Faculty Kolloquium and visit to the ITP

We were most happy to welcome Stephanie Wehner (TU Delft) to visit the Institute and deliver the last Faculty Kolloquium of the year 2015. Stephanie presented a very nice and pedagogical talk on the foundations of quantum thermodynamics. She also discussed her recent work on the revision of the concept of Carnot maximal efficiency for quantum thermal machines, which does not only depend on the temperature of the heat reservoirs. These are results in collaboration with Mischa Woods, a former PhD student of the Institute. You can read all details in arXiv:1506.02322

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There was also time for discussions Followed by a hearty Schwabian dinner of Goose and Rotkraut at the Zunfthaus in the Fischerviertel to celebrate the Christmas season.

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Stephanie was lucky with the weather and also brave enough to climb the tower of the Ulmer Münster (768 steps to reach the top) before catching the train home. The Münster is the one of the five tallest structures to be completed last century, with the steeple of almost 162 meters, the tallest church in the world. Below you can see two fantastic pictures she took in her ascent.

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Faculty Kolloquium.- Francisco Garcia Vidal (Universidad Autonoma de Madrid)

It has been a pleasure to get to know in person Francisco Garcia Vidal, who leads the Plasmonics Group at the Universidad Autonoma de Madrid. Francisco gave the Faculty Kolloquium and presented the foundations of this subject, the state of the art concerning plasmon generation and transmission and finalized his talk with a glimpse of the interesting work of his group in the context of exciton transport. Recently, Garcia Vidal and his group have shown that exciton conductance in organic materials can be largely enhanced when the molecules are strongly coupled to an electromagnetic mode. This is a result that could be relevant for the dynamics of photosynthetic systems in which exciton transport plays a key role. You can read further details in Phys. Rev. Lett. 114, 196402 (2015).

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After the talk, and as small compensation for the long trip in a day that is festive in Spain, we continued the discussions in a relaxed environment and took Francisco to sample the local cuisine and try out delicious home made Spaetzle.

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Angelo Bassi and Dario Tamascelli are visiting the Institute

We have had two visitors from North Italy this week.

Angelo Bassi (University of Trieste), a specialist in the Foundations of Quantum Mechanics, gave a very nice seminar on collapse models, explaining the rational underpinning their formulation and the possibility to experimentally test for non linear corrections to the Schrodinger equation.     You can read recent proposals from Angelo and his group to use optomechanical systems for this purpose in in arXiv:1510.01696 and arXiv:1510.05791.

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The talk was also a good opportunity to confirm the cult status of the Stefans’ cheese cake, which seems to be on its way to surpass the Quarkkuchen as the ITP signature seminar cake.

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Dario Tamascelli (University of Milan), with whom we have several collaborative projects, also visited the Institute and gave a seminar on the exploitation of Bloch oscillations for excitation and quantum state transfer across linear chains. Dario has recently held a sabbatical in Ulm. Joint work has been reported in Phys. Rev. E 91, 063306 (2015) and we hope to be soon reporting on rather exciting results. Stay tuned!

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Visitors

Janek Kolodynski (ICFO)

We have a current project together with Janek, currently holding a Marie Curie fellowship at the theory group of Toni Acin in ICFO, and Rafal Demkowicz-Dobrzanski, Janek’s former advisor, in Warsaw. We are trying to characterize the ultimate precision limit for noisy quantum metrology and made good progress towards a final draft during Janek’s visit. Below you can see Janek and Andrea Smirne working hand-in-hand at the whiteboard.

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Janek also presented a general seminar for the group to update everyone on the latest results concerning the derivation of general bounds in quantum metrology and the novel techniques he and Rafal developed to assess this problem. See Nature Communications 3, 1063 (2012) for details and stay tuned for our upcoming arXiv submission.

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 Hard work later paid off as Janek’s visit was well timed to coincide in the world famous ITP summer BBQ with celebrity chef duo Plenio & Hwang at the grill.

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Spyros Skurtis (FRIAS and University of Cyprus)

It was a pleasure to host Spyros at the Institute for a short stay where he lectured on fundamental concepts in coherent electron transfer, a subject where he has made seminal contributions, and also provided us with an update on the latest developments and open questions on this fascinating field.

Spyros has contributed a very nice book chapter on the subject for the recently published monograph on “Quantum Effects in Biology” edited by Mohseni, Omar, Engel and Plenio and published by CUP.

Theory work by Spyros and collaborators on the effect of coherent electron-phonon coupling in charge transfer has been very recently verified experimentally in the group of Julia Weinstein (see Science 346, 1492 (2014)). Here picosecond narrow-band IR excitation of high-frequency vibrations in an electronically excited donor-bridge-acceptor system in solution was shown to dramatically alter the transfer yield of by completely switching off one of the competing charge separation pathways.

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After the talks, it was time to socialize at the best sushi venue in town, the Konya-sushi restaurant across the river in Neu-Ulm. Mark Mitchison was also around and, following some joint reminiscences about British comedy, updated us about the latest in British politics and the Uber proliferation in London.

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Paloma Arroyo-Huidobro, currently at the Condensed Matter theory group led by Garcia-Vidal at the Universidad Autonoma de Madrid, visited the Institute in late February and presented a seminar talk on some of her results during her PhD. Paloma has worked on several issues in Plasmonics and discussed the possible implementation of a Brownian ratchet, where the motion of dielectric beads is rectified into one direction  by means of periodically turning on and off a laser beam acting on a specially asymmetric  array of plasmonic nanostrcutures. See Phys. Rev. B 88, 201401(R) (2013) for details. Paloma’s visit coincided with Cecilia’s return from her holidays in Buenos Aires so there were Argentinean alfajores to spice up the coffee time as well as some leftovers from Ramil’s wedding cake!! Ramil, our warmest congratulations.

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Angel Markov Rivas, a former member of the group, belonging to the honored circle of “los Historicos” that made the move from the UK to Germany to help build the new group, and who is currently a postdoctoral researcher at the Complutense of Madrid, visited the Institute and gave a nice seminar on the characterization of quantum non Markovianity. This topic was a cornerstone of Angel’s PhD and he has now become a real expert on the fine details of the formalism.  A review article is underway and we hope it will see the light in 2014.

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Jürgen Hauer, who holds an START grant of the Austrian FWF, is part of the Ultrafast Dynamics group of the Technical University of Vienna where he leads a junior research group focusing on two-dimensional electronic spectroscopy with ultrashort pulses. He have a current collaboration with him to model the exciton dynamics of J-aggregates. Jürgen seminar was assisted by the degustation of the world famous quark cake of the Ulmer Zückerbäcker.

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Jared Cole, currently a Research Fellow within the ARC Centre for Quantum Computer Technology at the University of Melbourne, visited us in 2013 and we expect him again in the summer of 2014. We have a couple of running joint projects with Jared and his student Jan Jeske. Details of a recent collaboration on quantum metrology under spatially correlated dephasing are available at arXiv:1307.6301.

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Javier Cerrillo-Moreno, a postdoc in JS Cao at MIT, and former PhD student in the group visited us and presented his nice work on the efficient simulation of many body steady state dynamics (See arXiv:1307.7743). Javier also impressed us with his award winning picture of the MIT campus with a Star Wars flavour. Javier will soon be back in Europe after accepting a position within the group of Tobias Brandes in TU Berlin.

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Arend Dijkstra, also a former postdoc in Cao’s group and currently at the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, visited us in January and presented a seminar on the influence of non-Markovian effects and initial correlations between electronic states and vibrations on excitonic energy transport across molecular aggregates. This is joint work with Cao and Fleming available at the arXiv:1309.4910.

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Prof. Leonas Valkunas has visited the ITP in February and delivered a faculty Kolloquium. He is the Chair of the Department of Theoretical Physics at Vilnius University, a member of the Lithuanian Academy of Sciences and Head of the Department of Molecular Compound Physics at the Center for Physical Sciences and Technology.  Prof. Valkunas is an outstanding representative of the strong spectroscopy tradition in the Baltic countries and has made significant contributions to the understanding of excitation and charge transfer processes in molecular aggregates. It was very interesting to discuss with him recent work on the identification and the discrimination of electronic and vibrational features in the 2D response of model heterodimers. You can find details in

Distinctive character of electronic and vibrational coherences in disordered molecular aggregates , V. Butkus, D. Zigmantas, D. Abramavicius, L. Valkunas, Chem. Phys. Lett. 587, 93-98 (2013)

Origin of long-lived oscillations in 2D-spectra of a Quantum Vibronic Model: Electronic vs Vibrational coherence, M.B. Plenio, J. Almeida, S.F. Huelga, J. Chem. Phys. 139, 235102 (2013)

Prof. Valkunas, who co-authored the well known textbook on “Photosynthetic Excitons”, together with Rienk van Grondelle and Herbert van Amenrongen, has recently published another reference that we have just added to the Institute library. See the pictures for illustration.

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Once in a while admin meetings lead to useful encounters. Indeed, recently Martin got to know Prof. Sven Rau, Head of the Institute of Inorganic Chemistry in Ulm, on such an occasion and invited him to speak at our weekly bio-meeting.  Sven gave an excellent introduction to the research activities in his group, which are aimed at the generation of light harvesting complexes, photo-catalytic reaction centers and supra-molecular aggregates designed for efficient light driven catalysts. In near future we will return the favour and hope that this will lead to a fruitful dialogue between the groups.

 

    

The meeting also gave us the opportunity to introduce Sven and his group to our absolute sweet favourite of the moment, the quark cake from the Ulmer Zuckerbäcker. Lecker!!

 

 

Charles Adams, a professor of Physics and leader of the atomic and molecular physics group at the University of Durham, has visited the group in December 2012. We know Charles since a long time and it has been very nice to catch up on his recent work. We are particularly interested on his results on Rydberg polaritons as possible test bed to analyzed transport in open quantum networks.

You can check details of Charles’ group activities at his web page http://massey.dur.ac.uk/csa/. See also http://physicsworld.com/cws/article/news/2013/feb/05/stored-photons-interact-in-atom-cloud for a recent feature article in Physics World.

    

Barbara Terhal, currently a Professor at the Institute for Quantum Information of Aachen University, and formerly a senior researcher at IBM, has visited the Institute and delivered a faculty colloquium on her recent work on Majorana fermions. For further details on her work, see  New J.Phys. 12, 083039 (2010) and Phys. Rev. Lett. 108, 260504 (2012).

             

     

In the evening we enjoyed some Thai food where discussions focussed largely on women, families and coherent interactions…

 

Professor Peter Zoller (IQC, Innsbruck), recently awarded the Wolf prize in Physics together with JI Cirac (MPQ) for their early work on the implementation of quantum computation using trapped ions, has visited the Institute.  Peter delivered a colloquium to the Faculty on his current work towards  the simulation of gauge theories and fermionic matter using cold atoms as quantum simulators.  You can read further details on this very interesting approach in arXiv:1211.2242v1.