Summary
Quantum computers (QCs) promise to exponentially speed up a number of problems in optimization, materials science, and chemistry. The caveat is that they may not even get the chance. One outstanding issue is the coherence time, which is how long a system can remain in a quantum state. We live in the era of noisy intermediate-scale quantum processors, and the time to execute the necessary number of gates in the quantum circuit may be longer than the coherence time of the quantum register. Extending coherence time can be accomplished by improving the properties for existing qubits, which is tedious and demands large resources but almost guarantees steady progress. Alternatively, looking for alternative qubits holds the promise of a breakthrough, if it does not end up becoming a wild goose chase. On p. 430 of this issue, Hays et al. (1) make progress on the latter approach for the Andreev spin qubit (ASQ).
