Now the team has managed to make the circuit perform a more complex problem. In a preprint currently under review, the researchers have shown that it can perform a logic operation known as XOR, in which the circuit takes in two binary numbers and determines whether the inputs are the same. This is a "nonlinear" classification task, says Dillavou, and "nonlinearities are the secret sauce behind all machine learning." Their demonstrations are a walk in the park for the devices you use every day. But that's not the point: Dillavou and his colleagues built this circuit as an exploratory effort to find better computing designs.