Quantum Computing

SUMMARY 1
1 PROGRESS IN COMPUTING 12
1.1 Origins of Contemporary Computing, 12
1.2 Quantum Computing, 14
1.3 Historical Progress in Computing: Moore’s Law, 16
1.4 Converting Transistors to Cheap Computers, 19
1.5 A Slowdown in Scaling, 20
1.6 Quantum: A New Approach to Computing, 21
1.7 Notes, 22
2 QUANTUM COMPUTING: A NEW PARADIGM 24
2.1 The Nonintuitive Physics of the Quantum World, 25
2.2 The Landscape of Quantum Technology, 27
2.3 Bits and Qubits, 30
2.4 Computing with Qubits, 38
2.5 Quantum Computer Design Constraints, 46
2.6 The Potential for Functional Quantum Computers, 51
2.7 Notes, 55
3 QUANTUM ALGORITHMS AND APPLICATIONS 57
3.1 Quantum Algorithms for an Ideal Gate-Based
Quantum Computer, 60
3.2 Quantum Error Correction and Mitigation, 71
3.3 Quantum Approximation Algorithms, 793.4 Applications of a Quantum Computer, 82
3.5 The Potential Role of Quantum Computers in the
Computing Ecosystem, 86
3.6 Notes, 87
4 QUANTUM COMPUTING’S IMPLICATIONS FOR
CRYPTOGRAPHY 95
4.1 Cryptographic Algorithms in Current Use, 96
4.2 Sizing Estimates, 104
4.3 Post-Quantum Cryptography, 105
4.4 Practical Deployment Challenges, 108
4.5 Notes, 112
5 ESSENTIAL HARDWARE COMPONENTS OF A
QUANTUM COMPUTER 113
5.1 Hardware Structure of a Quantum Computer, 114
5.2 Trapped Ion Qubits, 119
5.3 Superconducting Qubits, 122
5.4 Other Technologies, 127
5.5 Future Outlook, 129
5.6 Notes, 130
6 ESSENTIAL SOFTWARE COMPONENTS OF A SCALABLE
QUANTUM COMPUTER 135
6.1 Challenges and Opportunities, 136
6.2 Quantum Programming Languages, 137
6.3 Simulation, 145
6.4 Specification, Verification, and Debugging, 146
6.5 Compiling from a High-Level Program to Hardware, 149
6.6 Summary, 152
6.7 Notes, 153
7 FEASIBILITY AND TIME FRAMES OF
QUANTUM COMPUTING 156
7.1 The Current State of Progress, 156
7.2 A Framework for Assessing Progress in Quantum
Computing, 161
7.3 Milestones and Time Estimates, 169
7.4 Quantum Computing R&D, 179
7.5 Targeting a Successful Future, 187
7.6 Notes, 189APPENDIXES
A Statement of Task 195
B Trapped Ion Quantum Computers 196
C Superconducting Quantum Computers 205
D Other Approaches to Building Qubits 212
E Global R&D Investment 226
F Committee and Staff Biographical Information 230
G Briefers to the Committee 239
H Acronyms and Abbreviations 241
I Glossary