Circumventing detector backaction on a quantum cyclotron for a new measurement of electron and positron magnetic moments*

Measurement of the magnetic moment of the electron provides the most stringent test of the Standard Model.

The quantum cyclotron state of a trapped electron is detected by a quantum nondemolition (QND) method to avoid backaction change of the quantum state.

However, it still induces backaction frequency broadening of the cyclotron frequency.

A new detection scheme has been developed to circumvent the detection backaction broadening on the cyclotron frequency.

Theoretical concepts, experimental developments as well as progress toward new measurement of electron's magnetic moment will be presented.