Book contents
- Frontmatter
- Contents
- Acknowledgements
- 1 Introduction
- 2 Field quantization
- 3 Coherent states
- 4 Emission and absorption of radiation by atoms
- 5 Quantum coherence functions
- 6 Beam splitters and interferometers
- 7 Nonclassical light
- 8 Dissipative interactions and decoherence
- 9 Optical test of quantum mechanics
- 10 Experiments in cavity QED and with trapped ions
- 11 Applications of entanglement: Heisenberg-limited interferometry and quantum information processing
- Appendix A The density operator, entangled states, the Schmidt decomposition, and the von Neumann entropy
- Appendix B Quantum measurement theory in a (very small) nutshell
- Appendix C Derivation of the effective Hamiltonian for dispersive (far off-resonant) interactions
- Appendix D Nonlinear optics and spontaneous parametric down-conversion
- Index
- References
6 - Beam splitters and interferometers
Published online by Cambridge University Press: 05 September 2012
- Frontmatter
- Contents
- Acknowledgements
- 1 Introduction
- 2 Field quantization
- 3 Coherent states
- 4 Emission and absorption of radiation by atoms
- 5 Quantum coherence functions
- 6 Beam splitters and interferometers
- 7 Nonclassical light
- 8 Dissipative interactions and decoherence
- 9 Optical test of quantum mechanics
- 10 Experiments in cavity QED and with trapped ions
- 11 Applications of entanglement: Heisenberg-limited interferometry and quantum information processing
- Appendix A The density operator, entangled states, the Schmidt decomposition, and the von Neumann entropy
- Appendix B Quantum measurement theory in a (very small) nutshell
- Appendix C Derivation of the effective Hamiltonian for dispersive (far off-resonant) interactions
- Appendix D Nonlinear optics and spontaneous parametric down-conversion
- Index
- References
Summary
Experiments with single photons
Central to the entire discipline of quantum optics, as should be evident from the preceding chapters, is the concept of the photon. Yet it is perhaps worthwhile to pause and ask: what is the evidence for the existence of photons? Most of us first encounter the photon concept in the context of the photo-electric effect. As we showed in Chapter 5, the photo-electric effect is, in fact, used to indirectly detect the presence of photons – the photo-electrons being the entities counted. But it turns out that some aspects of the photo-electric effect can be explained without introducing the concept of the photon. In fact, one can go quite far with a semiclassical theory in which only the atoms are quantized with the field treated classically. But we hasten to say that, for a satisfactory explanation of all aspects of the photo-electric effect, the field must be quantized. As it happens, the other venerable “proof” of the existence of photons, the Compton effect, can also be explained without quantized fields.
In an attempt to obtain quantum effects with light, Taylor, in 1909, obtained interference fringes in an experiment with an extremely weak source of light. His source was a gas flame and the emitted light was attenuated by means of screens made of smoked glass.
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- Introductory Quantum Optics , pp. 135 - 149Publisher: Cambridge University PressPrint publication year: 2004
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