1,335 research outputs found
Optical mesons
An ''optical meson'' (two-photon quantum soliton) is proven to exist in a parametric waveguide. This could provide an ideal quantum soliton environment, because of more realistic formation lengths and much larger binding energies than chi((3)) quantum solitons. We estimate the binding energy, radius, and interaction length in comparison to the chi((3)) case in optical fibers
Ideal soliton environment using parametric band gaps
Simultaneous solitary wave solutions for laser propagation in nonlinear parametric media with up to (3 + 1) dimensions are proved to exist. The combination of the large dispersion of a Bragg grating and the strong nonlinearity of chi((2)) optical material results in stable behavior with short interaction distances and low power requirements. The solutions are obtained by using the effective mass approximation to reduce the coupled propagation equations to those describing a dispersive parametric nonlinear waveguide, and are verified by solving the complete set of coupled band-gap equations numerically
Dynamical Quantum Memories
We propose a dynamical approach to quantum memories using an
oscillator-cavity model. This overcomes the known difficulties of achieving
high quantum input-output fidelity with storage times long compared to the
input signal duration. We use a generic model of the memory response, which is
applicable to any linear storage medium ranging from a superconducting device
to an atomic medium. The temporal switching or gating of the device may either
be through a control field changing the coupling, or through a variable
detuning approach, as in more recent quantum memory experiments. An exact
calculation of the temporal memory response to an external input is carried
out. This shows that there is a mode-matching criterion which determines the
optimum input and output mode shape. This optimum pulse shape can be modified
by changing the gate characteristics. In addition, there is a critical coupling
between the atoms and the cavity that allows high fidelity in the presence of
long storage times. The quantum fidelity is calculated both for the coherent
state protocol, and for a completely arbitrary input state with a bounded total
photon number. We show how a dynamical quantum memory can surpass the relevant
classical memory bound, while retaining a relatively long storage time.Comment: 16 pages, 9 figure
Twistor and Polytope Interpretations for Subleading Color One-Loop Amplitudes
We use the relation of the one-loop subleading-color amplitudes to the
one-loop -point leading color amplitudes in SYM, to derive a
polytope interpretation for the former in the case, and a representation
in momentum twistor space for the general case. These techniques are
explored in detail for the 5-point and 6-point amplitudes. We briefly discuss
the implications for IR divergences.Comment: 30 pages, 2 figures; typos corrected, citations added; fig2 modified,
fig. 1 and explanations added, mostly around eq. 2.11; version accepted in
Nucl.Phys.
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