Physicists have long recognized the value of photonic graph states in quantum information processing. However, the difficulty of making these graph states has left this value largely untapped. In a step forward for the field, researchers from The Grainger College of Engineering at the University of Illinois Urbana-Champaign have proposed a new scheme they term “emit-then-add” for producing highly entangled states of many photons that can work with current hardware. Published in npj Quantum Information, their strategy lays the groundwork for a wide range of quantum enhanced operations including measurement-based quantum computing.
Entanglement is a key driver in delivering faster and more secure computational and information systems. But creating large, entangled states of more than two photons is challenging because the losses inherent in optical systems mean most photon sources have a low probability of successfully producing a photon that survives to the point of detection. Therefore, any attempt to build a large entangled state is full of missing photons, breaking the state apart. And identifying the missing spots would mean attempting detection of the photons, which is a destructive process itself, and precludes going back to fill those spots.
To circumvent this challenge, a team led by Associate Professor of Physics Elizabeth Goldschmidt and Professor of Electrical and Computer Engineering Eric Chitambar began with a different mindset.
