NSF-AFRL-REFLEQTS: Floquet effects at ultra-low driving fields for steady state quantum devices

Nontechnical Description The ability to engineer and manipulate quantum materials using light lies at the heart of emerging technologies in quantum sensing, optoelectronics, and ultrafast information processing. This project pioneers a new approach to such control through steady-state Floquet engineering—a method of using continuous-wave electromagnetic fields to create and stabilize novel quantum states of matter. Traditional Floquet methods have required extremely intense laser pulses, limiting practical applications. In contrast, the collaborative team at Columbia and University of Michigan will exploit modern nano-optics strategies to enhance light-matter interactions by orders of magnitude. These innovations will enable low-power, chip-scale implementation of enigmatic Floquet effects across a broad range of materials including two-dimensional semiconductors, superconductors, and magnetic systems. The proposed research will address foundational and technological challenges across five key goals: (1) developing steady-state Floquet platforms using enhanced cavities; (2) exploring Floquet-driven topological and superconducting phases; (3) enabling reconfigurable terahertz hardware; (4) creating tunable quantum emitters and low-noise short-wave infrared detectors; and (5) designing frequency transducers and nonlinear optical diodes. These breakthroughs promise to unlock new regimes of quantum control with broad implications for quantum communications, sensing, and materials science. In addition to its scientific contributions, the project will train a new generation of quantum engineers and scientists through interdisciplinary research, nanofabrication, and quantum device integration. The team’s documented commitment to education, innovation and technology transfer will help seed a robust workforce for the nation’s rapidly growing quantum technology sector. Technical Description Floquet engineering (FE) has emerged as a capable resource for creating new properties on demand in solids, and in atomic/molecular and circuit-QED systems. Despite its immense promise, the widespread application of FE to quantum technologies remains constrained by the fundamental challenges. To overcome these challenges, the Columbia – University of Michigan team, will employ a multi-pronged strategy: A) Cavity enhancement of light-matter coupling – plasmonic, nanotip, and photonic cavities will be used to dramatically enhance local field intensities by 102-104, further reducing the required external field strength. B) Low-frequency driving for favorable 1/ω scaling – driving at GHz–THz or targeting intra-excitonic transitions maximizes F while remaining within an achievable power regime; and C) Using moiré superlattices for enhanced lattice constant a – the larger moiré periodicity (10-nm scale) leads to proportional increases in F, enabling strong FE at lower field strengths. Integrating these methods on a chip-scale platform, with novel forms of Floquet field and across THz to optical frequencies, we will overcome challenges #1-3 and uncover pathways to on-chip Floquet device concepts closely aligned with REFLEQTS and NSF Quantum Leap Big Idea goals. 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.