13 research outputs found
Optical Absorption Measurements on Crystalline Silicon at 1550nm
Crystalline silicon is currently being discussed as test-mass material for
future generations of gravitational wave detectors that will operate at
cryogenic temperatures. We present optical absorption measurements on a
large-dimension sample of crystalline silicon at a wavelength of 1550nm at room
temperature. The absorption was measured in a monolithic cavity setup using the
photo-thermal self-phase modulation technique. The result for the absorption
coefficient of this float-zone sample with a specific resistivity of 11kOhm cm
was measured to be \alpha_A=(264 +/- 39)ppm/cm.Comment: 11 pages, 6 figures, 1 tabl
Observation of squeezed states with strong photon number oscillations
Squeezed states of light constitute an important nonclassical resource in the
field of high-precision measurements, e.g. gravitational wave detection, as
well as in the field of quantum information, e.g. for teleportation, quantum
cryptography, and distribution of entanglement in quantum computation networks.
Strong squeezing in combination with high purity, high bandwidth and high
spatial mode quality is desirable in order to achieve significantly improved
performances contrasting any classical protocols. Here we report on the
observation of the strongest squeezing to date of 11.5 dB, together with
unprecedented high state purity corresponding to a vacuum contribution of less
than 5%, and a squeezing bandwidth of about 170 MHz. The analysis of our
squeezed states reveals a significant production of higher-order pairs of
quantum-correlated photons, and the existence of strong photon number
oscillations.Comment: 7 pages, 6 figure
Observation of squeezed light with 10dB quantum noise reduction
Squeezing of light's quantum noise requires temporal rearranging of photons.
This again corresponds to creation of quantum correlations between individual
photons. Squeezed light is a non-classical manifestation of light with great
potential in high-precision quantum measurements, for example in the detection
of gravitational waves. Equally promising applications have been proposed in
quantum communication. However, after 20 years of intensive research doubts
arose whether strong squeezing can ever be realized as required for eminent
applications. Here we show experimentally that strong squeezing of light's
quantum noise is possible. We reached a benchmark squeezing factor of 10 in
power (10dB). Thorough analysis reveals that even higher squeezing factors will
be feasible in our setup.Comment: 10 pages, 4 figure
Status of the GEO 600 squeezed-light laser
In the course of the high-frequency upgrade of GEO 600, its optical
configuration was extended by a squeezed-light laser [1]. Recently, a
non-classically enhanced measurement sensitivity of GEO 600 was reported [2].
In this paper, a characterization of the squeezed-light laser is presented.
Thereupon, the status of the integration into GEO 600 is reviewed, focussing on
the sources of optical loss limiting the shot noise reduction by squeezing at
the moment. Finally, the possibilities for a future loss reduction are
discussed.Comment: Proceeding of the 9th Edoardo Amaldi Conference on Gravitational
Wave
Experimental characterization of frequency dependent squeezed light
We report on the demonstration of broadband squeezed laser beams that show a
frequency dependent orientation of the squeezing ellipse. Carrier frequency as
well as quadrature angle were stably locked to a reference laser beam at
1064nm. This frequency dependent squeezing was characterized in terms of noise
power spectra and contour plots of Wigner functions. The later were measured by
quantum state tomography. Our tomograph allowed a stable lock to a local
oscillator beam for arbitrary quadrature angles with one degree precision.
Frequency dependent orientations of the squeezing ellipse are necessary for
squeezed states of light to provide a broadband sensitivity improvement in
third generation gravitational wave interferometers. We consider the
application of our system to long baseline interferometers such as a future
squeezed light upgraded GEO600 detector.Comment: 8 pages, 8 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
The GEO600 squeezed light source
The next upgrade of the GEO600 gravitational wave detector is scheduled for
2010 and will, in particular, involve the implementation of squeezed light. The
required non-classical light source is assembled on a 1.5m^2 breadboard and
includes a full coherent control system and a diagnostic balanced homodyne
detector. Here, we present the first experimental characterization of this
setup as well as a detailed description of its optical layout. A squeezed
quantum noise of up to 9dB below the shot-noise level was observed in the
detection band between 10Hz and 10kHz. We also present an analysis of the
optical loss in our experiment and provide an estimation of the possible
non-classical sensitivity improvement of the future squeezed light enhanced
GEO600 detector.Comment: 8 pages, 4 figure
Long-term stable squeezed vacuum state of light for gravitational wave detectors
Currently, the German/British gravitational wave detector GEO600 is being
upgraded in course of the GEO-HF program. One part of this upgrade consists of
the integration of a squeezed light laser to nonclassically improve the
detection sensitivity at frequencies where the instrument is limited by shot
noise. This has been achieved recently [1]. The permanent employment of
squeezed light in gravitational wave observatories requires a long-term
stability of the generated squeezed state. In this paper, we discuss an
unwanted mechanism that can lead to a varying squeezing factor along with a
changing phase of the squeezed field. We present an extension of the
implemented coherent control scheme [2] that allowed an increase in the
long-term stability of the GEO600 squeezed light laser. With it, a quantum
noise reduction by more than 9 dB in the frequency band of 10 Hz - 10 kHz was
observed over up to 20 hours with a duty cycle of more than 99%