Bright Twins

By exploiting quantum correlations between photons, scientists can generate light with exceptionally low noise. Such “squeezed noise” is observed, for example, in twin beams—pairs of beams carrying the exact same number of photons. By using one of the beams to probe a sample and the other as a reference, researchers can achieve measurement accuracies impossible with classical light. Martin Finger at the Max Planck Institute for the Science of Light, Germany, and colleagues have now demonstrated a fiber-based source of twin beams with record brightness.