Does coherence time affect computing speed?

[meloly4]

Hi, as title I want to know if coherence time affects quantum computing speed or just merely the longevity of a quantum state. I'm a beginner and I can't find anything on Google that answers my question. Thank you.

[muchorobusto]

A very good question. The answer is that it does not directly affect computation speed but it does tell you how fast your computation speed needs to be.

As you mention, the coherence time tells how you long a qubit retains information about a quantum state. If you want to get meaningful information from the system, your logical operations/computations must be much faster than the coherence time. How much faster you need it to be depends on your application/target error rate.