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

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.

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.

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).

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.

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.

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.

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!

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

This week’s Physics Kolloquium has been given by Prof. Miguel Rubi, head of the Statistical Physics group at the University of Barcelona.  Miguel discussed several examples where considerable insight into the dynamics of complex biological systems, including DNA looping,  can be gained from simple analysis using the methods of conventional statistical mechanics.  You can read further details on the work carried out in his group at UB in www.ffn.ub.es/webmrubi/.
Given the proximity of Christmas, Javi Prior brought us some homemade Torta de Pascua, executed accord to a carefully preserved recipe by his granny.

Clive Emary, currently at TU Berlin working in the group led by Tobias Brandes, has visited the ITP in November and given a seminar on his work on non equilibrium phase transitions.  See arXiv:1207.5242 for details. We also discussed temporal Bell inequalities and the connection between the stationarity assumption and Leggett’s non invasive measurability condition. It was very a useful and clarifying discussion. Thanks Clive!
In the evening we had a fantastic dinner at our favourite Chinese restaurant, the Chausee. Many thanks to Jianming for the liaisons and for ensuring that we get the real thing. The Peking Duck also provided a good occasion to congratulate Clive on his new academic position at Hull in the UK!

Last week we had the visit of two young researches doing very interesting work. Alejandro Gonzalez-Tudela (left), working at the Universidad Autonoma of Madrid under the supervision of Carlos Tejedor and GianGiacomo Guerreschi, who is working in Innsbruck under the supervision of Hans Briegel.

Alejandro works in the interface of quantum optics and condensed matter and presented results on the theory of frequency-filtered and time-resolved N-photon correlations he has developed in collaboration with Elena del Valle et al (see arXiv:1203.6016) as well as his proposal for generating steady state entanglement mediated by plasmonic waveguides (details in Phys. Rev. Lett. 106, 020501 (2011)).

Giangiacomo’s work is focused on quantum biology, an area of research in which our group is also very interested in. He presented a seminar explaining the fundamental mechanisms underpinning the formation of radical pairs and discussed applications in chemical magnetometry by using molecular photoswitches to achieve additional control on the chemical reaction. You can read further details of this work in arXiv:1206.1280.

Mauro Patesnostro, Humboldt visiting Fellow at the ITP, has given an invited lecture to close our master course on Open Quantum Systems. Mauro lectured on cavity optomechanics and presented an overview on the state of the art of actual experiments as well as revising the theoretical approach to describe noisy effects in this type of systems. We are very grateful to Mauro for this very nice presentation.

To celebrate the end of the semester, we ordered a big Marmorkuchen from Troeglen. Definitely the best in town!

Jan Jeske, currently working on his PhD within the group of Jared Cole at the University of Melbourne, has visited the ITP this week. Jan gave a very interesting seminar on their recent results on correlated noise. Some interesting collaboration could arise if we find a way to apply his findings to the context of quantum metrology in the presence of correlated dephasing. This is the type of noise that is actually dominant in the implementations of precision spectroscopy using trapped ions.

David DiVicenzo has visited Ulm and given a Faculty Kolloquium. David worked in the field of quantum information science since its early days. After many years at IBM, where he worked in collaboration with Charles Bennett, David moved recently to Germany, together with his wife and collaborator Barbara Terhal, after being awarded a Humboldt Professorship. He is the first JARA Professor (Jülich-Aachen Research Alliance), and heads the new Institute for Quantum Information in Aachen. David is well known for his DiVincenzo checklist for a two level system realization to become a good qubit and has worked on many topics in theoretical condensed-matter physics, including analyzing the feasibility to use quantum-dot spin qubits and superconducting qubits for quantum information processing. During his talk David presented an extensive review on the latter.

We know David since many years and it was very nice to see him again in Ulm.

The sweet part of the event was provided by Debora Centreras, who has joined the group this week and brought some delicious Printen, a type of ginger cookies typical from Aachen. Oliver contributed to the caloric intake with chocolate from Switzerland. Just getting ready for the bikini operation…

Richard Jozsa, the Leigh-Trapnell professor of quantum physics (DAMTP, Cambridge), has visited us this week. We know Richard since a long time and it was great to see him in Ulm. Richard delivered the faculty Kolloquium and gave a most inspiring talk on the possible relevance of computational complexity issues in physics and in particular in quantum physics.

In the evening we had a relaxed dinner at zur Forelle so that Richard could taste some local food. European politics and the imminence of an economy cataclysm dominated the conversation…

We have been fortunate. For the second time this year, Rienk van Grondelle has visited the group and also given a faculty Kolloquium. Rienk is an Akademie Hoogleraar (Academy Professor) of the Royal Netherlands Academy of Arts and Sciences and ERC advanced grant holder. He leads the VU-Biophysics research group in Amsterdam, a world reference in photosynthesis research. Rienk and his group have made pioneering contributions towards unravelling the physics of photosynthetic excitation energy transfer. You can check their main publication here.

To introduce Rienk to local Schwäbian delicacies, we had dinner at zur Forelle, a typical restaurant in the Ulmer Fischerviertel. While some argue that they serve the best Maultaschen in town, I think I disagree… What are Maultaschen? Oh, those are Schwäbisch ravioli, sort of.

Dr Francesco Rao (FRIAS, Freiburg) visited the ITP and gave a double bid on our SFB colloquium. Francesco was kind enough to prepare a tutorial talk on protein dynamics for dummies and later told us about the general framework of his current work. Francesco and his team perform molecular dynamics simulations and complex network analysis in order to discern the role of dynamics in the context of protein function. You can read further details on his work here.
Spring is in full swing at the moment and we later enjoyed a nice meal at Auf dem Kreuz. It was a good opportunity to get some fresh white asparagus. That has to be one of the best things of Germany. Some misguided Spanish members of the group consider it second only to the Spanish ones from la Rioja and Navarra, a fact hotly disputed by the conoscenti from Schwaben! ;-0)

Marco del Rey, currently doing his PhD in Madrid under the supervision of Juan Leon (CSIC), and who was a guest research student in the group for 2 months, has visited us this week in order to complete his project. Marco worked intensely this week and with no coffee in sight it was time to try other therapies. Felipe has discovered a tea variety that keeps us going but it is not the same….

Easwar Magesan (Perimeter Institute and University of Waterloo) visited us this week. Easwar gave a very interesting seminar on his recent work, in collaboration with Jay Gambetta and Joseph Emerson, on randomized bechmarking protocols. Those are methods for partial characterization of the noise acting upon a given quantum process that do not suffer from the standard drawbacks affecting quantum process tomography. That is, the need to assume essentially perfect preparation and measurements steps and an exponential scaling in the resources with increasing number of qubits. You can read further details of Magesan’s work in Phys. Rev. Lett. 106, 180504 (2011).

Shash Virmani, presently a Lecturer at University of Strathclyde, and honorary member of the group, visited us this week. Shash gave a seminar on the notion of generalised entanglement, explaining how it might be more useful as a description of correlations in settings where measurements and state preparations are restricted. Shash has used this idea to improve the range of applicability of limited entanglement classical simulation algorithms. You can read the details of this work in his recent submission arXiv: 1201.0613.

Shash is known to have a sweet tooth so we took the opportunity and celebrated his visit with the world famous Sicilian cannoli from Pasticceria Alba.

PS: Despite new attempts from Koenraad, the coffee machine remains kaputt.

Stephan Hoyer (University of Berkeley) was our guest speaker for the weekly Quantum-BIO journal club. Stephan gave an interesting talk on his work to efficiently reconstruct quantum states from multidimensional spectroscopy data. He also tried to convince us that he found (quantum) purple bacteria on his recent trip to the beaches of Hawaii…

It is almost Easter and the whole of Ulm is full of bunnies and chocolate eggs so we could not resist the temptation to spice up the seminar with some extra calories.

We have two visitors this week, Filippo Caruso, one of our historicos and now at LENS, Florence, and Stephan Hoyer, from the University of Berkeley. Filippo brought us a nice cake typical from Sienna, Panforte Margherita, and Stephan brought us some Californian weather!

It is almost 20 degrees today with a wonderful blue sky.  Felipe has taken his bike out for the first time this year and he is a happy man…

On Thursday 22/3 Stephan will deliver a guest lecture at our quantum-bio journal club.

In January 2012, Niek van Hulst, from IFCO, Barcelona, visited the Institute and gave the Faculty weekly Kolloquium. Niek presented very interesting results on single molecule spectroscopy of LH2, a type of light harvesting complex, which point towards the existence of inter-ring quantum coherence. We discussed with Niek possible extensions of their methods towards other complexes and the interfacing of LH structures with controlled emitters/receptors. In the evening, it was time for some relaxed conversation and we head for the Pflugmerzler, which arguably serves the best steaks in town. It was snowing nicely when we came out…

Debora Contreras-Pulido had already visited us in London, when she was at the CSIC working with Ramon Aguado. She is now a postdoc in Aachen and visited IPT in January 2012. Debora is exploring the interplay of coherent interactions and noise in systems of quantum dots and the physics she and her collaborators have described shares many features with work we have done.

In January, Rienk van Grondelle and Elisabet Romero, from VI Amsterdam, visited the ITP. Rienk gave a seminar to the group on the basic principles underlying energy transfer in photosynthetic systems and Eli held a mini-course to teach us many details of the experimental techniques they have implemented to probe this type of systems as well as some rudiments concerning the biochemistry. We learnt a lot from them!

Rienk will visit Ulm again in June 2012 and give a Faculty Kolloquium.

Johan Strumpfer, working in the group of Klaus Schulten in Urbana, was also visiting the same week. Johan told us about their molecular simulation results to determine the spectral density for FMO. This type of calculations are extremely interesting for us and hope to collaborate with Johan in the future. After so many discussions, Javi Almeida was just starving… Johan sampled some local Maultaschen.

Luca Turin, currently at the Fleming Institute in Athens, visited the group in October 2011 and gave a Kolloquium to the Faculty. Luca has pioneered the idea that olfaction is underpinned by coherent effects and developed a theory that relies on coherent electron tunnelling phenomena. In collaboration with Makis Skoulakis he has also carried out an experimental program to test whether indeed olfaction is a reaction to vibrational molecular spectra rather than shape. Lucas’ visit overlapped with Filippo Caruso farewell and he had the opportunity to test Filippo’s tiramisu, the best one to be sampled on this part of the planet!

In the evening it was the occasion for some Schwabian food. Tania, Lucas’ wife, joined in. She coauthored with Luca a fascinating book. If you do not know which perfume to choose, check it.

Elisabetta Collini visited the ITP in September 2011. She has done pioneering experimental work towards the demonstration of coherent effects in biological systems and conjugated polymers, in collaboration with Greg Scholes. Elisabetta now holds an ERC starter grant and will build up a lab in Padova, adding to the European effort to consolidate this type of research. After her talk, we took her to sample to some local cuisine at the Drei Kannen…

James Wootton visited us in November 2011 presented his nice results on topological order. James was a master student with us at UH and later completed a PhD in Leeds under the supervision of Jiannis Pachos. He is currently a postdoc in Basel, within the group of David Loss.

Quantum Metrology is a topic close to our heart so we were very happy to have Piet Schmidt with us reporting on the current experimental effort at PTB. In June 2012, Piet is co-organizing a meeting in Bad Honef that will bring together specialists from different areas to discuss different forms of precision measurements (See http://www.iqo.uni-hannover.de/heraeus-seminar.html )

We were most pleased to host Greg Engel in Ulm twice this year. Greg visited us in spring and gave a Faculty Kolloquium and later attended the QuEBS 2011 with his whole gang. Greg’s experiments in Berkeley in 2007 have triggered a lot of attention and stimulated an increasing volume of theory work to try to explain the origin of the observed, long lived, excitonic coherence in the FMO complex. Since a few years Greg leads his own group in Chicago and has now reported results at ambient temperature and performed experiments in other complexes. It has been very good for us to be able to discuss with Greg and his people the details of their 2D results on FMO dynamics.

The flowers were for our secretary, Barbara Bender-Palm, whose work was key to make QuEBS a success.

It was a pleasure to see again Aki Ishisaki, who had visited us in London a few months before the big move. Aki has worked in the group of Graham Fleming in Berkeley for several years and made significant contributions to the theoretical analysis of energy transfer using hierarchy equations. He presented a seminar on recent work and discussed with us the pros-and-cons of the current numerical artillery aimed at providing an accurate description of what is going in these complex systems. After work, some local beer helped to make things clearer… (for Alex and Felipe; Aki only tried the water!) Aki is moving back to Japan in March 2012. Congratulations on your new job, Aki!

In September 2010 and as a part of the annual SFB summer school for graduate students, we organized a session on Quantum Effects in Biology. We were fortunate to have Greg Scholes and Elad Harel as invited speakers. Elad later spent some time with us at the Institute and reported on recent experimental work in Chicago, in particular, their new method to reduce the total duration of the experiment and their scheme to try to modify the environment structure so that to single out the presence of pure electronic coherence. This interaction was very inspiring for us. We rewarded Elad with an evening at Basils and the best tiramisu in Ulm (second only to Filippo Caruso’s!) That week we also hosted Madalin Guta (Nottingham) and Ashan Nazir (currently at UCL).