The "Standard Model" (SM), the framework for modern physics and cosmology, is the fundamental mathematical description of physical reality. The SM is a great triumph of modern physics - because its predictions have so often been confirmed by laboratory measurements,. The SM is also the great frustration of modern physics - because it not consistent with basic features of the universe.
A widely-publicized 2023 measurement of the size of the muon particle's magnetic moment, is the first that seems to disagree with a SM prediction. Is this a precursor of the most significant physics discovery in decades, that starts unraveling the mystery of the SM? A critical check is that this SM "breakdown" should also produce a discrepancy between the predicted and measured electron magnetic moments. This proposal is to develop apparatus and methods to get the unprecedented sensitivity that is required to observe the SM breakdown
The new approach is using special relativity and a quantum-limited detector for the first time to detect one-quantum transitions of one electron or positron in a Penning trap. The increased sensitivity and precision will come from a ten-times lower particle temperature. The cost is a more sophisticated readout method required because the signal is much smaller. The more complex detector also requires a great deal of active and passive magnetic shielding, and a low-magnetic-field detector location very close to the high field needed for the qubit.
A graduate student and a postdoc will develop and demonstrate the technology and new readout methods, then incorporate the new quantum-limited detector into the extensive apparatus needed to measure the electron and positron magnets. The quantum-limited detection has the potential to revolutionize measurements of the electron and magnetic moments, to provide the sensitivity needed to confirm or disprove the SM breakdown suggested by muon measurements.
