In a first, physicists have directly seen Hofstadter’s butterfly—a long-sought-after fractal in the quantum realm ...

A quantum version of a fractal pattern, known as "Hofstadter's butterfly," has long been predicted, but the new study marks the first time it has been directly observed experimentally in a real ...

A simple lab mistake revealed the elusive quantum butterfly, confirming a 50-year-old theory in an unexpected graphene experiment at Princeton.