Quantum optics is the part of optics which deals with quantum effects. In many cases, such effects are studied in the context of fundamental research. However, they are also very important in laser physics:
- Fundamental quantum-mechanical processes such as spontaneous and stimulated emission are of basic importance for the general operation and the performance of lasers.
- Quantum effects introduce laser noise, e.g. cause a finite linewidth and a finite level of intensity noise even if all technical noise sources are suppressed. Similarly, they set a lower limit to the amplifier noise of optical amplifiers.
Another area of quantum optics involves nonclassical light, such as squeezed states of light, having unusual quantum noise properties. This area is somewhat related to the topic of quantum nondemolition measurements, which make it possible, e.g., to determine the intensity of a light beam without altering it.
Quantum optics has practical applications, e.g. quantum cryptography, which is the use of quantum effects for secure transmission of information, and quantum metrology. The applied fields are also called quantum photonics as a field within quantum technology. The following types of products are specific for those fields:
|||W. P. Schleich et al., Quantum Optics in Phase Space, Wiley-VCH Verlag GmbH, Weinheim (1999)|
|||D. F. Walls and G. J. Milburn, Quantum Optics, Springer, Berlin (1994)|
|||R. Loudon, The Quantum Theory of Light, 3rd edition, Oxford University Press, New York (2000)|