Control of Many-Body States Using Strong Coherent Light-Matter Coupling in Terahertz Cavities
Abstract
The primary objective of modern research in condensed matter physics and material science is the optimization and tuning of electronic, structural, and magnetic phases of solids. Engineering and controlling phases of matter is crucial to advancing useful functionalities of materials for applications in sensing, information storage and processing. The main goal of this project is to develop a new approach to tuning properties of materials by changing the electromagentic environment of electrons through strong coherent coupling to vacuum fluctuations of terahertz metamaterials. Achieving strong resonant coupling between cavities and collective modes in solids, including phonons, magnons, and Josephson plasmons, will make it possible to control and tune electron-electron interactions, thus opening a new route for controlling correlated electron states. We will explore the possibility of enhancing ferroelectric, antiferromagnetic, and superconducting states using terahertz metamaterials such as split ring resonators. In contrast to previously studied photoinduced phases, which appear only as short-lived transient states, our goal is to create equilibrium phases of matter, where cavities facilitate formation of infinitely long lived states without the need for external pumping. This project will develop a new theoretical approach for analyzing quantum systems with ultrastrong light-matter coupling. Properties of such systems are extremely challenging to analyze because of the importance of including states with many photons in every coupled mode. The main limitation of the standard methods in the strongly interacting regime comes from the photon number truncation. The focus of this project will be on developing nonperturbative methods which circumvent this problem by introducing unitary transformations that entangle light and matter degrees of freedom and achieve asymptotic decoupling in the limit where light-matter interaction becomes the dominant energy scale. This approach offers a systematic way to derive the faithful tight-binding Hamiltonians for electrons in a periodic potential and strongly coupled to the electromagnetic field of a cavity. As a concrete application of this technique we will analyze properties of electrons in mono- and twisted bilayer-2D materials embedded in terahertz cavities. In this project we will also investigate the potential for using terahertz metamaterials as a new spectroscopic tool for analyzing pump and probe experiments. In particular, we will analyze the possibility of outcoupling photoexcited finite momentum collective modes, including Josepshon plasmons and magnons, as outgoing terahertz radiation beams.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 25, 2021
- Source ID
- W911NF2110184
Entities
People
- Eugene A. Demler
Organizations
- Army Contracting Command
- Harvard University
- United States Army