enQnet · Mesoscopic light-matter entanglement in hybrid solid-state networks

Hybrid quantum systems couple together multiple distinct physical degrees of freedom. They are essential to the quantum technological revolution as, for instance, the light-matter coupling provides a way to transfer information from electronic to optical systems or vice versa. They also allow studying fundamental physics of quantum information.I propose a theoretical project involving hybrid quantum networks consisting of coupled photonic and electronic systems. It will lead to a state-of-the-art blueprint for a quantum simulator and a set of new tools for understanding quantum mechanical entanglement in practice.Currently, there are efforts to build quantum computers and simulators. These systems are often based on superconducting circuits or trapped ions with one type of a system: a qubit which is a two-level system. However, simulating modes with multiple levels, optical or vibrational systems for example, is inefficient with qubits. This project aims to provide novel theoretical tools for a hybrid quantum network that would fare better because it already contains optical modes. The theoretical tools developed combine condensed matter physics and quantum optics including phase-space methods.I tackle the scientific objective in the following way: First, I focus on specific light-matter interactions of quantum dots and microwave cavities. I look into the smallest possible network of a quantum dot coupled to two cavities. In this simple network, I characterize the non-classical and non-local correlations of the two cavities, their entanglement, by studying the cross-correlations of the photons emitted by the cavities. Second, I expand the network by connecting quantum dots to the two cavities. This allows seeing the propagation of entanglement from the cavities to the terminating quantum dots. Finally, I extend the investigations to large hybrid networks which I will use for quantum simulation and to find new effective descriptions of entanglement propagation.