A Jetblue Airbus A321-200, registration N975JT performing flight B6-881 from New York JFK,NY (USA) to Saint Lucia (Saint Lucia) with 202 people on board, was enroute at FL310 about 220nm southwest of Bermuda (Bermuda) when the crew reported a smoke indication in the aft cabin, turned around and diverted to Bermuda for a safe landing about 35 minutes later. Emergency services inspected the aircraft but did not find any trace of fire, smoke or heat. . .