5,236 research outputs found
Conditional quantum state engineering in repeated 2-photon down conversion
The U(1,1) and U(2) transformations realized by three-mode interaction in the
respective parametric approximations are studied in conditional measurement,
and the corresponding non-unitary transformation operators are derived. As an
application, the preparation of single-mode quantum states using an optical
feedback loop is discussed, with special emphasis of Fock state preparation.
For that example, the influence of non-perfect detection and feedback is also
considered.Comment: 17 pages, 4 figures, using a4.st
Efficient optical quantum state engineering
We discuss a novel method of efficiently producing multi-photon states using
repeated spontaneous parametric downconversion. Specifically, by attempting
downconversion several times, we can pseudo-deterministically add photons to a
mode, producing various several-photon states. We discuss both expected
performance and experimental limitations.Comment: 4 pages, 4 figure
Study of a heat rejection system using capillary pumping
Results of an analytical study investigating the application of capillary pumping to the heat rejection loop of an advanced Rankine cycle power conversion system are presented. The feasibility of the concept of capillary pumping as an alternate to electromagnetic pumping is analytically demonstrated. Capillary pumping is shown to provide a potential for weight and electrical power saving and reliability through the use of redundant systems. A screen wick pump design with arterial feed lines was analytically developed. Advantages of this design are high thermodynamic and hydrodynamic efficiency, which provide a lightweight easily packaged system. Operational problems were identified which must be solved for successful application of capillary pumping. The most important are the development of start up and shutdown procedures, and development of a means of keeping noncondensibles from the system and of earth-bound testing procedures
Conditional quantum-state transformation at a beam splitter
Using conditional measurement on a beam splitter, we study the transformation
of the quantum state of the signal mode within the concept of two-port
non-unitary transformation. Allowing for arbitrary quantum states of both the
input reference mode and the output reference mode on which the measurement is
performed, we show that the non-unitary transformation operator can be given as
an -ordered operator product, where the value of is entirely determined
by the absolute value of the beam splitter reflectance (or transmittance). The
formalism generalizes previously obtained results that can be recovered by
simple specification of the non-unitary transformation operator. As an
application, we consider the generation of Schr\"odinger-cat-like states. An
extension to mixed states and imperfect detection is outlined.Comment: 7 Postscript figures, using Late
Quantum state conversion by cross-Kerr interaction
A generalized Mach-Zehnder-type interferometer equipped with cross-Kerr
elements is proposed to convert N-photon truncated single-mode quantum states
into (N+1)-mode single-photon states, which are suitable for further state
manipulation by means of beam splitter arrays and ON/OFF-detections, and vice
versa. Applications to the realization of unitary and non-unitary
transformations, quantum state reconstruction, and quantum telemanipulation are
studied.Comment: 22 pages, 4 figures, using a4.st
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