A landmark experiment from 1956 is followed up on page 733 by physicist Immanuel Bloch and his colleagues at the Johannes Gutenberg University in Mainz, Germany. They have investigated aspects of the Hanbury Brown–Twiss effect, which deals with the quantum effects of particle interference.

In their original work, Robert Hanbury Brown and Richard Twiss used two detectors to pick up photons from a single light source — in their case a star. They discovered that the detected photons 'bunched' — in other words if a photon was detected at one of the detectors, it was highly likely that a photon would be detected at the other detector at the same time. This effect is seen for all bosons — particles such as photons or certain neutral atoms. But when it comes to fermions, such as quarks or fermionic atoms, the opposite should be true — a phenomenon known as antibunching.

Antibunching was first seen with electrons in semiconductors. In the present experiment, Bloch and his team have detected it for the first time in neutral fermionic atoms — which has enabled them to reveal properties of cold quantum gases released from optical lattices. In future experiments, they hope to use the technique to examine the atomic mechanisms of high-temperature superconductivity in such gases.