Quantum coherence, correlation and decoherence in semiconductor nanostructures PDF
Preview Quantum coherence, correlation and decoherence in semiconductor nanostructures
Quantum Coherence, Correlation and Decoherence in Semiconductor Nanostructures This Page Intentionally Left Blank Quantum Coherence, Correlation and Decoherence in Semiconductor Nanostructures Edited by T. Takagahara Dept. of Electronics and Information Science, Kyoto Institute of Technology, Kyoto, Japan ACADEMIC PRESS An imprint of Elsevier Science Amsterdam• Boston • London • New York • Oxford • Paris San Diego • San Francisco • Singapore • Sydney • Tokyo This book is printed on acid-free paper. Copyright 2003, Elsevier Science Ltd. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Academic Press An Imprint of Elsevier Science 84 Theobald’s Road, London WC1X 8RR, UK http://www.academicpress.com Academic Press An Imprint of Elsevier Science 525 B Street, Suite 1900, San Diego, California 92101-4495, USA http://www.academicpress.com ISBN 0–12–682225–5 A catalogue record for this book is available from the Library of Congress A catalogue record for this book is available from the British Library Typeset by Replika Press Pvt. Ltd 100% EOU, India. Printed and bound in Great Britain by MPG Books Bodmin, Cornwall 02 03 04 05 06 07 MP 9 8 7 6 5 4 3 2 1 Preface Semiconductor nanostructures occupy an intermediate position between bulk materials and molecules and provide ample opportunities to discover unexpected phenomena and to reveal new physical aspects. The discrete energy spectra of electrons, holes and excitons due to the quantum confinement lead to the suppression of relaxation processes that dominate in bulk materials, resulting in reduced homogeneous linewidth of relevant transitions. The quantum confinement leads also to the relatively large oscillator strength of the excitonic transitions. The wavefunction is extended coherently over a nanostructure and all the atomic transition dipole moments within the wavefunction are added up coherently. It is well-known that the Sommerfeld factor which represents the relative importance of the continuum (unbound) exciton states is monotonically decreasing with reducing the dimensionality of the system. Thus the discrete exciton states play the essential role in the optical properties of semiconductor nanostructures. Thus we have sharp optical transitions with large oscillator strength. This is the physical basis of the recent remarkable progress in the linear and nonlinear optical spectroscopies of semiconductor quantum dots. Semiconductor nanostructures are attracting much interest as the most promising device to implement the quantum information processing and the quantum computation. The quantum coherence in nanostructures can be most elegantly manipulated by optical means. Thus the excitons and multi-excitons in semiconductor nanostructures are the most elementary objects in the quantum state control. Great progress has been made in the last decade in the research of optical properties, relaxation and decoherence processes in nanostructures. At the same time, the electron spin or the nuclear spin in semiconductors is very promising to manipulate the quantum coherence due to their long coherence times. The electron spin is reflected in the exciton polarization properties. The hyperfine interaction between the electron spin and the nuclear spin would be enhanced due to the quantum confinement of the electron wavefunction. Many interesting phenomena related to this interaction have been discovered recently. In addition to the enhanced exciton effect, the Coulomb interaction in semiconductor nanostructures leads to strong correlation among electrons and holes. Recently, it has been revealed that many-body interactions among carriers have specific spectral and temporal signatures in nonlinear optical responses. As a consequence, new ultrafast vi Preface spectroscopic techniques combined with microscopic many-body theory have brought dramatic progress in the study of many-body Coulomb interactions both in bulk and in quantum confined structures. In particular, the role of Coulomb correlation among more than two particles has been beautifully revealed in the last several years. Another recent highlight in the nanostructure optics is the physics of microcavity polariton. The striking aspect is the tunability of the exciton-photon coupling strength from the weak perturbative regime to the strong normal mode coupling regime. Recent experiments have revealed many interesting aspects of the nonlinear optical processes associated with microcavity polaritons. Especially, the composite nanocrystal-microcavity system is promising to realize the entangled states among several nanocrystals through the whispering gallery modes in the strong coupling regime. Such an entangled state is an indispensable step toward the quantum information processing. On the other hand, in the weak or intermediate coupling regime of the light-matter interaction, there appears an interesting feature in the resonant secondary emission, e.g. the coexistence of the coherent part (Rayleigh scattering) and the incoherent part (photoluminescence) and the interplay of disorder and polaritonic effects. Last but not least, there is a fundamental interest in the ultrafast coherent phenomena both in bulk semiconductors and in semiconductor nanostructures. The coherent nonlinear pulse propagation and the carrier-wave Rabi flopping have been observed successfully in the case of extremely strong pulse intensities. These studies have revealed a new paradigm of the coherent light-matter interaction. Fundamentally new high-field effects in semiconductor nanostructures have been predicted and are now being tested experimentally. The understanding of fundamental physics aspects of the optical coherence and the spin coherence is now being revolutionized. This revolutional progress would bring about breakthroughs in the field of the quantum information processing. In view of these rapidly growing fields of research, we believe that it is timely to publish a book which surveys the present status of our understanding of the quantum coherence, correlation and decoherence in semiconductor nanostructures, putting emphasis on the basic physics aspects. Kyoto, Japan T. Takagahara October 2002 List of Contributors Numbers in parentheses indicate the pages on which the authors’ contributions begin. S.R. Bolton (166), Physics Department, Williams College, 33 Lab Campus Drive, Williamstown, MA 01267, USA A.S. Bracker (207), Naval Research Laboratory, Washington, DC 20375, USA Gang Chen (281), Harrison M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1120, USA Pochung Chen (281), Department of Physics, University of California San Diego, La Jolla, CA 92093, USA Al.L. Efros (207), Naval Research Laboratory, Washington, DC 20375, USA J. Förstner (1), Institut für Theoretische Physik, Technische Universität Berlin, D-10623 Berlin, Germany D. Gammon (207, 281), Naval Research Laboratory, Washington, DC 20375, USA H. Giessen (1), Department of Physics and Material Sciences Center, Philipps-Universität, D-35032 Marburg, Germany J.R. Guest (281), Harrison M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1120, USA S. Hughes (40), Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, UK A. Knorr (1), Institut für Theoretische Physik, Technische Universität Berlin, D-10623 Berlin, Germany S.W. Koch (1), Department of Physics and Material Sciences Center, Philipps-Universität, D-35032 Marburg, Germany V.L. Korenev (207), A.F. Ioffe Institute, St Petersburg, Russia J. Kuhl (1), Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany S. Linden (1), Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany I.A. Merkulov (207), A.F. Ioffe Institute, St Petersburg, Russia O.D. Mücke (23), Institut für Angewandte Physik, Universität Karlsruhe (TH), Wolfgang- Gaede-Straße 1, 76131 Karlsruhe, Germany N.C. Nielsen (1), Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany viii List of Contributors C. Piermarocchi (281), Department of Physics, University of California San Diego, La Jolla, CA 92093, USA E. Runge (89), Humboldt University Berlin, Hausvogteiplatz 5-7, D-10117 Berlin, Germany; Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, D-01187 Dresden, Germany V. Savona (89), Humboldt University Berlin, Hausvogteiplatz 5-7, D-10117 Berlin, Germany L.J. Sham (281), Department of Physics, University of California San Diego, La Jolla, CA 92093, USA D.G. Steel (281), Harrison M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1120, USA T.H. Stievater (281), Harrison M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1120, USA T. Takagahara (395), Department of Electronics and Information Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan J.G. Tischler (207), Naval Research Laboratory, Washington, DC 20375, USA T. Tritschler (23), Institut für Angewandte Physik, Universität Karlsruhe (TH), Wolfgang- Gaede-Straße 1, 76131 Karlsruhe, Germany M. Wegener (23), Institut für Angewandte Physik, Universität Karlsruhe (TH), Wolfgang- Gaede-Straße 1, 76131 Karlsruhe, Germany Hailin Wang (366), Department of Physics and Oregon Center for Optics, University of Oregon, Eugene, OR 97403, USA R. Zimmermann (89), Humboldt University Berlin, Hausvogteiplatz 5-7, D-10117 Berlin, Germany Contents Preface..............................................................................................................................v List of Contributors ...................................................................................................... vii Chapter 1 Coherent nonlinear pulse propagation on a free-exciton resonance in a semiconductor N.C. Nielsen, S. Linden, J. Kuhl, J. Förstner, A. Knorr, S.W. Koch, and H. Giessen 1.1 Introduction ...........................................................................................................1 1.2 Theoretical background.........................................................................................2 1.3 Samples and experimental techniques..................................................................6 1.4 Results and discussion..........................................................................................8 Excitation-induced suppression of temporal polariton beating......................8 Self-induced transmission and multiple pulse breakup................................10 Phonon-induced dephasing of the excitonic polarization.............................17 1.5 Conclusions .........................................................................................................18 Acknowledgments...........................................................................................19 References.......................................................................................................19 Chapter 2 Carrier-wave Rabi flopping in semiconductors O.D. Mücke, T. Tritschler, and M. Wegener 2.1 Introduction .........................................................................................................23 2.2 Carrier-wave Rabi flopping ................................................................................25 Experiments ....................................................................................................27 Theory.............................................................................................................32 2.3 Conclusions .........................................................................................................37
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