| Preface | p. v |
| The Concept of Quantum-Dot Cellular Automata | p. 1 |
| Needed: A New Device Paradigm for the Nanoscale | p. 1 |
| The Physical Representation of Information | p. 2 |
| Dots in QCA | p. 3 |
| Metal dots | p. 3 |
| Molecular dots | p. 4 |
| Semiconductor dots | p. 4 |
| QCA Cells | p. 4 |
| The Quantum-Dot Cellular Automata Paradigm | p. 5 |
| Clocked QCA Cells | p. 7 |
| Clocked QCA Shift Devices | p. 8 |
| Power Gain | p. 8 |
| Robustness against Thermal Errors and Defects | p. 9 |
| Conclusions | p. 13 |
| References | p. 14 |
| QCA Simulation with the Occupation-Number Hamiltonian | p. 17 |
| Introduction | p. 17 |
| Formulation of the Occupation-Number Hamiltonian | p. 18 |
| Diagonalization of the Occupation-Number Hamiltonian | p. 19 |
| Application to the Evaluation of the Effects of Geometric Asymmetry on the Cell-to-Cell Response Function | p. 20 |
| References | p. 23 |
| Realistic Time-Independent Models of a QCA Cell | p. 25 |
| Introduction | p. 25 |
| Heterostructure with a Uniform Gate | p. 26 |
| Linear Gate | p. 27 |
| Linear Gate Deposited on Etched Surface | p. 33 |
| Modeling of a Complete QCA Cell | p. 36 |
| The Configuration-Interaction Method | p. 37 |
| Cell defined with a hole-array gate | p. 41 |
| Multiple-gate cell | p. 44 |
| Analysis of Cells with more than 2 Electrons | p. 46 |
| Many-electron driver cell | p. 47 |
| Semiclassical model | p. 49 |
| Many-electron driver cell | p. 50 |
| Analysis of Polarization Propagation along a Semiconductor-Based Quantum Cellular Automaton Chain | p. 52 |
| Model of a three-cell chain | p. 52 |
| Results | p. 57 |
| References | p. 62 |
| Time-Independent Simulation of QCA Circuits | p. 65 |
| Introduction | p. 65 |
| Semiclassical Model of QCA Circuits | p. 67 |
| Thermal Behavior | p. 73 |
| Analytical Model | p. 77 |
| Numerical simulation of more complex circuits | p. 80 |
| References | p. 84 |
| Simulation of the Time-Dependent Behavior of QCA Circuits with the Occupation-Number Hamiltonian | p. 87 |
| Introduction | p. 87 |
| Modeling of Chains of Quantum Cells | p. 87 |
| Time Evolution of Polarization for a Chain of QCA Cells without Dissipation | p. 89 |
| Time Evolution of Polarization for a Chain of QCA Cells with Dissipation | p. 93 |
| Imperfections: Variable Coupling Strength, Defects, Stray Charges | p. 97 |
| Variations of the intercellular distances | p. 99 |
| Defects in interdot barriers | p. 104 |
| Effect of stray charges | p. 106 |
| References | p. 107 |
| Time-Dependent Analysis of QCA Circuits with the Monte Carlo Method | p. 109 |
| Introduction | p. 109 |
| Six-Dot QCA Cell | p. 110 |
| Transition rates for a semi-cell | p. 113 |
| Analysis of the Parameter Space | p. 116 |
| Tunneling rate | p. 116 |
| Calculation of the energy imbalance | p. 120 |
| Simulation of Clocked and Nonclocked Devices | p. 124 |
| QCA circuit simulator | p. 125 |
| Simulation strategy | p. 126 |
| Binary wire simulations | p. 128 |
| Operation of a logic gate | p. 137 |
| Discussion | p. 139 |
| References | p. 140 |
| Implementation of QCA Cells with SOI Technology | p. 143 |
| Advantages of the SOI Material System | p. 143 |
| Fabrication of Si-Nanostructures | p. 148 |
| Experiments with the SOI Material System | p. 148 |
| Electrical Characterization of Double Dots | p. 154 |
| Electrical Characterization of a 4 Dot QCA Cell | p. 157 |
| Concept of an Experiment for the Detection of QCA Operation | p. 163 |
| Simulations | p. 173 |
| Possible Improvements | p. 175 |
| References | p. 176 |
| Implementation of QCA Cells in GaAs Technology | p. 179 |
| Introduction | p. 180 |
| Nanofabrication of GaAs Devices | p. 180 |
| Evaluation of the Achievable Precision | p. 185 |
| Electrical Characterization of QPCs | p. 189 |
| Modeling of Quantum Point Contacts: The Issue of Boundary Conditions | p. 189 |
| Electron Decay from an Isolated Quantum Dot | p. 194 |
| Lifetimes of the experimentally studied dot | p. 194 |
| Statistical analysis of the experimental data | p. 196 |
| First decays | p. 197 |
| Later decays | p. 197 |
| Modeling of electron decay from the isolated quantum dot | p. 198 |
| Theoretical framework | p. 200 |
| Equilibrium dot | p. 201 |
| Dot with excess electrons | p. 201 |
| Quasibound states of the dot | p. 205 |
| Results and discussion | p. 208 |
| References | p. 211 |
| Non-Invasive Charge Detectors | p. 213 |
| Introduction | p. 213 |
| Experiments on a Double Dot System with Non-Invasive Detector | p. 214 |
| Numerical Simulation of the Dot-Detector System | p. 216 |
| Determining the Operation of a AlGaAs-GaAs QCA Cell | p. 224 |
| Conclusion | p. 227 |
| References | p. 227 |
| Metal Dot QCA | p. 229 |
| Introduction | p. 229 |
| QCA Cell | p. 229 |
| Clocked QCA Devices Fabricated Using Metal Tunnel Junctions | p. 231 |
| Charging Process in QCA Half-Cell | p. 231 |
| QCA Latch Operation | p. 239 |
| Two Stage QCA Shift Register - a Clocked QCA Cell | p. 247 |
| Simulation of a Multi-Stage Shift Register | p. 248 |
| QCA Power Gain | p. 249 |
| References | p. 253 |
| Molecular QCA | p. 255 |
| Introduction | p. 255 |
| Aviram's Molecule: A Simple Model System | p. 256 |
| A Functioning Two-Dot Molecular QCA Cell | p. 261 |
| A Four-Dot Molecular QCA Cell | p. 264 |
| Conclusions | p. 264 |
| References | p. 266 |
| Magnetic Quantum-Dot Cellular Automata (MQCA) | p. 269 |
| Introduction | p. 269 |
| Magnetic QCA Structures | p. 271 |
| Modeling of Magnetic QCA Arrays | p. 273 |
| Conclusion | p. 275 |
| References | p. 275 |
| Final Remarks and Future Perspectives | p. 277 |
| Index | p. 281 |
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