Physicists in Israel have created a quantum interferometer on an atom chip. This device can be used to explore the fundamentals of quantum theory by studying the interference pattern between two beams of atoms. University of Groningen physicist, Anupam Mazumdar, describes how the device could be adapted to use mesoscopic particles instead of atoms. This modification would allow for expanded applications. A description of the device, and theoretical considerations concerning its application by Mazumdar, were published on 28 May in the journal Science Advances.

The device, created by scientists from the Ben-Gurion University of the Negev, is a so-called Stern Gerlach interferometer, which was first proposed 100 years ago by German physicists Otto Stern and Walter Gerlach. Their original aim of creating an interferometer with freely propagating atoms exposed to gradients from macroscopic magnets has not been practically realized until now. “Such experiments have been done using photons, but never with atoms,” explains Anupam Mazumdar, Professor of Theoretical Physics at the University of Groningen and one of the co-authors of the article in Science Advances.

The Israeli scientists, led by Professor Ron Folman, created an interferometer on an atom chip, which can confine and/or manipulate atoms. A beam of rubidium atoms is levitated over the chip using magnets. Magnetic gradients are used to split the beam according to the spin values of the individual atoms. Spin is a magnetic moment that can have two values, either up or down. The spin-up and spin-down atoms are separated by a magnetic gradient. Subsequently, the two divergent beams are brought together again and recombined. The spin values are then measured, and an interference pattern is formed. Spin is a quantum phenomenon, and throughout this interferometer, the opposing spins are entangled. This makes the interferometer sensitive to other quantum phenomena.