With long-lived ones, gosh, a ton. When you hear a researcher talk about "logical qubit" or less formally "long-lived qubit" they mean a reliable abstract compu

With long-lived ones, gosh, a ton. When you hear a researcher talk about "logical qubit" or less formally "long-lived qubit" they mean a reliable abstract computational component. When we talk about "physical qubits" we mean the unreliable real implementations like the one from this article. A rough rule of thumb is that you need a 1000 physical qubits to make one logical qubit. With 100 logical qubits (i.e. 100k physical qubits), you can start thinking about running chemistry simulations on the edge of what is possible with classical supercomputers. That is what I am excited about. There are also optimization problems, and some pretentious claims about quantum machine learning, which I am certain would be fun, but I am not as excited about. With 100 physical qubits, you can start testing non-trivial control schemes, circuit compilations, error correction methods, and many other building blocks.