AFRL-AFOSR-VA-TR-2017-0049 Superpersistent Currents in Dirac Fermion Systems

The principal Objective of the project was to uncover, understand, and exploit persistent currents in 2D Dirac material systems and pertinent phenomena in the emerging field of relativistic quantum nonlinear dynamics and chaos. Systematic theories and methods were developed to analyze and characterize persistent currents in these systems and their unusual physical properties. The main accomplishments are the following: (1) a physical understanding of conductance stability in chaotic and integrable graphene quantum dots with random impurities, (2) the analysis of conductance fluctuations in chaotic bilayer graphene quantum dots, (3) the identification of reverse Stark effect, anomalous optical transitions, and spin control in topological insulator quantum dots, (4) the discovery of nonlinear dynamics induced anomalous Hall effect in topological insulators, (5) the finding that chaos can enhance spin polarization in graphene, (6) the articulation of a robust relativistic quantum two-level system, (7) the discovery and understanding of a number of novel and unusual phenomena associated DISTRIBUTION A: Distribution approved for public release. with scattering of pesudospin-1 particles, (8) a proposal to resolve the paradox of breakdown of quantum-classical correspondence in optomechanics, (9) the detection of unusual level statistics in graphene billiards, (10) the unearthing of the phenomenon of superscattering of pseudospin-1 wave in a photonic lattice system, (11) the revelation of relativistic Zitterbewegung in non-Hermitian photonic systems, and (12) the elucidation of the robustness of persistent currents in twodimensional Dirac systems in the presence of random disorders. In addition, the phenomenon of magnetic field induced flow reversal in a ferrofluidic Taylor-Couette system was uncovered, and the issues of multistability, chaos, and random signal generation in semiconductor super lattice systems were addressed. The AFOSR support provided the opportunity to investigate a number of forefront problems beyond the original proposed research. In addition, the support helped create a new field of interdisciplinary research: Relativistic Quantum Nonlinear Dynamics and Chaos, which studies the relativistic quantum manifestations of classical chaos with applications to graphene and two-dimensional Dirac material systems. The AFOSR project resulted in 17 refereed-journal papers and two PhD dissertations. A new collaboration with AFRL in the areas of semiconductor superlattice and many body effects in pseudo spin-1 Dirac material systems was initiated. A half dozen plenary lectures and invited talks on topics derived from the project were delivered. Distribution Statement This is block 12 on the SF298 form. Distribution A Approved for Public Release Explanation for Distribution Statement If this is not approved for public release, please provide a short explanation. E.g., contains proprietary information. SF298 Form Please attach your SF298 form. A blank SF298 can be found here. Please do not password protect or secure the PDF The maximum file size for an SF298 is 50MB. SF298_FA9550-15-1-0151.pdf Upload the Report Document. File must be a PDF. Please do not password protect or secure the PDF . The maximum file size for the Report Document is 50MB. FA9550-15-1-0151-Final_Report_022217.pdf Upload a Report Document, if any. The maximum file size for the Report Document is 50MB. Archival Publications (published) during reporting period: 1. G.-L. Wang, L. Ying, and Y.-C. Lai, "Conductance stability in chaotic and integrable quantum dots with random impurities," Physical Review E 92, 022901, 1-10 (2015). 2. R. Bao, L. Huang, Y.-C. Lai, and C. Grebogi, "Conductance fluctuations in chaotic bilayer graphene quantum dots," Physical Review E 92, 012918, 1-8 (2015). 3. H.-Y. Xu and Y.-C. Lai, "Reverse Stark effect, anomalous optical transitions, and control of spin in topological insulator quantum dots," Physical Review B 92, 195120, 1-6 (2015). 4. S. Altmeyer, Y.-H. Do, and Y.-C. Lai, "Ring bursting behavior en route to turbulence in narrow gap Taylor-Couette flows," Physical Review E 92, 053018, 1-10 (2015). 5. S. Altmeyer, Y.-H. Do, and Y.-C. Lai, "Magnetic field induced flow reversal in a ferrofluidic Taylor-Couette system," Scientific Reports 5, 18589, 1-13 (2015). DISTRIBUTION A: Distribution approved for public release. 6. G.-L. Wang, H.-Y. Xu, and Y.-C. Lai, "Nonlinear dynamics induced anomalous Hall effect in topological insulators," Scientific Reports 6, 19803, 1-9 (2016). 7. L. Ying and Y.-C. Lai, "Enhancement of spin polarization by chaos in graphene quantum dot systems," Physical Review B 93, 085408, 1-8 (2016). 8. L. Ying, D.-H. Huang, and Y.-C. Lai, "Multistability, chaos, and random signal generation in semiconductor superlattices," Physical Review E 93, 062204, 1-9 (2016). 9. M.-K. Xu, Y.-S. Wang, R. Bao, L. Huang, and Y.-C. Lai, "Complex transport behaviors of graphene quantum dots subject to mechanical vibrations," Europhysics Letters 114, 47006, 1-6 (2016). 10. H.-Y. Xu, L. Huang, and Y.-C. Lai, "A robust relativistic quantum two-level system with edge-dependent currents and spin polarization," Europhysics Letter 115, 20005, 1-7 (2016). 11. H.-Y. Xu and Y.-C. Lai, "Revival resonant scattering, perfect caustics and isotropic transport of pesudospin-1 particles," Physical Review B 94, 165405, 1-16 (2016). 12. G.-L. Wang, Y.-C. Lai, and C. Grebogi, "Transient chaos: breakdown of quantum-classical correspondence in optomechanics," Scientific Reports 6, 35381, 1-13 (2016). 13. P. Yu, Z.-Y. Li, H.-Y. Xu, L. Huang, B. Dietz, C. Grebogi, and Y.-C. Lai, "Gaussian orthogonal ensemble statistics in graphene billiards with the shape of classically integrable billiards," Physical Review E 94, 062214, 1-12 (2016). 14. H.-Y. Xu and Y.-C. Lai, "Superscattering of pseudospin-1 wave in photonic lattice," Physical Review A 95, 012119, 1-7 (2017). 15. S. Altmeyer, Y.-H. Do, and Y.-C. Lai, "Dynamics of ferrofluidic flow in small aspect-ratio Taylor-Couette systems," Scientific Reports 7, 40012, 1-19 (2017). 16. G.-L. Wang, H.-Y. Xu, L. Huang, and Y.-C. Lai, "Relativistic Zitterbewegung in non-Hermitian quantum photonic waveguide systems," New Journal of Physics, in press . 17. L. Ying and Y.-C. Lai, "Robustness of persistent currents in two-dimensional Dirac systems with disorders," Physical Review B, revised. New discoveries, inventions, or patent disclosures: Do you have any discoveries, inventions, or patent disclosures to report for this period? No Please describe and include any notable dates Do you plan to pursue a claim for personal or organizational intellectual property? Changes in research objectives (if any): None Change in AFOSR Program Officer, if any: None DISTRIBUTION A: Distribution approved for public release. Extensions granted or milestones slipped, if any: None