1,684 research outputs found
A bright, pulsed two-mode squeezer
We report the realization of a bright ultrafast two-mode squeezer based on
type II parametric downconversion (PDC) in periodically poled
(PP-KTP) waveguides. It produces a pulsed two-mode squeezed
vacuum state: a photon-number entangled pair of truly single-mode pulses or, in
terms of continuous variables quantum optics, a pulsed, single mode
Einstein-Podolsky-Rosen (EPR) state in the telecom regime. We prove the single
mode character of our source by measuring its correlation function
and demonstrate a mean photon number of up to 2.5 per pulse, equivalent to 11dB
of two-mode squeezing.Comment: 4 pages, 3 figure
Effects of amputation and Corynebacterium parvum on tumour metastases in mice.
The effects of operation (lower-limb amputation) on the growth of the Lewis lung tumour and its metastases were studied. The role of C. parvum in counteracting these effects was investigated. Anaesthesia alone or with amputation did not affect primary tumour growth. C. parvum depressed this growth. Anaesthesia did not affect the number of pulmonary metastases, but amputation caused a significant increase. C. parvum inhibited metastases and completely counteracted the effects of operation on them. Large doses of cortisone acetate significantly increased metastases but small doses had no effect. Experiments with adrenalectomized mice suggested the effects of operation were due to non-specific stress
Aspects of the geography of recreation in Tasmania
The importance of outdoor holiday-making in Australia so far seems to have escaped the notice of
geographers in spite of the fact that the quality of the country's recreational resources is a
common matter of Australian pride. The author does not know of a single article in an academic
journal, or of a University thesis, which deals with the geographical aspects of recreation in
Australia. However, this omission is not peculiar to this part of the world; it seems in fact
that the importance of the subject is receiving due acknowledgement only in the United States of
America. This neglect, and the prospect of a continuing growth in the demand for recreation,
should give particular interest to a pioneer study in this field
New Reports of Exotic and Native Ambrosia and Bark Beetle Species (Coleoptera: Curculionidae: Scolytinae) From Ohio
In a 2007 survey of ambrosia and bark beetles (Coleoptera: Curculionidae: Scolytinae) along a transect in northeastern Ohio, we collected six exotic and three native species not previously reported from the state. These species include the exotic ambrosia beetles Ambrosiodmus rubricollis (Eichhoff), Dryoxylon onoharaensum (Murayama), Euwallacea validus (Eichhoff), Xyleborus californicus Wood, Xyleborus pelliculosusEichhoff, and Xylosandrus crassiusculus (Motschulsky). The native ambrosia beetle Corthylus columbianus Hopkins, and the native bark beetles Dryocoetes autographus (Ratzeburg) and Hylastes tenuis Eichhoff are also reported from Ohio for the first time. Our study suggests a northward range expansion for five of the six exotic species including, X. crassiusculus, which is an important pest of nursery and orchard crops in the southeastern United States
Accumulation at South Pole: Comparison of two 900-year records
This is the published version, also available here: http://dx.doi.org/10.1029/1999JD900501.Two 900-year records of annual accumulation at South Pole are compared to evaluate the origin and significance of observed variations. Despite difficulties establishing absolute timescales, due to problems identifying annual layer markers, the two records can be correlated with confidence after moderate smoothing. This correlation shows that over the time period considered (1050–1956 A.D.) no climatically significant changes in accumulation occurred. Instead, fluctuations preserved in the two cores reflect spatial variations in snow accumulation, associated with nonuniform deposition induced by surface relief on the scale of several kilometers
Intrinsically narrowband pair photon generation in microstructured fibres
In this paper we study the tailoring of photon spectral properties generated
by four-wave mixing in a birefringent photonic crystal fibre (PCF). The aim is
to produce intrinsically narrow-band photons and hence to achieve high
non-classical interference visibility and generate high fidelity entanglement
without any requirement for spectral filtering, leading to high effective
detection efficiencies. We show unfiltered Hong-Ou-Mandel interference
visibilities of 77% between photons from the same PCF, and 80% between separate
sources. We compare results from modelling the PCF to these experiments and
analyse photon purities.Comment: 23 pages, 17 figures, Comments Welcom
Nonclassical 2-photon interference with separate intrinsically narrowband fibre sources
In this paper, we demonstrate a source of photon pairs based on
four-wave-mixing in photonic crystal fibres. Careful engineering of the phase
matching conditions in the fibres enables us to create photon pairs at 597 nm
and 860 nm in an intrinsically factorable state showing no spectral
correlations. This allows for heralding one photon in a pure state and hence
renders narrow band filtering obsolete. The source is narrow band, bright and
achieves an overall detection efficiency of up to 21% per photon. For the first
time, a Hong-Ou-Mandel interference with unfiltered photons from separate fibre
sources is presented.Comment: 10 pages, 6 figure
A two-way photonic interface for linking Sr+ transition at 422 nm to the telecommunications C-band
We report a single-stage bi-directional interface capable of linking Sr+
trapped ion qubits in a long-distance quantum network. Our interface converts
photons between the Sr+ emission wavelength at 422 nm and the telecoms C-band
to enable low-loss transmission over optical fiber. We have achieved both up-
and down-conversion at the single photon level with efficiencies of 9.4% and
1.1% respectively. Furthermore we demonstrate noise levels that are low enough
to allow for genuine quantum operation in the future.Comment: 5 pages, 4 figure
Gigahertz pulse source by compression of mode-locked VECSEL pulses coherently broadened in the normal dispersion regime
Ultratunable quantum frequency conversion in photonic crystal fiber
Quantum frequency conversion of single photons between wavelength bands is a key enabler to realizing widespread quantum networks. We demonstrate the quantum frequency conversion of a heralded 1551 nm photon to any wavelength within an ultrabroad (1226 - 1408 nm) range in a group-velocity-symmetric photonic crystal fiber (PCF), covering over 150 independent frequency bins. The target wavelength is controlled by tuning only a single pump laser wavelength. We find internal, and total, conversion efficiencies of 12(1)% and 1.4(2)%, respectively. For the case of converting 1551 nm to 1300 nm we measure a heralded for converted light from an input with . We expect that this PCF can be used for a myriad of quantum networking tasks
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