We study the quasiparticle excitation and quench dynamics of the one-dimensional transverse-field Ising model with power-law (1/rα) interactions. We find that long-range interactions give rise to a confining potential, which couples pairs of domain walls (kinks) into bound quasiparticles, analogous to mesonic bound states in high-energy physics. We show that these bound states have dramatic consequences for the non-equilibrium dynamics following a global quantum quench, such as suppressed spreading of quantum information and oscillations of order parameters. The masses of these bound states can be read out from the Fourier spectrum of these oscillating order parameters. We then use a two-kink model to qualitatively explain the phenomenon of long-range-interaction-induced confinement. The masses of the bound states predicted by this model are in good quantitative agreement with exact diagonalization results. Moreover, we illustrate that these bound states lead to weak thermalization of local observables for initial states with energy near the bottom of the many-body energy spectrum. Our work is readily applicable to current trapped-ion experiments.

VL - 122 UR - https://arxiv.org/abs/1810.02365 CP - 150601 U5 - https://doi.org/10.1103/PhysRevLett.122.150601 ER - TY - JOUR T1 - Heisenberg-Scaling Measurement Protocol for Analytic Functions with Quantum Sensor Networks Y1 - 2019 A1 - Kevin Qian A1 - Zachary Eldredge A1 - Wenchao Ge A1 - Guido Pagano A1 - Christopher Monroe A1 - James V. Porto A1 - Alexey V. Gorshkov AB -We generalize past work on quantum sensor networks to show that, for d input parameters, entanglement can yield a factor O(d) improvement in mean squared error when estimating an analytic function of these parameters. We show that the protocol is optimal for qubit sensors, and conjecture an optimal protocol for photons passing through interferometers. Our protocol is also applicable to continuous variable measurements, such as one quadrature of a field operator. We outline a few potential applications, including calibration of laser operations in trapped ion quantum computing.

UR - https://arxiv.org/abs/1901.09042 ER -