIS OF RADIAL TERMS Approximations Functions of the Radial Basis Set Perturbed Functions Values of Radial Integrals for All Lanthanide Ions LUMINESCENCE OF LANTHANIDE-DOPED MATERIALS Experiments Electrostatic Model Effective Operator Formulation Confrontation with Nature: Tissue Selective Lanthanide Chelates Index *Each Chapter contains Up-to-date References
TL;DR: In this article, the ac Stark effect was used to induce resonant energy transfer between translationally cold 85Rb Rydberg atoms, and the two-atom dipole-dipole process was dramatically enhanced, due to induced degeneracy of the initial and final states.
Abstract: The ac Stark effect was used to induce resonant energy transfer between translationally cold 85Rb Rydberg atoms. When a 28.5 GHz dressing field was set at specific field strengths, the two-atom dipole-dipole process 43d5/2+43d5/2-->45p3/2+41f was dramatically enhanced, due to induced degeneracy of the initial and final states. This method for enhancing interactions is complementary to dc electric-field-induced resonant energy transfer, but has more flexibility due to the possibility of varying the applied frequency.
TL;DR: Optical Stark spectroscopy of solids has been closely associated with Alexander Kaplyanskii over the last four decades as discussed by the authors, with some emphasis on the use of spectral hole burning and coherent transient techniques to measure linear and quadratic Stark coefficients.
TL;DR: In this article, the fundamental, second, and third harmonics of the neodymium-doped yttrium aluminium garnet laser have been used to measure the zinc and cadmium plasma parameters.
TL;DR: This study demonstrates that electric fields may be used to enhance or suppress spin-rotation interactions in molecules and suggests that electric Fields might be used for controlling nonadiabatic spin transitions and spin-forbidden chemical reactions of cold molecules in a magnetic trap.
Abstract: The authors present a detailed study of low-temperature collisions between CaD molecules and He atoms in superimposed electric and magnetic fields with arbitrary orientations. Electric fields do not interact with the electron spin of the molecules directly but modify their rotational structure and, consequently, the spin-rotation interactions. The authors examine molecular Stark and Zeeman energy levels as functions of the angle between the fields and show that rotating fields may induce and shift avoided crossings between the Zeeman levels of the rotationally ground and rotationally excited states of the molecule. The dynamics of molecular collisions are extremely sensitive to external fields near these avoided crossings and it is shown that molecular collisions may be controlled by varying both the strength and the relative orientation of the fields. The effects observed in this study are due to interactions of the isolated molecules with external fields so the conclusions should be relevant for collisions of molecules with other atoms or collisions of molecules with each other. This study demonstrates that electric fields may be used to enhance or suppress spin-rotation interactions in molecules. The spin-rotation interactions induce nonadiabatic couplings between states of different total spins in systems of two open-shell species and it is suggested that electric fields might be used for controlling nonadiabatic spin transitions and spin-forbidden chemical reactions of cold molecules in a magnetic trap.
TL;DR: In this article, the authors proposed a method based on the relation between the gas temperature and the van der Waals broadening of argon atomic spectral lines with a Stark contribution negligible.
TL;DR: This work investigated the Stark spectroscopy of nine structurally diverse nucleosides containing nitrile or azide probes in positions that correspond to both the major and minor grooves of DNA, and observed the largest Stark tuning rate observed.
Abstract: The vibrational Stark effect (VSE) has proven to be an effective method for the study of electric fields in proteins via the use of infrared probes. To explore the use of VSE in nucleic acids, we investigated the Stark spectroscopy of nine structurally diverse nucleosides. These nucleosides contained nitrile or azide probes in positions that correspond to both the major and minor grooves of DNA. The nitrile probes showed better characteristics and exhibited absorption frequencies over a broad range; that is, from 2253 cm-1 for 2‘-O-cyanoethyl ribonucleosides 8 and 9 to 2102 cm-1 for a 13C-labeled 5-thiocyanatomethyl-2‘-deoxyuridine 3c. The largest Stark tuning rate observed was |Δμ| = 1.1 cm-1/(MV/cm) for both 5-cyano-2‘-deoxyuridine 1 and N2-nitrile-2‘-deoxyguanosine 7. The latter is a particularly attractive probe because of its high extinction coefficient (e = 412 M-1cm-1) and ease of incorporation into oligomers.
TL;DR: The Stark splitting of a single fourfold degenerate impurity located within the built-in potential of a metal-semiconductor contact is investigated using low temperature transport measurements and data is consistent with a boron impurity.
Abstract: The Stark splitting of a single fourfold degenerate impurity located within the built-in potential of a metal-semiconductor contact is investigated using low temperature transport measurements. A model is developed and used to analyze transport as a function of temperature, bias voltage, and magnetic field. Our data is consistent with a boron impurity. We report g factors of g_{1/2}=1.14 and g_{3/2}=1.72 and a linear Stark splitting 2Delta of 0.1 meV.
Journal Article•
TL;DR: In this paper, infrared control pulses are used to modify the field-free dynamical evolution during traversal of the avoided crossing, thus controlling the nonadiabatic branching ratio.
Abstract: intermediate field strength regime snonperturbative but nonionizingd. We illustrate this scheme for the case of nonadiabatic molecular photodissociation at an avoided crossing. Using the NRDSE exclusively, both the electronic branching ratio and predissociation lifetime may be controlled. Infrared control pulses are used to modify the field-free dynamical evolution during traversal of the avoided crossing, thus controlling the nonadiabatic branching ratio. Predissociation lifetimes may be either increased or decreased using properly timed short infrared pulses to modify phase differences between the diabatic wave packets. In contrast with the limiting cases of perturbative control sinterference between transitionsd and strong field control with ionizing laser fields, control via the NRDSE may be thought of as reversibly modifying the effective Hamiltonian during system propagation.
TL;DR: In this article, high quality gallium doped ZnO (Ga:ZnO) thin films were grown on c−Al2O3(1000) by plasma-assisted molecular beam epitaxy, and Ga concentration NGa was controlled in the range of 1×1018-2.5×1020∕cm3 by adjusting∕changing the Ga cell temperature.
Abstract: High quality gallium doped ZnO (Ga:ZnO) thin films were grown on c‐Al2O3(1000) by plasma-assisted molecular beam epitaxy, and Ga concentration NGa was controlled in the range of 1×1018–2.5×1020∕cm3 by adjusting∕changing the Ga cell temperature. From the low-temperature photoluminescence at 10K, the donor bound exciton I8 related to Ga impurity was clearly observed and confirmed by comparing the calculated activation energy of 16.8meV of the emission peak intensity with the known localization energy, 16.1meV. Observed asymmetric broadening with a long tail on the lower energy side in the photoluminescence (PL) emission line shape could be fitted by the Stark effect and the compensation ratio was approximately 14–17% at NGa⩾1×1020∕cm3. The measured broadening of photoluminescence PL emission is in good agreement with the total thermal broadening and potential fluctuations caused by random distribution of impurity at NGa lower than the Mott critical density.
TL;DR: Using laser-induced fluorescence-dip Stark spectroscopy, direct measurements of electric-field strengths during the breakdown phase of a low-pressure, pulsed discharge in xenon are performed for the first time quantitatively measure the time evolution of the driving force of the plasma breakdown process: the electric field.
Abstract: Using laser-induced fluorescence-dip Stark spectroscopy, we performed time-resolved, direct measurements of electric-field strengths during the breakdown phase of a low-pressure, pulsed discharge in xenon. With this experimental technique we could for the first time quantitatively measure the time evolution of the driving force of the plasma breakdown process: the electric field. Moving ionization fronts were measured with submicrosecond resolution. These ionization fronts were sustained by a spatially narrow, rapidly moving region of strong electric field.
TL;DR: In this article, a heuristic explanation for the relativistic effect of the electron electric dipole moment was proposed, which corrects a widespread misconception in the literature and shows that Schiff's theorem is not applicable when special relativity is taken into account.
Abstract: In most experimental searches for the electron electric dipole moment, one searches for a linear Stark effect in a paramagnetic atom or molecule and interprets the result in terms of the electric dipole moment of the unpaired valence electron(s). Schiff’s theorem states that in the limit of nonrelativistic quantum mechanics, there can be no linear Stark effect to first order in the electric dipole moment. Sandars has shown that Schiff’s theorem is not applicable when special relativity is taken into account. We give a heuristic explanation for this relativistic effect, which corrects a widespread misconception in the literature.
TL;DR: In this article, the optical transitions in ensembles of colloidal CdSe-based quantum dots (QDs) have been systematically studied as a function of the net QDs' polarity/polarization and of the solvent's polarity.
Abstract: The optical transitions in ensembles of colloidal CdSe-based quantum dots (QDs) have been systematically studied as a function of the net QDs’ polarity/polarization and of the solvent’s polarity. While the general trend observed for all QD systems dispersed in different solvents is similar, the spectral shifts are more pronounced in core QDs than in core/shell structures. Our results can be rationalized by taking account of the electric field experienced by the QDs that results from their effective polarization in solvents of different polarities (quantum confined Stark effect) as well as from the effect of the external dielectric environment (solvatochromatic effect).
TL;DR: Two solid-state sources of indistinguishable single photons are demonstrated, combining laser spectroscopy and optical microscopy at T = 1.4 K to identify individual molecules in two independent microscopes.
Abstract: We demonstrate two solid-state sources of indistinguishable single photons. High resolution laser spectroscopy and optical microscopy were combined at T = 1.4 K to identify individual molecules in two independent microscopes. The Stark effect was exploited to shift the transition frequency of a given molecule and thus obtain single photon sources with perfect spectral overlap. Our experimental arrangement sets the ground for the realization of various quantum interference and information processing experiments.
TL;DR: In this paper, a laser spectroscopic method for sensitive electric field measurements using krypton has been developed, which allows us to add Krypton as a small admixture to various low temperature plasmas and demonstrate the application of this method in the sheath region of a capacitively coupled radiofrequency (RF) discharge.
Abstract: A laser spectroscopic method for sensitive electric field measurements using krypton has been developed. The Stark effect of high Rydberg states of the krypton autoionizing series can be measured by a technique called fluorescence dip spectroscopy (FDS) with high spatial and temporal resolution. Calibration measurements have been performed in a reference cell with known electric field and they agree very well with numerical solutions of Schrodinger's equation for jl-coupled states. The application of this method has been demonstrated in the sheath region of a capacitively coupled radiofrequency (RF) discharge. The laser spectroscopic method allows us to add krypton as a small admixture to various low temperature plasmas.
TL;DR: In this paper, a hydrogen pellet is injected into a plasma in the Large Helical Device (LHD). Strong radiation from a dense plasma formed around the pellet, the so-called "pellet cloud", is observed and its spectrum is analyzed.
Abstract: A hydrogen pellet is injected into a plasma in the Large Helical Device (LHD). Strong radiation from a dense plasma formed around the pellet, the so-called 'pellet cloud', is observed and its spectrum is analysed. Emission lines of neutral hydrogen exhibit Stark broadening profiles and the electron density is evaluated through comparison with theoretical data (e.g. 2.1 ? 1023?m?3). The continuum radiation is dominated by two components which correspond to radiative recombination and radiative electron attachment, respectively, the latter of which yields negative ions. From the absolute intensity and its dependence on the wavelength of the continuum radiation, the electron temperature (1.02?eV), the atom density (1.7 ? 1025?m?3) and the observed plasma volume (1.6 ? 10?5?m3) are determined. These results indicate that the plasma state is close to complete LTE (local thermodynamic equilibrium). The Balmer-? line profile is deformed owing to the reabsorption effect. With the help of one-dimensional radiation transport calculation, the plasma thickness in the direction of the observation (2.4 ? 10?3?m) is estimated. The result suggests that the pellet cloud is extended anisotropically in the direction perpendicular to the observation.
TL;DR: In this article, the authors analyzed the contribution of screening of the quantum-confined Stark effect (QCSE) to the emission enhancement behavior in the process of surface plasmon (SP) coupling with an InGaN∕GaN quantum well (QW), which is 20nm away from a Ag thin film that supports the SP.
Abstract: The authors analyze the contribution of the screening of the quantum-confined Stark effect (QCSE) to the emission enhancement behavior in the process of surface plasmon (SP) coupling with an InGaN∕GaN quantum well (QW), which is 20nm away from a Ag thin film that supports the SP. From the measurements of excitation power dependent photoluminescence and time-resolved photoluminescence (TRPL) spectroscopy, and the fitting to the TRPL data based on a rate-equation model, it is found that when the excitation level is high, the QCSE screening effect not only contributes significantly to the emission enhancement but also increases the SP coupling rate because of the blueshift of emission spectrum caused by the screening effect. Therefore, the emission strength from SP radiation, relative to that from QW radiative recombination, increases with the excited carrier density. Also, a saturation behavior of SP-QW coupling is observed from the fitting procedure.
TL;DR: The standard theory of line broadening is sufficiently accurate for the entire set of plasma conditions and spectral transitions considered here, while an alternative theory is shown to be inadequate for the higher-density region.
Abstract: We present results for Stark broadening of high principal quantum number (up to n=15) Balmer lines, using an analytical (the ''standard theory'') approach and two independently developed computer simulation methods. The line shapes are calculated for several sets of plasma parameters, applicable to radio-frequency discharge (N{sub e}{approx_equal}10{sup 13} cm{sup -3}) and magnetic fusion (N{sub e}{approx_equal}10{sup 15} cm{sup -3}) experiments. Comparisons of the calculated line profiles to the experimental data show a very good agreement. Density and temperature dependences of the linewidths, as well as relative contributions of different Stark-broadening mechanisms, are analyzed. It is seen that the standard theory of line broadening is sufficiently accurate for the entire set of plasma conditions and spectral transitions considered here, while an alternative theory (''advanced generalized theory'') is shown to be inadequate for the higher-density region. A discussion of possible reasons for this disagreement is given.