ANYL 357 |
| We are exploring the analytical applications of correlated detection of pairs of photons generated by parametric downconversion. The photons can be separated into signal and reference beams that are detected by single-photon avalanche diodes. Measurement of the count rate in the reference channel and the coincidence rate can give an absolute determination of the detection efficiency of the signal beam detector. This principle is the foundation of quantum error correction in several types of spectroscopy with precision limited chiefly by the detector shot noise. Flicker, drift, and shot noise of the source are removed. Polarization modulation can be an intrinsic part of the entangled photon generation considerably simplifying measurements of dichroism and rotary dispersion. In addition to noise reduction, it has been shown that measurements with entangled photons can increase spatial or temporal resolution by a factor equal to the entangled photon number. Thus, the resolution of many optical measurements or processes can be improved by at least twofold over single-photon values. In our experimental setup, photon pairs are generated by downconversion in a type II BBO crystal with a 351-nm pump beam from an argon ion laser. A Michelson interferometer in the reference beam is used for single-photon measurements of the coherence length for tomography experiments, and one leg of the interferometer is used to vary the delay in a fourth-order coincidence interferometer for entangled photon detection. Results of experiments in polarization-sensitive quantum-optical coherence tomography will be presented. This research was sponsored by the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy under contract DE-AC05-00OR22725 with Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC. |
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ACS Award in Chromatography in Honor of J. Michael Ramsey
1:30 PM-5:00 PM, Tuesday, August 21, 2007 BCEC -- 104C, Oral
Division of Analytical Chemistry |