Showing papers by "Jay E. Sharping published in 2002"
TL;DR: This source of quantum-correlated photon pairs based on parametric fluorescence in a fiber Sagnac loop, given its spectral properties and robustness, is well suited for use in fiber-optic quantum communication and cryptography networks.
Abstract: In this letter, we present a source of quantum-correlated photon pairs based on parametric fluorescence in a fiber Sagnac loop. The photon pairs are generated in the 1550-nm fiber-optic communication band and detected with InGaAs-InP avalanche photodiodes operating in a gated Geiger mode. A generation rate > 10/sup 3/ pairs/s is observed, which is limited by the detection electronics at present. We also demonstrate the nonclassical nature of the photon correlations in the pairs. This source, given its spectral properties and robustness, is well suited for use in fiber-optic quantum communication and cryptography networks.
326 citations
TL;DR: In this article, the authors demonstrate optical parametric oscillation based on four-wave mixing in microstructure fiber, which is the first time to the best of our knowledge that such an approach has been used.
Abstract: We demonstrate, for the first time to our knowledge, optical parametric oscillation based on four-wave mixing in microstructure fiber. The measured wavelength-tunability range of the device (40 nm) and the threshold-pump peak power (34.4 W) are in good agreement with the theory of four-wave mixing in optical fibers. The ellipticity of the fiber's polarization modes allows the device to be implemented in a relatively simple Fabry-Perot configuration. Spectral peaks that are due to cascaded-mixing processes are easily observed in our setup, which may provide a way to extend the tunability range of existing high-power lasers.
144 citations
TL;DR: In this article, the authors demonstrate all-optical switching of picosecond pulses between the output ports of a microstructure-fiber-based polarization Sagnac interferometer.
Abstract: In this letter, we demonstrate all-optical switching of picosecond pulses between the output ports of a microstructure-fiber-based polarization Sagnac interferometer. High contrast switching of 2.6-ps FWHM signal pulses due to cross-phase modulation induced by 4.9-ps pump pulses in a 5.8-m long microstructure fiber is achieved at wavelengths near 1550 and 780 nm. The spectral and temporal behavior of the switching device are investigated and compared with numerical simulations based on coupled-wave theory.
90 citations
TL;DR: It is shown that features of the microstructure fiber can be exploited for generation of low-energy continuous-variable entangled pulses for use in all-fiber teleportation experiments and the dependence of this quantum-noise reduction on various system parameters is studied.
Abstract: We demonstrate, for the first time to our knowledge, the generation of squeezed light by means of soliton self-phase modulation in microstructure fiber. We observe and characterize the formation of solitons in the microstructure fiber at 1550 nm. A maximum squeezing of 2.7 dB is observed, corresponding to 4.0 dB after correcting for detection losses. The dependence of this quantum-noise reduction on various system parameters is studied in detail. Features of the microstructure fiber can be exploited for generation of low-energy continuous-variable entangled pulses for use in all-fiber teleportation experiments.
38 citations
13 citations
TL;DR: A Mach-Zehnder nonlinear fiber interferometer is studied for the generation of amplitude-squeezed light using linearization of the quantum nonlinear Shroedinger equation and includes in the model the effect of distributed linear losses in the fiber.
Abstract: We study a Mach-Zehnder nonlinear fiber interferometer for the generation of amplitude-squeezed light. Numerical simulations of experiments with microstructure fiber are performed using linearization of the quantum nonlinear Shrodinger equation. We include in our model the effect of distributed linear losses in the fiber.
12 citations
Posted Content•
TL;DR: In this paper, a fiber-based source of polarization-entangled photon pairs that is well suited for quantum communication applications in the 15$\mu$m band of standard telecommunication fiber is presented.
Abstract: We present a fiber-based source of polarization-entangled photon pairs that is well suited for quantum communication applications in the 15$\mu$m band of standard telecommunication fiber Quantum-correlated signal and idler photon pairs are produced when a nonlinear-fiber Sagnac interferometer is pumped in the anomalous-dispersion region of the fiber Recently, we have demonstrated nonclassical properties of such photon pairs by using Geiger-mode InGaAs/InP avalanche photodiodes Polarization entanglement in the photon pairs can be created by pumping the Sagnac interferometer with two orthogonally polarized pulses In this case the parametrically scattered signal-idler photons yield biphoton interference with $>$90% visibility in coincidence detection, while no interference is observed in direct detection of either the signal or the idler photons
6 citations
01 Jan 2002
TL;DR: In this paper, an all-fiber source of quantum-correlated photon pairs is demonstrated, where two pump photons scatter through the Kerr nonlinearity of the fiber to create simultaneous signal and idler photons.
Abstract: Q uantum entanglement refers to the nonclassical dependency of physically separated quantum systems. It is an essential resource that must be freely available for implementing many of the novel functions of quantum information processing, such as database searching, clock synchronization, teleportation, computing and cryptography.1 The efficient generation and transmission of quantum entanglement is therefore of prime importance. With the ubiquitous standard optical fiber serving as the transmission medium and the widespread availability of efficient active and passive fiber devices, technological synergy between the generation and propagation components of the overall quantum network can be achieved by deploying sources of entanglement that rely on the nonlinearity of the fiber itself. Such fiber-based sources of quantum entanglement would also have the advantage of modal purity over their crystal counterparts,2,3 which is very important for realizing complex networks that involve many quantum operations. In our quest to develop fiber-based devices for quantum information processing, we have recently demonstrated an allfiber source of quantum-correlated photon pairs.4 The operating physical mechanism in this source is nondegenerate fourphoton mixing, wherein two pump photons scatter through the Kerr nonlinearity of the fiber to create simultaneous signal and idler photons. Our experiment is conducted near the zero-dispersion wavelength of standard dispersion-shifted fiber, where such scattering is enhanced owing to phase matching of the photon wave functions. It must be pointed out here that in a conventional wavelength-divisionmultiplexed classical optical communication line, one strives to suppress the fourphoton or four-wave mixing process, which otherwise causes cross talk between the wavelength channels and sets limits on the total data capacity of the communication line. In our experiment, the four-photon mixing takes place in a nonlinear-fiber Sagnac interferometer (NFSI), which we previously used to generate quantum-correlated twin beams in the fiber.5 The pump is a mode-locked train of ~3-ps-long pulses. The pulsed operation serves two important purposes: the NFSI amplifier can be operated at low average powers and the production of the signal/ idler fluorescence photons is confined to well-defined temporal windows, allowing use of a gated detection scheme to increase the signal-to-noise ratio. To measure the nonclassical (i.e., quantum) correlations between the signal and the idler photons, one must effectively suppress the pump photons from reaching the detectors. Since a typical pump pulse contains ~108 photons and we are interested in detecting ~0.01 signal (idler) photons/pulse, a pump-to-signal (idler) rejection ratio in excess of 100 dB is required. We achieved this specification by sending the fluorescence photons through a free-space double-grating spectral filter that separates the signal and idler photons from each other and from the pump photons not rejected by the NFSI. To demonstrate the quantum nature of the four-photon scattering at the "single" photon level, we assembled a photonFigure 1.C oincidence rates as a function of the single-photon rates in two different cases: signalidler fluorescence produced by a pump pulse (diamonds) and signal-idler fluorescence produced by two consecutive pump pulses (triangles). T he line represents the calculated "accidental" counts. T he inset shows a plot of the detected idler photons as a function of the injected pump photons (hollow circles). A second-order polynomial is shown to fit the experimental data. T he contributions of the dark counts, linear scattering and quadratic scattering are plotted separately as well. counting apparatus for detecting the signal and idler photons in coincidence. This apparatus is based on commercial InGaAs avalanche photodiodes operating in the gated Geiger mode.4 In the inset in Fig. 1, we show the number of scattered photons, NS, versus the number of pump photons, NP, injected into the NFSI. We fit the experimental data with a second-order polynomial fit, including the number of dark counts during the gate interval, ND. The fit clearly shows that the quadratic scattering ( ∝NP) in the fiber can dominate over the residual linear scattering ( ∝NP) of the pump, owing to imperfect filtering. The main body of Fig. 1 shows the coincidence-counting results. The diamonds represent the rate of coincidence counts versus the rate of the signal (idler) photons generated during the same pump pulse. The triangles represent the measured coincidence rate versus the signalphoton count rate when the signal is delayed with respect to the idler by one pulse period. For two independent photon sources, each with a count rate RS <<1, the "accidental" coincidence rate RC is given by RC = RS 2, regardless of the photon statistics of the sources. This quadratic relation is plotted as the solid line in Fig. 1, which fits the delayed-coincidence data (triangles) very well. These measurements show that while the fluorescence photons produced by the adjacent pump pulses are independent, those coming from the same pump pulse show a strong correlation, which is a signature of their non-classical behavior. This work was supported by the Department of Defense Multidisciplinary University Research Initiative program administered by the Army Research Office under Grants DAAD19-00-1-0177 and DAAD19-00-1-0469, and by the U.S. Office of Naval Research under Grant N00014-91-J-1268.
5 citations
24 May 2002
TL;DR: In this paper, a microstructure fiber (MF) based optical parametric oscillator (MFOPO) was used to obtain tunable radiation at wavelengths shorter than that of the pump.
Abstract: Summary form only given. Parametric processes in /spl chi//sup (2)/ materials have long been used to generate light at wavelengths where conventional laser sources are not available. Here we report what we believe to be the first demonstration of a microstructure fibre (MF) based optical parametric oscillator (MFOPO). By pumping near the MF's zero-dispersion wavelength, we obtain tunable radiation at wavelengths shorter than that of the pump. Cascaded four-wave mixing (FWM) is also observed, wherein the oscillating signal, the pump, and the idler create radiation at new wavelengths. By pumping an appropriately tailored MF with Ti:sapphire or other high-power laser sources, such cascaded FWM may provide a viable route for the generation of tunable blue-green light. Our experiment also provides a detailed study of one of the nonlinear processes occurring below the supercontinuum threshold.
5 citations
2 citations
Journal Article•
29 Jul 2002
TL;DR: In this article, experimental progress towards demonstrating fiber-based sources of quadrature as well as polarization entanglement for quantum communication applications in the 1.5 µm band of standard telecommunication fiber is presented.
Abstract: We present recent experimental progress towards demonstrating fiber-based sources of quadrature as well as polarization entanglement for quantum communication applications in the 1.5 µm band of standard telecommunication fiber.