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Polarization-entangled photon pairs using spontaneous four-wave mixing in a fib...
Almeida, Álvaro J.; Carneiro, Steven R.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We generate polarization-entangled photon pairs in the 1550-nm wavelength telecom band, using spontaneous fourwave mixing in a highly nonlinear fiber loop. With accidental coincidences subtracted, we obtain coincidence fringes with visibilities greater than 86%, and thus observe a violation of Clauser, Horne, Shimony and Holt (CHSH) inequality by 2.7 standard deviations. The experimental setup is built using on...
Correlated photon-pair generation in a highly nonlinear fiber using spontaneous...
Almeida, Álvaro J.; Martins, Luís M.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We generate 1550 nm correlated photon pairs through the spontaneous four-wave mixing (SpFWM) process in a highly nonlinear fiber (HNLF). The pair source quality generation is evaluated by the coincidence-to-accidental ratio (CAR) parameter. It is verified that the spontaneous Raman scattering (SpRS) photons generated inside the fiber contribute to the degradation of the source. Nevertheless, a CAR value of 2.77...
Time coincidence of entangled photon pairs using spontaneous four-wave mixing i...
Almeida, Álvaro J.; Carneiro, Steven R.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We obtained a source of entangled photon pairs in the 1550-nm wavelength band using spontaneous four-wave mixing (SpFWM) in a Sagnac fiber loop. Time coincidence of entangled photon pairs was verified for a 300-m dispersion-shifted fiber (DSF), using an avalanche photodiode (APD). ; QuantTel - Quantum Secure Telecommunications ; Quant- PrivTel - Quantum Private Telecommunications - PTDC/EEATEL/ 103402/2008
Fiber-optical communication system using polarization-encoding photons
Almeida, Álvaro J.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We present a single-photon source based on the stimulated four-wave mixing process with adjustable linear state of polarization. This source allowed us to generate non-orthogonal states of polarization, that can be used for quantum key distribution experiments. The average number of photon counts as a function of the angle of the analyzer was obtained for two non-orthogonal linear states of polarization. The re...
Single-photon source based on FWM with adjustable linear SOP
Almeida, Álvaro J.; Silva, Nuno A.; Muga, Nelson J.; Pinto, Armando N.We present a setup able to generate and detect single photons in optical fibers using the stimulated four-wave mixing (FWM) process. The results show an accurate generation of single photons at four different linear states of polarization (SOPs), with angles 0, 45, 90 and -45 degrees. The detection was performed in back-to-back configuration and after transmission over an optical fiber with a length up to 10 m.
Single-photon source with adjustable linear SOP
Almeida, Álvaro J.; Fernandes, Gil G.; Pinto, Armando N.In this work we generate and detect single photons in optical fibers using the stimulated four-wave mixing (FWM)process. The results show an accurate generation of single photons at four different linear states of polarization (SOPs), with angles 0, 45, 90 and -45 degrees. ; QuantTel - Quantum Secure Telecommunications
Neptune Trojans and Plutinos: colors, sizes, dynamics, and their possible colli...
Almeida, Álvaro. J. C.; Peixinho, N.; Correia, A. C. M.Neptune Trojans and Plutinos are two subpopulations of trans-Neptunian objects located in the 1:1 and the 3:2 mean motion resonances with Neptune, respectively, and therefore protected from close encounters with the planet. However, the orbits of these two kinds of objects may cross very often, allowing a higher collisional rate between them than with other kinds of trans-Neptunian objects, and a consequent siz...
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