721 research outputs found
Experimental demonstration of a Displacement noise Free Interferometry scheme for gravitational wave detectors showing displacement noise reduction at low frequencies
This paper reports an experimental demonstration of partial displacement
noise free laser interferometry in the gravitational wave detection band. The
used detuned Fabry-Perot cavity allows the isolation of the mimicked
gravitational wave signal from the displacement noise on the cavities input
mirror. By properly combining the reflected and transmitted signals from the
cavity a reduction of the displacement noise was achieved. Our results
represent the first experimental demonstration of this recently proposed
displacement noise free laser interferometry scheme. Overall we show that the
rejection ratio of the displacement noise to the gravitational wave signal was
improved in the frequency range of 10 Hz to 10 kHz with a typical factor of 60.Comment: 5 pages, 3 figure
Prospects of higher-order Laguerre Gauss modes in future gravitational wave detectors
The application of higher-order Laguerre Gauss (LG) modes in large-scale
gravitational wave detectors has recently been proposed. In comparison to the
fundamental mode, some higher-order Laguerre Gauss modes can significantly
reduce the contribution of coating Brownian noise. Using frequency domain
simulations we give a detailed analysis of the longitudinal and angular control
signals derived with a LG33 mode in comparison to the fundamental TEM00 mode.
The performance regarding interferometric sensing and control of the LG33 mode
is found to be similar, if not even better in all aspects of interest. In
addition, we evaluate the sensitivity gain of the implementation of LG33 modes
into the Advanced Virgo instrument. Our analysis shows that the application of
the LG33 mode results in a broadband improvement of the Advanced Virgo
sensitivity, increasing the potential detection rate of binary neutron star
inspirals by a factor 2.1.Comment: 12 pages, 8 figure
Coherent control of broadband vacuum squeezing
We present the observation of optical fields carrying squeezed vacuum states
at sideband frequencies from 10Hz to above 35MHz. The field was generated with
type-I optical parametric oscillation below threshold at 1064nm. A coherent,
unbalanced classical modulation field at 40MHz enabled the generation of error
signals for stable phase control of the squeezed vacuum field with respect to a
strong local oscillator. Broadband squeezing of approximately -4dB was measured
with balanced homodyne detection. The spectrum of the squeezed field allows a
quantum noise reduction of ground-based gravitational wave detectors over their
full detection band, regardless of whether homodyne readout or radio-frequency
heterodyne readout is used.Comment: 9 pages, 8 figure
XUV lasing during strong-field assisted transient absorption in molecules
Using ab-initio non-Born-Oppenheimer simulations, we demonstrate
amplification of XUV radiation in a high-harmonic generation type process using
the example of the hydrogen molecular ion. A small fraction of the molecules is
pumped to a dissociative Rydberg state from which IR-assisted XUV amplification
is observed. We show that starting at sufficiently high IR driving field
intensities the ground state molecules become quasi-transparent for XUV
radiation, while due to stabilization gain from Rydberg states is maintained,
thus leading to lasing from strongly driven Rydberg states. Further increase of
the IR intensity even leads to gain by initially unexcited molecules, which are
quickly excited by the driving IR pulse
Quantum engineering of squeezed states for quantum communication and metrology
We report the experimental realization of squeezed quantum states of light,
tailored for new applications in quantum communication and metrology. Squeezed
states in a broad Fourier frequency band down to 1 Hz has been observed for the
first time. Nonclassical properties of light in such a low frequency band is
required for high efficiency quantum information storage in electromagnetically
induced transparency (EIT) media. The states observed also cover the frequency
band of ultra-high precision laser interferometers for gravitational wave
detection and can be used to reach the regime of quantum non-demolition
interferometry. And furthermore, they cover the frequencies of motions of
heavily macroscopic objects and might therefore support the attempts to observe
entanglement in our macroscopic world.Comment: 12 pages, 3 figure
Visualizing quantum entanglement and the EPR paradox during the photodissociation of a diatomic molecule using two ultrashort laser pulses
We investigate theoretically the dissociative ionization of a H2+ molecule
using two ultrashort laser (pump-probe) pulses. The pump pulse prepares a
dissociating nuclear wave packet on an ungerade surface of H2+. Next, an UV (or
XUV) probe pulse ionizes this dissociating state at large (R = 20 - 100 bohr)
internuclear distance. We calculate the momenta distributions of protons and
photoelectrons which show a (two-slit-like) interference structure. A general,
simple interference formula is obtained which depends on the electron and
protons momenta, as well as on the pump-probe delay on the pulses durations and
polarizations. This interference can be interpreted as visualization of an
electron state delocalized over the two-centres. This state is an entangled
state of a hydrogen atom with a momentum p and a proton with an opposite
momentum. -p dissociating on the ungerade surface of H2+. This pump-probe
scheme can be used to reveal the nonlocality of the electron which intuitively
should be localized on just one of the protons separated by the distance R much
larger than the atomic Bohr orbit
Experimental demonstration of higher-order Laguerre-Gauss mode interferometry
The compatibility of higher-order Laguerre-Gauss (LG) modes with
interferometric technologies commonly used in gravitational wave detectors is
investigated. In this paper we present the first experimental results
concerning the performance of the LG33 mode in optical resonators. We show that
the Pound-Drever-Hall error signal for a LG33 mode in a linear optical
resonator is identical to that of the more commonly used LG00 mode, and
demonstrate the feedback control of the resonator with a LG33 mode. We
succeeded to increase the mode purity of a LG33 mode generated using a
spatial-light modulator from 51% to 99% upon transmission through a linear
optical resonator. We further report the experimental verification that a
triangular optical resonator does not transmit helical LG modes
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
Broadband squeezing of quantum noise in a Michelson interferometer with Twin-Signal-Recycling
Twin-Signal-Recycling (TSR) builds on the resonance doublet of two optically
coupled cavities and efficiently enhances the sensitivity of an interferometer
at a dedicated signal frequency. We report on the first experimental
realization of a Twin-Signal-Recycling Michelson interferometer and also its
broadband enhancement by squeezed light injection. The complete setup was
stably locked and a broadband quantum noise reduction of the interferometers
shot noise by a factor of up to 4\,dB was demonstrated. The system was
characterized by measuring its quantum noise spectra for several tunings of the
TSR cavities. We found good agreement between the experimental results and
numerical simulations
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