Jonasson, who helped Edinburgh to the Premier League championship last season, has signed for the One51 Aces as the second of the two riders they are allowed to use on a doubling-up basis with the lower division.
He will share the No 7 slot with Steve Boxall, who will start the season as first choice when his commitments with Newcastle allow.
Jonasson, aged 20, is widely regarded as one of Sweden's finest prospects.
Team manager Chris Morton said: "Signing Thomas is a major coup for us because he is a great prospect who is highly regarded at home.
"He will be a very busy rider next season as he will also be racing in Sweden and Poland but he can accommodate the dates on which we'll need him."
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