Facebook Chief Technology Officer Mike Schroepfer has made the “difficult decision” to step down from his role, he announced Wednesday. Schroepfer, who has worked for the social network for 13 years and oversees its work in artificial intelligence (AI), virtual reality, and the blockchain, said he will transition to a new part time role as Facebook’s first senior fellow at the company next year. “This is a difficult decision because of how much I love Facebook and how excited I am about the future we are building together,” Schroepfer wrote on his Facebook profile. “This change in role will allow me to dedicate more time to my family and my personal philanthropic efforts while staying deeply connected to the company working on key initiatives including recruiting and developing technical talent and continuing to foster our AI investments in critical technologies like PyTorch.” Another longtime Facebook executive, Andrew Bosworth, who Schroepfer affectionately referred to as Boz, will …