We describe a new experimental configuration suitable for observing the topological phase of Aharonov and Casher in atomic systems. Using this we have been able to show experimentally that the Aharonov-Casher phase is both independent of velocity and proportional to electric field and we have verified the predicted size of the effect with an accuracy of 4%.

• Received 3 August 1993

DOI:https://doi.org/10.1103/PhysRevLett.71.3641