94 research outputs found
Waveguide-based OPO source of entangled photon pairs
In this paper we present a compact source of narrow-band energy-time
entangled photon pairs in the telecom regime based on a Ti-indiffused
Periodically Poled Lithium Niobate (PPLN) waveguide resonator, i.e. a waveguide
with end-face dielectric multi-layer mirrors. This is a monolithic doubly
resonant Optical Parametric Oscillator (OPO) far below threshold, which
generates photon pairs by Spontaneous Parametric Down Conversion (SPDC) at
around 1560nm with a 117MHz (0.91 pm)- bandwidth. A coherence time of 2.7 ns is
estimated by a time correlation measurement and a high quality of the entangled
states is confirmed by a Bell-type experiment. Since highly coherent
energy-time entangled photon pairs in the telecom regime are suitable for long
distance transmission and manipulation, this source is well suited to the
requirements of quantum communication.Comment: 13 page
Engineering integrated pure narrow-band photon sources
Engineering and controlling well defined states of light for quantum
information applications is of increasing importance as the complexity of
quantum systems grows. For example, in quantum networks high multi-photon
interference visibility requires properly devised single mode sources. In this
paper we propose a spontaneous parametric down conversion source based on an
integrated cavity-waveguide, where single narrow-band, possibly distinct,
spectral modes for the idler and the signal fields can be generated. This mode
selection takes advantage of the clustering effect, due to the intrinsic
dispersion of the nonlinear material. In combination with a CW laser and fast
detection, our approach provides a means to engineer a source that can
efficiently generate pure photons, without filtering, that is compatible with
long distance quantum communication. Furthermore, it is extremely flexible and
could easily be adapted to a wide variety of wavelengths and applications.Comment: 13 pages, 7 figure
Line-narrowing transient Raman technique which resolves closely spaced hydrogen-bonded aggregates
An ultrafast coherent Raman spectroscopy with tunable excitation is presented. It is applied to the analysis of vibrational spectra of hydrogen-bonded aggregates of pyridine and methanol. Whereas the spontaneous Raman spectrum exhibits a broad and featureless band, the line-narrowed spectra reveal three distinct lines. The concentration dependence of these lines suggests an assignment to well-defined aggregates of different sizes
Photon extrabunching in ultrabright twin beams measured by two-photon counting in a semiconductor
For many years twin beams originating from parametric down-converted light beams have aroused great interest and attention in the photonics community. One particular aspect of the twin beams is their peculiar intensity correlation functions, which are related to the coincidence rate of photon pairs. Here we take advantage of the huge bandwidth offered by two-photon absorption in a semiconductor to quantitatively determine correlation functions of twin beams generated by spontaneous parametric down-conversion. Compared with classical incoherent sources, photon extrabunching is unambiguously and precisely measured, originating from exact coincidence between down-converted pairs of photons, travelling in unison. These results strongly establish that two-photon counting in semiconductors is a powerful tool for the absolute measurement of light beam photon correlations at ultrashort timescales
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