The song in question was created by researchers at Sony, who used the company’s Flow Machines software to analyze a database of some 13,000 lead sheets (basic scores that record the melody and harmony of tracks) from different genres around the world. The software writes its own melodies, and a human composer, Benoît Carré, was drafted to turn material into a fully produced track. He simply inputted a desired style of music (in this case The Beatles) and got to work.

Source: This AI-written pop song is almost certainly a dire warning for humanity – The Verge