Book contents
- Frontmatter
- Contents
- Foreword
- Preface
- 1 Historical perspective
- 2 Present situation, remaining conceptual difficulties
- 3 The theorem of Einstein, Podolsky, and Rosen
- 4 Bell theorem
- 5 More theorems
- 6 Quantum entanglement
- 7 Applications of quantum entanglement
- 8 Quantum measurement
- 9 Experiments: quantum reduction seen in real time
- 10 Various interpretations
- 11 Annex: Basic mathematical tools of quantum mechanics
- Appendix A Mental content of the state vector
- Appendix B Bell inequalities in non-deterministic local theories
- Appendix C An attempt for constructing a “separable” quantum theory (non-deterministic but local)
- Appendix D Maximal probability for a state
- Appendix E The influence of pair selection
- Appendix F Impossibility of superluminal communication
- Appendix G Quantum measurements at different times
- Appendix H Manipulating and preparing additional variables
- Appendix I Correlations in Bohmian theory
- Appendix J Models for spontaneous reduction of the state vector
- Appendix K Consistent families of histories
- References
- Index
7 - Applications of quantum entanglement
Published online by Cambridge University Press: 05 September 2012
- Frontmatter
- Contents
- Foreword
- Preface
- 1 Historical perspective
- 2 Present situation, remaining conceptual difficulties
- 3 The theorem of Einstein, Podolsky, and Rosen
- 4 Bell theorem
- 5 More theorems
- 6 Quantum entanglement
- 7 Applications of quantum entanglement
- 8 Quantum measurement
- 9 Experiments: quantum reduction seen in real time
- 10 Various interpretations
- 11 Annex: Basic mathematical tools of quantum mechanics
- Appendix A Mental content of the state vector
- Appendix B Bell inequalities in non-deterministic local theories
- Appendix C An attempt for constructing a “separable” quantum theory (non-deterministic but local)
- Appendix D Maximal probability for a state
- Appendix E The influence of pair selection
- Appendix F Impossibility of superluminal communication
- Appendix G Quantum measurements at different times
- Appendix H Manipulating and preparing additional variables
- Appendix I Correlations in Bohmian theory
- Appendix J Models for spontaneous reduction of the state vector
- Appendix K Consistent families of histories
- References
- Index
Summary
Quantum entanglement does not only provide a field of fundamental studies, but can also be harnessed as a tool for applications. In this chapter, after introducing two general theorems that are useful in the context of this discussion (§7.1), we propose a few examples: quantum cryptography (§7.2), teleportation (§7.3), and quantum computing (§7.4). For the moment, only quantum cryptography has given rise to real applications, and has been used in practical (and even commercial) applications; its purpose is the sharing of cryptographic keys between several partners by using a protocol where privacy is guaranteed by fundamental laws of physics. As for quantum computation, it is based on the general manipulation of quantum information, and is probably a more futuristic field of research in terms of applications, but it is certainly a domain of intense activity throughout the world.
Strictly speaking, none of these subjects in itself brings a really new view on the interpretation of quantum mechanics. Nevertheless, in addition to their strong intrinsic interests, they provide very direct and particularly interesting applications of its basic principles. This is the reason we study them in this chapter. We will only summarize the main ideas; the interested reader is invited to read the proposed references.
Two theorems
The two theorems that follow are similar; one deals with the creation and duplication of quantum states, the other with their determination.
No-cloning
The duplication of a quantum state, often called “quantum cloning”, is an operation where one starts from one particle in an arbitrary quantum state and reaches a situation where two particles are in the same state ∣φ〈.
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- Do We Really Understand Quantum Mechanics? , pp. 150 - 167Publisher: Cambridge University PressPrint publication year: 2012
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