Book contents
- Frontmatter
- Contents
- Preface
- 1 Elements of probability theory
- 2 Random (or stochastic) processes
- 3 Some useful mathematical techniques
- 4 Second-order coherence theory of scalar wavefields
- 5 Radiation from sources of any state of coherence
- 6 Second-order coherence theory of vector electromagnetic fields
- 7 Some applications of second-order coherence theory
- 8 Higher-order correlations in optical fields
- 9 Semiclassical theory of photoelectric detection of light
- 10 Quantization of the free electromagnetic field
- 11 Coherent states of the electromagnetic field
- 12 Quantum correlations and photon statistics
- 13 Radiation from thermal equilibrium sources
- 14 Quantum theory of photoelectric detection of light
- 15 Interaction between light and a two-level atom
- 16 Collective atomic interactions
- 17 Some general techniques for treating interacting systems
- 18 The single-mode laser
- 19 The two-mode ring laser
- 20 The linear light amplifier
- 21 Squeezed states of light
- 22 Some quantum effects in nonlinear optics
- References
- Author index
- Subject index
13 - Radiation from thermal equilibrium sources
Published online by Cambridge University Press: 05 April 2013
- Frontmatter
- Contents
- Preface
- 1 Elements of probability theory
- 2 Random (or stochastic) processes
- 3 Some useful mathematical techniques
- 4 Second-order coherence theory of scalar wavefields
- 5 Radiation from sources of any state of coherence
- 6 Second-order coherence theory of vector electromagnetic fields
- 7 Some applications of second-order coherence theory
- 8 Higher-order correlations in optical fields
- 9 Semiclassical theory of photoelectric detection of light
- 10 Quantization of the free electromagnetic field
- 11 Coherent states of the electromagnetic field
- 12 Quantum correlations and photon statistics
- 13 Radiation from thermal equilibrium sources
- 14 Quantum theory of photoelectric detection of light
- 15 Interaction between light and a two-level atom
- 16 Collective atomic interactions
- 17 Some general techniques for treating interacting systems
- 18 The single-mode laser
- 19 The two-mode ring laser
- 20 The linear light amplifier
- 21 Squeezed states of light
- 22 Some quantum effects in nonlinear optics
- References
- Author index
- Subject index
Summary
We have now derived a number of general properties of a quantized electromagnatic field, and have encountered some useful formalisms for treating certain problems in quantum optics. We have introduced the correlation functions of the field, and we have seen in a general way how they are related to measurements. In selecting examples for illustration we have tended to focus our attention largely on certain idealized quantum states of the field, such as Fock states and coherent states. However, there exists an important class of optical fields with simple properties, the so-called thermal fields, which includes most fields commonly encountered in practice, that has not yet been discussed. These fields are produced by sources in thermal equilibrium, and they exhibit many features that can be treated almost exactly in our formalism. We now turn our attention to such fields.
Blackbody radiation
The density operator
Blackbody radiation is the name given to an electromagnetic field in thermal equilibrium with a large thermal reservoir or heat bath at some temperature T. By definition, such a field is assumed to be coupled to the heat bath, and it is therefore not a strictly free field in the sense of the previous chapters. However, the coupling can be as weak as we wish, and it is well known from the general theory of statistical thermodynamics that the properties of a system with many degrees of freedom in thermal equilibrium (described by a canonical ensemble) are often similar to those of an equivalent isolated system (described by a microcanonical ensemble).
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- Information
- Optical Coherence and Quantum Optics , pp. 659 - 682Publisher: Cambridge University PressPrint publication year: 1995