Guang Yang

Light races through a maze of mirrors and beam splitters, but at the end of its journey, it doesn't just flash on a detector: it transforms itself. In the new photonic computer, nonlinear modules have been added to the familiar linear circuits, and now light can perform any quantum operation, not just a subset.

The Universe is less than a billion years old, yet at its centers already sit black holes with masses of a billion suns. According to the conventional picture, they grew by voraciously devouring matter, but calculations show that 'feeding' must have been almost continuous, while visible quasar flares last only a few million years. So where does all the accreting fuel go?