1ST-GRADE MATH---PRIMITIVE QUANTUM COMPUTERS have arrived earlier than expected, and they have already performed simple calculations, researchers announced at last month's AAAS meeting in Seattle. Whereas ordinary computers essentially manipulate on-off switches each representing a 0 or a 1, quantum computers are potentially more powerful because they employ quantum systems which can exist in two states simultaneously to represent both 0 and 1 at the same time. Independently, an MIT-Los Alamos team and a Harvard-MIT group have proposed an unexpected way to make a quantum computer: use a cup of liquid. When exposed to a magnetic field, one in a million of the atoms will settle into a "spin" state in which the atoms' internal magnets are aligned with the field. One can then cause each of these spins to act as a "quantum bit" (or "qubit") by firing electromagnetic pulses which cause each spin to enter two states simultaneously. Subsequent pulses can then perform logic operations, by exploiting the fact that the spin state of a particular kind of atom can affect the spin state of a different atom in the same molecule or in a neighboring one. By manipulating the spins in three distinct types of quantum systems that exist within the liquid, the MIT-Los Alamos group has constructed a three-qubit system that has successfully executed the mathematical calculation 1+1=2. With their current approach, the researchers believe 10-qubit systems may be possible. (Science, 17 January; The Economist, February 22, 1997; also see MIT Media Lab site on quantum computation)