An atom laser that behaves exactly like a light laser has been developed, opening up new possibilities in applications such as holograms. The research team, led by Dr. Andrew Truscott of the Australian National University Center of Excellence for Quantum-Atom Optics, showed that a beam of helium atoms can be made to have properties similar to a coherent laser light beam. “If you measure the time between the arrivals of the photons in a laser beam, you find that the photons are randomly spaced, with all arrival times between photons equally probable,” Truscott said. “On the other hand, incoherent sources — such as a lightbulb — exhibit what is called photon bunching, where it is more likely that photons arrive within a short space of time of each other. This bunching in an incoherent light source is manifested by photons arriving in pairs (second order) or in triplets (third order).” “Our experiment shows, for the first time, that the same second- and third-order coherence properties also apply to atoms,” added professor Ken Baldwin. “This very cold [within one-millionth of a degree of absolute zero] atom laser also had a random distribution of arrival times with no bunching — indicating that it was perfectly coherent.” Fellow team member Dr. Robert Dall added that, by warming up the atoms, the research team showed that the atoms no longer behaved coherently and once again exhibited bunching in pairs and triplets. The work was done with doctoral students Sean Hodgman and Andrew Manning, and the paper was published in Science. For more information, visit: www.anu.edu