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Quantum Physics, quant-ph,General Relativity and Quantum Cosmology, gr-qc
Abstract:
The shot-noise limited peak sensitivity of cavity-enhanced interferometric
measurement devices, such as gravitational-wave detectors, can be improved by
increasing the cavity finesse, even when comparing fixed intra-cavity light
powers. For a fixed light power inside the detector, this comes at the price of
a proportional reduction in the detection bandwidth. High sensitivity over a
large span of signal frequencies, however, is essential for astronomical
observations. It is possible to overcome this standard sensitivity-bandwidth
limit using non-classical correlations in the light field. Here, we investigate
the internal squeezing approach, where the parametric amplification process
creates a non-classical correlation directly inside the interferometer cavity.
We analyse the limits of the approach theoretically, and measure 36% increase
in the sensitivity-bandwidth product compared to the classical case. To our
knowledge this is the first experimental demonstration of an improvement in the
sensitivity-bandwidth product using internal squeezing, opening the way for a
new class of optomechanical force sensing devices.