Polarization speed meter for gravitational-wave detection

Abstract

We propose a modified configuration of an advanced gravitational-wave detector that is a speed meter type interferometer with improved sensitivity with respect to quantum noise. With the addition of polarization controlling components to the output of an arm cavity Michelson interferometer, an orthogonal polarization state of the interferometer can be used to store signal, returning it later with opposite phase to cancel position information below the storage bandwidth of the opposite mode. This modification provides an alternative to an external kilometer scale Fabry-Pérot cavity, as presented in earlier work of Purdue and Chen [P. Purdue and Y. Chen. PRD 66, 122004 (2002)]. The new configuration requires significantly less physical infrastructure to achieve speed meter operation. The quantity of length and alignment degrees of freedom is also reduced. We present theoretical calculations to show that such a speed meter detector is capable of beating the strain sensitivity imposed by the Standard Quantum Limit over a broad range of frequencies for Advanced LIGO-like parameters. The benefits and possible difficulties of implementing such a scheme are outlined. We also present results for tuning of the speed meter by adjusting the degree of polarization coupling, a novel possibility that does not exist in previously proposed designs, showing that there is a smooth transition from speed meter operation to that of a signal recycling Michelson behavior.

Speedmeter scheme for gravitational-wave detectors based on EPR quantum entanglement

“…A possible method of implementation of two independent position meters within the standard Michelson interferometer topology is to use the two orthogonal polarisations of light. Note that polarisation-based schemes of speed meter (the Sagnac interferometer or the Michelson interferometer with the additional sloshing cavity) were discussed already in literature several times [20,[30][31][32][33][34].…”

Quantum limits of interferometer topologies for gravitational radiation detection

“…Since the momentum is proportional to the speed, the speed meter can therefore detect gravitational wave without being limited by the radiation-pressure noise [23]. There are several speed-meter configurations, e.g., the Sagnac interferometer [36,37,26,27] and a recent proposed scheme by using different polarizations [38]. In Figure 12, we show one particular variant, which is proposed in [25], by using a sloshing cavity.…”

A new quantum speed-meter interferometer: measuring speed to search for intermediate mass black holes

“…An alternative scheme, proposed in ref. 13 , makes use of the differential optical mode of the Michelson interferometer with the polarization orthogonal to that of the pumping laser as an effective sloshing cavity. The polarization separation of the signal light fields from the “sloshing” ones is achieved with six optical elements: two quarter wave plates (QWP), 2 mirrors, a polarization beam splitter (PBS) and an additional (omitted in ref.…”

“…The polarization separation of the signal light fields from the “sloshing” ones is achieved with six optical elements: two quarter wave plates (QWP), 2 mirrors, a polarization beam splitter (PBS) and an additional (omitted in ref. 13 ) birefringent plate that flips the sign of the vertically polarized signal sidebands reflected from the “sloshing cavity”.…”