Cryo Prison: Not something they use any more than any other kind of prison (although at least it would be more humane) – but in related concepts, they do keep uploaded mind-states of executed felons around in dead storage (places like the Aeon Pit) just in case. Turns out that with sufficient technology, you actually can undo the death penalty.
Aeon Pit
Death Storage
[redacted]
Secure Storage SWG, Fifth Directorate, Imperial State Security
Tertiary Monitoring Node
“Alert flag just came up: storage node 4-23-3317, outside penetration, profiled as hostile. Dispatching response team.”
“Belay that. Class 23, confirm?”
“Yes…”
“Then monitor the situation for an hour, and if the flag’s cleared down, send maintenance in to secure it.”
“Don’t we need to contain it? It’s an Aeon Pit site.”
“Yeah, but it’s death storage.”
“So it’s dead storage, but that doesn’t mean the contents aren’t dangerous to let out!”
“Not dead storage, death storage. One of those places where we keep the cleaners when they aren’t working so they don’t mingle with the nice people. They may be deadly, murderous bastards, but they’re our deadly, murderous bastards, so we can let them handle their own cleanup, read me? They’ll probably enjoy it.”