Over the years , he has worked with classical and bluegrass artists such as Joshua Bell , Yo-Yo Ma , BÃ la Fleck , Sam Bush , James Taylor , Jerry Douglas , Mike Marshall , Mark O'Connor , Alison Krauss , the members of Nickel Creek , and Mary Chapin Carpenter . His collaborators have spanned a wide range of musical styles and talents ; among them are Joshua Bell , Yo-Yo Ma , BÃ la Fleck , Zakir Hussain , Sam Bush , James Taylor , Chris Thile , Mike Marshall , Mark O'Connor , Alison Krauss , Mary Chapin Carpenter , and the trio Nickel Creek .