Jiang Qing led the type of life so dramatically implausible, so full of power and corruption and disgrace and misery, that it could only ever be fully realized on the operatic stage. The wife of Mao Zedong, who was known in China as the White-Boned Demon, was already memorialized in song by John Adams in his opera, Nixon in China, but now, composer Bright Sheng has made her the title character in his latest work, Madame Mao, which premieres this weekend in Santa Fe. Sheng’s opera presents Jiang Qing as a conflicted and multifaceted woman, to the degree that she is actually portrayed by two different singers representing the two distinct stages of her life.