Magnetic phase diagram of a spin-1/2 XXZ chain with modulated Dzyaloshinskii-Moriya interaction

Critical metrology of minimally accessible anisotropic spin chains

We address quantum metrology in critical spin chains with anisotropy and Dzyaloshinskii-Moriya (DM) interaction, and show how local and quasi-local measurements may be exploited to characterize global properties of the systems. In particular, we evaluate the classical (magnetization) and quantum Fisher information of the relevant parameters for the density matrix of a single spin and that of a pair of spins ranging from nearest to sixth-nearest neighbors, to the limiting case of very distant spins. Our results allow us to elucidate the role of the different parameters and to individuate the optimal working regimes for the precise characterization of the system, also clarifying the effects of correlations on the estimation precision.

Anomalous behavior in entanglement speed profile through spin chains

The origin of the uniform Dzyaloshinskii-Moriya interaction (DMI), which is responsible for the creation of chiral magnetism, has been the subject of extensive research. Recently, modern technology has allowed for its production and utilization in a modulated form. Not only can magnetic phases of spin chains be enriched by the presence of such a potential as detailed in Japaridze et al. [Phys. Rev. E 104, 014134 (2021)10.1103/PhysRevE.104.014134], but the capacity of such systems for information transmission is also greatly enhanced. The current paper examines the impact of a staggered pattern of DMI (STDMI) on a chain with a substrate XX Heisenberg interaction. It is demonstrated how enhancing the intensity of this coupling improves the propagation of an entangled quantum state. Additionally, as our analysis has shown, the initial condition over the system's state has a profound effect on the speed at which entanglement spreads. The aberrant behavior of the entanglement's speed profile in response to fine-tuning of the phase factor which adjusts the initial state is the focus of this paper. This anomalous behavior is characterized by dramatic drops in speed for certain phase factor values. We have also shown that, using wave interference principles, we can predict exactly why these phenomena occur. This research will pave the way for additional studies on STDMI and its potential applications in the field of quantum information.