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About September 2011

This page contains all entries posted to Physics Announcements in September 2011. They are listed from oldest to newest.

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September 2011 Archives

September 14, 2011

Seminar: Wednesday, Sep.14, 2011 at 3:30pm

Imaging Infrared and Terahertz radiation using non-linear optics
Dr. Matthew DeCamp
University of Delaware, Dept. of Physics and Astronomy

Molecular vibrations are resonant with electromagnetic radiation in the infrared (IR) portion of the electromagnetic spectrum (0-100THz) making vibrational spectroscopy a very powerful tool for identifying complex molecular compounds, ranging from proteins to explosives. However, the photon energy of IR radiation is often too small to detect using standard room temperature semi-conductor devices. In addition, far-IR radiation (0-10THz) overlaps with the radiation of a blackbody at room temperature, making spectral separation from the thermal background difficult. For this reason, current IR detection technology often utilizes cryogenically cooled detectors, which in addition to being very expensive are not easily portable, making field and/or clinical applications very difficult. In this talk, I will be discussing new techniques for detecting infrared radiation using standard semi-conductor technology by utilizing non-linear optical methods. This new technology may lead to low-cost, portable detection tools for research, clinical, and security applications.

Location: Physics Bldg., Room 401

September 21, 2011

Seminar: Wednesday, Sep 21, 2011 at 3:30pm

Single Photon Frequency Up-Conversion and its Applications in Quantum Information Research
Xiao Tang
Information Technology Laboratory, National Institute of Standards and Technology

In this talk, we will present the recent efforts at NIST on the single photon frequency upconversion technique and its applications in quantum information research.

Silicon-based single photon detectors (Si-APDs) are high efficiency and low noise detectors for visible and near visible wavelengths, but do not work at the near infrared (NIR) wavelength range where the important telecom bands (mainly 1310 and 1550 nm) are. The performance of InGaAs based detectors for NIR photons needs to be improved. Upconversion detectors provide a good alternative, in which the NIR photons are converted to visible first and then detected by a Si-APD.

The single photon upconversion technique is based on the sum frequency generation (SFG) in nonlinear optics. A few years ago, NIST adapted the optical frequency upconversion technique to develop single photon detectors for the illusive NIR photons and used the detectors in a fiber-based high speed quantum key distribution (QKD) system. Since then, the devices have been significantly improved. In the recent years, the team’s effort is focused on the applications of the up-conversion technique in quantum information research. We will briefly introduce the applications in the research areas including the QKD system, the ultra sensitive NIR spectrometer, the entangled photon source, quantum dots, and higher-order NIR photon temporal correlations. A multiple wavelength pump technique for increasing system date rates beyond the initial limitation will be mentioned. We will also point out some potential applications of the upconversion technique in future quantum information systems.

Location: Physics Bldg., Room 401

September 28, 2011

Seminar: Wednesday, Sept 28, 2011 at 3:30 pm

Polarization Entanglement, Special Reference Frames, and Advanced Waves
Dr. Robert French
Oakland Community College, Highland Lakes Campus, Waterford, MI.

This talk sketches a program towards giving a physically realist model of the photon in terms of properties of the electromagnetic field. It is both shown how to rework traditional wave and particle concepts so as to have a unified concept and how parallel electromagnetic fields can be associated with each charged particle. An account of both light propagation and of interactions with matter is sketched. A suggestion, utilizing advanced waves, is made as to how the account may be able to explain EPR correlations in the case of polarization entanglement. A possible empirical test, using a pockels cell with a fast driver is also discussed.

Location: Physics Bldg., Room 401