arXiv subjects

Simon Chelkowski

Publications and source records attributed to Simon Chelkowski.

14 recordsLinked to original sources

arXiv2011

Review of the Laguerre-Gauss mode technology research program at Birmingham

Gravitational wave detectors from the advanced generation onwards are expected to be limited in sensitivity by thermal noise of the optics, making the reduction of this noise a key factor in the success of such detectors. A proposed method for reducing the impact of this noise is to use higher-order Laguerre-Gauss (LG) modes for the readout beam, as opposed to the currently used fundamental mode. We present here a synopsis of the research program undertaken by the University of Birmingham into the suitability of LG mode technology for future gravitational wave detectors. This will cover our previous and current work on this topic, from initial simulations and table-top LG mode experiments up to implementation in a prototype scale suspended cavity and high-power laser bench.

astro-ph.IM↗

arXiv2010

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.

astro-ph.IM↗

arXiv2009

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.

gr-qc↗

arXiv2009

A Xylophone Configuration for a third Generation Gravitational Wave Detector

Achieving the demanding sensitivity and bandwidth, envisaged for third generation gravitational wave (GW) observatories, is extremely challenging with a single broadband interferometer. Very high optical powers (Megawatts) are required to reduce the quantum noise contribution at high frequencies, while the interferometer mirrors have to be cooled to cryogenic temperatures in order to reduce thermal noise sources at low frequencies. To resolve this potential conflict of cryogenic test masses with high thermal load, we present a conceptual design for a 2-band xylophone configuration for a third generation GW observatory, composed of a high-power, high-frequency interferometer and a cryogenic low-power, low-frequency instrument. Featuring inspiral ranges of 3200Mpc and 38000Mpc for binary neutron stars and binary black holes coalesences, respectively, we find that the potential sensitivity of xylophone configurations can be significantly wider and better than what is possible in a single broadband interferometer.

gr-qc↗

arXiv2009

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.

gr-qc↗

arXiv2008

Pushing towards the ET sensitivity using 'conventional' technology

Recently, the design study `Einstein gravitational wave Telescope' (ET) has been funded within the European FP7 framework. The ambitious goal of this project is to provide a conceptual design of a detector with a hundred times better sensitivity than currently operating instruments. It is expected that this will require the development and implementation of new technologies, which go beyond the concepts employed for the first and second detector generations. However, it is a very interesting and educational exercise to imagine a Michelson interferometer in which conventional technologies have been pushed to - or maybe beyond - their limits to reach the envisaged sensitivity for the Einstein Telescope. In this document we present a first sketchy analysis of what modifications and improvements are necessary to go, step-by-step, from second generation gravitational wave detectors to the Einstein Telescope.

gr-qc↗

arXiv2007

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.

quant-ph↗

arXiv2007

Squeezed-field injection for gravitational wave interferometers

In a recent table-top experiment we demonstrated the compatibility of three advanced interferometer techniques for gravitational wave detection, namely power-recycling, detuned signal-recycling and squeezed field injection. The interferometer's signal to noise ratio was improved by up to 2.8 dB beyond the coherent state's shot-noise. This value was mainly limited by optical losses on the squeezed field. We present a detailed analysis of the optical losses of in our experiment and provide an estimation of the possible nonclassical performance of a future squeezed field enhanced GEO600 detector.

quant-ph↗

arXiv2007

Demonstration of a squeezed light enhanced power- and signal-recycled Michelson interferometer

We report on the experimental combination of three advanced interferometer techniques for gravitational wave detection, namely power-recycling, detuned signal-recycling and squeezed field injection. For the first time we experimentally prove the compatibility of especially the latter two. To achieve a broadband non-classical sensitivity improvement we applied a filter cavity for compensation of quadrature rotation. Signal to noise ratio was improved by up to 2.8 dB beyond the coherent state's shot noise. The complete set-up was stably locked for arbitrary times and characterized by injected single-sideband modulation fields.

quant-ph↗

arXiv2007

Coherent control of vacuum squeezing in the Gravitational-Wave Detection Band

We propose and demonstrate a coherent control scheme for stable phase locking of squeezed vacuum fields. We focus on sideband fields at frequencies from 10Hz to 10kHz which is a frequency regime of particular interest in gravitational wave detection and for which conventional control schemes have failed so far. A vacuum field with broadband squeezing covering this entire band was produced using optical parametric oscillation and characterized with balanced homodyne detection. The system was stably controlled over long periods utilizing two coherent but frequency shifted control fields. In order to demonstrate the performance of our setup the squeezed field was used for a nonclassical sensitivity improvement of a Michelson interferometer at audio frequencies.

quant-ph↗

arXiv2007

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.

quant-ph↗

arXiv2007

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.

quant-ph↗

arXiv2007

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.

quant-ph↗

arXiv2003

Squeezed-input, optical-spring, signal-recycled gravitational-wave detectors

We theoretically analyze the quantum noise of signal-recycled laser interferometric gravitational-wave detectors with additional input and output optics, namely frequency-dependent squeezing of the vacuum entering the dark port and frequency-dependent homodyne detection. We combine the work of Buonanno and Chen on the quantum noise of signal-recycled interferometers with ordinary input-output optics, and the work of Kimble el al. on frequency-dependent input-output optics with conventional interferometers. Analytical formulas for the optimal input and output frequency dependencies are obtained. It is shown that injecting squeezed light with the optimal frequency-dependent squeezing angle into the dark port yields an improvement on the noise spectral density by a factor of exp(-2r) (in power) over the entire squeezing bandwidth, where r is the squeezing parameter. It is further shown that frequency-dependent (variational) homodyne read-out leads to an additional increase in sensitivity which is significant in the wings of the doubly resonant structure. The optimal variational input squeezing in case of an ordinary output homodyne detection is shown to be realizable by applying two optical filters on a frequency-independent squeezed vacuum. Throughout this paper, we take as example the signal-recycled topology currently being completed at the GEO600 site. However, theoretical results obtained here are also applicable to the proposed topology of Advanced LIGO.

gr-qc↗