Pass-through Mach-Zehnder topologies for macroscopic quantum measurements

TL;DR

This paper explores pass-through Mach-Zehnder interferometer topologies with Fabry-Perot cavities for macroscopic quantum measurements, aiming to reduce coating noise in gravitational-wave detector prototypes.

Contribution

It introduces and analyzes two variants of Mach-Zehnder topologies, including a novel quantum speed meter configuration, for improved macroscopic quantum measurement techniques.

Findings

Pass-through Mach-Zehnder topology reduces coating Brownian noise.

The paper proposes a new quantum speed meter variant.

Potential for enhanced sensitivity in gravitational-wave prototypes.

Abstract

Several relatively small-scale experimental setups aimed on prototyping of future laser gravitational-wave detectors and testing of new methods of quantum measurements with macroscopic mechanical objects, are under development now. In these devices, not devoted directly to the gravitational-wave detection, Mach-Zehnder interferometer with pass-through Fabry-Perot cavities in the arms can be used instead of the standard Michelson/Fabry-Perot one. The advantage of this topology is that it does not contain high-reflectivity end mirrors with multilayer coatings, which Brownian noise could constitute the major part of the noise budget of the Michelson/Fabry-Perot interferometers. We consider here two variants of this topology: the "ordinary" position meter scheme, and a new variant of the quantum speed meter.