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General Relativity and Quantum Cosmology, gr-qc
Abstract:
Using the force-susceptibility formalism of linear quantum measurements, we
study the dynamics of signal recycled interferometers, such as LIGO-II. We show
that, although the antisymmetric mode of motion of the four arm-cavity mirrors
is originally described by a free mass, when the signal-recycling mirror is
added to the interferometer, the radiation-pressure force not only disturbs the
motion of that ``free mass'' randomly due to quantum fluctuations, but also and
more fundamentally, makes it respond to forces as though it were connected to a
spring with a specific optical-mechanical rigidity. This oscillatory response
gives rise to a much richer dynamics than previously known for SR
interferometers, which enhances the possibilities for reshaping the noise
curves and, if thermal noise can be pushed low enough, enables the standard
quantum limit to be beaten. We also show the possibility of using servo systems
to suppress the instability associated with the optical-mechanical interaction
without compromising the sensitivity of the interferometer.
