: It is hard to obtain individual photons in the gamma-ray part of the spectrum because natural production via radioactive decay is irregular and creation by particle accelerators is expensive. Now, Olga Kocharovskaya of Texas A&M University in College Station and her colleagues have developed a method to produce regularly spaced, 100-ns pulses of single gamma-ray photons from the decay of cobalt-57. When 57
Co decays, it emits pairs of photons. Kocharovskaya's team caught the photons with a vibrating sheet of iron foil. Because of the vibration, the photons are absorbed at a range of distances from the source. Careful control over the vibration allows the photons' reemission to occur in evenly spaced pulses, which are then registered by a detector. Because gamma rays have very short wavelength and energies at least 10 000 times that of visible light, coherent pulses could be used for advanced spectroscopy or quantum communications.