Quantum noise cancellation in asymmetric speed meters with balanced homodyne readout

Zhang, T. et al. (2018) Quantum noise cancellation in asymmetric speed meters with balanced homodyne readout. New Journal of Physics, 20, 103040. (doi: 10.1088/1367-2630/aae86e)

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The Sagnac speed metre topology has been identified as a promising technique to reduce quantum back-action in gravitational-wave interferometers. However, imbalance of the main beamsplitter has been shown to increase the coupling of laser noise to the detection port, thus reducing the quantum noise superiority of the speed metre, compared to conventional approaches, in particular at low frequencies. In this paper, we show that by implementing a balanced homodyne readout scheme with a suitable choice of the point from which the local oscillator (LO) is derived, the excess laser noise contribution is partly compensated, and the resulting speed metre can be more sensitive than state-of-the-art position metres. This is achieved by picking-off the LO from either the reflection port of the interferometer or the anti-reflective coating surface of the main beamsplitter. We show that either approach relaxes the relative intensity noise (RIN) requirement of the input laser. For example, for a beam splitter imbalance of 0.1% in the Glasgow speed metre proof of concept experiment, the RIN requirement at frequency of 100 Hz decreases from 4× 10^(-10)/√Hz to 4× 10^(-7)/√Hz, moving the RIN requirement from a value that is hard to achieve in practice, to one which is routinely obtained.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Bell, Dr Angus and Pascucci, Daniela and Hild, Professor Stefan and Callaghan, Jack and Barr, Dr Bryan and Sorazu Lucio, Dr Borja and Leavey, Mr Sean and Houston, Ewan and Dupej, Peter and Briggs, Mr Joseph and Zhang, Teng and Graef, Dr Christian and Danilishin, Dr Stefan and SPENCER, Andrew and WRIGHT, Jennifer and Steinlechner, Dr Sebastian and Huttner, Dr Sabina and Strain, Professor Kenneth and Hennig, Jan Simon
Authors: Zhang, T., Knyazev, E., Steinlechner, S., Khalili, F. Y., Barr, B.W., Bell, A.S., Dupej, P., Briggs, J., Graef, C., Callaghan, J., Hennig, J.S., Houston, E.A., Huttner, S.H., Leavey, S.S., Pascucci, D., Sorazu, B., Spencer, A., Wright, J., Strain, K.A., Hild, S., and Danilishin, S.L.
College/School:College of Science and Engineering > School of Physics and Astronomy
Research Centre:College of Science and Engineering > School of Physics and Astronomy > Institute for Gravitational Research
Journal Name:New Journal of Physics
Publisher:Institute of Physics Publishing Ltd.
ISSN (Online):1367-2630
Published Online:15 October 2018
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in New Journal of Physics 20:103040
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
713721Investigations in gravitational radiationSheila RowanScience & Technology Facilities Council (STFC)ST/N005422/1S&E P&A - PHYSICS & ASTRONOMY