Scientists from Cornell University and the U.S. Department of Energy's (DOE) Brookhaven National Laboratory (BNL) have successfully demonstrated the world's first capture and reuse of energy in a multi-turn particle accelerator, where electrons are accelerated and decelerated in multiple stages and transported at different energies through a single beamline. This advance paves the way for ultra-bright particle accelerators that use far less energy than today's machines.