A laser made from a superconducting artificial atom could aid information transfer in quantum computing. To create the laser, a team from Dartmouth College embedded a pair of electrons called a Cooper pair in a high-quality microwave cavity. As stated in the research, when the tunneling Cooper pair energy is equal to a multiple of the cavity photon frequency, the cavity is pumped to a strong non-equilibrium state. According to the researchers, this produced “a regime of strongly correlated electronic-photonic transport,” in which the effects of photonic back-action on the Cooper pair could be observed. The electrons essentially dance back and forth across the atom in time with the oscillating waves of the light. Laser emission spectrum versus frequency and bias voltage for single-photon emission. Courtesy of Darmouth College. “The artificial atom is made of nanoscale pieces of superconductor,” said Dr. Alex Rimberg, a professor of physics and astronomy at Dartmouth. “The reason for using the artificial atom is that you can now make it part of an electrical circuit on a chip, something you can't do with a real atom, and it means we have a much clearer path toward interesting applications in quantum computing.” “Our laser might offer an easy way of producing the kinds of weird quantum states of light that could be used to carry quantum information around,” Rimberg said. “A computer that does a calculation but has no way of getting the information anywhere else isn’t particularly useful.” The research was published in Physical Review B (doi: 10.1103/PhysRevB.90.020506). For more information, visit www.dartmouth.edu.