51 research outputs found
Squeezed light at 1550 nm with a quantum noise reduction of 12.3 dB
Continuous-wave squeezed states of light at the wavelength of 1550 nm have
recently been demonstrated, but so far the obtained factors of noise
suppression still lag behind today's best squeezing values demonstrated at 1064
nm. Here we report on the realization of a half-monolithic nonlinear resonator
based on periodically-poled potassium titanyl phosphate which enabled the
direct detection of up to 12.3 dB of squeezing at 5 MHz. Squeezing was observed
down to a frequency of 2 kHz which is well within the detection band of
gravitational wave interferometers. Our results suggest that a long-term stable
1550 nm squeezed light source can be realized with strong squeezing covering
the entire detection band of a 3rd generation gravitational-wave detector such
as the Einstein Telescope
High-bandwidth squeezed light at 1550 nm from a compact monolithic PPKTP cavity
We report the generation of squeezed vacuum states of light at 1550 nm with a
broadband quantum noise reduction of up to 4.8 dB ranging from 5 MHz to 1.2 GHz
sideband frequency. We used a custom-designed 2.6 mm long biconvex
periodically-poled potassium titanyl phosphate (PPKTP) crystal. It featured
reflectively coated end surfaces, 2.26 GHz of linewidth and generated the
squeezing via optical parametric amplification. Two homodyne detectors with
different quantum efficiencies and bandwidths were used to characterize the
non-classical noise suppression. We measured squeezing values of up to 4.8 dB
from 5 to 100 MHz and up to 3 dB from 100 MHz to 1.2 GHz. The squeezed vacuum
measurements were limited by detection loss. We propose an improved detection
scheme to measure up to 10 dB squeezing over 1 GHz. Our results of GHz
bandwidth squeezed light generation provide new prospects for high-speed
quantum key distribution.Comment: 8 pages, 4 figure
Gaussian entanglement distribution with gigahertz bandwidth
The distribution of entanglement with Gaussian statistic can be used to
generate a mathematically-proven secure key for quantum cryptography. The
distributed secret key rate is limited by the {entanglement strength, the
entanglement bandwidth and the bandwidth of the photo-electric detectors}. The
development of a source for strongly, bi-partite entangled light with high
bandwidth promises an increased measurement speed and a linear boost in the
secure data rate. Here, we present the experimental realization of a Gaussian
entanglement source with a bandwidth of more than 1.25\,GHz. The entanglement
spectrum was measured with balanced homodyne detectors and was quantified via
the inseparability criterion introduced by Duan and coworkers with a critical
value of 4 below which entanglement is certified. Our measurements yielded an
inseparability value of about 1.8 at a frequency of 300\,MHz to about 2.8 at
1.2\,GHz extending further to about 3.1 at 1.48\,GHz. In the experiment we used
two 2.6\,mm long monolithic periodically poled potassium titanyl phosphate
(PPKTP) resonators to generate two squeezed fields at the telecommunication
wavelength of 1550\,nm. Our result proves the possibility of generating and
detecting strong continuous-variable entanglement with high speed.Comment: 5 pages, 3 figures, published in Optics Letter
Observation of continuous-wave squeezed light at 1550 nm
We report on the generation of continuous-wave squeezed vacuum states of
light at the telecommunication wavelength of 1550 nm. The squeezed vacuum
states were produced by type I optical parametric amplification (OPA) in a
standing-wave cavity built around a periodically poled potassium titanyl
phosphate (PPKTP) crystal. A non-classical noise reduction of 5.3 dB below the
shot noise was observed by means of balanced homodyne detection.Comment: 4 pages, 3 figure
High-efficiency frequency doubling of continuous-wave laser light
We report on the observation of high efficiency frequency doubling of 1550 nm
continuous-wave laser light in a nonlinear cavity containing a periodically
poled potassium titanyl phosphate crystal (PPKTP). The fundamental field had a
power of 1.10 W and was converted into 1.05 W at 775 nm, yielding a total
external conversion efficiency of (95 \pm 1)%. The latter value is based on the
measured depletion of the fundamental field being consistent with the absolute
values derived from numerical simulations. According to our model, the
conversion efficiency achieved was limited by the non-perfect mode-matching
into the nonlinear cavity and the pump power available. Our result shows that
cavity-assisted frequency conversion based on PPKTP is well suited for
low-decoherence frequency conversion of quantum states of light.Comment: 3 pages, 3 figure
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