Quantum coherence : from quarks to solids / W. Pötz, J. Fabian, U. Hohenester (eds.).

Format:

Book

Conference/Event

Contributor:

Pötz, Walter.

Fabian, Jaroslav.

Hohenester, U. (Ulrich)

Conference Name:

Internationale Universitätswochen für Theoretische Physik (42nd : 2004 : Schladming, Austria)

Series:

Lecture notes in physics 0075-8450 ; 689.

Lecture notes in physics, 0075-8450 ; 689

Language:

English

Subjects (All):

Coherence (Nuclear physics)--Congresses.

Coherence (Nuclear physics).

Quantum computers--Congresses.

Quantum computers.

Mesoscopic phenomena (Physics)--Congresses.

Mesoscopic phenomena (Physics).

Genre:

Conference papers and proceedings.

Physical Description:

xiv, 189 pages : illustrations (some color) ; 24 cm.

Place of Publication:

Berlin ; New York : Springer, [2006]

Summary:

Quantum coherence is a phenomenon that plays a crucial role in various forms of matter. The thriving field of quantum information as well as unconventional approaches to use mesoscopic systems in future optoelectronic devices provide the exciting background for this set of lectures. The lectures originate from the well-known Schladming Winter Schools and are carefully edited so as to address a broad readership ranging from the beginning graduate student up to the senior scientist wanting to keep up with or to enter newly emerging fields of research.

Contents:

Entanglement, Bell Inequalities and Decoherence in Particle Physics / R.A. Bertlmann 1

1.1 Particle Physics 2

2 QM of K-mesons 3

2.1 Strangeness 3

2.2 CP Violation 4

2.3 Strangeness Oscillation 4

2.4 Regeneration of K[subscript s] 5

3 Analogies and Quasi-Spin 6

4 Time Evolution - Unitarity 7

5 Bell Inequalities for Spin-[fraction12]Particles 9

6 Bell Inequalities for K-mesons 11

6.1 Analogies and Differences 12

6.2 Bell-CHSH Inequality - General Form 13

6.3 Bell Inequality for Time Variation 14

6.4 Bell Inequality for Quasi-Spin States - CP Violation 15

7 Decoherence in Entangled K[superscript 0]K[superscript 0] System 18

7.1 Density Matrix 19

7.2 Model 21

7.3 Entangled Kaons 22

7.4 Measurement 23

7.5 Experiment 24

8 Connection to Phenomenological Model 26

9 Entanglement Loss - Decoherence 28

9.1 Von Neumann Entropy 29

9.2 Separability 30

9.3 Entanglement of Formation and Concurrence 33

10 Outlook 36

Quantum Gates and Decoherence / S. Scheel, J.K. Pachos, E.A. Hinds, P.L. Knight 47

1.1 Why Quantum Information Processing? 47

1.2 Quantum Gates vs. Classical Gates 48

2 Atomic Realisation - Atom Chips and the Mott Transition in Optical Lattices 51

2.1 Bose-Einstein Condensates and the Mott Transition 51

2.2 Quantum Computation with a 1D Optical Lattice 54

2.3 Experimental Realization with Atom Chips 58

3 Photonic Realisation - Passive Linear Optics and Projective Measurements 60

3.1 Qubit Encoding and Single-Qubit Operations 60

3.2 Measurement-Induced Nonlinearities 61

3.3 Construction of Simple Quantum Gates 64

3.4 Multi-Mode Gates 66

3.5 Conditional Dynamics and Scaling of Success Probabilities 67

4 Decoherence Mechanisms - QED in Causal Dielectric Media 69

4.1 Decoherence Mechanisms Affecting Atoms and Photons 69

4.2 Field Quantisation in Causal Media 71

4.3 Thermally Induced Spin Flips Near Metallic Wires 74

4.4 Imperfect Passive Optical Elements 77

Spin-Based Quantum Dot Quantum Computing / X. Hu 83

2 General Features of the Quantum Dot Quantum Computing Schemes 84

2.1 Classification of the QC Schemes 84

2.2 GaAs Quantum Dot QC Architecture 86

2.3 Si Quantum Dot QC Architecture 86

2.4 Si Donor Nuclear Spin QC Architecture 87

2.5 Si Donor Electron Spin QC Architecture 88

3 Electron Spin Coherence in Semiconductors 89

3.1 Spin Decoherence Channels in Semiconductors 91

3.2 Spectral Diffusion for Electron Spins 92

4 Spin Manipulations and Exchange 94

4.1 Spin Hamiltonian in a GaAs Double Quantum Dot: Coulomb Interaction and Pauli Principle 94

4.2 Implications of Si Conduction Band Structure to Electron Exchange 99

4.3 Single Spin Detection Schemes 103

4.4 Approaches to Generate and Detect Electron Spin Entanglement in Quantum Dots 104

5 Current Experimental Status 105

5.1 Single Electron Trapping in Horizontal QDs 105

5.2 Single Spin Detection 106

5.3 Electron-Nuclear Spin Interaction in QDs 107

5.4 Fabrication of Donor Arrays in Si 108

Microscopic Theory of Coherent Semiconductor Optics / T. Meier, S.W. Koch 115

2 Semiclassical Theory 118

3 Time-Dependent Hartree-Fock Approximation 119

3.1 Excitonic Linear Absorption Spectra in Different Dimensions 122

4 Many-Body Coulomb Correlations 125

4.1 Second-Order Born Approximation 125

4.2 Density-Dependent Exciton Saturation and Broadening 129

4.3 Dynamics-Controlled Truncation Scheme: Coherent x[superscript (3)]-Limit 132

4.4 Signatures of Coherent Four-Particle Correlations in x[superscript (3)] 140

4.5 Dynamics-Controlled Truncation Scheme: Coherent x[superscript (5)]-Limit 145

4.6 Signatures of Coherent Four-Particle Correlations Up to x[superscript (5)] 145

5 Conclusions and Outlook 148

Exciton and Polariton Condensation / D. Porras, J. Fernandez-Rossier, C. Tejedor 153

1.1 Coherence 154

1.2 Condensation 156

1.3 Bosonic Limit of Excitons 156

2 Exciton Condensation: Standard Theory 157

2.1 Non-Interacting Bosons 157

2.2 Weakly Interacting Bosons 158

2.3 Interacting Electron-Hole Pairs: Excitonic Insulator 159

2.4 Electron-Hole Liquid 164

3 Emission of Light 164

4 Magnetoexcitons 167

5 Multicomponent Condensates 168

5.1 Phase Diagram 168

5.2 Coherence Effects 170

6 Polariton Condensation 172

6.1 Polariton Dynamics 173

6.2 Evolution of the Polariton Distribution: Macroscopic Occupation 178

7 Polariton Laser 180

7.1 Equation of Motion for the Density Matrix 181

7.2 Emission Spectrum 182.

Notes:

Lectures presented at the 42nd Internationale Universitätswochen für Theoretische Physik in Schladming, Austria, from Feb. 28 to Mar. 6, 2004.

Includes bibliographical references.

ISBN:

3540300856

OCLC:

64572004

Publisher Number:

9783540300854