We can record an interference pattern one photon at a time.
The photons behave nothing like macroscopic particles. 

Laser Diffraction Pattern

Single Photon Diffraction Pattern

Knowing the slit the photon traveled through and measuring an interference pattern are incompatible observables in quantum mechanics.

Polarizers with perpendicular transmission axes cover the slits and mark the path.

The interference pattern measured with the laser disappears.

The interference pattern measured one photon at a time disappears.

Erasing the path information restores the interference pattern.

A linear polarizer with its transmission axis oriented at 45o is placed between the double slit and the detector.

The interference pattern measured with the laser reappears.

The interference pattern measured one photon at a time reappears.