We construct a quantum bit commitment scheme using a double-slit setup
similar to Wheeler's delayed choice experiment. Bob sends photons toward the
double-slit, and Alice commits by determining either the slit from which each
photon emerges (for b=0), or its landing position on a screen (for b=1).
Since the photon's wave front expands at the speed of light, Alice cannot delay
the detection indefinitely, or it would very soon be out of her control no
matter how much resources she has.Comment: 6 pages, no figure. arXiv admin note: substantial text overlap with
arXiv:0910.264
