Oliver T. Slattery

Quantum transduction of telecommunications-band single photons from a quantum dot by frequency upconversion

Transducing non-classical states of light from one wavelength to another is required for integrating disparate quantum systems that take advantage of telecommunications-band photons for optical-fibre transmission of quantum information and near-visible, stationary systems for manipulation and storage. In addition, transducing a single-photon source at 1.3 mm to visible wavelengths would be integral to linear optical quantum computation because of near-infrared detection challenges. Recently, transduction at single-photon power levels has been accomplished through frequency upconversion, but it has yet to be demonstrated for a true single-photon source. Here, we transduce triggered single photons from a semiconductor quantum dot at 1.3 mm to 710 nm with 21% (75%) total detection (internal conversion) efficiency. We demonstrate that the upconverted signal maintains the quantum character of the original light, yielding a second-order intensity correlation, g (2) (t), that shows that the optical field is composed of single photons with g (2) (0) 5 0.165< 0.5.

The State of the Art and Practice in Digital Preservation

The goal of digital preservation is to ensure long-term access to digitally stored information. In this paper, we present a survey of techniques used in digital preservation. We also introduce representative digital preservation projects and case studies that provide insight into the advantages and disadvantages of different preservation strategies. Finally, the pros and cons of current strategies, critical issues for digital preservation, and future directions are discussed.

Long-wavelength-pumped upconversion single-photon detector at 1550 nm: performance and noise analysis

We demonstrate upconversion-assisted single-photon detection for the 1.55-μm telecommunications band based on a periodically poled lithium niobate (PPLN) waveguide pumped by a monolithic PPLN optical parametric oscillator. We achieve an internal conversion efficiency of 86%, which results in an overall system detection efficiency of 37%, with excess noise as low as 10(3) counts s(-1). We measure the dark count rate versus the upconversion pump-signal frequency separation and find the results to be consistent with noise photon generation by spontaneous anti-Stokes Raman scattering. These results enable detailed design guidelines for the development of low-noise quantum frequency conversion systems, which will be an important component of fiber-optic quantum networks.

Stability Comparison of Recordable Optical Discs—A Study of Error Rates in Harsh Conditions

The reliability and longevity of any storage medium is a key issue for archivists and preservationists as well as for the creators of important information. This is particularly true in the case of digital media such as DVD and CD where a sufficient number of errors may render the disc unreadable. This paper describes an initial stability study of commercially available recordable DVD and CD media using accelerated aging tests under conditions of increased temperature and humidity. The effect of prolonged exposure to direct light is also investigated and shown to have an effect on the error rates of the media. Initial results show that high quality optical media have very stable characteristics and may be suitable for long-term storage applications. However, results also indicate that significant differences exist in the stability of recordable optical media from different manufacturers.

Experimental study of high sensitivity infrared spectrometer with waveguide-based up-conversion detector 1

We have developed an up-conversion spectrometer for signals at single photon levels near the infrared region based on a tunable up-conversion detector that uses a periodically poled lithium niobate waveguide as the conversion medium. We also experimentally studied its characteristics including sensitivity, dark count rate, spectral scan speed, signal transfer function of the waveguide, and polarization sensitivity. The overall single photon detection efficiency of the up-conversion spectrometer is about 32%. With its ultra high sensitivity the spectrometer can measure spectra for signals at a level as low as -126 dBm. We have demonstrated the spectrometers high sensitivity by measuring the spectrum of a greatly attenuated multimode emission from a laser diode at the 1310 nm band.

Simultaneous Wavelength Translation and Amplitude Modulation of Single Photons from a Quantum Dot

Hybrid quantum information devices that combine disparate physical systems interacting through photons offer the promise of combining low-loss telecommunications wavelength transmission with high fidelity visible wavelength storage and manipulation. The realization of such systems requires control over the waveform of single photons to achieve spectral and temporal matching. Here, we experimentally demonstrate the simultaneous wavelength translation and amplitude modulation of single photons generated by a quantum dot emitting near 1300 nm with an exponentially decaying waveform (lifetime ≈1.5 ns). Quasi-phase-matched sum-frequency generation with a pulsed 1550 nm laser creates single photons at 710 nm with a controlled amplitude modulation at 350 ps time scales.

Reducing noise in single-photon-level frequency conversion

We demonstrate low-noise and efficient frequency conversion by sum-frequency mixing in a periodically poled LiNbO(3) (PPLN) waveguide. Using a 1556 nm pump, 1302 nm photons are efficiently converted to 709 nm photons. We obtain 70% conversion efficiency in the PPLN waveguide and >50% external conversion efficiency with 600 noise counts per second at peak conversion with continuous-wave pumping. We simultaneously achieve low noise and high conversion efficiency by careful spectral filtering. We discuss the impact of low-noise frequency translation on single-photon upconversion detection and quantum information applications.

49.2: Rotating-Wheel Braille Display for Continuous Refreshable Braille

Refreshable Braille provides a critical path to display accessibility. High cost and reliability issues severely limit the market for existing Braille displays. A novel wheel-based design addresses reliability issues, and provides continuous Braille text with many-fold reduction in cost.

Up-conversion single-photon detector using multi-wavelength sampling techniques

The maximum achievable data-rate of a quantum communication system can be critically limited by the efficiency and temporal resolution of the systems single-photon detectors. Frequency up-conversion technology can be used to increase detection efficiency for IR photons. In this paper we describe a scheme to improve the temporal resolution of an up-conversion single-photon detector using multi-wavelength optical-sampling techniques, allowing for increased transmission rates in single-photon communications systems. We experimentally demonstrate our approach with an up-conversion detector using two spectrally and temporally distinct pump pulses, and show that it allows for high-fidelity single-photon detection at twice the rate supported by a conventional single-pump up-conversion detector. We also discuss the limiting factors of this approach and identify important performance-limiting trade offs.

Experimental demonstration of an active quantum key distribution network with over gbps clock synchronization

We demonstrate a three-node QKD network that allows multiple users to share secure keys. This QKD network operates on the 850 nm and 1550 nm wavelengths at 1.25 Gbps clock rate. The communication route is controlled by MEMS optical switches. In this paper, we report the network structure and experimental results including the performance of the optical switch, polarization recovery, and timing alignment technology during switching. This demonstration experimentally shows that QKD can be extended to active multi-node networks.