June 2022 - semfis - Mailing lists@ IFISC

IFISC Seminar on Wednesday, Jun 08, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 03 Jun '22

03 Jun '22

IFISC Seminar on Wednesday Jun 08, 2022 at 14:30 Place: IFISC Seminar Room Title: Beating Carnot efficiency with periodically driven chiral conductors Speaker: Sungguen Ryu, IFISC Abstract: Classically, the power generated by an ideal thermal machine cannot be larger than the Carnot limit. This profound result is rooted in the second law of thermodynamics. A hot question is whether this bound is still valid for microengines operating far from equilibrium. Here, we demonstrate that a quantum chiral conductor driven by AC voltage can indeed work with efficiencies much larger than the Carnot bound. The system also extracts work from common temperature baths, violating Kelvin-Planck statement. Nonetheless, with the proper definition, entropy production is always positive and the second law is preserved. The crucial ingredients to obtain efficiencies beyond the Carnot limit are: i) irreversible entropy production by the photoassisted excitation processes due to the AC field and ii) absence of power injection thanks to chirality. Our results are relevant in view of recent developments that use small conductors to test the fundamental limits of thermodynamic engines. Reference: Sungguen Ryu, Rosa L&oacute;pez, Lloren&ccedil; Serra &amp; David S&aacute;nchez&nbsp;Nature Communications volume 13, Article number: 2512 (2022)&nbsp; Presential seminar in the seminar room, with parallel Zoom stream:&nbsp;https://zoom.us/j/98286706234?pwd=bm1JUFVYcTJkaVl1VU55L0FiWDRIUT09 Url event:https://ifisc.uib-csic.es/en/events/seminars/beating-carnot-efficiency-with-periodically-driven/

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Talk on Friday, Jun 10, 2022 at 11:00
by semfis＠ifisc.uib-csic.es 03 Jun '22

03 Jun '22

Talk on Friday Jun 10, 2022 at 11:00 Place: IFISC Seminar Room Title: The process of doing a PhD - lessons learned from being a student and a supervisor Speaker: Tobias Galla, IFISC Abstract: This is a bit of an experiment. At the beginning of the session, I will summarise some of the lessons I learned during my own time as a PhD student, and then later as a supervisor,&nbsp;about the process of doing a PhD. This is about the different stages of a PhD, the role of the supervisor and of the student in these stages, about frustration along the way, and why it is normal to struggle. This is based on these notes here:&nbsp;<a dir="ltr" href="https://t.co/5xQ3q60CBj" rel="noopener noreferrer" target="_blank">tinyurl.com/ybqdcx76</a>. Hopefully this will then trigger some discussion, and members of the audience can perhaps contribute from their own experience (both students and supervisors). The meeting&nbsp;is meant to be interactive.&nbsp;I will try my best to avoid the impression that I have all the answers and that I know&nbsp;`how do to a PhD&#39;. Of course I don&#39;t, and of course everything&nbsp;I will say is highly biased by my own experiences, and won&#39;t&nbsp;apply to everyone.&nbsp;Nevertheless, I think it is useful to have a discussion of this type.&nbsp;I hope that this&nbsp;will be interesting and helpful for students and supervisors. Presential&nbsp;in the seminar room, with parallel Zoom&nbsp;stream:&nbsp;https://zoom.us/j/98286706234?pwd=bm1JUFVYcTJkaVl1VU55L0FiWDRIUT09 Url event:https://ifisc.uib-csic.es/en/events/seminars/the-process-of-doing-a-phd-lessons-learned-from-be/

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Reminder: IFISC Seminar, TODAY - Thursday, Jun 02, 2022 at 14:30
by semfis＠ifisc.uib-csic.es 02 Jun '22

02 Jun '22

IFISC Seminar on Thursday Jun 02, 2022 at 14:30 Place: IFISC Seminar Room Title: Yu-Shiba-Rusinov subgap excitations in hybrid superconductor/semiconductor nanowires containing quantum dots Speaker: Ramón Aguado , Instituto de Ciencia de Materiales de Madrid, CSIC Abstract: The physics of a quantum impurity in a superconductor is governed by the fermionic parity and spin of the two possible ground states, doublet or singlet, and their corresponding Yu-Shiba-Rusinov subgap excitations. After an introduction about their role in hybrid superconductor/semiconductor nanowires containing quantum dots [1], I will focus on semiconducting nanowires fully wrapped by a superconductor where an external magnetic flux gives rise to new regimes hitherto unexplored [2]. In the second part, I will discuss the physics of a superconducting qubit whose Josephson energy is governed by a fully tunable quantum dot. Specifically, a circuit QED setup allows to probe both its ground state and quasiparticle dynamics, resulting in, arguably, the most in-depth experimental study of a superconducting quantum impurity to date [3]. These results hold promise for realizing Andreev qubits with long parity lifetimes. [1] Lee et al Phys. Rev. Lett. 109, 186802 (2012); Žitko et al, Phys. Rev. B 91, 045441 (2015); &nbsp;Lee et al, Nature Nanotech., 9, 79-84 (2014). [2] Valentini et al, Science 373, 82-88 (2021); Escribano et al, Phys.&nbsp;Rev.&nbsp;B 105, 045418 (2022). [3] Bargerbos et al arXiv:2202.12754. PRX Quantum, in press. Note the unusual day of the week.&nbsp;The seminar is presential with parallel zoom stream: https://zoom.us/j/98286706234?pwd=bm1JUFVYcTJkaVl1VU55L0FiWDRIUT09 Url event:https://ifisc.uib-csic.es/en/events/seminars/yu-shiba-rusinov-subgap-excitations-in-hybrid-supe/

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