Quantum Computing’s Revolutionary Promise Is Bringing Real-World Solutions

The hardest idea in quantum mechanics to hold in a non-physicist’s head is that a thing can be in two states at once. Not flickering between them too quickly to see but both, genuinely, at the same time, until someone measures and it settles into one. That contradiction turns out to be the best way to describe the decades-old argument over the state of quantum computing itself.

Quantum has been a technology that the Nobel Committee, the National Security Agency and half of Silicon Valley agree will rewrite what a computer can do. It is also, simultaneously, a thing so far from finished that it’s been safe to file away along with cold fusion and, until recently, artificial intelligence as technological marvels that are always at least 30 years beyond the horizon.

An ordinary computer stores information in bits, which are switches with exactly two states: on or off, one or zero. A quantum computer uses quantum bits, or qubits, which can be both at once. String enough of them together and the number of states they can hold simultaneously grows so fast that a few hundred of them can represent more possibilities than there are atoms in the observable universe. What you could do with a computer that runs on qubits has been a promise that science has been chasing for a very long time.