[mort96]

No, I believe it's literally zero but we don't have a measurement apparatus with infinite precision so we need some cut-off.

[fooker]

It's only literal zero for superconductors close to 0K temperature.

For high temperature superconductors (50-70+K), it's not literal zero for superconducting mechanisms discovered so far.

[someplaceguy]

Thanks, that makes sense.