Sub-Standard Quantum Limit in Suspended Interferometers – QuantumFrontiers

Probing the limits imposed on precision interferometry with suspended macroscopic mirrors by the quantum nature of light and aim to surpass them.

Activities

This topical group operates a 10-metre prototype interferometer facility located in the institute for gravitational physics. The 10-m prototype offers an environment with extremely low displacement noise, a large volume in ultra-high vacuum, a highly stable laser with a power of 35 watts, a very stable DC supply network, comprehensive detection of environmental influences, fully digital control infrastructure and sufficient flexibility to quickly change the experimental setup - if necessary.

The first and most important experiment being set up in this facility is a Michelson interferometer, which explores the interferometric standard quantum limit (SQL). To achieve the SQL, the interferometer sensitivity must be limited only by the quantum noise at the measurement frequency. The SQL can be surpassed by exploiting correlations between the amplitude and phase quantum fluctuations of the light inside the interferometer. Different approaches for surpassing the SQL will be tested and analysed.

Competences/Services

low noise mirror suspensions
seismic isolation systems (active/passive)
low noise actuators
precision interferometry
shot noise limited photodiodes
laser stabilisation (amplitude/frequency)
optical scattering of mirrors
vacuum out-gassing test chamber
microscopical investigation of surfaces
in vacuum seismically isolated platforms

Scientific Output

Publications

Brown DD, Jones P, Rowlinson S, Leavey S, Green AC, Töyrä D et al. PYKAT: Python package for modelling precision optical interferometers. SoftwareX. 2020 Dec;12. 100613.
doi.org/10.48550/arXiv.2004.06270
,
doi.org/10.1016/j.softx.2020.100613

Kirchhoff R, Mow-Lowry CM, Bergmann G, Hanke MM, Koch P, Köhlenbeck SM et al. Local active isolation of the AEI-SAS for the AEI 10 m prototype facility. Classical and quantum gravity. 2020 May 4;37(11). 115004.
doi.org/10.1088/1361-6382/ab857e

Koch P, Cole GD, Deutsch C, Follman D, Heu P, Kinley-Hanlon M et al. Thickness uniformity measurements and damage threshold tests of large-area GaAs/AlGaAs crystalline coatings for precision interferometry. Optics express. 2019 Dec 9;27(25):36731-36740.
doi.org/10.1364/OE.27.036731
,
doi.org/10.15488/10464

TG Members

Involved Members and their Relevant Expertise

Members	Institution	Relevant Expertise
David Wu, Leader	LUH	Sub-Standard Quantum Limit Interferometry
Harald Lück	AEI	Next Generation Gravitational Wave Observatories; Sub-Standard Quantum Limit Interferometry
Matteo Carlassara	AEI	Multi-stage suspended optics
Michèle Heurs	LUH	Backaction-Evading Techniques
Benno Willke	AEI	Squeezed Light Sources; Advanced Light Sources
Philip Koch	AEI	Multi-stage suspended optics; Vacuum outgassing test chamber; Optical scattering of optical components
Johannes Lehmann	AEI	Precision laser interferometry; Multi-stage suspended optics; Seismic isolation platforms; Vacuum compatable sensors and actuators
Juliane von Wrangel	AEI	Precision glass welding and bonding of quasi-monolithic suspended mirrors
Janis Wöhler	AEI	Precision laser interferometry; Coating thermal noise measurements
Henning Vahlbruch	AEI	Squeezed states of light
Sara al-Kershi	AEI	Multi-stage suspended optics
Firoz Khan	AEI	Optical scattering of optical components; Scattered light mitigation
Paul Hapke	AEI	Steady state simulations of interferometers using FINESSE

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