2000/09/30 by Andrew J. Berglund, Berglund, Andrew J.
Computer Science · Physics and Astronomy · #FOS: Physical sciences #Laser-Matter Interactions and Applications #Quantum Information and Cryptography #Quantum Physics (quant-ph) #Quantum optics and atomic interactions #quant-ph
paper · pdf · doi:10.48550/arxiv.quant-ph/0010001
18 pages, 11 figures, corrected top/bottom margins
openalex publication_date 2000/09/30 · arxiv created 2000/10/03 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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.