Annual-modulation fingerprint of the axion wind induced sideband triplet in quantum dot spin qubit sensors

We propose a phase-coherent, narrowband magnetometer for searching couplings between axions and axionlike particles and electron spins, using gate-defined silicon quantum dot spin qubits. With repeated Ramsey echo sequences and dispersive readout, the qubit precession response can be tracked with sub-Hz spectral resolution. The accessible axion mass window is determined using a series of filtering protocols with consideration of sensing noise (including readout errors and <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mn>1</a:mn> <a:mo>/</a:mo> <a:mi>f</a:mi> </a:math> noise). We demonstrate clear indication of sidereal modulation of the signal due to Earth’s rotation, while Earth’s orbital motion induced annual amplitude envelope that generates sidebands at fixed frequency spacing <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mo>±</c:mo> <c:msub> <c:mi mathvariant="normal">Ω</c:mi> <c:mo stretchy="false">⊕</c:mo> </c:msub> </c:math> around the sidereal component, for axion mass between <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mrow> <g:mn>1</g:mn> <g:mo>−</g:mo> <g:mn>10</g:mn> <g:mtext> </g:mtext> <g:mtext> </g:mtext> <g:mi mathvariant="normal">μ</g:mi> <g:mi>eV</g:mi> </g:mrow> </g:math> , our proposed method covers <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:msub> <j:mi>g</j:mi> <j:mrow> <j:mi>a</j:mi> <j:mi>e</j:mi> </j:mrow> </j:msub> </j:math> from <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"> <l:msup> <l:mn>10</l:mn> <l:mrow> <l:mo>−</l:mo> <l:mn>14</l:mn> </l:mrow> </l:msup> </l:math> to <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"> <n:msup> <n:mn>10</n:mn> <n:mrow> <n:mo>−</n:mo> <n:mn>10</n:mn> </n:mrow> </n:msup> </n:math> . Incorporating this daily and annual modulation pattern in a likelihood analysis enhances the rejection of stationary or instrumental noise. Our analysis indicates that spin-qubit magnetometry can achieve sensitivities approaching those suggested by astrophysical considerations, thus providing a complementary, laboratory-based probe of axion-electron interactions. Although we focus on silicon spin qubit architectures, the approach is broadly applicable to spin-based quantum sensors.