interference experiment with opposite orientations of spin

[Nick]

Hi everybody!

Quantum mechanics teaches us that one can observe an interference
between two electron beams. Is it still possible to observe an
interference pattern, if the two beams have opposite projections of
spin along some axis? Or does it depend on the way the interference
pattern is observed?

Best regards,
Nikolay

[gao]

There will be no interference pattern if only the projections of spin
remain opposite in any observed way. Since the interference only emerge
between beams with identical particles,in addition of that, if you want
get clear patterns, each of the beam must bear enough coherence.
Hope this help.

[BDH]

A double-slit experiment is not the same thing as the interference of
two beams - the slits are smaller than the particle wavelength. If you
focused an electron beam on a sufficiently fine two-slit grating, with
filters on each side letting electrons of only one (opposite) spin go
through (an exceedingly difficult experient) then you would NOT see
interference.