Abstract

The minimal-coupling Hamiltonian, which describes the quantum mechanical interaction of charged matter and electromagnetic fields, implies that the phase of the matter-wave wave function depends on the vector and scalar potentials, whether or not gradients of those potentials produce forces. For steady potentials the resulting phase shifts have been detected as the magnetic and electrostatic Aharanov-Bohm effects. A similar effect occurs for optical-frequency fields. Free electrons cannot absorb energy from or emit energy into a uniform steady optical field, but the quantum-mechanical phase is nonetheless shifted. That shift can be detected by electron interferometry. The interaction between light and electrons results from the pondermotive potential, which is proportional to the square of the vector-potential amplitude. Only moderate intensities are required to produce detectable phase shifts. Both electron and optical waveguides can be fabricated in high-mobility GaAs/AlGaAs technology. In a device containing an optical waveguide and an electron interferometer, the optical Aharanov-Bohm effect could be detected as a resistance change. The pondermotive potential is also capable of shifting the oscillation frequency of a Josephson junction when the light interacts with superconducting condensate on only one side of the junction.

© 1990 Optical Society of America