Universality class of Ising critical states with long-range losses

Abstract

We show that spatial resolved dissipation can act on Ising lattices molding the universality class of their critical points. We consider non-local spin losses with a Liouvillian gap closing at small momenta as ∝ q α , with α a positive tunable exponent, directly related to the power-law decay of the spatial profile of losses at long distances. The associated quantum noise spectrum is gapless in the infrared and it yields a class of soft modes asymptotically decoupled from dissipation at small momenta. These modes are responsible for the emergence of a critical scaling regime which can be regarded as the non-unitary analogue of the universality class of long-range interacting Ising models. In particular, for 0 < α < 1 we find a non-equilibrium critical point ruled by a dynamical field theory ascribable to a Langevin model with coexisting inertial (∝ ω 2 ) and frictional (∝ ω) kinetic coefficients, and driven by a gapless Markovian noise with variance ∝ q α at small momenta. This effective field theory is beyond the Halperin-Hohenberg description of dynamical criticality, and its critical exponents differ from their unitary long-range counterparts. Furthermore, by employing a one-loop improved RG calculation, we estimate the conditions for observability of this scaling regime before incoherent local emission intrudes in the spin sample, dragging the system into a thermal fixed point. We also explore other instances of criticality which emerge for α > 1 or adding longrange spin interactions. Our work lays out perspectives for a revision of universality in driven-open systems by employing dark states supported by non-local dissipation.

Algebraic theory of quantum synchronization and limit cycles under dissipation

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Competition between lasing and superradiance under spintronic pumping

“…Recent studies have shown the usefulness of non-local dissipation in generating entanglement between distant qubits in both fields of quantum optics and spintronics, by investigating spins immersed in a optical cavity [67][68][69] and nitrogen-vacancy qubits in proximity to a magnetic medium [70]. For the latter, dynamical phase transitions in the magnet controlled by electrical pumping, may provide an efficient tunability of non-local dissipation, which could be studied along the lines of this work.…”

Impact of Dissipation on Universal Fluctuation Dynamics in Open Quantum Systems

“…Such open quantum systems have attracted many theoretical and experimental researchers in recent years, and nontrivial consequences of dissipation have been uncovered in a variety of quantum phenomena. In particular, universal dynamics has been extensively explored from various viewpoints such as measurement-induced phase transitions [5][6][7][8][9][10][11][12][13][14][15][16], selforganized criticality [17][18][19], and non-equilibrium phase transitions [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Open quantum systems have thus become a novel playground for studying universal quantum non-equilibrium phenomena.…”