The 20-year-old, who is Wigan's understudy to England full-back Sam Tomkins, is moving to the City of Salford Stadium initially for a month and trained with his new team-mates on Tuesday.
"Jack will be in the squad," said Salford coach Phil Veivers, who was assistant coach at Wigan when Murphy came onto the scene. "I've watched him develop. He's a fine player and has been a good understudy to Sam Tomkins for the last 18 months."
Murphy made a try-scoring Super League debut in Tomkins's absence against Bradford last June and played against the City Reds in a pre-season friendly at Barton a fortnight ago.
"This is a good chance for me to get some first-team games under my belt," he said. "I am looking forward to meeting the Salford boys and competing for a place in the side."
Wigan's rugby general manager Kris Radlinski said: "This loan move is a great opportunity for Jack to gain some more Super League experience and we are more than happy for him to head to Salford on a one-month loan deal.
"We have an excellent relationship with the Reds and their head coach Phil Veivers, and we feel this deal will benefit all parties."
Murphy will initially help Salford to offset the loss of Australian full-back Luke Patten, who was among a host of experienced players to leave the club at the end of last season.
Veivers has been able to make only one signing so far - that of St Helens second-rower Andrew Dixon - because of delays over the club's proposed takeover by Dr Marwan Koukash.
Veivers has targeted seven more signings and will make his moves once the takeover is completed, which could happen on Wednesday.