Does it matter what their productivity is as long as it's above 0 of whatever? Leon Theremin invented the "Buran eavesdropping system" while "working" at the sharashka, used to spy on embassies in Moscow via their windows.

Another fun anecdote related to Theremin:

> Theremin invented another listening device called The Thing, hidden in a replica of the Great Seal of the United States carved in wood. In 1945, Soviet school children presented the concealed bug to the U.S. Ambassador as a "gesture of friendship" to the USSR's World War II ally. It hung in the ambassador’s residential office in Moscow and intercepted confidential conversations there during the first seven years of the Cold War, until it was accidentally discovered in 1952.

Interesting life in general: https://en.wikipedia.org/wiki/Leon_Theremin