Electron-beam lithography system

• Subject Area: Condensed Matter Physics
• Term: Funded in 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 460700859

The electron beam lithography system (EBL) requested by the group of Prof. Lange allows for the fabrication of resonators for the terahertz (THz) and mid-infrared spectral range, enabling control of electric and magnetic near fields on strongly subwavelength scales. Tailoring near fields of THz modes by quantitative, parameter-free numerical simulations, we design and fabricate ultrastrong and deep-strong light-matter coupling in cavity quantum electrodynamical (c-QED) structures, as well as near-field enhancing resonators enabling THz experiments with atomically strong fields. This subwavelength control of electromagnetic fields plays a central role for our group’s quest to investigate extreme limits of light-matter interaction in which optical nonlinearities occur on time scales significantly shorter than a single cycle of light. Recent research highlights include the observation of dynamical Bloch oscillations and high-harmonics generation, lightwave acceleration of Dirac electrons in topological insulators, minimally dissipative spin switching in antenna-enhanced THz near fields, non-adiabatic control of deep-strongly light-matter coupled electrons in switchable THz resonators, and the observation of carrier-wave Rabi flopping of ultrastrongly coupled resonances.Typical resonator structures are deposited on a planar substrate hosting an electronic excitation. We routinely fabricate metallic resonators measuring between 1 and 100 µm, with feature sizes down to 50 nm. Efficient far-field coupling is achieved by arranging the structures in arrays of up to 106 elements. Alternative approaches based on single antennas combine strong THz fields with optical probe pulses, providing a unique high-field laboratory with subwavelength precision. The requested system will allow us to continue this research and explore novel directions of THz subcycle physics in condensed-matter systems. Recent experiments in c-QED have utilized the vacuum modes of optical resonators to control electronic transport, chemical reactions, or superconductivity, in equilibrium. In contrast, we will investigate the corresponding strong-field dynamics at previously inaccessible coupling strengths, where the vacuum Rabi frequency exceeds the carrier frequency. To this end, we will further boost the coupling strength of cavity-coupled Landau electrons by advanced nanostructuring, investigate nonlinearities of ultrastrongly coupled semiconductor intersubband transitions, and explore novel c-QED concepts including superconducting resonators or atomically thin materials such as transition metal dichalcogenides. Transitioning from linear to non-perturbatively nonlinear dynamics, we expect to unveil novel phenomena including high-order nonlinearities, generation of non-classical light, resonances generated by nonlinear interactions, or phase transitions. Simultaneously subwavelength and subcycle control of near fields will play a key role in unravelling the relevant quantum dynamics.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Elektronenstrahllithographiesystem
• Instrumentation Group: 0910 Geräte für Ionenimplantation und Halbleiterdotierung
• Applicant Institution: Technische Universität Dortmund
• Leader: Professor Dr. Christoph Lange