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A Stern-Gerlach interferometer uses spin-dependent magnetic forces to split matter-wave components and subsequently recombine them coherently. Splitting alone is a spin-position correlation; interference requires restoring sufficient overlap in both position and momentum while controlling the relative phase.

An atom-chip realization uses accurately timed magnetic-field gradients to drive the separating and recombining trajectories. Reading the final spin populations reveals phase-dependent interference after recombination. Residual trajectory mismatch or uncontrolled magnetic noise reduces contrast, explaining why reversing the average force is insufficient by itself to make a complete interferometer.^[ref]

Yair Margalit is an experimental physicist credited as first author of a detailed realization of a complete Stern-Gerlach interferometer. In this experiment, gradients of a magnetic field generated by an atom chip split atomic wave packets according to their internal spin state and then recombined them coherently.

Recombination matters: separating two paths shows state-dependent motion, whereas recovering quantum interference tests preservation of the relative phase. The reported arrangement used controlled microscopic field sources; it should not be confused with the original macroscopic-magnet Stern-Gerlach experiment.^[ref]