Description:

Observations and applications of quantum mechanical phenomena at a macroscopic scale are among the most important goals shared between quantum information science (QIS) and condensed matter physics (CMP). In this talk, I will describe how recent dialogues between QIS and CMP resulted in a novel approach to this goal: an efficient protocol to prepare a large scale quantum many-body state with useful quantum entanglement in noisy quantum devices. This is particularly important in the noisy intermediate-scale quantum (NISQ) era, where decoherence poses a major challenge. The key idea is to synergistically combine multiple ingredients from CMP, QIS, and computation: the robustness of phases of matter, quantum teleportation induced by projective measurements, and computationally assisted feedback control. As a concrete example, I will present how to efficiently and robustly prepare long-range entangled states in a shallow quantum circuit in the presence of imperfections and noises. Taking further steps, I will explain a new perspective to understand the robustness of “useful” quantum entanglement against non-unitary dynamics, which will lead to a fundamental understanding of what can be verified in the NISQ platforms.

Jong Yeon Lee, Postdoctoral Scholar, Kavli Institute of Theoretical Physics (UC Santa Barbara)

Host: Professor Jens Koch