Quantum states of the art


I explained in part one what qubits are and how they behave. Entanglement and superposition are fundamental to the field.

Quantum gate computers

Traditional digital computers can perform a lot of different operations on numbers represented by binary digits, or bits. They can add them. They can invert them, turning all the ones into zeroes, and zeroes into ones. These transformations are called SUM and NOT. There are others, like AND, OR, XOR and more. For historical hardware reasons, these operations are called “gates.” Classical computers can apply lots of different gates to bits.

Quantum annealing

A basic rule in physics says that objects tend to seek the lowest-energy state they can find. Lifting weights in the gym is hard, because the low-energy state for the weight is on the floor. You have to do work (add energy) to change that. Pizza fresh from the oven burns your mouth because it’s got a lot of heat energy stored in it; wait a bit, and that heat will leak out, warming up the plate and the air a little bit, as the pizza seeks a lower-energy state.

Which is better?

Google is at the forefront of the state of the art in quantum gate hardware. Its most sophisticated quantum processing unit, the Sycamore, has 54 qubits. It’s demonstrated quantum supremacy (that is, it’s provably better than any classical system) by performing in 200 seconds a computation that would have taken the world’s fastest supercomputer 10,000 years.


My secret professional superpower is finding smart folks working on interesting things and hanging out with them. Once again, this strategy has paid off. Useful insights and correct ideas in this post are from, or inspired by, the folks below. Errors, naturally, stay right here at home.



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Mike Olson

Mike Olson

Berkeley-based techie with an interest in business. Worried about the world.