Historical research guide · 0571 · 2008

Proposed Ultra-High Sensitivity High-Frequency Gravitational Wave Detector

Robert M. L. Baker Jr. · Gary V. Stephenson · Fangyu Li

In one minute

Robert Baker of GravWave LLC, Gary Stephenson of Seculine Consulting and Fangyu Li of Chongqing University set out a full instrument for catching gravitational waves at gigahertz frequencies — the band LIGO cannot reach. The trick is a conversion the literature has known since Gertsenshtein in 1962: run a gravitational wave through a strong static magnetic field and it hands energy to an electromagnetic wave, so the thing you finally count is microwave photons. Their design crosses a focused microwave beam with a several-tesla magnet; where the two meet, detection photons are born and travel out sideways, at right angles to both. Fractal-membrane mirrors focus them onto single-photon microwave receivers. Everything else in the paper is about silence: a mosaic of superconducting tiles lining the cryogenic vessel as a Faraday cage, absorbing baffles forming tunnels to each receiver, and a working temperature below 48 millikelvin. The authors put the reachable sensitivity at spacetime strains of about ten to the minus thirty-two.

Connection

Chapter 10 argues that electromagnetism and gravity are two ends of one coupling, and this paper is that coupling built as hardware, running it backwards to read the metric instead of writing it. For chapter 4 it is a stated number to aim at — the strain amplitude a table-sized instrument could resolve — and for chapter 11 it is another design in which superconductors do the load-bearing work. Read it with the companion analysis of signal flux and background noise at /library/stm-c15757c634 and with the relic-wave case at /library/stm-c1ad7838f6.

From the source

The detector works by the inverse Gertsenshtein effect: a gravitational wave crossing a strong static magnetic field converts into electromagnetic waves, so what the instrument counts is microwave photons born in the interaction zone where a Gaussian beam, the magnetic field and the gravitational wave all meet at the same frequency and speed.Abstract; Introduction
The detection photons leave along an axis perpendicular to both the Gaussian beam and the static magnetic field, and are focused onto the receivers by paraboloid fractal-membrane reflectors; because signal photons and background photons travel at right angles, the instrument is photon-noise limited rather than background limited.Noise, closing paragraphs; Figures 1 and 6
External noise is excluded by a tight mosaic of superconducting tiles, for example yttrium barium copper oxide, lining the inside of the cryogenic containment vessel as a near-perfect Faraday cage, and internal thermal photons are suppressed by holding the vessel below 48 millikelvin and by microwave-absorbing baffles forming tunnels to each detector.Noise; Figure 7
With a continuous Gaussian beam, an observation interval of one thousand seconds and a beam field amplitude of 1.17 thousand volts per metre, a gravitational-wave amplitude of three times ten to the minus thirty-two yields about 490 detection photons — roughly sixteen times the thirty photons the Yale circuit-QED single-photon receiver needs.Analysis, paragraph following equation (2)
Raising the microwave power, raising the magnet strength and placing a receiver at each end of the detection axis could lift the sensitivity of the earlier Li, Baker, Fang, Stephenson and Chen detector by a factor of one hundred to one hundred thousand, reaching spacetime strain amplitudes of about ten to the minus thirty-two down to ten to the minus thirty-four for plane waves from a point source or a laboratory generator.Detection sensitivity
Relic gravitational waves arrive from every direction, so only a small fraction of them cross the reaction zone; the authors’ own preliminary estimate is that the minimum detectable relic amplitude is about two orders of magnitude larger than for a point source, roughly ten to the minus thirty down to ten to the minus thirty-two.Detection sensitivity, closing paragraph; Conclusions

The way in

https://doi.org/10.1063/1.2844941

Historical source-access record. This guide links to the original; it does not reproduce the paper text.

LICENCE CHECK. The version of record is AIP Conference Proceedings 969, pages 1045 to 1054, from STAIF-2008, the Space Technology and Applications International Forum; copyright sits with the American Institute of Physics and no Creative Commons statement appears on the publisher record. SOURCE REACHED. The authors’ own copy is posted free to read at gravwave.com as Discussion-Focus Paper 1.2 for the 2nd HFGW International Workshop, Institute for Advanced Studies at Austin, 17 to 20 September 2007 — the draft the proceedings version was made from — and this sheet’s summary and claims were written from that text, read in full; the locators use its section headings. DATA NOTE. The Crossref record lists Mohamed S. El-Genk as a fourth author. He is the editor of the STAIF proceedings, not an author of this paper, whose authors are Baker, Stephenson and Li.

How to cite it

Robert M. L. Baker Jr., Gary V. Stephenson, Fangyu Li (2008) Proposed Ultra-High Sensitivity High-Frequency Gravitational Wave Detector doi:10.1063/1.2844941

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