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SPECIAL AMO/QO PHYSICS SEMINAR


"Transmission of a Weak Optical Pulse Through a Dense Quantum Absorber"


Dr. John F. Reintjes
Sotera Defense Solutions
Naval Research Laboratory, Washington, DC


ABSTRACT 

We consider the transmission of a weak optical pulse (energy = 1 hν) through a dense quantum absorber with resonant frequency ν. Conventional semiclassical analysis predicts that, if the medium is completely absorbing (αL = ∞), the entire optical pulse will be absorbed. However, when we look for the energy in the atoms, no excited atoms will be measured on 1/e of the trials. On other trials, two or more atoms can be measured in the excited state even though the system was supplied with only 1 hν of energy. On the other hand, if the medium transmits 50% of the light (αL = 0.69) the predicted energy of the transmitted optical pulse is 0.5 hν, with the remaining 0.5 h ν transferred to a quantized medium that absorbs energy only in units of 1 hν. It is tempting to conclude from these difficulties with conservation of energy that semiclassical analysis breaks down in this regime and quantized optical fields are required.

We describe a semiclassical treatment of the light-matter interaction that accommodates weak optical pulses. We find that the probabilistic back reaction of the quantum absorber on the classical pulse impresses statistical behavior on the pulse that does not arise from quantization of the optical field. All properties of the optical transmission and atomic absorption are self-consistent without contradiction. Issues relating to the conservation of energy are resolved by considering the implications of the violation of the Bell inequalities for physical realism and the nature of a quantum superposition state. The results of our analysis agree in the average with those of conventional semiclassical theory, and with the predictions of quantum electrodynamics under the assumption of an initial coherent state for the optical field.



Wednesday, April 17, 2013
IQSE 578, 10:00 a.m.
Mitchell Physics Building


Institute for Quantum Science and Engineering
Texas A&M University

(Coffee and Cookies to be served 15 minutes prior start time)