Book contents
- Frontmatter
- Dedication
- Contents
- Preface
- 1 Quantum measurement theory
- 2 Useful concepts from information theory
- 3 Continuous measurement
- 4 Statistical mechanics, open systems, and measurement
- 5 Quantum feedback control
- 6 Metrology
- 7 Quantum mesoscopic systems I: circuits and measurements
- 8 Quantum mesoscopic systems II: measurement and control
- Appendix A The tensor product and partial trace
- Appendix B A fast-track introduction for experimentalists
- Appendix C A quick introduction to Ito calculus
- Appendix D Operators for qubits and modes
- Appendix E Dictionary of measurements
- Appendix F Input–output theory
- Appendix G Various formulae and techniques
- Appendix H Some proofs and derivations
- References
- Index
1 - Quantum measurement theory
Published online by Cambridge University Press: 05 September 2014
- Frontmatter
- Dedication
- Contents
- Preface
- 1 Quantum measurement theory
- 2 Useful concepts from information theory
- 3 Continuous measurement
- 4 Statistical mechanics, open systems, and measurement
- 5 Quantum feedback control
- 6 Metrology
- 7 Quantum mesoscopic systems I: circuits and measurements
- 8 Quantum mesoscopic systems II: measurement and control
- Appendix A The tensor product and partial trace
- Appendix B A fast-track introduction for experimentalists
- Appendix C A quick introduction to Ito calculus
- Appendix D Operators for qubits and modes
- Appendix E Dictionary of measurements
- Appendix F Input–output theory
- Appendix G Various formulae and techniques
- Appendix H Some proofs and derivations
- References
- Index
Summary
Introduction and overview
Much that is studied in quantum measurement theory, and thus in this book, is very different from that studied in its classical counterpart, Bayesian inference. While quantum measurement theory is in one sense a minimal extension of the latter to quantum states, quantum measurements cause dynamical changes that never need appear in a classical theory. This has a multitude of ramifications, many of which you will find in this book. One such consequence is a limit to the information that can be obtained about the state of a quantum system, and this results in relationships between information gained and dynamics induced that do not exist in classical systems. Because of the limits to information extraction, choosing the right kinds of measurements becomes important in a way that it never was for classical systems. Finding the best measurements for a given purpose, and working out how to realize these measurements, is often nontrivial.
The relationship between information and disturbance impacts the control of quantum systems using measurements and feedback, and we discuss this application in Chapter 5. The ability to extract information about quantum systems is also important in using quantum systems to make precise measurements of classical quantities such as time, acceleration, and the strengths of electric and magnetic fields. This subject is referred to as quantum metrology, and we discuss it in Chapter 6.
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- Chapter
- Information
- Quantum Measurement Theory and its Applications , pp. 1 - 47Publisher: Cambridge University PressPrint publication year: 2014
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