GEO600 gravitational wave detector at the fundamental quantum limit

by: R. Demkowicz-Dobrzanski, K. Banaszek, R. Schnabel


UWAW (University of Warsaw)
LUH (Gottfried Wilhelm Leibniz Universitaet Hannover)

Gravitational wave detectors are to date one of the most precise measuring devices, reaching length measurement sensitivities at an apparently absurd levels of fractions of the size of the proton. More surprisingly, the precision may be further enhanced by replacing standard laser light sources with non-classical light were inherent quantum properties such as entanglement or squeezing promise even higher signal to noise ratios beating the so called shot noise limit characteristic for the standard light sources. While the general non-classical states of light are extremely hard to produce, a quantum enhanced strategy based on interfering standard laser light with the so called squeezed vacuum state has already been implemented in a full scale operating mode in the GEO600 gravitational wave detector. While this is the most accessible way to make use of quantum properties of light to improve sensitivity, we show that actually in realistic scenarios which take into account light losses it is also the optimal one. To this end, we have employed theoretical tools to demonstrate that no other, no matter how sophisticated, non-classical states of light nor more advanced detection schemes would lead to an appreciable higher sensitivities under given energy constraints and loss levels. In other words one can say that the GEO600 gravitational wave detector makes the most of what is offered by the quantum theory of light for the purpose of enhancing the measurement precision.

Workpackage: wp-1.4: Multi-parameter estimation and non-linear metrology


Project & realization: Pixels United.
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