BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Sachin Verma (Indian Institute of Technology) DTSTART:20221118T140000Z DTEND:20221118T150000Z DTSTAMP:20260423T021006Z UID:QTech/17 DESCRIPTION:Title: T hermoelectric transport through strongly correlated quantum-dot based hybr id devices: A non-equilibrium many body Green’s function approach\nb y Sachin Verma (Indian Institute of Technology) as part of QHS Lecture Ser ies on Superconducting Phenomena and Electronics\n\n\nAbstract\nWe shall p resent our analytical study of a quantum dot (QD) based thermoelectric par ticle-exchange heat engine (N-QD-N) for both finite and infinite on-dot Co ulomb correlation. Employing Keldysh's nonequilibrium Green's function for malism for different decoupling schemes in the equation of motion\, we hav e analyzed the thermoelectric properties within the non-linear transport r egime. As the simplest mean-field approximation is insufficient for analyz ing thermoelectric properties in the Coulomb blockade regime\, one needs t o employ a higher-order approximation to study strongly correlated QD-base d heat engines. Therefore\, we initially used the Hubbard-Ⅰ approximatio n to study the quantum dot level position (gate voltage)\, thermal gradien t\, and on-dot Coulomb interaction dependence of the thermoelectric proper ties. To provide further insight into a more practical QD heat engine oper ation\, we used an approach beyond Hubbard-Ⅰ with strong on-site Coulomb repulsion\, i.e.\, U→∞. Within this infinite-U limit\, we examine the role of the symmetric dot-reservoir tunneling and external serial load re sistance in optimizing the performance of the strongly correlated quantum dot heat engine. Our infinite-U results show a good quantitative agreement with recent experimental data and real time diagrammatic theory. Thus Gre en's function EOM technique which is a computationally inexpensive and str aightforward analytical method gives reliable results in the Coulomb block ade regime. The present analysis can be extended to examine the optimal pe rformance of other realistic low dimensional heat engines based on multipl e quantum dots and multiple reservoirs within the strong Coulomb blockade regime.\n\nWe shall also briefly highlight our recent results for a hybrid QD system in which a Bardeen-Cooper-Schrieffer (BCS) superconductor repla ces the normal metallic drain reservoir. The results show that this hybrid superconductor-quantum dot system (N-QD-S) exhibits a finite thermal resp onse\, thus making it a promising candidate for low-temperature thermal ap plications such as quantum dot-based power generators\, refrigerators\, qu antum heat valves\, and rectifiers.\n\nReferences\n\n1. Sachin Verma and A jay\, (Manuscript under review) (2022)\narXiv preprint: arXiv:2208.06686v1 \n\n2. Sachin Verma and Ajay\, Journal of Physics: Condensed Matter 34\, 1 55601 (2022)\, \nDOI: 10.1088/1361-648X/ac4ced\n\n3. M. Josefsson\, A . Svilans\, A. M. Burke\, E. A. Hoffmann\, S. Fahlvik\, C. Thelander\, M. Leijnse\, and H. Linke\, Nature Nanotech 13\, 920–924\, (2018)\, M. Jose fsson\, A. Svilans\, H. Linke\, and M. Leijnse\, Phys. Rev. B 99\, 235432\ , (2019)\n\n4. S. M. Tabatabaei\, D. Sánchez\, A.L. Yeyati\, and R. Sánc hez\, Phys. Rev. B 106\, 115419\, (2022)\n LOCATION:https://researchseminars.org/talk/QTech/17/ END:VEVENT END:VCALENDAR