Nonlocal restoration of two-mode squeezing in the presence of strong optical loss

We present the experimental realization of a theoretical effect discovered by Olivares and Paris, in which a pair of entangled optical beams undergoing independent losses can see nonlocal correlations restored by the use of a nonlocal resource correlating the losses. Twin optical beams created in an entangled Einstein-Podolsky-Rosen (EPR) state by an optical parametric oscillator above threshold were subjected to 50% loss from beamsplitters in their paths. The resulting severe degradation of the signature quantum correlations observed between the two beams was then suppressed when another, independent EPR state impinged upon the other input ports of the beamsplitters, effectively entangling the losses inflicted to the initial EPR state. The additional EPR beam pair was classically coherent with the primary one but had no quantum correlations with it. This result may find applications as a quantum tap for entanglement.Comment: 14 pages, 6 figures, submitted for publicatio

Broadband amplitude squeezing in a periodically poled KTiOPO_4 waveguide

We generated -2.2 dB of broadband amplitude squeezing at 1064 nm in a periodically poled KTiOPO_4 (PPKTP) waveguide, by coupling of the fundamental and second harmonic continuous-wave fields. This is the largest amount of squeezing obtained to date in a KTP waveguide, limited by propagation losses. This result paves the way for further improvements by use of lower-loss buried ion-exchanged waveguides.Comment: 3 pages, 2 figures, submitted for publicatio

Spectral Analysis of a Four Mode Cluster State

We theoretically evaluate the squeezed joint operators produced in a single optical parametric oscillator which generates quadripartite entangled outputs, as demonstrated experimentally by Pysher et al. \cite{pysher}[Phys. Rev. Lett. 107, 030505 (2011)]. Using a linearized fluctuation analysis we calculate the squeezing of the joint quadrature operators below threshold for a range of local oscillator phases and frequencies. These results add to the existing theoretical understanding of this potentially important system.Comment: 4 pages, 6 figure

Quantum coherent control of highly multipartite continuous-variable entangled states by tailoring parametric interactions

The generation of continuous-variable multipartite entangled states is important for several protocols of quantum information processing and communication, such as one-way quantum computation or controlled dense coding. In this article we theoretically show that multimode optical parametric oscillators can produce a great variety of such states by an appropriate control of the parametric interaction, what we accomplish by tailoring either the spatio-temporal shape of the pump, or the geometry of the nonlinear medium. Specific examples involving currently available optical parametric oscillators are given, hence showing that our ideas are within reach of present technology.Comment: 14 pages, 5 figure

Towards universal quantum computation through relativistic motion

We show how to use relativistic motion to generate continuous variable Gaussian cluster states within cavity modes. Our results can be demonstrated experimentally using superconducting circuits where tuneable boundary conditions correspond to mirrors moving with velocities close to the speed of light. In particular, we propose the generation of a quadripartite square cluster state as a first example that can be readily implemented in the laboratory. Since cluster states are universal resources for universal one-way quantum computation, our results pave the way for relativistic quantum computation schemes

Fabrication of full-scale fiber-reinforced hot-gas filters by chemical vapor depostion. Final report, November 1, 1994 -- December 32, 1995

The overall goal of this contract and its extensions has been to develop a hot gas candle filter which is light weight, has a thin wall, resists mechanical and thermal shock, and is resistive to alkali attack. A ceramic fiber reinforced, ceramic matrix composite approach has been followed to fabricate this new candle filter. Past reports covered the first test results of two ceramic composite candle filters at the Westinghouse Science and Technology Center in March of 1993, subsequent improvements made in the filters construction and fabrication processing, and the testing of six improved full size, 60 mm diameter by 1575 mm length, filters that met or exceeded performance requirements set for them. Completion of the 172 hours of simulated PFBC testing and thermal transients plus maintaining less than 4 ppm clean side ash concentration provided a basis for moving to the next step of testing in the Tidd PFBCC Demonstration Project. In this contract extension 3M fabricated 110 filters to be used for tests in demonstration power plant facilities and other tests that become available. The filters were tested to meet all quality assurance specifications and inventoried for Oak Ridge National Laboratory, ORNL. The filters are being shipped to various industrial, university, and national laboratory test facilities as requested by ORNL. Ten ceramic composite filters were installed in December, 1994 in the Tidd PFBC Demonstration Project filter vessel for their test period No. 5. Five filters were installed in a top cluster and five in a bottom cluster. The filters were removed in May 1995 after operating for 1 1 1 0 hours in a temperature range of 760{degrees}C to 843{degrees}C, with 80% of the run above 815{degrees}C