ABSTRACT
In this Letter, we present the design and performance of the frequency-dependent squeezed vacuum source that will be used for the broadband quantum noise reduction of the Advanced Virgo Plus gravitational-wave detector in the upcoming observation run. The frequency-dependent squeezed field is generated by a phase rotation of a frequency-independent squeezed state through a 285 m long, high-finesse, near-detuned optical resonator. With about 8.5 dB of generated squeezing, up to 5.6 dB of quantum noise suppression has been measured at high frequency while close to the filter cavity resonance frequency, the intracavity losses limit this value to about 2 dB. Frequency-dependent squeezing is produced with a rotation frequency stability of about 6 Hz rms, which is maintained over the long term. The achieved results fulfill the frequency dependent squeezed vacuum source requirements for Advanced Virgo Plus. With the current squeezing source, considering also the estimated squeezing degradation induced by the interferometer, we expect a reduction of the quantum shot noise and radiation pressure noise of up to 4.5 dB and 2 dB, respectively.
ABSTRACT
In this paper, we use quantum-mechanical formalism to describe the time evolution of a classical dynamical system with fluctuating parameters. By appropriate choice of "interaction picture representation," and the use of the Baker-Campbell-Hausdorff formula in the chronological time ordered evolution, we have obtained analytical expressions for the Lyapunov exponent of the energy evolution of the dynamical system. Our approach proved to be very powerful in handling either stochastic or highly correlated processes. The approach lends itself to generalizations for use in a wide field of applications.
