M. Tobar - Precision low energy experiments to test fundamental physics and search for dark matter

by Michael Tobar (University of Western Australia)

Room "B. Rossi" (LNGS)

Room "B. Rossi"



At the University of Western Australia, the Frequency and Quantum Metrology research group within the Department of Physics has a rich history of developing precision tools for both fundamental physics and industrial applications. This includes the development of novel high-Q resonant photonic cavities such as whispering gallery modes and re-entrant cavities for example. These photonic cavities have been used in a range of applications, including highly stable low noise classical and atomic oscillators, low noise readout and measurement systems, high sensitivity displacement sensors, high precision electron spin resonance spectroscopy, high precision measurement of material properties and high-Q hybrid quantum systems strongly coupled to form quasi-particles.
The aforementioned technology has allowed the realization of precision measurement tools and techniques to test some of the core aspects of fundamental physics, such as searches for Lorentz invariance violations in the photon [1], phonon [2,3] and gravity sectors [4-6], variations in fundamental constants [7,8] and searching for ultra-light dark matter (ULDM) and weakly interacting sub-eV particle (WISP) dark matter[9-19]. We have also studied modified Maxwell’s equations and as a result have developed new experiments to test for Lorentz invariance violations, dark matter axions and hidden sector photons. We continue to follow this tradition and have recently gained funding to apply our expertise to new directions in fundamental physics with particular focus on detecting ULDMs and axions [9-19]. An overview of our current experiments, including status and future directions will be given. This includes experiments that take advantage of axion-photon coupling and axion-spin coupling to search for axion dark matter [9-19]. High acoustic Q phonon systems to search for high frequency gravity waves, scalar dark matter and tests of quantum gravity [20,21].

[1] M Nagel etal, Direct terrestrial test of Lorentz symmetry in electrodynamics to 10−18. Nature Comm., 6:8174 EP, 09 2015.

[2] A Lo etal, Acoustic Tests of Lorentz Symmetry Using Quartz Oscillators. Phys. Rev. X, 6, 011018, 2016.

[3] M Goryachev etal, Next Generation of Phonon Tests of Lorentz Invariance using Quartz BAW Resonators, IEEE Trans. UFFC, 65(6), pp. 991-1000, 2018.

[4] C-G Shao etal, Combined search for a lorentz-violating force in short-range gravity varying as the inverse sixth power of distance. Phys. Rev. Lett., 122:011102, Jan 2019.

[5] C-G Shao etal, Combined search for lorentz violation in short-range gravity. Phys. Rev. Lett., 117:071102, Aug 2016.

[6] C-G Shao etal, Search for lorentz invariance violation through tests of the gravitational inverse square law at short ranges. Phys. Rev. D, 91:102007, May 2015.

[7] M. E. Tobar etal, Testing local position and fundamental constant invariance due to periodic gravitational and boost using long-term comparison of the syrte atomic fountains and h-masers. Phys. Rev. D, 87:122004, Jun 2013.

[8] J Guena etal, Improved tests of local position invariance using 87Rb and 133Cs fountains. Phys. Rev. Lett., 109:080801, Aug 2012.

[9] BT McAllister etal, Axion dark matter coupling to resonant photons via magnetic field. Phys. Rev. Lett., vol. 116, 161804, 2016.

[10] BT McAllister, SR Parker, ME Tobar, 3D lumped LC resonators as low mass axion haloscopes. Phys. Rev. D 94, 042001, 2016.

[11] BT McAllister etal, The ORGAN experiment: An axion haloscope above 15 GHz. Physics of the Dark Universe, 18, 67–72, 2017.

[12] M Goryachev etal, Axion detection with negatively coupled cavity arrays. Phys. Lett. A, vol. 382, pp 2199–2204, 2018.

[13] BT McAllister etal, Tunable Super-Mode Dielectric Resonators for Axion Haloscopes. Phys. Rev. Applied, vol. 9, 014028, 2018.

[14] M Goryachev etal, Probing Dark Universe with Exceptional Points. Physics of the Dark Universe, vol. 23, 100244, 2019.

[15] B McAllister etal, Cross-correlation Signal Processing for Axion and WISP Dark Matter Searches. IEEE T-UFFC, 66(1) 236-43, 2019.

[16] G Flower etal, Broadening Frequency Range of a Ferromagnetic Axion Haloscope with Strongly Coupled Cavity-Magnon Polaritons. Physics of the Dark Universe, vol. 25, 100306, 2019.

[17] ME Tobar etal, Modified Axion Electrodynamics as Impressed Electromagnetic Sources Through Oscillating Background Polarization and Magnetization. Physics of the Dark Universe, vol. 26, 100339, 2019.

[18] M Goryachev etal, Axion Detection with Precision Frequency Metrology. Physics of the Dark Universe, vol. 26, 100345, 2019.

[19] G Flower etal, Experimental implementations of cavity-magnon systems: from ultra-strong coupling to applications in precision measurement. New J. Phys., vol. 21, 095004, 2019.

[20] M Goryachev, ME Tobar, Gravitational wave detection with high frequency phonon trapping acoustic cavities. Phys. Rev. D, 90(10), 102005, 2014.

[21] PA Bushev etal, Testing the generalized uncertainty principle with macroscopic mechanical oscillators and pendulums, accepted to be published in Phys. Rev. D, 2019.

Michael E. Tobar received the Ph.D. degree in physics from the University of Western Australia (UWA), Perth, W.A., Australia, in 1994. He is currently a Professor of Physics with the Department of Physics at the University of Western Australia and leads the Frequency and Quantum Metrology research group at UWA. His research group is part of two nation-wide Australian Research Council (ARC) Centres of Excellence; the ARC Centre of Excellence for Engineered Quantum Systems (EQUS) funded from 2018-24; and the ARC Centre of Excellence for Dark Matter Particle Physics (CDAMP) funded from 2020-26. His research interests encompass the broad discipline of frequency metrology, precision and quantum measurements and low temperature, condensed matter and quantum physics. In particular he is interested in undertaking precision tests of fundamental physics, including low energy precision searches for dark matter, Lorentz invariance violations and searches for high frequency gravitational waves. He also leads the ORGAN axion Dark Matter detector collaboration co-funded by both Centres as well as an ARC Infrastructure grant.
Prof. Tobar has co-authored about 300 journal publications in these fields of research and has 12 patents. Notably, between 2009 and 2014 He was awarded a Laureate Fellowship by the ARC, the top nation-wide research fellowship. Other significant awards include the 2014 Cady Award presented by the IEEE, the 2014 Clunies-Ross award presented by the Australian Academy of Science and Technology, the 2012 Alan Walsh medal presented by the Australian Institute of Physics, the 2010 WA scientist of the year, presented by the WA dept. of Commerce, the 2009, Barry Inglis medal presented by the National Measurement Institute for precision measurement and the 2006 Boas medal presented by the Australian Institute of Physics. Also, during 2007 he was elevated to Fellow of the IEEE, 2008 Fellow of the Australian Academy of Technological Sciences and Engineering and 2012 Fellow of the Australian Academy of Science. He also received a citation from the Australian Learning and Teaching Council for inspiring research students to reach their full potential and transform to successful research scientists through participation in ground-breaking research.