Federico Capasso, a physicist, was one of the inventors of the quantum cascade laser during his work at Bell Laboratories. He is currently on the faculty of Harvard University. A physicist is a scientist trained in physics. ... The quantum cascade laser or QC laser is a unipolar laser which uses electrons as its only charge carrier. ... Bell Telephone Laboratories or Bell Labs was originally the research and development arm of the United States Bell System, and was the premier corporate facility of its type, developing a range of revolutionary technologies from telephone switches to specialized coverings for telephone cables, to the transistor. ... Harvard University is a private university in Cambridge, Massachusetts, USA and a member of the Ivy League. ...