We consider the non-equilibrium dynamics of a simple system consisting of interacting spin-1/2 particles subjected to a collective damping. The model is close to situations that can be engineered in hybrid electro/opto-mechanical settings. Making use of large-deviation theory, we find a Gallavotti-Cohen symmetry in the dynamics of the system as well as evidence for the coexistence of two dynamical phases with different activity levels. We show that additional damping processes smooth out this behavior. Our analytical results are backed up by Monte Carlo simulations that reveal the nature of the trajectories contributing to the different dynamical phases.Understanding and controlling the dynamical behavior of quantum systems has seen flourishing interest [1][2][3] propelled by theoretical and experimental progress that has made it possible to observe and manipulate such systems with unprecedented accuracy. Much attention has also been devoted recently to the notion of dynamical phase transitions in such systems, relating them to the nonanalyticity of, e.g., the Loschmidt echo [4] or the logarithm of a biased partition function in large-deviation (LD) theory [5], which has a natural interpretation in terms of the statistics of rare trajectories observed in experiments. The study of the dynamics of quantum systems through LD methods [6-8] emerged recently both as an extension of the theory as applied to classical systems [9][10][11][12] and as a dynamical complement to the standard analysis of equilibrium phase transitions in many-body systems [13]. Here, nonanalyticities in the LD free-energy function of a system, extracted from the equations governing its dynamical behavior, are identified in the literature with dynamical phase transition points [6].Following [6], in this paper we are interested in studying the statistical properties of rare quantum-jump trajectories [14] of a system that interacts with a heat bath driving the system out of equilibrium. We consider the dynamical LD properties of a simple three-spin quantum open model, which departs from those recently studied in two respects: first, dissipation is due to nonclassical bilinear jump operators; and second, we consider a current-like dynamical order parameter. The two central results in this paper are (a) the observation of intermittency between dynamical phases of distinct activity, itself a consequence of the reducibility of the dynamics in an appropriate limit due to the collective jump operators; and (b) the existence of a Gallavotti-Cohen symmetry in LD functions associated with the time-asymmetric order parameter, analogous to that found in driven classical systems [15], which gives rise to a fluctuation theorem [16] relating to the quantum jump rate. Our system therefore provides a minimal but extendible model that uncovers the effects of thermal baths and the nontrivial interplay between local and global decay channels [17] on the non-equilibrium dynamics of a quantum system.We start with three spins-1/2, which we label = j 1, 2, 3, placed at ...