A former employee of Citadel LLC was sentenced to three years in prison Thursday for stealing trading information valued at $10.1 million from the mammoth Chicago hedge fund and from a New Jersey high-frequency trading firm where he previously worked.Yihao Pu, a 27-year-old computer science engineer, in August pleaded guilty to counts of unlawful possession and unlawful transmission of trade secrets. The government sought a prison term of up to nine years.Sahil Uppal received three months’ probation for obstructing …