MD-83
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; General Declared Emergency
Aircraft
Take off was normal until 800 AGL when a very loud bang followed by several less severe bangs occurred followed by the aircraft yawing to the left. Engine instruments indicated complete rollback of left engine. Left throttle was retarded to idle and all engine and systems indications  indicated normal and no more noises were coming from the engine. I declared an emergency with ATC and piloted the aircraft back to [the runway] with the right engine operating normally and the left engine at idle. All QRH procedures were accomplished and appropriate personnel notified. After an uneventful landing and exiting [runway] we had ARFF confirm the left engine appeared normal; with no hot spots or leaks. I taxied single engine (right) to gate while having ARFF follow us to keep an eye on the engine. Shut down at gate with no further abnormal indications.
[Narrative 2 had no additional information.]
MD-83 flight crew reported left engine loss of power shortly after takeoff; the result of a probable compressor stall. Flight declared an emergency and returned to departure airport with affected engine at idle thrust.