Towards the Standard Quantum Limit in a Table-Top Interferometer

We discuss the development and expected performance of a table-top experiment for measuring quantum fluctuations in a suspended-test-mass interferometer. The ultimate goal of this experiment is to perform measurements of the quantum noise-limited displacement sensitivity of the interferometer at the level of the standard quantum limit (5×10−19 m/sqrt(Hz) at 100 Hz). The case is made for an experiment that will show the feasibility of preparing a macroscopic quantum-limited system within a regular laboratory environment. This will be achieved by suspending a cryogenically cooled, high-finesse, optical cavity via a multi-stage suspension. We motivate the utility of our experiment in providing an increased understanding of the nature of quantum fluctuations in current
and future gravitational wave detectors, as well as opening an avenue for research into aspects of macroscopic quantum mechanics and quantum gravity. We explain how these requirements drove our design specification. Given the extremely small displacements in question, particular attention is devoted to discussing noise mitigation, with a focus on the suppression of seismic and thermal
noise.