Today’s smartphones, laptops and supercomputers contain billions of tiny electronic processing elements called transistors that are switched either on or off, signifying a 1 or a 0 in the binary language computers use to express and calculate all information. Qubits are essentially quantum transistors. They can exist in two well-defined states—say, up and down—which represent 1 and 0. But they can also occupy both those states at the same time, which adds to their computing prowess. And two—or more—qubits can be entangled, a strange quantum phenomenon in which particles’ states correlate even if the particles lie across the universe from each other. This ability completely changes how computations can be carried out, and it is part of what makes quantum computers so powerful, says Nathalie de Leon, a quantum physicist at Princeton University. Furthermore, simply observing a qubit can change its behavior, a feature that de Leon says might create even more of a quantum benefit. “Qubits are pretty strange. But we can exploit that strangeness to develop new kinds of algorithms that do things classical computers can’t do,” she says.