Quantum Theory of All-Optical Switching in Nonlinear Sagnac Interferometers

Recently, our group has demonstrated an ultrafast, low-loss, fiber-loop switch based on a nonlinear Sagnac-interferometer design, using which entangled photons were shown to be routed without any measurable degradation in their entanglement fidelity [Hall {\it et al.}, Phys. Rev. Lett. {\bf 106}, 053901 (2011)]. Such a device represents an enabling technology for a rich variety of networked quantum applications. In this paper we develop a comprehensive quantum theory for such switches in general, i.e., those based on nonlinear Sagnac interferometers, where the in-coupling of quantum noise is carefully modeled. Applying to the fiber-loop switch, the theory shows good agreement with the experimental results without using any fitting parameter. This theory can serve as an important guiding tool for configuring switches of this kind for future quantum networking applications.Comment: To appear in New J. Physic

Distilling Quantum Entanglement via Mode-Matched Filtering

We propose a new avenue towards distillation of quantum entanglement that is implemented by directly passing the entangled qubits through a mode-matched filter. This approach can be applied to a common class of entanglement impurities appearing in photonic systems where the impurities inherently occupy different spatiotemporal modes than the entangled qubits. As a specific application, we show that our method can be used to significantly purify the telecom-band entanglement generated via the Kerr nonlinearity in single-mode fibers where a substantial amount of Raman-scattering noise is concomitantly produced.Comment: 6 pages, 2 figures, to appear in Phys. Rev.

Antibunched Emission of Photon-Pairs via Quantum Zeno Blockade

We propose a new methodology, namely "quantum Zeno blockade," for managing light scattering at a few-photon level in general nonlinear-optical media, such as crystals, fibers, silicon microrings, and atomic vapors. Using this tool, antibunched emission of photon pairs can be achieved, leading to potent quantum-optics applications such as deterministic entanglement generation without the need for heralding. In a practical implementation using an on-chip toroidal microcavity immersed in rubidium vapor, we estimate that high-fidelity entangled photons can be produced on-demand at MHz rates or higher, corresponding to an improvement of $\gtrsim10^7$ times from the state-of-the-art.Comment: to appear in Phys. Rev. Let

Exploring the validity of the problem solving inventory with Mexican American high school students

http://www.cambio.missouri.edu/Library/The Problem Solving Inventory (PSI; Heppner & Petersen, 1982) is a widely used measure to assess one's perceived ability in problem-solving behaviors and attitudes in the United States and many other countries. In this study, a bilevel model was examined with a Mexican American high school student sample (N = 164) using confirmatory factor analysis. Results of the confirmatory factor analysis supported the bilevel model with the current sample of Mexican American high school students. The data provided support for the PSI and enhances the generalizability of some of the previous findings based on the U.S., Turkish, and South African samples. Also, this study provides crosscultural information that promotes our knowledge about the efficacy of problem-solving constructs across different age and cultural groups.Dr. Lisa Flores, Thesis Superviso