7,040 research outputs found
Generating Hermite polynomial excited squeezed states by means of conditional measurements on a beam splitter
A scheme for conditional generating a Hermite polynomial excited squeezed
vacuum states (HESVS) is proposed. Injecting a two-mode squeezed vacuum state
(TMSVS) into a beam splitter (BS) and counting the photons in one of the output
channels, the conditional state in the other output channel is just a HESVS. To
exhibit a number of nonclassical effects and non-Guassianity, we mainly
investigate the photon number distribution, sub-Poissonian distribution,
quadrature component distribution, and quasi-probability distribution of the
HPESVS. We find that its nonclassicality closely relates to the control
parameter of the BS, the squeezed parameter of the TMSVS, and the photon number
of conditional measurement. These further demonstrate that performing the
conditional measurement on a BS is an effective approach to generate
non-Guassian state.Comment: 8 pages, 8 figures. arXiv admin note: text overlap with
arXiv:quant-ph/9703039 by other author
Counter-propagating solitons in microresonators
Solitons occur in many physical systems when a nonlinearity compensates wave
dispersion. Their recent formation in microresonators opens a new research
direction for nonlinear optical physics and provides a platform for
miniaturization of spectroscopy and frequency metrology systems. These
microresonator solitons orbit around a closed waveguide path and produce a
repetitive output pulse stream at a rate set by the round-trip time. In this
work counter-propagating solitons that simultaneously orbit in an opposing
sense (clockwise/counter-clockwise) are studied. Despite sharing the same
spatial mode family, their round-trip times can be precisely and independently
controlled. Furthermore, a state is possible in which both the relative optical
phase and relative repetition rates of the distinct soliton streams are locked.
This state allows a single resonator to produce dual-soliton frequency-comb
streams having different repetition rates, but with high relative coherence
useful in both spectroscopy and laser ranging systems.Comment: Qi-Fan Yang and Xu Yi contributed equally to this wor
Spatial-mode-interaction-induced dispersive-waves and their active tuning in microresonators
The nonlinear propagation of optical pulses in dielectric waveguides and
resonators provides a laboratory to investigate a wide range of remarkable
interactions. Many of the resulting phenomena find applications in optical
systems. One example is dispersive wave generation, the optical analog of
Cherenkov radiation. These waves have an essential role in fiber spectral
broadeners that are routinely used in spectrocopy and metrology. Dispersive
waves form when a soliton pulse begins to radiate power as a result of
higher-order dispersion. Recently, dispersive wave generation in microcavities
has been reported by phase matching the waves to dissipative Kerr cavity (DKC)
solitons. Here, it is shown that spatial mode interactions within a microcavity
can also be used to induce dispersive waves. These interactions are normally
avoided altogether in DKC soliton generation. The soliton self frequency shift
is also shown to induce fine tuning control of the dispersive wave frequency.
Both this mechanism and spatial mode interactions provide a new method to
spectrally control these important waves.Comment: Qi-Fan Yang and Xu Yi contributed equally to this wor
A Structural Model of Demand, Cost, and Export Market Selection for Chinese Footwear Producers
In this paper we use micro data on both trade and production for a sample of large Chinese manufacturing firms in the footwear industry from 2002-2006 to estimate an empirical model of export demand, pricing, and market participation by destination market. We use the model to construct indexes of firm-level demand, cost, and export market profitability. The empirical results indicate substantial firm heterogeneity in both the demand and cost dimensions with demand being more dispersed. The firm-specific demand and cost components are very useful in explaining differences in the extensive margin of trade, the length of time a firm exports to a destination, and the number and mix of destinations, as well as the export prices, while cost is more important in explaining the quantity of firm exports on the intensive margin. We use the estimates to analyze the reallocation resulting from removal of the quota on Chinese footwear exports to the EU and find that it led to a rapid restructuring of export supply sources in favor of firms with high demand and low cost indexes.
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