Tunable phase transition in a dissipative two-spin system: A renormalization group study

We proposed and theoretically studied a model of two separated spins coupled to a common bosonic bath. In our SU(2)-symmetric model, the phase transition point and the stable fixed point representing the nonclassical phase can be continuously tuned by the distance between the two spins. Thus the fixed point collision and annihilation (FPCAA) could be achieved by simply changing the distance. Moreover, we studied in detail variation of the critical value when the distance is changed. Finally, we also discussed several possible generalizations of our model which may be worth further studying. Our work is essential for realization of FPCAA in such systems and paves the way for studying related physics such as deconfined criticality and quasiuniversality.