Detection prospects of millicharged dark matter in unconventional interferometer

Abstract We propose a novel idea to discover millicharged particles (mCPs) captured by the earth during its existence. It has been demonstrated that the mCPs accumulation inside the earth leads to the enhancement of its number density much larger than the corresponding virial density. We propose to utilize an unconventional laser interferometer to probe these earth-bound mCPs through the detection of the photons’s phase shift. We demonstrate that, for mCPs mass in the range between 1 GeV to $$10^{12}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>12</mml:mn> </mml:msup> </mml:math> GeV, the sensitivity of probing their fractional electric charge $$\epsilon $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>ϵ</mml:mi> </mml:math> could reach as low as $$10^{-12}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>12</mml:mn> </mml:mrow> </mml:msup> </mml:math> to $$10^{-6}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>6</mml:mn> </mml:mrow> </mml:msup> </mml:math> provided that mCPs number density is greater than $$1~{\textrm{cm}^{-3}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>1</mml:mn> <mml:mspace/> <mml:msup> <mml:mtext>cm</mml:mtext> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> and the interferometer operates at the Heisenberg limit.