CHICAGO — The U.S. Department of Energy’s Argonne National Laboratory in suburban Chicago is home to one of the newest, fastest, most efficient supercomputers in the country, called MIRA. But despite the new equipment, lawmakers are concerned that the United States is losing the international supercomputing race, a field it has dominated for decades. Lined up in a sprawling room on the second floor of Argonne National Laboratory’s Theory and Computing Sciences building is the future of supercomputing. Argonne Director Eric Isaacs says MIRA can go where few computers can.