Alexander V. Sergienko

Generating ultra-broadband biphotons via chirped QPM down-conversion

Nonlinear Optics: Nonlinear optical response has enhanced our ability to produce coherent light throughout the optical spectral region.

Parameter Estimation in Quantum Optical Coherence Tomography

Quantum optical coherence tomography (QOCT) has been used for axial imaging based on quantum interferometry. We demonstrate a technique for the estimation of sample parameters (positions of reflecting layers, refractive indices, dispersion coefficients) for closely spaced layered media, based on measurement of QOCT interferograms.

Engineering Multiparameter Entangled State with Adaptive Optics

We discuss the possibility of actively manipulating entangled states generated by type-II parametric down conversion. We study what effect active manipulation of wavevector using adaptive mirror will have on the behavior of polarization-temporal interference.

Effect of Dispersion on Fidelity of a Quantum Interferometer

We analyze the effect of frequency dispersion on the Shannon mutual information for high-resolution phase measurement with Mach-Zehnder interferometers, comparing input states of monochromatic photons to those of nonzero-bandwidth photons produced by parametric downconversion.

Engineering Robust Optical Entanglement for Quantum Communication

A robust source of polarization-entangled photons for quantum communication at telecom wavelength is implemented. The benefits of using Superconducting Photon Counting Detectors (SSPD) have been evaluated.

Quantum Cryptography with Optical Entanglement at 1.5 μm

We report on the engineering, preparation, and utilization of polarization entangled-photon states in the telecommunications window of 1.5 μm for secure quantum key distribution.

Counterpropagating entangled photons in a periodically poled nonlinear waveguide

Entangled photons, which may be generated through the process of spontaneous parametric down-conversion (SPDC) in a crystal with /spl chi//sup (2)/ nonlinearity, have long been in the spotlight for quantum-optics experiments. The generation of entangled photons by quasi-phase matching (QPM) in lithium niobate offers the promise of increased photon-pair production and, with the integration of a waveguide structure, control of the spatial characteristics of the down-converted photons. It turns out that the use of a waveguide structure, in conjunction with periodic poling to achieve quasi-phase matching, offers another critically important feature: the possibility of generating counterpropagating signal and idler photons. We consider the conditions required for generating counterpropagating photon beams and explore some of the unique properties of this source of light using a periodically poled LiNbO/sub 3/ waveguide.