First Long-Term Application of Squeezed States of Light in a Gravitational-Wave Observatory

We report on the first long-term application of squeezed vacuum states of light to improve the shot-noise-limited sensitivity of a gravitational-wave observatory. In particular, squeezed vacuum was applied to the German/British detector GEO600 during a period of three months from June to August 2011, when GEO600 was performing an observational run together with the French/Italian Virgo detector. In a second period squeezing application continued for about 11 months from November 2011 to October 2012. During this time, squeezed vacuum was applied for 90.2% (205.2 days total) of the time that science-quality data was acquired with GEO600. Sensitivity increase from squeezed vacuum application was observed broad-band above 400Hz. The time average of gain in sensitivity was 26% (2.0dB), determined in the frequency band from 3.7kHz to 4.0kHz. This corresponds to a factor of two increase in observed volume of the universe, for sources in the kHz region (e.g. supernovae, magnetars). We introduce three new techniques to enable stable long-term application of squeezed light, and show that the glitch-rate of the detector did not increase from squeezing application. Squeezed vacuum states of light have arrived as a permanent application, capable of increasing the astrophysical reach of gravitational-wave detectors.Comment: 4 pages, 4 figure

Apex Exponents for Polymer--Probe Interactions

We consider self-avoiding polymers attached to the tip of an impenetrable probe. The scaling exponents $\gamma_1$ and $\gamma_2$, characterizing the number of configurations for the attachment of the polymer by one end, or at its midpoint, vary continuously with the tip's angle. These apex exponents are calculated analytically by $\epsilon$-expansion, and numerically by simulations in three dimensions. We find that when the polymer can move through the attachment point, it typically slides to one end; the apex exponents quantify the entropic barrier to threading the eye of the probe

A simple high-sensitivity technique for purity analysis of xenon gas

We report on the development and performance of a high-sensitivity purity-analysis technique for gaseous xenon. The gas is sampled at macroscopic pressure from the system of interest using a UHV leak valve. The xenon present in the sample is removed with a liquid-nitrogen cold trap, and the remaining impurities are observed with a standard vacuum mass-spectroscopy device. Using calibrated samples of xenon gas spiked with known levels of impurities, we find that the minimum detectable levels of N2, O2, and methane are 1 ppb, 160 ppt, and 60 ppt respectively. This represents an improvement of about a factor of 10,000 compared to measurements performed without a coldtrap.Comment: 20 pages, 5 figure

The Critical Coupling Likelihood Method: A new approach for seamless integration of environmental and operating conditions of gravitational wave detectors into gravitational wave searches

Any search effort for gravitational waves (GW) using interferometric detectors like LIGO needs to be able to identify if and when noise is coupling into the detector's output signal. The Critical Coupling Likelihood (CCL) method has been developed to characterize potential noise coupling and in the future aid GW search efforts. By testing two hypotheses about pairs of channels, CCL is able to identify undesirable coupled instrumental noise from potential GW candidates. Our preliminary results show that CCL can associate up to $\sim 80$ of observed artifacts with $SNR \geq 8$, to local noise sources, while reducing the duty cycle of the instrument by $\lesssim 15$. An approach like CCL will become increasingly important as GW research moves into the Advanced LIGO era, going from the first GW detection to GW astronomy.Comment: submitted CQ

Complete physical simulation of the entangling-probe attack on the BB84 protocol

We have used deterministic single-photon two qubit (SPTQ) quantum logic to implement the most powerful individual-photon attack against the Bennett-Brassard 1984 (BB84) quantum key distribution protocol. Our measurement results, including physical source and gate errors, are in good agreement with theoretical predictions for the Renyi information obtained by Eve as a function of the errors she imparts to Alice and Bob's sifted key bits. The current experiment is a physical simulation of a true attack, because Eve has access to Bob's physical receiver module. This experiment illustrates the utility of an efficient deterministic quantum logic for performing realistic physical simulations of quantum information processing functions.Comment: 4 pages, 5 figure

Study of a zirconium getter for purification of xenon gas

Oxygen, nitrogen and methane purification efficiencies for a common zirconium getter are measured in 1050 Torr of xenon gas. Starting with impurity concentrations near 10^{-6} g/g, the outlet impurity level is found to be less than 120*10^{-12} g/g for O2 and less than 950*10^{-12} g/g for N2. For methane we find residual contamination of the purified gas at concentrations varying over three orders of magnitude, depending on the purifier temperature and the gas flow rate. A slight reduction in the purifier's methane efficiency is observed after 13 mg of this impurity has been absorbed, which we attribute to partial exhaustion of the purifier's capacity for this species. We also find that the purifier's ability to absorb N2 and methane can be extinguished long before any decrease in O2 performance is observed, and slower flow rates should be employed for xenon purification due to the cooling effect that the heavy gas has on the getter.Comment: 14 pages, 5 figure

A Xenon Condenser with a Remote Liquid Storage Vessel

We describe the design and operation of a system for xenon liquefaction in which the condenser is separated from the liquid storage vessel. The condenser is cooled by a pulse tube cryocooler, while the vessel is cooled only by the liquid xenon itself. This arrangement facilitates liquid particle detector research by allowing easy access to the upper and lower flanges of the vessel. We find that an external xenon gas pump is useful for increasing the rate at which cooling power is delivered to the vessel, and we present measurements of the power and efficiency of the apparatus.Comment: 22 pages, 7 figures Corrected typos in authors lis

A prototype vector magnetic field monitoring system for a neutron electric dipole moment experiment

We present results from a first demonstration of a magnetic field monitoring system for a neutron electric dipole moment experiment. The system is designed to reconstruct the vector components of the magnetic field in the interior measurement region solely from exterior measurements