CONTROLLED-NOT LOGIC GATE inverts one of two inputs conditionally on the state of the second. The authors created a quantum controlled-NOT gate using the interaction between the nuclear spins of hydrogen and carbon in chloroform molecules. First, an oscillatory pulse selectively rotates the carbon nucleus 90 degrees. This nucleus then precesses rapidly (if the adjacent hydrogen is in one state) or slowly (if the hydrogen is in the opposite state). Waiting a suitable amount of time and then applying another 90-degree pulse causes the carbon to invert (left) or to remain the same as it was originally (right), depending on the state of the neighboring hydrogen.