Controlling a Qubit with a Comb (image) American Physical Society Caption The spectrum of pulse trains from a mode-locked laser consists of a sequence of optical frequencies that are evenly spaced. Pairs of frequencies formed from two 'teeth' on the comb have a definite phase relationship with one another and the pair can control a spin qubit on a trapped ion via a stimulated Raman process. Physicists have now extended this capability to any frequency by splitting the pulses and shifting each with an acousto-optic modulator. Credit American Physical Society Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.