(AdvancesScienceMag) Researchers from the University of Tokyo have demonstrated an on-demand entanglement synthesizer that programmably generates aentangled states from a single squeezed light source. This is achieved by a loop-based circuit that is dynamically controllable at nanosecond time scales and processes optical pulses in the time domain. They verified the generation of five different small-scale entangled states and a large-scale cluster state containing more than 1000 modes without changing the optical circuit. Moreover, their circuit enabled storage and release of one part of the generated entangled state, thus working as a quantum memory. The demonstration should open a way for a more general entanglement synthesizer and a scalable quantum processor.