Relevant bibliographies by topics / Coherent oscillations

Academic literature on the topic 'Coherent oscillations'

Author: Grafiati
Published: 11 March 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Coherent oscillations.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Coherent oscillations"

1

Le Van Quyen, Michel, Lyle E. Muller, Bartosz Telenczuk, Eric Halgren, Sydney Cash, Nicholas G. Hatsopoulos, Nima Dehghani, and Alain Destexhe. "High-frequency oscillations in human and monkey neocortex during the wake–sleep cycle." Proceedings of the National Academy of Sciences 113, no. 33 (August 1, 2016): 9363–68. http://dx.doi.org/10.1073/pnas.1523583113.

Full text
Abstract:
Beta (β)- and gamma (γ)-oscillations are present in different cortical areas and are thought to be inhibition-driven, but it is not known if these properties also apply to γ-oscillations in humans. Here, we analyze such oscillations in high-density microelectrode array recordings in human and monkey during the wake–sleep cycle. In these recordings, units were classified as excitatory and inhibitory cells. We find that γ-oscillations in human and β-oscillations in monkey are characterized by a strong implication of inhibitory neurons, both in terms of their firing rate and their phasic firing with the oscillation cycle. The β- and γ-waves systematically propagate across the array, with similar velocities, during both wake and sleep. However, only in slow-wave sleep (SWS) β- and γ-oscillations are associated with highly coherent and functional interactions across several millimeters of the neocortex. This interaction is specifically pronounced between inhibitory cells. These results suggest that inhibitory cells are dominantly involved in the genesis of β- and γ-oscillations, as well as in the organization of their large-scale coherence in the awake and sleeping brain. The highest oscillation coherence found during SWS suggests that fast oscillations implement a highly coherent reactivation of wake patterns that may support memory consolidation during SWS.
APA, Harvard, Vancouver, ISO, and other styles
2

Salzwedel, Robert, Andreas Knorr, Dominik Hoeing, Holger Lange, and Malte Selig. "Theory of radial oscillations in metal nanoparticles driven by optically induced electron density gradients." Journal of Chemical Physics 158, no. 6 (February 14, 2023): 064107. http://dx.doi.org/10.1063/5.0139629.

Full text
Abstract:
We provide a microscopic approach to describe the onset of radial oscillation of a silver nanoparticle. Using the Heisenberg equation of motion framework, we find that the coupled ultrafast dynamics of coherently excited electron occupation and the coherent phonon amplitude initiate periodic size oscillations of the nanoparticle. Compared to the established interpretation of experiments, our results show a more direct coupling mechanism between the field intensity and coherent phonons. This interaction triggers a size oscillation via an optically induced electron density gradient occurring directly with the optical excitation. This source is more efficient than the incoherent heating process currently discussed in the literature and well-describes the early onset of the oscillations in recent experiments.
APA, Harvard, Vancouver, ISO, and other styles
3

Hoseini, Mahmood S., Jeff Pobst, Nathaniel Wright, Wesley Clawson, Woodrow Shew, and Ralf Wessel. "Induced cortical oscillations in turtle cortex are coherent at the mesoscale of population activity, but not at the microscale of the membrane potential of neurons." Journal of Neurophysiology 118, no. 5 (November 1, 2017): 2579–91. http://dx.doi.org/10.1152/jn.00375.2017.

Full text
Abstract:
Bursts of oscillatory neural activity have been hypothesized to be a core mechanism by which remote brain regions can communicate. Such a hypothesis raises the question to what extent oscillations are coherent across spatially distant neural populations. To address this question, we obtained local field potential (LFP) and membrane potential recordings from the visual cortex of turtle in response to visual stimulation of the retina. The time-frequency analysis of these recordings revealed pronounced bursts of oscillatory neural activity and a large trial-to-trial variability in the spectral and temporal properties of the observed oscillations. First, local bursts of oscillations varied from trial to trial in both burst duration and peak frequency. Second, oscillations of a given recording site were not autocoherent; i.e., the phase did not progress linearly in time. Third, LFP oscillations at spatially separate locations within the visual cortex were more phase coherent in the presence of visual stimulation than during ongoing activity. In contrast, the membrane potential oscillations from pairs of simultaneously recorded pyramidal neurons showed smaller phase coherence, which did not change when switching from black screen to visual stimulation. In conclusion, neuronal oscillations at distant locations in visual cortex are coherent at the mesoscale of population activity, but coherence is largely absent at the microscale of the membrane potential of neurons. NEW & NOTEWORTHY Coherent oscillatory neural activity has long been hypothesized as a potential mechanism for communication across locations in the brain. In this study we confirm the existence of coherent oscillations at the mesoscale of integrated cortical population activity. However, at the microscopic level of neurons, we find no evidence for coherence among oscillatory membrane potential fluctuations. These results raise questions about the applicability of the communication through coherence hypothesis to the level of the membrane potential.
APA, Harvard, Vancouver, ISO, and other styles
4

Kay, Leslie M., and Philip Lazzara. "How Global Are Olfactory Bulb Oscillations?" Journal of Neurophysiology 104, no. 3 (September 2010): 1768–73. http://dx.doi.org/10.1152/jn.00478.2010.

Full text
Abstract:
Previous studies in waking animals have shown that the frequency structure of olfactory bulb (OB) local field potential oscillations is very similar across the OB, but large low-impedance surface electrodes may have favored highly coherent events, averaging out local inhomogeneities. We tested the hypothesis that OB oscillations represent spatially homogeneous phenomena at all scales. We used pairs of concentric electrodes (200 μm outer shaft surrounding an inner 2–3 μm recording site) beginning on the dorsal OB at anterior and medial locations in urethane-anesthetized rats and measured local field potential responses at successive 200 μm depths before and during odor stimulation. Within locations (outer vs. inner lead on a single probe), on the time scale of 0.5 s, coherence in all frequency bands was significant, but on larger time scales (10 s), only respiratory (1–4 Hz) and beta (15–30 Hz) oscillations showed prominent peaks. Across locations, coherence in all frequency bands was significantly lower for both sizes of electrodes at all depths but the most superficial 600 μm. Near the pial surface, coherence across outer (larger) electrodes at different sites was equal to coherence across outer and inner (small) electrodes within a single site and larger than coherence across inner electrodes at different sites. Overall, the beta band showed the largest coherence across bulbar sites and electrodes. Therefore larger electrodes at the surface of the OB favor globally coherent events, and at all depths, coherence depends on the type of oscillation (beta or gamma) and duration of the analysis window.
APA, Harvard, Vancouver, ISO, and other styles
5

Sassaroli, Angelo, Kristen Tgavalekos, and Sergio Fantini. "The meaning of “coherent” and its quantification in coherent hemodynamics spectroscopy." Journal of Innovative Optical Health Sciences 11, no. 06 (November 2018): 1850036. http://dx.doi.org/10.1142/s1793545818500360.

Full text
Abstract:
We have recently introduced a new technique, coherent hemodynamics spectroscopy (CHS), which aims at characterizing a specific kind of tissue hemodynamics that feature a high level of covariation with a given physiological quantity. In this study, we carry out a detailed analysis of the significance of coherence and phase synchronization between oscillations of arterial blood pressure (ABP) and total hemoglobin concentration ([Hbt]), measured with near-infrared spectroscopy (NIRS) during a typical protocol for CHS, based on a cyclic thigh cuff occlusion and release. Even though CHS is based on a linear time invariant model between ABP (input) and NIRS measurands (outputs), for practical reasons in a typical CHS protocol, we induce finite “groups” of ABP oscillations, in which each group is characterized by a different frequency. For this reason, ABP (input) and NIRS measurands (output) are not stationary processes, and we have used wavelet coherence and phase synchronization index (PSI), as a metric of coherence and phase synchronization, respectively. PSI was calculated by using both the wavelet cross spectrum and the Hilbert transform. We have also used linear coherence (which requires stationary process) for comparison with wavelet coherence. The method of surrogate data is used to find critical values for the significance of covariation between ABP and [Hbt]. Because we have found similar critical values for wavelet coherence and PSI by using five of the most used methods of surrogate data, we propose to use the data-independent Gaussian random numbers (GRNs), for CHS. By using wavelet coherence and wavelet cross spectrum, and GRNs as surrogate data, we have found the same results for the significance of coherence and phase synchronization between ABP and [Hbt]: on a total set of 20 periods of cuff oscillations, we have found 17 coherent oscillations and 17 phase synchronous oscillations. Phase synchronization assessed with Hilbert transform yielded similar results with 14 phase synchronous oscillations. Linear coherence and wavelet coherence overall yielded similar number of significant values. We discuss possible reasons for this result. Despite the similarity of linear and wavelet coherence, we argue that wavelet coherence is preferable, especially if one wants to use baseline spontaneous oscillations, in which phase locking and coherence between signals might be only temporary.
APA, Harvard, Vancouver, ISO, and other styles
6

Choi, Jeong-Ryeol. "Characterizing Quantum Effects in Optically Induced Nanowire Self-Oscillations: Coherent Properties." Photonics 8, no. 7 (June 25, 2021): 237. http://dx.doi.org/10.3390/photonics8070237.

Full text
Abstract:
Mechanical properties of metallic-nanowire self-oscillations are investigated through a coherent-state analysis. We focus on elucidating the time behavior of quantum energy in such oscillations, in addition to the analysis of fluctuations, evolution of eigenstates, and oscillatory trajectories. The quantum energy varies somewhat randomly at first, but, at a later time, it undergoes a stable periodical oscillation; the mean energy in the stabilized motion is large when the frequency of the driving force is resonated with that of the intrinsic oscillation of the nanowire. We confirmed that when the oscillatory amplitude is sufficiently low, the quantum energy is quite different from the classical one due to zero-point energy, which appears in the quantum regime. Because the power in such an oscillation is typically ultra low, quantum effects in the nanowire oscillations are non-negligible. Detailed analysis for the evolution of the probability densities and their relation with the oscillation trajectories of the nanowire are also carried out. Characterizing quantum effects in the actual oscillatory motions and clarifying their difference from the classical ones are important in understanding nanowire self-oscillations.
APA, Harvard, Vancouver, ISO, and other styles
7

Gelperin, A., L. D. Rhines, J. Flores, and D. W. Tank. "Coherent network oscillations by olfactory interneurons: modulation by endogenous amines." Journal of Neurophysiology 69, no. 6 (June 1, 1993): 1930–39. http://dx.doi.org/10.1152/jn.1993.69.6.1930.

Full text
Abstract:
1. The procerebral (PC) lobe of the terrestrial mollusk Limax maximus contains a highly interconnected network of local olfactory interneurons that receives direct axonal projections from the two pairs of noses. This olfactory processing network generates a 0.7-Hz oscillation in its local field potential (LFP) that is coherent throughout the network. The oscillating LFP is modulated by natural odorants applied to the neuroepithelium of the superior nose. 2. Two amines known to be present in the PC lobe, dopamine and serotonin, increase the frequency of the PC lobe oscillation and alter its waveform. 3. Glutamate, another putative neurotransmitter known to be present in the lobe, suppresses the PC lobe oscillation by a quisqualate-type receptor and appears to be used by one of the two classes of neurons in the PC lobe to generate the basic LFP oscillation. 4. The known activation of second messengers in Limax PC lobe by dopamine and serotonin together with their effects on the oscillatory rhythm suggest the hypothesis that these amines augment mechanisms mediating synaptic plasticity in the olfactory network, similar to hypothesized effects of amines in vertebrate olfactory systems. 5. The use of a distributed network of interneurons showing coherent oscillations may relate to the highly developed odor recognition and odor learning ability of Limax.
APA, Harvard, Vancouver, ISO, and other styles
8

van Loosdrecht, P. H. M., B. Beschoten, I. Dotsenko, and S. van Smaalen. "Optically induced coherent voltage oscillations in K0.3MoO3." Journal de Physique IV 12, no. 9 (November 2002): 303–6. http://dx.doi.org/10.1051/jp4:20020420.

Full text
Abstract:
Optical induced transient changes of the electrical conductivity are investigated in the non-linear transport regime of the blue bronze K0.3MoO3 below its Peierls transition using the impulsive infrared excitation of a free-electron laser a t energies above the Peierls gap. The transients of the sample voltage have typical relaxation times of 0.5-2 ms superimposed by coherent voltage oscillations, which exhibit lifetimes of up 100 ms. The frequency of those voltage oscillation is found to be time dependent. This, in comparison with voltage oscillations purely driven by static electrical fields, enables the study of quasiparticle dynamics in the charge density condensate of the blue bronze.
APA, Harvard, Vancouver, ISO, and other styles
9

Akeju, Oluwaseun, M. Brandon Westover, Kara J. Pavone, Aaron L. Sampson, Katharine E. Hartnack, Emery N. Brown, and Patrick L. Purdon. "Effects of Sevoflurane and Propofol on Frontal Electroencephalogram Power and Coherence." Anesthesiology 121, no. 5 (November 1, 2014): 990–98. http://dx.doi.org/10.1097/aln.0000000000000436.

Full text
Abstract:
Abstract Background: The neural mechanisms of anesthetic vapors have not been studied in depth. However, modeling and experimental studies on the intravenous anesthetic propofol indicate that potentiation of γ-aminobutyric acid receptors leads to a state of thalamocortical synchrony, observed as coherent frontal alpha oscillations, associated with unconsciousness. Sevoflurane, an ether derivative, also potentiates γ-aminobutyric acid receptors. However, in humans, sevoflurane-induced coherent frontal alpha oscillations have not been well detailed. Methods: To study the electroencephalogram dynamics induced by sevoflurane, the authors identified age- and sex-matched patients in which sevoflurane (n = 30) or propofol (n = 30) was used as the sole agent for maintenance of general anesthesia during routine surgery. The authors compared the electroencephalogram signatures of sevoflurane with that of propofol using time-varying spectral and coherence methods. Results: Sevoflurane general anesthesia is characterized by alpha oscillations with maximum power and coherence at approximately 10 Hz, (mean ± SD; peak power, 4.3 ± 3.5 dB; peak coherence, 0.73 ± 0.1). These alpha oscillations are similar to those observed during propofol general anesthesia, which also has maximum power and coherence at approximately 10 Hz (peak power, 2.1 ± 4.3 dB; peak coherence, 0.71 ± 0.1). However, sevoflurane also exhibited a distinct theta coherence signature (peak frequency, 4.9 ± 0.6 Hz; peak coherence, 0.58 ± 0.1). Slow oscillations were observed in both cases, with no significant difference in power or coherence. Conclusions: The study results indicate that sevoflurane, like propofol, induces coherent frontal alpha oscillations and slow oscillations in humans to sustain the anesthesia-induced unconscious state. These results suggest a shared molecular and systems-level mechanism for the unconscious state induced by these drugs.
APA, Harvard, Vancouver, ISO, and other styles
10

Vos, L. "Damping of coherent oscillations." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 391, no. 1 (May 1997): 56–63. http://dx.doi.org/10.1016/s0168-9002(97)00025-9.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Coherent oscillations"

1

Jerebtsov, Serguei Nikolaevich. "Femtosecond time-resolved spectroscopy of coherent oscillations in nanomaterials." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1358.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Blum, Julia Maria. "Coherent brain oscillations during processes of human sensorimotor learning /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17951.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Buehlmann, Andrés. "Information processing in the cortex: the relevance of coherent oscillations for neuronal communication." Doctoral thesis, Universitat Pompeu Fabra, 2010. http://hdl.handle.net/10803/7566.

Full text
Abstract:
Les oscil·lacions d'activitat neuronal són un fenomen omnipresent a l'escorça cerebral. La funció d'aquestes oscil·lacions, però, no està clara. ¿Són només un epifenomen de les elevades taxes de descàrrega de potencials d'acció, o representen un procés fonamental? Per tal d'aclarir aquesta qüestió, en aquest treball hem aplicat models computacionals basats en xarxes neurobiològicament plausibles per tal d'investigar alguns dels resultats experimentals recents més rellevants. Primerament, estudiem la rellevància de les oscil·lacions en processos d'atenció i després en un context més general de teoria d'informació. Els resultats donen suport a la idea que les oscil·lacions representen un mecanisme independent. Demostrem que l'atenció modula les oscil·lacions gamma de manera independent de la taxa de descàrrega de potencials d'acció. També es mostra que la transmissió d'informació entre àrees corticals depèn tant de la fase com de la potència espectral de les oscil·lacions. A més, la velocitat amb què es produeix aquesta transmissió d'informació augmenta en funció de la potència espectral en bandes de freqüències específiques. Aquests resultats suggereixen que les oscil·lacions representen un mecanisme biològicament plausible per mitjançar les interaccions entre àrees cerebrals i, per tant, per establir un vincle entre activitat neuronal i comportament.
Oscillatory neuronal activity is an omnipresent phenomenon in the cerebral cortex. However, the actual function of these oscillations remains unclear. Are they just an epiphenomenon of elevated firing rates or do they represent a fundamental process on their own? Based on experimental work, we apply computational modeling to address this question. We first study the role of oscillations in attentional processes and then in a more general, information theoretical context. Our results support the idea that oscillations represent an independent mechanism. In particular, we show that attention modulates gamma oscillations independently of rates and that the flow of information between brain areas depends both on the phase and on the spectral power of oscillations. Moreover, we show that the speed of information exchange increases as a function of spectral power in specific frequency bands. Taken together, these results suggest that oscillations are a mechanism employed by the brain to control actual interactions between brain areas and thus likely have a link to behavior.
APA, Harvard, Vancouver, ISO, and other styles
4

Karpov, Ivan [Verfasser], Oliver [Akademischer Betreuer] Boine-Frankenheim, and Shaukat [Akademischer Betreuer] Khan. "Damping of Coherent Oscillations in Intense Ion Beams / Ivan Karpov ; Oliver Boine-Frankenheim, Shaukat Khan." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1125627530/34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Magnuson, Matthew Evan. "Effects of severing the corpus callosum on coherent electrical and hemodynamic interhemispheric oscillations intrinsic to functional brain networks." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47681.

Full text
Abstract:
Large scale functional brain networks, defined by synchronized spontaneous oscillations between spatially distinct anatomical regions, are essential to brain function and have been implicated in disease states, cognitive capacity, and many sensing and motor processes. In this work, we sever the corpus callosum in the rodent model to determine if structural connectivity (specifically the primary interhemispheric pathway) organizes and influences bilateral functional connectivity and brain-wide spatiotemporal dynamic activity patterns. Prior to the callosotomy work, resting state brain networks were evaluated using blood oxygen level dependent (BOLD) and cerebral blood volume (CBV) magnetic resonance imaging contrast mechanisms, and revealed that BOLD and CBV provide highly similar spatial maps of functional connectivity; however, the amplitude of BOLD connectivity was generally stronger. The effects of extended anesthetic durations on functional connectivity were also evaluated revealing extended isoflurane anesthetic periods prior to the switch to dexmedetomidine attenuates functional activity for a longer duration as compared to a shorter isoflurane paradigm. We also observed a secondary significant evolution of functional metrics occurring during long durations of dexmedetomidine use under the currently accepted and refined dexmedetomidine sedation paradigm. Taking these previous findings into account, we moved forward with the callosotomy study. Functional network integrity was evaluated in sham and full callosotomy groups using BOLD and electrophysiology. Functional connectivity analysis indicated a similar significant reduction in bilateral connectivity in the full callosotomy group as compared to the sham group across both recording modalities. Spatiotemporal dynamic analysis revealed bilaterally symmetric propagating waves of activity in the sham data, but none were present in the full callosotomy data; however, the emergence of unilateral spatiotemporal patterns became prominent following the callosotomy. This finding suggests that the corpus callosum could be largely responsible for maintaining bilateral network integrity, but non-bilaterally symmetric propagating waves occur in the absence of the corpus callosum, suggesting a possible subcortical driver of the dynamic cascading event. This work represents a robust finding indicating the corpus callosum's influence on maintaining integrity in bilateral functional networks.
APA, Harvard, Vancouver, ISO, and other styles
6

Marsh, Richard. "Superconducting phase coherent electron transport in nano-engineered ferromagnetic vortices." Thesis, Royal Holloway, University of London, 2013. http://repository.royalholloway.ac.uk/items/66b15a59-0b9f-4e68-b0aa-47e93f77349a/6/.

Full text
Abstract:
This thesis presents an experimental study of the superconducting proximity effect in sub-micrometer sized ferromagnetic discs. Such discs belong to a class of mesoscopic ferromagnets intermediate between microscopic magnets with dimensions below about 10nm that behave as single giant spins and macroscopic structures that are larger than approximately 1 micrometer where domains are formed to minimise stray fields. The magnetic structure of mesoscopic magnets is strongly dependent on their geometric shape, allowing for purposeful engineering of magnetic structures using modern lithographic techniques. The ground magnetic state of mesoscopic ferromagnetic discs is the magnetic vortex where unusual time-asymmetric triplet superconductivity is predicted to exist and survive up to the non-magnetic coherence length, that is orders in magnitude larger than the ferromagnetic singlet coherence length. Magnetic Force Microscopy (MFM) was used to directly study the magnetic structure of the discs. To detect the proximity effect in the vortices, Andreev interferometers were used with normal parts replaced with mesoscopic ferromagnetic discs in the magnetic vortex state. The samples were fabricated using electron-beam lithography and a modified shadow evaporation technique developed within this project, allowing the whole structure to be made with highly precise alignment, without breaking vacuum and avoiding redundant ferromagnetic elements disturbing the magnetic vortices. Observations were made of superconducting phase periodic oscillations in the conductance of the Andreev interferometers. Such oscillations provide unambiguous evidence of phase coherent electron transport through the ferromagnetic vortex. Finally, further experiments are discussed that would provide a more detailed understanding of the long range proximity effect in SFS junctions.
APA, Harvard, Vancouver, ISO, and other styles
7

Grinberg, Patricio. "Slow light in two dimensional semi-conductor photonic crystals." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00830962.

Full text
Abstract:
We report on the combination of slow light propagation with the resonance properties of a photonic crystal (PhC) cavity and with the slow mode of a PhC waveguide. We demonstrate theoretically and experimentally that slow light induced by the Coherent Population Oscillation (CPO) effect enables to have small-size and ultrahigh quality (Q) factor cavity, regardless of the technological and design issues. The experimental proof is performed in a L3 2D PhC cavity with semiconductor quantum wells as active, medium in which the CPO effect is induced. We achieve a cavity Q-factor of 520000, which corresponds to an enhancement by a factor 138 in comparison with the original Q-factor of the cavity. We present a theoretical approach to the combination of CPO-based slow light and slow mode in PhC waveguides, showing that the total group index is a multiplication of the group indices associated respectively to the CPO slow light and to the waveguide slow mode. We also set the basis for the experimental demonstration by designing and fabricating samples in the clean room facilities of LPN and addressing the challenging issue of coupling and extracting light in and from the waveguides. A particular design of the PhC in the waveguide is issued as a grating that allows to couple light perpendicularly to the plane of the PhC from free space. The vertical coupler has also been designed and fabricated along the waveguide and has been experimentally characterized. Slow light based on CPO effect in the PhC waveguides is always under experimental investigation.
APA, Harvard, Vancouver, ISO, and other styles
8

Delagnes, Jean-Christophe. "Contrôle de la propagation d'impulsions ultracourtes : effets de déplacements lumineux." Toulouse 3, 2005. http://www.theses.fr/2005TOU30227.

Full text
Abstract:
Cette thèse présente l'étude théorique et expérimentale du contrôle des phénomènes de propagation cohérente d'impulsions ultracourtes dans un milieu résonant optiquement dense. Dans une première partie, nous décrivons les phénomènes élémentaires des effets de propagation. Dans un second temps, nous développons l'idée de contrôler par un champ fort, les propriétés transitoires d'une autre impulsion faible et résonante qui se propage simultanément dans le milieu. Le champ fort induit des modifications transitoires dans le milieu, qui modifient par rayonnement le champ de l'impulsion résonante qui se propage. Nous étudions enfin une configuration où les deux impulsions, polarisées orthogonalement, excitent de manière résonante un système à quatre niveaux dégénérés. Deux chemins interfèrent modulant ainsi l'énergie de l'impulsion transmise. La combinaison des déplacements lumineux et de ces interférences, permet de contrôler aussi bien le gain que la forme temporelle de l'impulsion
The topic of this work deals with theoretical and experimental study of the control of ultrashort pulse coherent propagation in optically dense medium. First, we describe the basics of propagation phenomena. Secondly, we study the idea of using a strong driving pulse, to control the transient properties of a weak resonant pulse simultaneously propagating in the medium. The strong field induces transient modifications in the medium, which modify the electric field of the weak resonant propagating pulse. Finally, we study a configuration where two orthogonally polarized pulses, excite resonantly a four level system degenerated two by two. With the strong field mixing the states, the emission and absorption path of the weak field have similar contribution. The two paths interfere thus modulating the transmitted pulse energy. The interplay of the light shift and the interference enables us to control the gain and the pulse temporal shape as well
APA, Harvard, Vancouver, ISO, and other styles
9

Witham, Claire. "Oscillations and corticomuscular coherence in the sensorimotor system." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440587.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Titimbo, Chaparro Kelvin Ruben. "CREATION AND DETECTION OF SQUEEZED PHONONS IN PUMP AND PROBE EXPERIMENTS: A FULLY QUANTUM TREATMENT." Doctoral thesis, Università degli studi di Trieste, 2015. http://hdl.handle.net/10077/10941.

Full text
Abstract:
2013/2014
Femtosecond pump and probe techniques are standard experimental methodologies used for studying ultrafast dynamics in solids, in particular phonon oscillations in target materials. So far, only semiclassical methods have been employed in order to theoretically interpret the experimental data. In contrast, a fully quantum treatment will be presented here taking into account the quantum features of the generation mechanism of excited phonons by pump laser pulses, and of the process of accessing their behaviour by probe laser pulses. A single effective Hamiltonian will be used to model the interaction between photons and phonons both for the pumping and probing processes. In addition, as they interact with their environment, mainly electrons in the target, the excited phonons cannot be considered an isolated system. Their dynamics is then that typical of open quantum systems and generated by a master equation of Lindblad form, that takes into account the dissipative and noisy effects due to the environment.In this formalism, phonon oscillations can be analysed through suitable probe photon observables. Specifically, unlike in the existing literature, we will not focus only upon the scattered probe pulse intensity, namely on the probe photon number, but also on the number variance. Through the latter some quantum features of the phonon state can be accessed; in particular, specific signals of the presence of squeezed phonons can thus be identified.
Le tecniche di "pump and probe" impulsato sono metodologie sperimentali standard usate nello studio delle dinamiche ultraveloci nei solidi, in particolare delle oscillazioni di fononi. Usualmente l'interpretazione teorica dei dati sperimentali si basa su approssimazioni semiclassiche. Una descrizione completamente quantistica e` invece sviluppata nella presente trattazione: e` basata sull'introduzione di un'unica hamiltoniana di interazione tra fotoni e fononi, capace di descrivere in modo effettivo sia il processo di eccitazione che di rivelazione dei fononi. In generale, tali fononi non possono essere considerati come isolati, ma costituiscono un sistema quantistico aperto, cioe` in interazione debole con l'ambiente esterno, formato principalmente da elettroni e dagli altri costituenti del materiale in studio. La loro dinamica deve percio` venir descritta tramite una equazione master, che tenga conto di effetti di rumore e dissipazione. In questo formalismo, le proprieta` dei fononi eccitati dagli impulsi laser di "pump" possono essere analizzate attraverso lo studio di opportune osservabili caratterizzanti i fotoni di "probe". Piu` specificatamente, si e` analizzato il comportamento non solo dell'intensita` media della luce di "probe" riflessa, cioe` del numero medio di fotoni, ma anche della relativa varianza. In questo modo, si possono evidenziare alcune caratteristiche quantistiche dei fononi: in particolare, sono stati individuati segnali specifici della presenza di fononi "squeezed"
XXVII Ciclo
1986
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Coherent oscillations"

1

Leisching, P., C. Waschke, P. Haring Bolivar, W. Beck, H. Roskos, K. Leo, H. Kurz, K. Köhler, and P. Ganser. "Bloch Oscillations in Superlattices." In Coherent Optical Interactions in Semiconductors, 325–29. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9748-0_22.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Dekorsy, T., A. Bartels, H. Kurz, and K. Köhler. "Coherent Acoustic Phonon Oscillations in Superlattices." In Springer Series in Chemical Physics, 272–74. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-72289-9_82.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Kuznetsov, Alex V., and Christopher J. Stanton. "Theory of Coherent Phonon Oscillations in Semiconductors." In Hot Carriers in Semiconductors, 217–20. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0401-2_51.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Destexhe, A., and A. Babloyantz. "Cortical Coherent Activity Induced by Thalamic Oscillations." In Neural Network Dynamics, 234–49. London: Springer London, 1992. http://dx.doi.org/10.1007/978-1-4471-2001-8_17.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Nikhil Kumar, C. S. "Coherent Spin-Wave Oscillations Through External Feedback." In Magnetic Resonators, 31–45. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6176-2_3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Kuznetsov, Alex V., and Christopher J. Stanton. "Theory of Coherent Phonon Oscillations in Bulk GaAs." In Ultrafast Phenomena in Semiconductors, 353–403. New York, NY: Springer New York, 2001. http://dx.doi.org/10.1007/978-1-4613-0203-2_7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Mullen, K., E. Ben-Jacob, and Z. Schuss. "Coherent Voltage Oscillations in Ultra-Small Capacitance Structures." In The Jerusalem Symposia on Quantum Chemistry and Biochemistry, 245–59. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4752-8_19.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Rast, Mark Peter. "Photospheric Downflows: How Deep, How Coherent, How Important?" In SCORe ’96: Solar Convection and Oscillations and their Relationship, 135–38. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5167-2_13.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Ishioka, Kunie, and Oleg V. Misochko. "Coherent Lattice Oscillations in Solids and Their Optical Control." In Springer Series in Chemical Physics, 23–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03825-9_2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Ishioka, Kunie, and Oleg V. Misochko. "Coherent Lattice Oscillations in Solids and Their Optical Control." In Springer Series in Chemical Physics, 47–63. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03825-9_3.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Coherent oscillations"

1

Smirl, Arthur L., W. Sha, Shekhar Patkar, and W. F. Tseng. "Coherent Charge Oscillations in Bulk GaAs." In Ultrafast Electronics and Optoelectronics. Washington, D.C.: OSA, 1995. http://dx.doi.org/10.1364/ueo.1995.umb2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Maynard, Marie-Aude, Romain Bouchez, Pascal Neveu, Jasleen Lugani, Sanmoy Mandal, Chitram Banerjee, Rupamanjari Ghosh, Fabien Bretenaker, Etienne Brion, and Fabienne Goldfarb. "Storage based on Coherent Population Oscillations." In CLEO: QELS_Fundamental Science. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/cleo_qels.2016.fm4c.7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

SUN, C. K., J. C. LIANG, H. L. CHEN, Y. K. HUANG, A. ABARE, and S. P. DENBAARS. "COHERENT CONTROL OF SEMICONDUCTOR PHONON OSCILLATIONS." In Proceedings of the 8th Asia-Pacific Physics Conference. WORLD SCIENTIFIC, 2001. http://dx.doi.org/10.1142/9789812811523_0045.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Maynard, Marie-Aude, Allan Johnes Ferreira de Almeida, Jaqueline Sales, Daniel Felinto, José W. Tabosa, Fabien Bretenaker, and Fabienne Goldfarb. "Optical memory based on coherent population oscillations." In International Conference on Fibre Optics and Photonics. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/photonics.2014.t2a.4.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Arrieta-Yáñez, Francisco, Oscar G. Calderón, Sonia Melle, F. Carreño, and M. A. Antón. "Tunable phase control of coherent population oscillations." In Slow and Fast Light. Washington, D.C.: OSA, 2008. http://dx.doi.org/10.1364/sl.2008.jmb31.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Maynard, Marie-Aude, Fabien Bretenaker, and Fabienne Goldfarb. "Optical memory based on coherent population oscillations." In Frontiers in Optics. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/fio.2014.ftu5c.3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Roskos, Hartmut G., Martin C. Nuss, Jagdeep Shah, Karl Leo, David A. B. Miller, Stefan Schmitt-Rink, and Klaus Köhler. "Terahertz Radiation from Coherent Electron Oscillations in a Double-Quantum-Well Structure." In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.fa2.

Full text
Abstract:
We report the direct observation of coherent charge oscillations in an asymmetric semiconductor double-well potential with a thin tunneling barrier between the wells. Such a structure allows tuning of the energy levels of the two wells by an external electric bias field. At a certain resonance bias (here: -0.4 V), the conduction band levels are aligned and the electron wave functions extend over both wells. A 100 fs optical pulse resonant in energy to the lowest interband transition generates an exciton wave packet in a single well only.[1] From this nonstationary state the electrons begin to oscillate between the two wells at a frequency that is determined by the tunneling probability through the barrier between the two wells. The holes remain localized because the valence band energy levels are not aligned at this bias. Electrons and holes together form an oscillating dipole that emits electromagnetic radiation in the THz frequency range until the phase coherence of the oscillating wave packets is destroyed.
APA, Harvard, Vancouver, ISO, and other styles
8

Cho, G. C., W. Kiitt, M. Strähnen, A. Esser, U. Lemmer, and H. Kurz. "Direct Time Resolved Observation of Coherent Phonon Oscillations in Ill-V-compounds." In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/up.1990.thd7.

Full text
Abstract:
Femtosecond time resolved coherent phonon oscillations are observed for the first time through impulsive stimulated Raman scattering (ISRS)/1/ in semiconductor Ill-V-compounds. Individual cycles of the phonon oscillations as well as the vibrational dephasing are demonstrated via a modulation of the time resolved reflectivity signatures through the electro-optic effect. The observed linear behaviour of oscillation amplitude on pump intensity confirms the excitation of coherent longitudinal polar optic phonons with a single femtosecond pulse via ISRS in GaAs, InP and AIGaAs. The macroscopic electric field associated with the lattice vibrations is measured via the electro-optic effect. This is confirmed through the distinct variation of reflectivity signal modulation versus relative orientation of probe beam polarization and crystal orientation in our pump/probe experiments.
APA, Harvard, Vancouver, ISO, and other styles
9

Hunsche, S., K. Wienecke, T. Dekorsy, and H. Kurz. "Laser-Induced Softening of Coherent Phonons: Pathway to Nonthermal Melting." In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/up.1996.fb.2.

Full text
Abstract:
We investigate the dynamics of coherent optical phonons in single-crystal Tellurium after high-density excitation of free electrons by intense femtosecond laser pulses. The experiments are performed in a standard time-resolved pump-probe setup using pulses of a Ti-Sapphire oscillator that are amplified in a 6.8 kHz dye amplifier. The pulse duration is <100 fs, much shorter than the oscillation period of the A1 optical phonon mode of Tellurium, leading to an impulsive and selective excitation of this phonon via the “displacive excitation” mechanism.1 The coherent lattice vibrations are detected via transient reflectivity changes that show clearly-resolved oscillations as a function of pump-probe delay, as shown in the inset of Fig. 1. The main plot shows Fourier spectra of the oscillating signal contribution, obtained after subtraction of the slowly-varying background, at various excitation densities.
APA, Harvard, Vancouver, ISO, and other styles
10

Eilam, A., I. Azuri, A. V. Sharypov, and A. D. Wilson-Gordon. "Spatial Optical Memory Based on Coherent Population Oscillations." In Laser Science. Washington, D.C.: OSA, 2010. http://dx.doi.org/10.1364/ls.2010.ltub4.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Coherent oscillations"

1

Onillon, E., and J. Brennan. DAMPING COHERENT QUADRUPOLE OSCILLATIONS IN THE AGS. Office of Scientific and Technical Information (OSTI), September 1994. http://dx.doi.org/10.2172/1151308.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Martin, Joshua. Nonlinear, Multidimensional, and Beyond Mean-Field Coherent Neutrino Flavor Oscillations. Office of Scientific and Technical Information (OSTI), August 2022. http://dx.doi.org/10.2172/1880466.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Xu, J., J. Claus, and A. G. Ruggiero. A Feedback Device to Damp the Coherent Oscillations from Injection Errors in RHIC. Office of Scientific and Technical Information (OSTI), July 1990. http://dx.doi.org/10.2172/1119328.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Follum, James D., Francis K. Tuffner, and Brett G. Amidan. Integration of a Self-Coherence Algorithm into DISAT for Forced Oscillation Detection. Office of Scientific and Technical Information (OSTI), March 2015. http://dx.doi.org/10.2172/1177709.

Full text
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Coherent oscillations' for particular source types:
Journal articles Dissertations / Theses
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography