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ORIGINAL PAPER南不二男, 1964, 「述語文の構造」, 『国語研究』18, pp. 1-19.MINAMI, Fujio, 1964, Jutsugo-bun-no kōzō, Kokugo Kenkyū [Inquiries into the Japanese Language] 18, pp. 1-19.Translated by John Haig (University of Hawaii)Proofed by Stephen Wright HORN (NINJAL)

Coherent control is an optical technique to manipulate quantum states of matter. The coherent control of 40-THz optical phonons in diamond was demonstrated by using a pair of sub-10-fs optical pulses. The optical phonons were detected via transient transmittance using a pump and probe protocol. The optical and phonon interferences were observed in the transient transmittance change and its behavior was well reproduced by quantum mechanical calculations with a simple model which consists of two electronic levels and shifted harmonic oscillators., Comment: 5 pages, 6 figures

The coherent control of optical phonons has been experimentally demonstrated in various physical systems. While the transient dynamics for optical phonons can be explained by phenomenological models, the coherent control experiment cannot be explained due to the quantum interference. Here, we theoretically propose the generation and detection processes of the optical phonons and experimentally confirm our theoretical model using the diamond optical phonon by the double-pump-probe type experiment., Comment: 11 pages, 5 figures

Surface plasmon polariton (SPP) propagation on a Au thin film has been observed by tip-enhanced Rayleigh scattering. The interference pattern has been observed around the edge of the film. The interference is due to the near-field scattering light at the tip and SPP radiation from the edge of the film. From the interference width, we evaluated the wave number of SPP on the Au film. By changing the wavelength of the incidence light, we have obtained the dispersion relation of the SPP. The experimentally obtained dispersion relation is well corresponding to the calculated one using bulk Au parameters.

Europium (III) (Eu(3+))-doped nanoporous silica spheres were synthesized, and the states of Eu(3+) ions in the silica framework structure were investigated. The ordered nanopores were preserved with the doping at the Eu(3+) molar concentration to Si up to 10 mol%, and the O-Si-O and Si-OH groups in the structures were clearly rearranged with the doping, indicating the interaction of Eu(3+) with the O atoms. The significant morphological changes in the spheres were observed with the doping. The photoluminescence spectral shapes due to the transitions of (5)D(0)-(7)F(1) and (5)D(0)-(7)F(2) were indicative of the presence of the Eu(3+) in an environment of a low symmetry. It was found that the Eu(3+) was located inside the silica framework to electrostatically interact with the environmental O atoms, which would prevent the aggregation among Eu(3+) ions to show the efficient luminescence. Therefore, the interactions between the Eu(3+) ions and silica framework structures in the spheres were successfully clarified.

Europium (III) (Eu 3+ )-containing nanoporous silicas were successfully synthesized by two different loading methods (adsorption or doping), and the states of the Eu 3+ in the structure were investigated. The Eu 3+ -adsorption indicated that the Eu 3+ interacts with hydroxyl groups on the pore surface and H 2 O molecules to enhance the quenching, whereas the Eu 3+ -doping indicated that the Eu 3+ was located inside the structure framework that produced the efficient luminescence. The interaction between the Eu 3+ and silica structure depended on the loading method.

We have studied micro-photoluminescence spectra of self-assembled single GaAs/AlGaAs quantum dots (QDs). Under non-resonant optical excitation, a single GaAs QD exhibits several sharp peaks in the PL spectra whose origins are the recombination of neutral or charged multi-excitonic complexes. In single photon correlation measurements, photons emitted from charged biexcitons and charged excitons show bunching which indicates that photon pairs are generated from the cascade recombination of the charged biexcitons. The result of polarization correlation measurements shows that each photon of the pairs is polarized linearly and orthogonally. These polarization features can be understood by the superposition of elliptically polarized photons affected by the electron–hole exchange interaction in the anisotropic QD.

Spin Information Achieved by Energy Transfer Via Optical Near Fields Between Quantum Dots and Its Robustness A. Sato1, F. Minami1, H. Hori2 4, and K. Kobayashi3 4 ∗ 1Department of Physics, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro-ku, Tokyo 152-8551, Japan 2Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8551, Japan 3Department of Electrical and Electronics Engineering, University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan 4Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 4-3-11 Takeda, Kofu, Yamanashi 400-8551, Japan

We have studied micro-photoluminescence spectra of a self-assembled single GaAs quantum dot under 8 K. With strong pulsed excitation, the micro-photoluminescence spectrum shows bright emission lines originated from an exciton, a positively charged exciton, and a biexciton, together with weak lower energy emissions reflecting multi-excitonic structures with more carriers. We have identified the origins of these weak emission lines, and showed the existence of charged biexciton states, through single photon correlation measurements and excitation power dependence of the photoluminescence intensity. In addition, investigating the radiative recombination process of the charged biexciton, we have determined the electron–hole exchange energy in the GaAs quantum dot.

A simple but flexible 2D lattice model is proposed to discuss localization and tunneling of a dressed photon in disordered nanomaterial systems. It is shown that a 1D finite disordered system with site-dependent masses is obtained after the contraction from 2D to 1D. A dressed photon description for a photon-electronic polarization–phonon interacting system is used to examine the spatial distribution of a dressed photon associated with coherent phonons in such a system. The temporal and tunneling behaviors of a dressed photon between two closely separated nanosystems are also investigated numerically. The model proposed is applicable to an arbitrary shape of nanostructure, and photon localization and tunneling inherent in the shape of the nanostructure is expected to be applied to the local manipulation of quantum states of nanostructure in excitation transfer processes, including spin and phonon degrees of freedom.

In self-assembled multilayer arrays of micrometer-sized spheres which include small amount of fluorescent particles, unique six-dot-triangular and seven-dot-hexagonal patterns have been known to appear in the fluorescence microscopic image. Although it has been suggested that these patterns correspond to local domain structures, i.e., face centered cubic (fcc) or hexagonal closed packing (hcp), no convincing evidence has been presented. In this study, we fabricated well-controlled photonic clusters by use of micromanipulation and investigated the relation between the propagation patterns and the domain structures. While the minimum fcc and hcp clusters exhibited the triangular and hexagonal patterns, respectively, it was also found that the propagation patterns are dependent on the size of the clusters.

Four-wave mixing (FWM) technique is used to study the phonon induced dephasing of the excitons in CdTe self-assembled quantum dots. The FWM signals show two different decay structures with fast and slow decay components, indicating a non-Lorentzian line-shape with a zero-phonon line and a broadband from exciton–acoustic phonon interaction in the spectral region. The dephasing of the zero-phonon line and the sideband components both show non-linear characteristics with respect to temperature. The experimental data are reproduced well by a theoretical model taking into account the carrier–acoustic phonon coupling.

We discuss the mechanism of the spin and excitation energy transfer in a quantum-dot pair system driven by optical near fields (ONFs). When one of the pair is excited either by an ONF or effectively by a far field, the energy and spin information of the induced exciton can be transferred to the other quantum dot via a near-field optical interaction. Moreover, it is possible to flip the electron spin during the transfer process, depending on the resonant state of the energy levels of the quantum dots. We present the electron-spin selection rules, and calculate the spin and excitation energy transfer rates between the quantum-dot pair and the spin polarization, in terms of the exciton–polariton basis for ONFs. A way of making experimental observations is also suggested.

The qubits can be entangled when they interact with a common Ohmic reservoir. We analyze how the reservoir-induced entanglement of qubits can be observed as the beat signal in the decay curve of the macroscopic polarization. The origin of this effect is the Lamb phase shift on the qubit array. We quantify the amount of the reservoir-induced entanglement and show how to experimentally evaluate it from the decay curve of the macroscopic polarization. We discuss how the beat signal can be discriminated from the other kinds of beat signals. We also show that our analysis can be used to estimate the reservoir characteristics.

We measured time-resolved photon echo signals by using the heterodyne detection technique on GaAs multiple quantum wells. Oscillation structure with a period of about 0.8 ps is observed when the time interval (delay time) of two pulses which generate the photon echo signal is shorter than 0.4 ps. The oscillating structure disappears when the delay time is longer than 0.6 ps. Temperature and excitation density dependence indicate that the origin of this oscillation is the interaction between a normal exciton and an exciton coupled with a specific acoustic phonon mode which is identified by calculating the Rytov model.

Coherent optical pulse transmitted through GaSe is investigated in both energy and time domains by using the frequency-resolved optical gating technique. The free induction decay signal due to the coherent emission from excitons is observed. The temporal evolution of the intensity of optical pulse passing through the sample exhibits a coherent dip as a result of a destructive interference between the coherent emission and the input optical field. Furthermore, the dispersion of the refractive index at the excitonic resonance is obtained.

Micro-photoluminescence is used to study the temperature dependence of CdTe self-assembled quantum dots. The observation of the micro-photoluminescence spectra with temperature shows that there are two different structures, namely the zero-phonon line and the phonon sidebands. When the temperature increases, the sidebands become clearer and show substantial broadening. The experimental data are reproduced well by a theoretical model taking into account the carrier-acoustic-phonon coupling. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Micro-photoluminescence ( μ -PL) is used to study the temperature dependence of self-assembled quantum dots (QD) in semiconductors. The observation of the PL with temperature shows that there are two different states within the PL emission, namely the zero-phonon line and the phonon sidebands. When the temperature increases, the effect of the sidebands become clearer and show substantial broadening. The theory also shows good agreement with the experimental data, and in the present experiments, PL and μ -PL spectra have been measured at temperatures of 5 K ⩽T⩽90 K in both CdTe and GaAs self-assembled QD samples.

We report on the polarization dependence for hyper-Rayleigh scattering (HRS) in two-photon resonance with exciton states in ZnSe. The HRS signal is enhanced drastically when twice the incident photon energy is resonant with the excitation energy of the 2P excitons in ZnSe/GaAs thin films. The selection rules for the HRS in two-photon resonance with the 2P excitons are different from those for nonlinear susceptibility determined by crystal symmetry. Further, we report a study of the symmetries of the 2P excitonic wave function with linearly- and circularly-polarized incident beams. The heavy and light hole 2P excitons belong to different symmetries of the base functions.

We develop a theory of active dephasing control of qubit systems in array structures by using the multi-wave mixing technique. Assuming an acoustic phonon with a cutoff frequency ω c as the reservoir boson, we evaluate the state evolution of the qubit–reservoir system under irradiation of an optical pulse sequence. The effect of active dephasing control by the optical π pulses would be observed as diffracted echo signals in the phase-matching direction. The analysis for the case of weak pulse control is also presented.

The phase characteristics of transmitted optical pulses in a three-dimensional photonic crystal were investigated in both energy and time domains by using a spectrally-resolved cross-correlation technique. The temporal evolution of femtosecond pulses passing through polystyrene colloidal crystals exhibits a large phase distortion near the stop bands. The dispersion curve estimated from the phase shift shows good correspondence with that calculated from a photonic band calculation. The group velocity significantly slows down near the stop bands. These results are in good agreement with a photonic band theory.

The phonon bottleneck effect is studied in InAs/GaInP quantum dots (QDs). The time-resolved photoluminescence spectra from the lowest ( n =1) and second lowest ( n =2) exciton states in QDs are measured in the temperature range of 5– 200 K . We find that the rise time of the n =1 level is about 500 ps when the excitation energy is in resonance with the n =2 level. This is a long time compared to about 200 ps in non-resonant excitation, and therefore the bottleneck effect exists between the levels n =2 and 1. In order to understand the source of the bottleneck, the temperature dependence of carrier relaxation time between the exciton levels is investigated in the assigned temperature range. With increasing temperature, the relaxation time decreases to 200 ps at 200 K . The data are in good agreement with the theoretical fit of the relaxation probability for multi-phonon processes.

The signals due to six-wave mixing (SWM) processes are observed for two-dimensional excitons and biexcitons. The signal intensity of the SWM process strongly depends on the pulse area of the excitation light. The pulse area is estimated by comparing the intensities of four-wave mixing (FWM) signals in two different directions. The photon echo and the transient-grating signals due to the biexcitonic state of GaSe were observed by SWM. When we change the order of the excitation pulses in our SWM experiments, the excitonic phase relaxation process can be observed in the negative delay-time region.

The energy levels of electrons and holes confined in GaAs/AlGaAs quantum dots (QDs) are studied using photoluminescence (PL) measurements under high pressure, as well as micro-PL (μPL) measurements of single QDs. From the high-pressure measurements, the band lineups of the GaAs QD are determined. The GaAs QD valence-band heavy-hole ground-state-first excited-state separation is 24 meV . From the μPL measurements, the GaAs QD conduction band electron ground state-first excited state separation is 96 meV .

We present results on the influence of temperature on the exciton lineshape in self-assembled III–V semiconductor quantum dots. Micro photoluminescence (μ-PL) is used to observe the temperature dependence of the exciton line in self-assembled GaAs and InGaAs semiconductor single quantum dots (QDs). The observation of the PL with temperature shows that there are two different states within the PL emission, namely the zero-phonon line and the phonon sidebands. The sidebands and the zero-phonon line both show non-linear characteristics with respect to temperature. When the temperature increases, the effect of the sidebands become clearer and show substantial broadening. The theory also shows good agreement with the experimental data, and in the present experiments, PL and μ-PL spectra have been measured at temperatures of 5K ≤ T ≤ 90 K in GaAs and InGaAs self-assembled QD samples. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We report on a detailed experimental study of multiexcitonic effects in the carrier dynamics in single GaAs/Al 0.3 Ga 0.7 As quantum dot (QD) obtained by means of molecular beam droplet epitaxy. The PL spectrum shows large modifications with the time delay and the excitation power density. During the early stages after pulse excitation the QD ground-state emission consists in a broad band. Increasing the delay time (or decreasing the excitation power) the low energy tail of the PL band rapidly decreases and the PL bandwidth is reduced, eventually collapsing with well-resolved sharp lines (FWHM < 0.5 meV). We attribute the different contributions to emissions from single exciton, few exciton and many exciton levels inside the QD.

Excitonic PL emissions in high-quality ZnTe epilayers grown on GaAs by hot-wall epitaxy were investigated by their annealing behaviors and compared with PL emissions of Ga-doped CdTe. The observed donor- and acceptor-bound excitons were ascribed to gallium donors and to arsenic acceptors diffused from GaAs substrate, respectively. In addition to these bound excitons, an intense emission line was observed at 525.90 nm (2.3575 eV) in relatively thin ZnTe films of less than 6 μm. It was found from the PL spectrum change by annealing under Zn saturation that the 526.90 nm line is due to recombination from excitons trapped at defect complexes, probably Zn-vacancy/Ga-donor complexes.

Time-resolved magneto photoluminescence in a diluted magnetic semiconductor Cd 0.9 Mn 0.1 Te has been carried out with varying exciton density from 10 14 to 10 19 cm m 3 . The reduction of the Zeeman shift and that of the magnetic polaron energy was found under strong photoexcitation. The spectral feature is interpreted in terms of the heating of the manganese spin subsystem. Polarization dependence of the spin heating is observed for the first time, revealing the contribution of the spin flip between excitons and magnetic ions to the heating process.

We carried out time-resolved magneto-photoluminescence experiments in a diluted magnetic semiconductor Cd 0.9 Mn 0.1 Te with varying exciton density. We found a reduction of the Zeeman shift and of the binding energy of magnetic polarons under strong excitation condition. The spectral feature is interpreted by the heating effect of manganese spins. Polarization dependence of the spin heating is observed for the first time, revealing the contribution of spin flip between excitons and magnetic ions to the heating process.

The photoluminescence from localized excitons in In 0.25 Ga 0.75 N was enhanced up to 6.6 times by approaching a gold nano-particle to nano-meter vicinity. Mapping images of enhanced photoluminescence and topological images were measured simultaneously with a spatial resolution of 100 nm. With an improved measurement system and selection of relatively flat area of the sample, we propose that the segregated metallic In droplet ought to play an important role for the present tip-enhance effect.

The phase characteristics of transmitted optical pulses were investigated in the energy- and the temporal domain using the spectrally resolved cross-correlation technique. The temporal evolution of fs pulses passing through GaAs/AlGaAs quantum wells indicates a long tail due to the coherent emission from the exciton. The phase discontinuity was observed in the time-domain data. The phase of the coherent emission signal is found to differ by 180° from that of the incident light field. Furthermore, we report the pulse propagation effect when the pre-excited coherent exciton exists in the sample. The resultant data shows that the ultrashort optical pulses are strongly affected by the phase difference between the coherent emission and the coherent exciton polarization.

The polarization rotation induced by the light pulse excitation is investigated on GaAs heterostructures. The temporal profile of the rotation angle shows an exponential decay reflecting the spin relaxation of excitons. The spectrally resolved transients exhibit not only the magnitude but the direction of the polarization rotation varies with the detection energy. The spectral features are in quantitative agreement with a calculation, where the saturation, the energy shift and the damping of the spin-polarized exciton resonance are taken into account.

Time-resolved three-pulse photon echoes of the exciton in layered semiconductor GaSe are investigated by using up-conversion technique. The time-resolved echo signal depends on the separation time between the first and second pulses. The shape of the echo signal changes as the separation time increases. The time-resolved signal also depends on the waiting time between the second and third pulses. For a short waiting time, the temporal evolution of the echo signal shows an ideal photon-echo-like (Gaussian-like) shape. On the other hand, for longer waiting times, the temporal shape of the echo signal changes dramatically and has an extra peak at the arrival time of the third pulse. This behavior can be explained by spectral diffusion in the three-pulse photon echo process.

The coherent emission in the direction of the reflection has been investigated under the Brewster angle of incidence by using phase-locked pulse pairs to excite resonantly the excitons in the anisotropic crystal GaSe. The interferogram of the reflected pulse has a long tail corresponding to the free induction decay signal. We also observed the phase difference between the coherent emission from the Γ4 and Γ6 excitonic polarizations in the direction of the reflection.

Excitation intensity dependence of photoluminescence signals is observed in Cd 0.9 Mn 0.1 Te at 2 K with varying exciton density from 10 14 to 10 19 cm −3 . For intermediate density regime ( 16 cm −3 ) , the transient spectral shift reflecting the magnetic polaron formation is found to decrease with an increase in density. For high-density regime (>10 17 cm −3 ) , the polaron shift disappears, and the density-dependent red shift caused by the band-gap renormalization is observed. The experimental findings demonstrate that the magnetic polaron is unstable at high-density condition.

Magneto-optical studies on self-organized quantum dots (QDs) of Cd 1− x Mn x Te were reported. Cd 1− x Mn x Te QDs with Mn composition less than 10% were grown successfully on the ZnTe(1 0 0) surface by atomic layer epitaxy. A typical dot size of 20 nm in diameter and 2 nm in height and density of the order of 10 11 cm −2 were confirmed by atomic force microscope (AFM) measurement. In photoluminescence (PL) measurements on capped QDs, the excitonic emission from Cd 1− x Mn x Te dots was observed but the spectra were composed of two lines with a separation of 20–26 meV at low temperatures. In the dependence on the temperature, the excitation intensity and the magnetic field, the PL line at the lower-energy side exhibited peculiar behaviors, compared to that in the higher-energy side — rapid quenching with an increase of temperature up to 20 K, much smaller Zeeman shift under magnetic fields, and the saturation of the circular polarization at low magnetic fields. These features of the lower-energy line were discussed in relation to the excitonic magnetic polaron in QDs. Preliminary results of time-resolved PL and spatial-resolved PL using the far-field microscope are also shown.

The spectral diffusion across the exciton line in GaSe is observed in two types of four-wave-mixing experiments. In the stimulated photon echo experiment, the signal shows a non-exponential decay as the waiting time between the second and third pulses increases. This behavior begins clearly from a few 10 ps of the waiting time. The deformation of the signal profile depending on the delay time of first two pulses is also observed in the transient grating-type signal. These results are in good agreement with the result of a theoretical calculation based on a stochastic model.

We report on micro photoluminescence (μ-PL) experiments in CdTe and CdMnTe quantum dots (QDs). PL spectra of the CdTe QDs indicate an ensemble of discrete narrow lines, each of which arises from a single dot emission. High emission efficiency of the present QDs allows the time resolving of the μ-PL signal. Dependence of the PL decay time on the QD size shows the evidence for the quantum size effect of the radiative recombination process. For CdMnTe QDs, it is found that the discrete spectral feature disappears in the μ-PL spectrum, reflecting the fast relaxation kinetics of excitons in the manganese doped QDs.

We have studied the effect of oxygen incorporation into AlGaInP on carrier recombination in GaInP/AlGaInP double heterostructures (DH) grown by MBE using a solid phosphorus valved cell. It was found that photoluminescence efficiency and interfacial recombination velocity of the DH were determined by residual oxygen concentration in the AlGaInP layers. The non-radiative recombination rate in AlGaInP was proportional to the oxygen concentration. We achieved AlGaInP with oxygen concentrations below 4 × 10 16 cm -3 (the detection limit of the SIMS measurement), nonetheless decay of the carriers in the DH was still governed by interfacial recombination. There was a discrepancy in interfacial recombination velocity as a function of oxygen concentration between samples previously grown by MOCVD and our samples currently grown by MBE.

We demonstrate the decoherence control of excitons on a layered compound semiconductor GaSe by using successive femtosecond pulses. The intermediate pulses act as π pulses, which reverse the time evolution of non-Markovian dynamics. By changing the incident timing of the π pulses, we determine the effective pulse interval condition for suppressing the decoherence of excitons by optical pulse irradiation.

We performed a three-pulse six-wave mixing (SWM) measurement on a gallium arsenide (GaAs) multiple quantum well and observed the time-resolved SWM signal using the heterodyne detection technique. The second pulse acts as a π pulse that reverses the time evolution of the non-Markovian dynamics. By changing the pulse interval conditions, we confirmed the suppression of exciton decoherence by π pulse irradiation (bang–bang control).