Pass-through Mach-Zehnder topologies for macroscopic quantum measurements

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.

Anomalous dynamic backaction in interferometers

“…The latter condition is important, because the canonical optical spring (on dark port) can only be stabilized with either additional feedback/control loops or second laser carrier [52][53][54], which is undesirable in the experiment. Thus, the offset from dark fringe makes a useful additional degree of freedom in shaping of the optical spring, and, in principle, may help in converting the latter into the so-called optical inertia [55] which allows broadband reduction of quantum noise. However, since a large offset from dark fringe will couple mean power and technical laser noise into the detector port, certain changes in the GWD topology will be required to make use of the stable single-carrier optical spring, such e.g.…”

Paired carriers as a way to reduce quantum noise of multicarrier gravitational-wave detectors

“…C(x) = fmax fmin log 10 S sum (2πf, x)+S tech (2πf ) d(log 10 f ) , (21) where S sum is the total quantum noise spectral density defined by Eq. (A17), S tech is the total spectral density of the technical noise calculated by means of the standard LSC software tool GWINC [33], f min = 5Hz and f max = 1.5kHz are the minimal and the maximal frequencies of the optimization procedure, and x is the set of parameters to be optimized.…”

Trade-off between quantum and thermal fluctuations in mirror coatings yields improved sensitivity of gravitational-wave interferometers

“…Pérot topology instead of the Michelson/Fabry-Pérot one was suggested in [42]. However, the implementation of these methods in the near future is improbable, for corner reflectors were shown to have high optical losses [43] and the latter two solutions require too radical modifications of the GW detector optical setup.…”

“…In many proposed methods of diverse technical noise sources mitigation [10][11][12][13][14][15][16][17][18], the authors assumed quantum noise of the interferometer as independent of the technical noise budget and thus did not take it into consideration. Equally lukewarm were the researchers of the quantum noise, who proposed a plenty of sophisticated and witty ways for its reduction [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], towards the technical noise sources, tacitly implying them being independent on the quantum fluctuations of light inside the interferometer.…”

“…In [40], authors suggested to replace the end mirrors by coatingless corner reflectors, while in [41] the short anti-resonance-tuned Fabry-Pérot cavities have to play the role of ETMs. Even more radical solution to use the pass-through Mach-Zehnder/Fabry-Pérot topology instead of the Michelson/Fabry-Pérot one was suggested in [42]. However, the implementation of these methods in the near future is improbable, for corner reflectors were shown to have high optical losses [43] and the latter two solutions require too radical modifications of the GW detector optical setup.…”