Terahertz 2D Coherent Spectroscopy of Superconductivity: Deciphering Subcycle Quantum Dynamics and Interference

About This Grant

Non-technical Abstract: Understanding and controlling quantum behavior in materials is a key challenge that could shape the future of technology—from faster computers to advanced medical imaging and secure communication. This project brings together two powerful fields—superconductivity and terahertz nonlinear optics—to explore how fundamental quantum effects can be more precisely controlled in real superconducting materials. A cutting-edge technique called terahertz two-dimensional coherent spectroscopy allows researchers to “see” and manipulate quantum processes in ways not possible before. This work not only opens new pathways for scientific discovery but also helps train the next generation of scientists and innovators through hands-on research and educational outreach activities. By bridging fundamental science with real world practical applications and workforce development, this project has the potential to drive innovation and broaden public understanding of quantum technologies. Technical Abstract: This research explores ultrafast quantum dynamics in light-induced superconducting states using terahertz two-dimensional coherent spectroscopy. The project addresses how quantum excitations—such as Floquet bands and Leggett mode echoes—emerge and interact under strong terahertz driving fields. Processes involving interactions among such excitations are crucial for understanding and controlling non-equilibrium phases in quantum materials. The research leverages terahertz two-dimensional coherent spectroscopy to achieve correlation tomography with both temporal and spectral resolution, surpassing the capabilities of conventional time- and frequency-domain techniques. The approach enables the disentanglement of overlapping quantum pathways and reveals interactions between collective modes and quasiparticles. The research team builds on prior discoveries in iron-based and nickelate superconductors, where signatures of Higgs dynamics and unconventional order parameters were identified. Key objectives include visualizing quantum beating of Floquet bands, demonstrating coherent quantum emission from superconducting collective states, and uncovering rephasing echo signals mediated by Leggett modes. By advancing fundamental coherent dynamics of superconductivity, this activity opens new routes for dynamic manipulation of quantum materials and contributes to the broader effort to develop functional quantum systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.