As a result of the acquisition, Quantum, which employs seven people and has more than 25 clients, has been renamed Quantum Freshwater UK.
The clients it brings to Freshwater include Ernst & Young, the Professional Golfers' Association and the Ryland Group.
Quantum MD Edward Carter and deputy MD Anne Parry, who founded the agency in 1997, have become MD and deputy MD of the new company. Carter will now report to Freshwater UK CEO Steve Howell.
'We are continuing to look for acquisition opportunities in the north of England,' said Howell. He added that he would like to have offices 'on both sides of the Pennines' and was interested in mid-sized agencies.