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.
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.
Phys.Rev. D68 (2003) 042001 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.
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.
Fly ash is the residue of coal combustion collected by electrostatic or cyclone separator. It is one of the largest quantities of waste disposed in the world. Fly ash represents mostly less than 100 ...micron in size spherical particles with pozzolanic and hydraulic properties depending on its composition. Utilization of fly ash depends on its chemical, mineralogical composition and morphology. Because of coal nature, fly ash represents a significant drawback with presence of radionuclides such as 226Ra, 232Th and 40K. The fly ash can be used for various applications. The main amount of the fly ash is used for building materials production as cement additive and concrete production. Therefore, the determination of radiological properties both in the fly ash and final products are important parameters to consider. Radioactive isotopes cause release of alpha, beta, particles gamma rays and radon exhalation. However, fly ash addition doesn't increase the gamma dose substantially. Moreover, radioactive elements are generally immobilized within glass phase and therefore, radon emanation is not high. In this review the latest development of utilization of the various fly ashes with a different level of radioactive elements content for value added application are presented and a possible new direction of applications are discussed.
•Have reviewed published papers on radioactivity of fly ashes.•Critically assessed previous papers on characterization of radioactive fly ashes.•Assessed building materials prepared with addition of radioactive fly ash in terms of radiological safety.•The directions for future research and development were proposed.
