Dual Aharonov–Casher effect in singlet-exciton systems

Dual Aharonov–Casher (DAC) phase (or He–McKellar–Wilkens phase), which is defined as a quantum topological phase acquired by a neutral particle only with an electric dipole moment μE being taken on a closed path around a magnetic monopole wire, is theoretically investigated in singlet-exciton systems. In the Sangsterʹs interference scheme, a moving 2s exciton in magnetic fields feels an effective electric field in co-moving frame, which causes a superposition of opposite parity states, i.e., |2s〉 and |2p〉, due to the motional Stark effect. The superposition gives rise to a nonvanishing electric dipole moment required for the DAC effect to the exciton. The accumulated phase is determined by detecting photon emissions from 2p states as a function of applied magnetic fields.