Continuous quantum states now have a unifying theory

Researchers have, for the first time, certified the non-Gaussianity of experimentally prepared multi-photon-added coherent states of light using a newly introduced framework called nonlinear squeezing. This approach addresses a critical gap in quantum technology, where Gaussian squeezed states are proving insufficient for achieving quantum advantage and a unifying theory for continuous quantum states has been lacking. The work demonstrates third- and fifth-order quantum nonlinearities, significantly exceeding current technological capabilities, and “enables uncovering intricate quantum properties in cutting-edge experiments,” according to the study. This framework provides a new tool for developing quantum technologies by quantifying excess noise and verifying genuine quantumness in continuous systems. The certification of multi-photon-added coherent states as non-Gaussian marks a departure from reliance on Gaussian squeezed states, a shift prompted by their limitations in achieving quantum advantage. Current quantum technologies often use Gaussian squeezed states, but these states are proving insufficient for complex computations demanding genuinely quantum resources. This realization has driven the development of a framework for quantifying non-Gaussian characteristics in continuous quantum states, allowing for a more precise evaluation of their potential. The newly defined generalized nonlinear…