In an electron biprism interferometer the coherent wave packets are travelling on laterally separated paths from the source to the interference plane. They may experience on their paths different electromagnetic and inertial fields, be deflected and pick up quantum mechanical phase shifts due to the corresponding potentials. In order to study the influence of electromagnetic fields, a Wien filter (i.e., crossed magnetic and electric fields perpendicular to the beam path, matched in such a way that the electric force on the electrons is just canceled by the Lorentz force) inserted into the beam path has proved to be a very versatile tool: It introduces a longitudinal shift of the wave packets and allows to measure the coherence lengths, the spectral content of the wave packet, to optimize longitudinal coherence and to observe Aharonov-Bohm phase shifts. It turns out that longitudinal coherence is not destroyed easily but sometimes only``hidden'', if the longitudinal shifts caused by electric fields exceed the coherence length. Longitudinal coherence and fringe visibility turns out to be a local feature of the electron wave field. We will see that ``which-path information'' and fringe visibility exclude one another. Quantum phase shifts induced by inertial fields and vector potentials are accessible due to the possiblity to put the miniaturized electron interferometer on a turntable.
For more information about the wien filter click here.
Interferometry with particles. For more information click here.
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