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Quantum coherence and control in one- and two-photon optical systems

Andrew J. Berglund
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Abstract

We investigate coherence in one- and two-photon optical systems, both theoretically and experimentally. In the first case, we develop the density operator representing a single photon state subjected to a non-dissipative coupling between observed (polarization) and unobserved (frequency) degrees of freedom. We show that an implementation of ``bang-bang'' quantum control protects photon polarization information from certain types of decoherence. In the second case, we investigate the existence of a "decoherence-free" subspace of the Hilbert space of two-photon polarization states under the action of a similar coupling. The density operator representation is developed analytically and solutions are obtained numerically. NOTE: This manuscript is taken from the author's undergraduate thesis (A.B. Dartmouth College, June 2000, advised by Dr. Walter E. Lawrence), under the supervision of Dr. Paul G. Kwiat.

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Andrew J. Berglund. 2000-10-03. Quantum coherence and control in one- and two-photon optical systems. https://arxiv.org/abs/quant-ph/0010001

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