Our latest paper just got published by Physical Review Letter! Let me briefly explain what our manuscript is about:

Factorization and criticality in finite interacting spin systems under a nonuniform magnetic field

Exact ground states of strongly interacting spin systems are normally highly entangled and  complex. Yet at particular finite values of the applied magnetic field such systems may exhibit a completely separable exact ground state, i.e. a simple product state where each spin points along a specific direction. Such remarkable phenomenon is known as ground state factorization.

Here we show the existence of an exceptionally degenerate set of completely separable ground states in XXZ systems immersed in a nonuniform field, arising at a remarkable quantum critical point where all magnetization plateaus merge. These points can emerge in arrays of any size, spin and dimension for a wide range of nonuniform field configurations, and exhibit other special critical properties like long range pair entanglement in their immediate vicinity.

The XXZ model is an archetypal quantum spin system which has helped to understand interacting many-body systems and their quantum phase transitions, and which has recently received renewed attention due the possibility of its finite size simulation with state-of-the-art technologies and its potential for implementing quantum information processing tasks. Among other possibilities, present results open the way to design exactly separable ground states in such system through a finite controlled field, which can be used as initial states for quantum protocols.

You can find the paper here:

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.220605

And on the arXiv:

https://arxiv.org/abs/1708.00565