Detecting milli-Hz gravitational waves with optical resonators

Abstract We propose a gravitational wave (GW) detector based on ultrastable optical cavities enabling the detection of GW signals in the mostly unexplored <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:msup> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> Hz frequency band. We illustrate the working principle of the detector and discuss that several classes of GW sources, both of astrophysical and cosmological origin, may be within the detection range of this instrument. Our work suggests that terrestrial GW detection in the milli-Hz frequency range is potentially within reach with current technology.