Quantum cellular automata : theory, experimentation and prospects / Massimo Macucci, editor.

Format:

Book

Contributor:

Macucci, Massimo.

Language:

English

Subjects (All):

Cellular automata.

Physical Description:

xiii, 284 : illustrations ; 24 cm

Place of Publication:

London : Imperial College Press, [2006]

Summary:

The Quantum Cellular Automation (QCA) concept represents an attempt to break away from the traditional three-terminal device paradigm that has dominated digital computation. Since its early formulation in 1993 at Notre Dame University, the QCA idea has received significant attention and several physical implementations have been proposed.

This book provides a comprehensive discussion of the simulation approaches and the experimental work that have been undertaken on the fabrication of devices capable of demonstrating the fundamentals of QCA action. Complementary views of future perspectives for QCA technology are presented, highlighting a process of realistic simulation and of targeted experiments that can be assumed as a model for the evaluation of future device proposals.

Contents:

1 The Concept of Quantum-Dot Cellular Automata / C. S. Lent 1

1.1 Needed: A New Device Paradigm for the Nanoscale 1

1.2 The Physical Representation of Information 2

1.3 Dots in QCA 3

1.3.1 Metal dots 3

1.3.2 Molecular dots 4

1.3.3 Semiconductor dots 4

1.4 QCA Cells 4

1.5 The Quantum-Dot Cellular Automata Paradigm 5

1.6 Clocked QCA Cells 7

1.7 Clocked QCA Shift Devices 8

1.8 Power Gain 8

1.9 Robustness against Thermal Errors and Defects 9

2 QCA Simulation with the Occupation-Number Hamiltonian / M. Macucci, M. Governale 17

2.2 Formulation of the Occupation-Number Hamiltonian 18

2.3 Diagonalization of the Occupation-Number Hamiltonian 19

2.4 Application to the Evaluation of the Effects of Geometric Asymmetry on the Cell-to-Cell Response Function 20

3 Realistic Time-Independent Models of a QCA Cell / J. Martorell, D. W. L. Sprung, M. Girlanda, M. Macucci 25

3.2 Heterostructure with a Uniform Gate 26

3.3 Linear Gate 27

3.4 Linear Gate Deposited on Etched Surface 33

3.5 Modeling of a Complete QCA Cell 36

3.6 The Configuration-Interaction Method 37

3.6.1 Cell defined with a hole-array gate 41

3.6.2 Multiple-gate cell 44

3.7 Analysis of Cells with more than 2 Electrons 46

3.7.1 Many-electron driver cell 47

3.7.2 Semiclassical model 49

3.7.3 Many-electron driver cell 50

3.8 Analysis of Polarization Propagation along a Semiconductor-Based Quantum Cellular Automaton Chain 52

3.8.1 Model of a three-cell chain 52

3.9 Results 57

4 Time-Independent Simulation of QCA Circuits / L. Bonci, S. Francaviglia, M. Gattobigio, C. Ungarelli, G. Iannaccone, M. Macucci 65

4.2 Semiclassical Model of QCA Circuits 67

4.3 Thermal Behavior 73

4.4 Analytical Model 77

4.4.1 Numerical simulation of more complex circuits 80

5 Simulation of the Time-Dependent Behavior of QCA Circuits with the Occupation-Number Hamiltonian / I. Yakimenko, K.-F. Berggren 87

5.2 Modeling of Chains of Quantum Cells 87

5.3 Time Evolution of Polarization for a Chain of QCA Cells without Dissipation 89

5.4 Time Evolution of Polarization for a Chain of QCA Cells with Dissipation 93

5.5 Imperfections: Variable Coupling Strength, Defects, Stray Charges 97

5.5.1 Variations of the intercellular distances 99

5.5.2 Defects in interdot barriers 104

5.5.3 Effect of stray charges 106

6 Time-Dependent Analysis of QCA Circuits with the Monte Carlo Method / L. Bonci, M. Gattobigio, G. Iannaccone, M. Macucci 109

6.2 Six-Dot QCA Cell 110

6.2.1 Transition rates for a semi-cell 113

6.3 Analysis of the Parameter Space 116

6.3.1 Tunneling rate 116

6.3.2 Calculation of the energy imbalance 120

6.4 Simulation of Clocked and Nonclocked Devices 124

6.4.1 QCA circuit simulator 125

6.4.2 Simulation strategy 126

6.4.3 Binary wire simulations 128

6.4.4 Operation of a logic gate 137

7 Implementation of QCA Cells with SOI Technology / F. E. Prins, C. Single, G. Wetekam, D. P. Kern, M. Macucci, L. Bonci, G. Iannaccone, M. Gattobigio 143

7.1 Advantages of the SOI Material System 143

7.2 Fabrication of Si-Nanostructures 148

7.3 Experiments with the SOI Material System 148

7.4 Electrical Characterization of Double Dots 154

7.5 Electrical Characterization of a 4 Dot QCA Cell 157

7.6 Concept of an Experiment for the Detection of QCA Operation 163

7.7 Simulations 173

7.8 Possible Improvements 175

8 Implementation of QCA Cells in GaAs Technology / Y. Jin, C. G. Smith, J. Martorell, D. W. L. Sprung, P. A. Machado, M. Girlanda, M. Governale, G. Iannaccone, M. Macucci 179

8.2 Nanofabrication of GaAs Devices 180

8.3 Evaluation of the Achievable Precision 185

8.4 Electrical Characterization of QPCs 189

8.5 Modeling of Quantum Point Contacts: The Issue of Boundary Conditions 189

8.6 Electron Decay from an Isolated Quantum Dot 194

8.6.1 Lifetimes of the experimentally studied dot 194

8.6.2 Statistical analysis of the experimental data 196

8.6.3 First decays 197

8.6.4 Later decays 197

8.6.5 Modeling of electron decay from the isolated quantum dot 198

8.6.6 Theoretical framework 200

8.6.7 Equilibrium dot 201

8.6.8 Dot with excess electrons 201

8.6.9 Quasibound states of the dot 205

8.6.10 Results and discussion 208

9 Non-Invasive Charge Detectors / G. Iannaccone, C. Ungarelli, M. Governale, M. Macucci, S. Gardelis, C. G. Smith, J. Cooper, D. A. Ritchie, E. H. Linfield 213

9.2 Experiments on a Double Dot System with Non-Invasive Detector 214

9.3 Numerical Simulation of the Dot-Detector System 216

9.4 Determining the Operation of a AlGaAs-GaAs QCA Cell 224

10 Metal Dot QCA / G. L. Snider, A. O. Orlov, R. K. Kummamuru 229

10.2 QCA Cell 229

10.3 Clocked QCA Devices Fabricated Using Metal Tunnel Junctions 231

10.4 Charging Process in QCA Half-Cell 231

10.5 QCA Latch Operation 239

10.6 Two Stage QCA Shift Register - a Clocked QCA Cell 247

10.7 Simulation of a Multi-Stage Shift Register 248

10.8 QCA Power Gain 249

11 Molecular QCA / C. S. Lent 255

11.2 Aviram's Molecule: A Simple Model System 256

11.3 A Functioning Two-Dot Molecular QCA Cell 261

11.4 A Four-Dot Molecular QCA Cell 264

12 Magnetic Quantum-Dot Cellular Automata (MQCA) / A. Imre, G. Csaba, G. H. Bernstein, W. Porod 269

12.2 Magnetic QCA Structures 271

12.3 Modeling of Magnetic QCA Arrays 273

13 Final Remarks and Future Perspectives / M. Macucci 277.

Notes:

Includes bibliographic references and index.

ISBN:

1860946321

OCLC:

70106365