Quantum Simulation of Many-Body Physics with Trapped Ions
Over the past three decades, quantum information processing has seen incredible progress, both in theory and experiments, predominantly driven by physicists’ wish to solve many-body problems that are deemed impossible on classical computers, beyond a few particles, due to the exponential growth of the Hilbert space. Today, Feynman’s proposal to design a fully controllable quantum device, that is capable of simulating classically intractable problems, is closer to reality than ever.
Trapped ions have been shown to be prime candidates for quantum simulation and computation platforms. The spin (or qubit) information is encoded into two electronic states and can be coherently controlled via laser light fields. Moreover, laser light fields are used to couple the spin degrees of freedom to the common motion of the ions, realizing either entangling gates for quantum computation or engineered spin-spin interactions with tunable interaction ranges for quantum simulations.
In this talk, two experiments focused on quantum simulations of interacting many-body systems will be presented. The first experiment addresses a fundamental question in interacting systems: how fast can information propagate in such systems? We demonstrate that a local perturbation generates entanglement, which propagates through the entire system. Additionally, we investigate the velocity of correlation-spreading for different interaction lengths, showing that the picture of a light-cone-like propagation becomes invalid for long-range interactions. In the second experiment, we report on the first observation of a dynamical quantum phase transition, i.e. non-analytical points (kinks) in the time evolution of quenched systems. We show that these phase transitions are indeed robust against deformations of the underlying Hamiltonian, i.e. changes in the interaction parameters, and uncover a previously unknown relation between these special points in time and entanglement growth.