The first issue of Physical Review A appeared in 1970, 50 years ago this year. On the occasion of this golden anniversary, the journal asked its editors to pick the three most interesting and influential papers. The paper by Spreeuw and his collaborators was chosen as one of the three "classic" papers.

Donut modes

In the 1992 paper, the authors address the question whether light can have so-called "orbital angular momentum". That is: if light is propagating with a spiralling wave front, can it make another object spin? By studying certain donut-shaped propagation modes that lasers can produce, they showed that this is indeed the case, and argued that such light can in principle twist a lens that it goes through - an effect which was indeed later observed in the laboratory. Over the past three decades, the effect first suggested by Allen, Beijersbergen, Spreeuw and Woerdman has found many applications and the paper has been cited over 4000 times.