Molecules and molecular systems can host entangled pairs of spins, which are promising for applications in quantum information science. Such chemical platforms offer qubits with tailorable properties at precise locations. On page 28 , Michael Wasielewski explains how molecular spin pairs can be formed, used to perform quantum gate operations, and scaled up to three and four qubits. (Image by Kiyoshi Takahase Segundo/ Alamy Stock Photo; colorization by PHYSICS TODAY.)