Microwave Cavity Resonator with Electromagnetic Induced Absorption to Enable a Test of the Electric-Scalar Aharonov-Bohm Effect

The Aharonov-Bohm (AB) effect is a quantum mechanical phenomenon where potentials, rather than classical fields, produce observable effects on a quantum system. The original electromagnetic version included both electric-scalar and magnetic-vector potentials. While the magnetic-vector AB effect has been extensively tested due to the relative simplicity of its experimental setup, the scalar-electric AB effect, which involves a geometric phase created over time by a time-dependent electric potential without spatial variation, remains elusive. Despite its theoretical importance, a clean experimental realization of the scalar-electric AB effect has yet to be achieved. Recently, a novel temporal experiment has been proposed, offering a promising path toward the first clean measurement of the scalar-electric AB effect on a quantum system, such as an atomic clock. This method creates sidebands in a manner similar to the AC Stark effect². We report the new realization of a cylindrical microwave cavity resonator operating in the TM_0,1,0 mode excited using an interferometric setup³. This allowed precise manipulation of the electric field and potential within the resonator by adjusting the phase and amplitude in the two interferometer arms driving the system. Through fine tuning, a 25 dB suppression of the electric field at the resonance frequency was achieved, while simultaneously enhancing the time-varying electric-scalar potential. Under these conditions, the system exhibited a phenomenon analogous to electromagnetically induced absorption, caused by the cancellation of the electric field at resonance. This effect, regarded as a form of extreme dispersion, led to an order of magnitude increase in the cavity's phase response. This experimental setup introduces the potential for testing the scalar-electric AB effect on a quantum system under conditions involving a time-varying electric-scalar potential, without the presence of either an electric field or a magnetic-vector potential, an experiment that has not yet been realized.

1. Y. Aharonov and D. Bohm, Phys. Rev., 115:485–491, Aug 1959.

2. RY Chiao, H Hart, M Scheibner, J Sharping, NA Inan, DA Singleton, ME Tobar, PRA, 107:042209, 2023.

3. M Hatzon, G Flower, M Goryachev, J Bourhill, ME Tobar, arXiv:2410.01333 [physics.ins-det]