This image shows the effects of trying to measure the passage of electrons through one of the slits by the placement of a photographic plate near the left slit. The interference pattern on the lower photographic plate is then completely washed out.

A code developed with Amir Farbin (MIT Phys '97) carried out the calculations. The algorithm uses a Feynman sum/Green's function method and a simple finite difference representation of the kinetic energy operator. Some artifacts of the finite difference approximation are evident in the figure.

A. Farbin is developing an interactive 2d solver based on the same algorithm. The generosity of the MIT UROP office supports his work.