Periodic Reporting for period 4 - TRANSFORMER (Structural transformations and phase transitions in real-time)
Reporting period: 2023-03-01 to 2024-08-31
O1 focused on pushing the limits of LIED to capture space-time images of single molecules. This was a crucial step in exploring quantum systems at new space-time scales. Through various experiments, we proved we could image the positions of atoms in a single molecule using just one attosecond electron pulse. In O1.1 we demonstrated that even neutral molecules could be imaged despite ionization and assessed how ionization affects bond detection accuracy. We also controlled electron movements during imaging, reducing uncertainty to the attosecond scale, and developed a new method to extract molecular structures. In O1.2 we expanded LIED’s application to more complex, dynamic molecules, utilizing machine learning to identify structures, including chiral molecules.
O2 we tackled the challenge of simultaneously measuring both electron and nuclear movements, essential for understanding quantum physics. We imaged the hydrogen molecule(H2) during tunneling ionization, tracking electron exit points and nuclear changes. This was the first time both electron and nuclear movements were imaged together. Another major breakthrough(O2.2) involved combining XANES and EXAFS with attosecond X-rays, offering unprecedented detail on electron and nuclear structures. This helped answer key questions about electron scattering in materials like graphite and how energy flows within the material, crucial for understanding processes like polymerization in the chemical industry.
O3 combined our findings to address quantum phase transitions, where electron and nuclear movements are tightly coupled. In O3.1 we applied LIED to study molecular phase transitions in both simple and complex molecules, developing new imaging techniques using machine learning. In O3.2 we used advanced X-ray and harmonic spectroscopy to explore electronic and structural phase transitions in solids. Key breakthroughs included the first optical imaging of quantum phase transitions in high-temperature superconductors and the pioneering control of topological phase transitions, leading to a patent for a novel method in valleytronics.
In summary, the TRANSFORMER project exceeded its ambitious goals, leading to groundbreaking discoveries across quantum dynamics, phase transitions, and imaging techniques. These achievements have had wide-reaching impact, generating high-impact publications and establishing cutting-edge methodologies that will drive future advancements in science and technology with near-immediate applications.
Within O1.1 we successfully imaged neutral molecules with LIED, even under ionization, as documented in publications like Proc. Nat. Acad. Sci. and Rep. Prog. Phys. We also examined how ionization affects bond detection and evaluated the limits of quantum recollision, collaborating with the groups of Dudovich(Weizmann) and Bauer(Rostock). Our work resolved debates over the quantum trajectory contributions to LIED imaging and reduced temporal uncertainty to the attosecond regime. Additionally, we developed a method for extracting molecular structures from LIED data, proving its validity across different molecular systems.
In O1.2 we extended LIED imaging to complex and dynamic molecular systems, employing machine learning to identify the structures of highly complex and chiral molecules.
O2 achieved simultaneous electron and nuclear coordinate measurements. In O2.1 we imaged the H2 molecule during tunneling ionization, tracking the tunnel exit in momentum space and linking it to real space, while also monitoring changes in the nuclear wave packet. This marks the first imaging of a correlated electron-nuclear wavepacket, with a forthcoming publication.
O2 yielded groundbreaking advancements, using attosecond soft-X-ray pulses to extract electronic and nuclear information. This deepened our understanding of XANES and EXAFS, particularly in graphite, solving key questions about electron scattering and its lattice coupling. This research also provided insight into light absorption, electron/hole excitation, and phonon coupling—key steps in polymerization important for the chemical industry.
O3 integrated previous outcomes to tackle quantum phase transitions, where electronic and nuclear couplings challenge current methods. In O3.1 we used LIED to study molecular phase transitions, from simple triatomic species to complex chiral systems, developing new imaging methods using sparsity and machine learning for structure identification.
O3 saw remarkable progress. We employed attosecond X-ray and harmonic spectroscopy to disentangle electronic and structural phase transitions in solids. Highlights include optical imaging of quantum phase transitions in high-Tc superconductors and the first lightwave control of a topological phase transition, leading to valleytronics independent of material properties. This work resulted in a patent application for a novel method in valleytronics in bulk materials(EP23382921.7).
In conclusion, the project exceeded its ambitious goals, achieving significant breakthroughs in quantum dynamics, imaging, and phase transitions, made possible by TRANSFORMER grant.