A critical phase induced by Berry phase and dissipation in a spin-chain

Motivated from experiments on spin-chains embedded in a metallic bath, as well as closed quantum systems described by long-range interacting Hamiltonians, we study a critical quantum spin-chain perturbed by dissipation, or equivalently, after space-time rotation, long-range spatial interactions. The interplay of dissipation and the Wess-Zumino (Berry phase) term results in a rich phase diagram with multiple renormalization group fixed points. For a range of the exponent that characterizes the dissipative bath, we find a stable, gapless, non-relativistic phase of matter whose existence necessarily requires coupling to the dissipative bath. Upon tuning the exponent, we find that the fixed-point corresponding to this gapless, stable phase 'annihilates' a fixed point that describes the transition out of this phase to a dissipation-induced ordered phase. Implications of our work for Kondo lattice systems and engineered long-range interacting quantum systems will also be discussed.