 Hello. Welcome. Welcome to our awards ceremony. So we have many, many guests here from SPIE, from OSA, from the European Optical Society, from ICO, and others. So we're going to do many awards. And we're going to start with your awards. So the awards for the participants for presentations and the awards for posters. Unfortunately, I was gone. It was a tough job. We had a lot of judges out there. And just to let you know, anybody that helped us judge could not be in the competition. And it was tough. We really tried to converge and it was a real tough job. We really assigned numbers and it was just tough. It always is, but this year was particularly tough. We just had a lot of good posters and a lot of great presentations. I think it helped having the guy up here giving us the Jean-Luc, giving us the toolkit for giving presentations. So I'll start. So anyway, that's the background. I think we'll start with the presentation of the awards for best presentations. So these were the three minute presentations which you did to advertise your poster because that's in the order in which we did things. I'm going to ask Anthony Johnson, who's past president of the Optical Society, to come up and take over this part. So this is Anthony Johnson, past president of OSA. And a long time friend of ICDP. This is his 31st year here. Good afternoon everyone. My name is Anthony Johnson. And I was president of the Optical Society many years ago in 2002. And it's such a pleasure to come here every year and take part in the winter school and also in the organization of deciding what's the next school is going to be. And also taking part in the awards for outstanding presentations. And so we have from the Optical Society we have four awards. And for our third place we have from Pakistan Abdul Rahman. And the title of his research, the design of S-Ban Klystron from Linear Accelerator Applications. For second place we have a participant from Indonesia. The name is Devi Wadani. And the title of her research, Surface Plasma Resonance based biosensor as a potentially powerful tool for detecting bovine and porcelain gelatin difference. For first place we actually have a tie. The first participant is from the Ukraine. And her name is Hannah Budesheva. And also first place we have a participant from Iran. And the name is Hossein Kadil. The research is entitled the role of size asymmetry in heterodimers of plasmonic nanoparticles for surface enhanced Raman scattering. Thanks a lot Anthony and congratulations winners. All right now we're going to turn our attention to the posters. What you are advertising in your talks. And for that I want to bring up Katharina Spahnberg, past president of SPIE. When I am standing here I have many many young faces in front of me and that's a beautiful view. Because you are the fortunate students of this year's winter school or winter college who were appointed for this. And here at this fantastic facility the ICDP you have the opportunity to learn a lot from many lectures from world renowned lecturers. And also of course building network with your peer students. And I am sure that you after having gone through this winter college will collect memories learning experience that you will enjoy and utilize during your future career whatever you will be. ICDP really is an international site. You students here you represent more than 25 countries and with the faculty almost 30 countries around the world. I will cite the Abdus Salam who you know was the initiator and founder of this school. He said scientific thought and inspiration are the common and shared heritage of mankind. That's what he said in his Nobel lecture December 8th 40 years ago. The Nobel lecture is always on December 8th. Always the same day. Not depending on the week day but December 8th. And the Nobel prize is always given out December 10th on the death day of Alfred Nobel. And that has an Italian connection because of flower decoration in the concert hall where the ceremony takes place is every year a gift from San Remo. So the flower decoration remembers people who are there about Italy. Coming back to this about scientific heritage. You are young. You are young career people but you come here to share your scientific findings by your posters by your presentations and the learning societies. I represent as we heard the international society for optics and photonics is one of the sponsors of this school together with OSA who we just heard and we as representatives of the learning societies are extremely honored by having this opportunity to serve you young people. You are the future. You are the hope for the future. You will build your countries. We have heard many nice stories about how you connect yourself to the society even to the highest government of your country. So for me standing here distributing the prizes it's an honor to do that and I'm quite sure that the learning societies whatever the name is they are proud of being part of your career. And of course everything in life is competition so not everybody can win the prize. And one way of adding is to give two prizes on the same position and that's what SBI has done now. So from my secret paper here I start with a third place and there we have two winners representing two countries starting with an I, India and Italy. Okay now you know a little bit so the rest of you can sort of understand it's not me if you are not from India or Italy. Okay I start being a female with a female winner and the title, citation, prize citation is for structural and chemical characterization or starch granules using microscopy and spectroscopic techniques. And this goes to Indira Govindaria just. Okay Indira congratulations. Thank you. And now you have to take you are so well dressed so you fit perfect in this photo your national dress almost. Okay so that was India now we have Italy and I start again with a prize citation to sort of narrow the possibility for people here. It's metal oxide nanoparticles coated with chitosan for efficient fertilization. Okay there we have him. It's Marco Leonardo. A real true Italian name. Okay it's better yeah. Okay I'm sorry. Maybe Indira can come back and show her. I would also say that it's a little envelope there also for something that that can be very useful. Okay we continue to the second place and the gender starts with an M and then the country starts with an M. Okay a little squeeze here. I read the prize citation clad less grating sensor for monitoring of sugar levels in beverages after all this winter college is about food and agriculture. So we have here Muhammad Saini a male from a country which is also starting with an M Malaysia. Yes thank you. Now we come to the first prize and it's a little bit of a repetition of country. You will understand when I read the name but we start with a prize citation micro tapered fiber based curvature and acoustic sensors. It's summit dust from India. That's the connection. So we give all the prize winners a hand. Thank you so much. Okay now we're returning to congratulations winners. Well deserved. We're turning to the ICO, ICTP prize named after Galliano Donardo. So Galliano Donardo was really the father of optics activities here at ICTP passed away in 2007 and we're just always trying to keep alive the the spirit and the program that Galliano started with Abdul Salam. So what I'd like to do our I think we promised you the director the director actually is feeling ill but but we have something have a person even more important and that's Sandro Scandal. Professor Scandalow is the officer in charge of ICTP and he's quite a brilliant scientist. If you were if you were watching the opening of the International Year Periodic Table you would have seen him giving a wonderful speech and inventing two brand new elements at the same time. But anyway let me let me give you a Sandro Scandalow from ICTP. Thank you Joe. Welcome really more welcome to everyone. Also from the director Professor Cavido who is unfortunately not able to be here today as Joe just said. It's actually I'm very pleased to be here in front of this audience participants in this college the winter college in optics which has been one of the most important and traditional activities of the ICTP. It's actually remarkable I was looking at the statistics of this of the college this year and noticed that you have 52 female participants. I think this is really remarkable sorry 52% sorry so yeah so more than half of the I think this is an exception it's probably the only activity at the ICTP with exception of a workshop we organize precisely to support career development for women in physics. I think this is really the unique activity in this respect so I'd really like to you know actually I'd like to learn from you what kind of actions you put in place in order to I notice that you have two out of three directors are women this is certainly has helped that really like to learn from you because this is a serious problem in physics particularly in theoretical physics which is the main theme of the ICTP so that's something we really need to work and improve here at the ICTP. So again so welcome to this ceremony for the 2019 ICO ICTP Galliano-Denard Award the award as you might know recognizes the work of young researchers under 40 from developing countries were active in optics and photonics and have contributed to the promotion of research activities in their own or another developing country. The world was established in 2000 jointly between the ICTP and the International Commission for Optics which is represented today here by the president Roberto Ramponi and in September 2007 ICTP and ICO agreed to dedicate the award to the memory and legacy of the late professor Denardo who as Joe was saying before I mean greatly contributed to the development of optics in developing countries and also was for many years the director of the Office of External Activities here at the ICTP. It's really been one of the leading figures of ICTP particularly in the first years of its existence. So I think I'd like now to call Roberta on the floor and she's going to announce the winners and read the citations please Roberta. Thank you Sandra. It's always a great pleasure to be here for this occasion of this award that Sandra said is shared between ICO and ICTP and I would first of all like to thank the committee of the award that is chaired by Murad Skal who unfortunately couldn't be here this year and the other members of the committee are Anna Consortini, Michio Danilo, Joni Mela and Amadou Vaghe and I would like to thank them all for the excellent work that they have done. We had very, very good candidates this year and the same as it happened before the committee didn't manage to find a single winner so we are going to have two winners that will share the prize. The first one is Mohammed Fariad from Lambs Department of Physics in Lower Pakistan and he is awarded for his contributions to the understanding of light interaction with nanostructured materials and applications in the area of optical surface waves, solar cells, optical metamaterials and the modeling of wave propagation in the nanostructured mediums and as you know in this ceremony the winners will also give a lecture later so we will have by Mohammed Fariad the lecture surface, multi-plasmonics, fundamentals and applications to optical sensing so please Mohammed if you can come here. The other winner is from Argentina, Cristian Thomas Schmigelow University of Buenos Aires-Balboa and he's awarded for his contributions to the field of quantum optics and light matter interaction and in particular the demonstration of transfer of optical orbital momentum to bound electrons and studies on interaction of twisted light with trapped ions and he will then give the lecture on spectroscopy with twisted light or how ions learn to stop worrying and love the twist so please congratulations again and I leave the floor again to Joe who will be chairing the two lectures presentation. Okay thank you very much Sandro and Roberta. Yeah that's right wait a minute okay all right so we're going to have two talks more or less 30 minutes apiece on the topics you just heard the titles by the way we're sharing the prize but we didn't divide up the cash prize so any right we're not that mean all right so I think we're going to start with you Mohammed Fariad so please come up and I think we have a microphone for you so you free your hands yeah that's right so just to remind you the title is surface multi-plasmonics fundamentals and applications to optical sensing. Thank you very much yeah so I would like to begin by thanking the ICO and ICTP for this award I'm really humbled and honored to be selected for this award I would also like to thank the award committee for choosing me for this honor and my topic of today's talk is surface wave resonance and its applications in optical sensing and as was told I am from Lahore University of Management Sciences which is a relatively new university in Lahore which was established about 30 years ago but it's a science and engineering department was established about 10 years ago and what we are trying to do there at lunch is establish a program in science and engineering which is at par with the leading universities in the world okay so the before I begin with my talk let me just give a little introduction of my research work so I have been working on solar cells plus morning solar cells which are nanostructured solar cells and also I have worked on the solutions of Maxwell Equations for anisotropic mediums like uniaxial, biaxial and gyratropic and other mediums and recently we have authored a book on diodec green functions in modern metamaterials which are anisotropic in nature. I have also been recently working on photonic crystals especially one-dimensional photonic crystals which can also be anisotropic and some work on hyperbolic zero index negative phase velocity metamaterials is also being done in our group but today's talk which is also my major contribution in optics is on surface plasma, ploid and waves which are guided by nanostructured thin films which are sculptured at the nanoscale to get the properties that we want and also we will see their potential applications in optical sensors. I would also like to take this opportunity to invite you to submit your papers on optics to optic I'm one of the editor working with this journal which is actually a 70 years old journal and here's a glimpse of the activities related to optics that we have been doing at at LAMS. We have actually recently established a very active SPI student chapter which is doing outreach activities in nearby primary and middle schools and we have also been actually motivated by the same optics school when I came here in 2015 and we organized a similar school in LAMS in 2016 and hopefully we will do it again soon and we're also developing an optics lab from a grant from the government of Pakistan and we have been running several seminars at leading universities in Pakistan like recently established ITU, Punjab University, Faisal Badairi Culture University and also my alma mater Khaidiazam University where I did my undergrad. I have conducted several workshops on plasmonics and recently on anesthetropic mediums and also have been an invited speaker in Nathya Gali summer college which is one of the premier summer college in physics in Pakistan. So with this let me begin with my talk. So I will cover in this talk the basics of the chronicle boundary value problem and I will discuss some of the work that we have done in surface multi-plasmonics and then I will go on to discuss a few results where we have learned how to excite these surface waves and then I will discuss their applications in optical sensing. Now surface waves are the surface electromagnetic waves which are guided by an interface between two different materials. We can have a material which can be a metal or a crystal or something and then another material which is different than that. So there are a lot of types of surface waves but the most famous is the surface plasmon RSPP wave which is guided by a metal and a dielectric material and that's what actually the most commonly known surface wave is where we have free electrons in metal and as the surface wave propagates the electron oscillates so we call it plasmonic waves. So this wave is actually very important in plasmonics because it's bound to an interface which makes its wavelength to be much smaller than the free space wavelength which means that we can probe structures that can be that are smaller than the free space wavelength. So we can have sub wavelength imaging and because it's very localized to the interface this is then very sensitive to small changes in the material properties near the interface. For example something changes here or something changes here it affects the characteristics of these waves a lot so this because of this reason it's used in optical sensors and because of its shorter wavelength it's used in imaging at nanoscale. So this is a wave which is actually known for no more than 60 years a lot of work has been done in plasmonics with this SPP wave but almost all of the work until a decade ago was done on a metal and a dielectric where they are both homogenous isotropic simple materials. When I started work on it so this was the state of affair and our goal at that time was to see if we can increase the number of waves because if we can increase the number of waves we can have chemical sensors that can sense two or three or four things at the same time. If you have only one wave which is possible when you have both materials which are simple isotropic homogenous medium you only get one SPP wave and that is also P polarized you don't get any S polarized SPP wave and because of that we have chemical sensor which sends one thing at a time or if we want to use this surface wave in communication we have only one channel for communicating information from one side to the other and also in solar cells since only P polarized wave is excited S polarized which is half of the incident light cannot be converted into cannot be absorbed by the solar cells. So idea at that time was to see if we can get multiple SPP waves at the same frequency. Now I'll come to that and before that let me just introduce little bit terminology we call SPP wave when we have one side metal and the other side dielectric and we call it Diakonov wave which I actually recently discovered when both side of the material are dielectric materials but one medium is anisotropic and then we have TAM waves which are guided by an interface between two material which are both isotropic but one is periodically non-homogeneous like a crystal and then Diakonov TAM waves are when we have nanostructure materials which are anisotropic and periodic and then these eulerzanic wave I'll briefly discuss which were actually the first surface wave that were predicted in 1903 which also exists between two dielectric medium but one is lossy because initially people were trying to understand radio wave propagation at the interface of earth and air are the interface of sea water and air so I'll have a few slides on this as well. Okay so coming back to the surface waves so there are three things that surface wave have to satisfy in order for them to be surface waves one is that they should satisfy Maxwell equations because they're electromagnetic waves and then they have to satisfy the boundary conditions at the interface and the last condition which make them surface wave is that they should decay as we move away from the interface so any wave that satisfy these three condition is a surface electromagnetic wave and we call it SPP wave if one side is the metal and we can study these waves in several waves but one of the basic thing is what we call a canonical problem in which we take two material and both material occupy half space so this is going to infinity this is going to infinity so that there is only one interface left to interrogate so that when we get the solutions there's no confusion if it is a surface wave or not so let's see a few numerical results so this is the simplest situation where we have a metal on one side and a photonic crystal which has a few layers in one unit cell and it is repeating itself towards this side and we see that for each period of the photonic crystal we have multiple solution we have like say at point five one two three solution at one point five one two three four five six solutions so there are multiple surface waves that can exist at this interface instead of only one so in UUL case when we have SPP wave we have one surface wave only and that also P polarized but here we have both P and S polarized surface wave it mean we can use multiple channel for communication or optical sensor and other things so this power profile show that the wave is localized to this interface we can see the similar thing if we have let's say a magnetic permeability variation on one side so here it's a metal and then this side is a magnetic material so if the magnetic permeability is varying we still get multiple solutions and here it's an example of a nanostructured material so this is a sculpture thin film which is actually chiral helices like this which are too small to be visible here so all these columns that you see they're essentially these helices that are grown in this way so even in this case we see that at different wavelengths we have multiple solutions of surface waves so more than one surface wave can exist at this interface so this canonical problem is used to tell us that what type of surface waves can exist at the interface but of course that cannot be used to excite the surface wave because we assume this metal and the dielectric to occupy half spaces to excite the surface wave we have to use some coupling technique and the simplest one is to use a prism for example this is actually the most common specimen configuration which is used by people to excite surface wave here when you have incident light from this side the evanescent wave couple to this interface here and the reflectance is reduced at this particular angle so whenever we have a reflectance dip or the absorption peak it means surface wave is being excited at this interface so this technique can be used to excite these surface waves so for example here I have shown the absorptions for p polarized incident light and we see that we see multiple peaks in absorption with and each peak indicates one surface wave that is being excited at this interface of a metal and a rugged filter which is a periodic dielectric material so instead of one we have several p polarized surface waves this shows the power profile on both side of the interface so we see that in the metal the power decays as we move away and in the rugged filter the power decays but it decays periodically because the medium is periodic here's another example for time waves here there's no metal because this is a dielectric this is a dielectric but we see the same thing that as a function of incidence angle we see several reflectance dips both for the p polarized incidence and for the s polarized incidence so it means we can get multiple surface waves of both p and s polarized incident light similarly here as an example of diacon of time surface waves the difference between this and previous is that here we have one periodically non-homogenous but also an anisotropic medium it's anisotropic because this direction is special in which the these helices are growing so we see that when we have incident light from here we have multiple absorption peaks and each peak both for p and s polarized case represent a different surface wave so using this periodically non-homogenous material we can excite more than one surface waves which means we can design optical sensors which can sense more than one thing at the same time this is also the same diacon of time wave but excited with an air pottering materials because this is important because we can replace this air with some fluid and we can sense the effective index of that fluid using the shift in these peaks here it's the parametric study of the same thing where we show that they can be excited in the prism couple configuration using an s and tf instead of a sculpture thin film a chiral sculpture thin film so here is actually the first experimental proof of those diacon of time waves that we were discussing theoretically before where we fabricated the same chiral sculpture thin films next to a homogeneous material and we see that there are reflectance dips that doesn't change when we change the thickness of this material which means that a surface wave has been lost at this interface because if the reflectance changes when we change the thickness of this material it means it's a waveguide mode and not a surface wave mode because waveguide modes change when the thickness of the waveguide change so far we saw that we have some prediction by the canonical problem and those waves can be excited in the prism couple configuration but not all surface waves can be excited in the prism couple and actually one of the example is this uh uh euler zenek waves which are actually uh mostly called zenek wave because people didn't know about euler's work for a long time uh and zenek in 1907 he was studying the radio wave propagation at the interface of sea water and air but euler has studied the same thing at the interface of earth and air since earth and sea water they're both lossy dielectric materials so it's actually the same thing so this wave which was predicted in 1903 and 1907 actually people have been trying to find it for a century and there was no conclusive proof because they was trying to excited using a prism couple configuration where you shine radio wave directly on the earth's surface and these waves they couldn't be excited the reason is this that their wave number is actually less than one instead of greater than one for SPP waves we get a wave number greater than one but for euler's zenek wave we get a wave number which is smaller than one and we also first tried to excited in prism couple and we saw that uh because the brag reflect the brag angle also comes there so there was no conclusive evidence for this so we shifted to the the grating couple configuration and there there's no because we can have several non-specular mode which can excite the surface wave so we were able to see their excitation in the grating couple instead of the prism couple configuration so actually almost 110 years after the prediction of these surface waves we were able to excite them using the grating couple configuration and the funny thing is this that a couple of years later after this paper was published I get an email from the granddaughter of euler and she thanked us that you have discovered euler's work which has been forgotten by people so you brought that into light and gave him the credit even though it has been only being called zenek wave instead of euler's zenek wave because she was she has actually commissioned a biography of euler so there was an author who was searching the citation of euler and so from that she came to us so there was a lesson for us that whenever you write a scientific paper always try to go to the earliest and the basic work that has been done then the topic so that you give credit to people where the credit is due anyway so this experimental work showed that when a canonical problem predicts that the surface wave should be excited here we can see the same excitation in the grating couple configuration but not in the prism couple configuration so let me now present a few results an optical sensing that we have worked on the basic principle of optical sensing using plasmonics is actually this that you have an absorptance peak for some refractive index let's say 1.127 of the dielectric medium so when the medium changes the these absorptance peaks they shift because the surface wave that is being excited here it changes its characteristics so the angle where the peak where the surface wave is excited is shift so that shift tells us the amount of refractive index that has changed so with this thing we can sense the refractive index of any species that is here and before this multi-plasmonic work where we have several peaks people used to have only one peak one plasmonic peak so there is only one channel to observe the shift but now with the multiple peaks we have multiple channels to observe the shift due to the same refractive index or we can have multiple analyzes there that we can sense through different peaks so let me present a few results so for example here we have a CTF a columnar thin film which has straight columns and when we excited using air let's say the dip is here and when this CTF is filled with water that dip shifts and this shift gives us an indication of the refractive index that has changed there so similarly here is the same thing but with the sculpture pneumatic thin film instead of columnar thin film and we can see that we can use this thing for sensing and we have like one two three four five channels to observe the shift in the refractive index we have been presenting the work with Diakonov time wave which is excited at the interface of two dielectric material so this actually affords us two sensing categories when you have plasmonics wave one is metal and the other is dielectric so when you have to sense some fluid you can only change the dielectric side but metal remains fixed but when you have a surface wave that is being excited at the interface of dielectric and dielectric you can actually change the dielectric on both side so the sensing is actually enhanced because you can affect the material on both sides instead of just on one side which is done with plasmonics so with Diakonov time waves we can actually increase the sensitivity and we have shown theoretically that the sensitivity is actually much higher using Diakonov waves than using plasmonic waves we can go to let's say 82 degree or 58 degrees instead of about 30 degrees per r i u so this is the same thing in configuration one where we have this anisotropic dielectric here and the other dielectric on the other side and we have this other configuration this so this one is configuration one so when you have dielectric isotropic dielectric here this becomes configuration number two and we showed that if you add one percent silver nanoparticles not more not less you can increase the sensitivity of this sensor and if instead of the nanoparticle use a hyperbolic chiral sculptured thin film you can increase the sensitivity to actually several thousands of degrees per refractive index units for example a small change in effective index of 0.001 can shift the peak by three four degrees in the absorption spectrum and we we can see that this enhancement in sensitivity is because the field is highly localized to the interface even though it's oscillating rapidly but since the field strength is higher in the hyperbolic film so the sensitivity is also higher so with this I would like to conclude that the work has shown that the periodically non-homogeneous dielectric material can suppose multiple surface waves and not only SPP waves we can have other types of surface waves that can be excited in the prism couple configuration and even though I presented results only for optical sensing where we can use multiple peaks to optically sense the change in effective index we have worked on multiple morning solar cells where we saw that the efficiency of solar cells can be increased because of these multiple peaks in absorption so with this I would like to conclude and acknowledge my PST and postdoc advisor professor Akhilesh Lakhdakia from Penn State who most of this work was done with him even though some later work we are now trying to do independently at LAMS but his constant support has been a great source of career advancement for me and also huge encouragement from and still continue to be from my Amphiladvisor at Kaidiazum University and also my current collaborator Tom McKay at University of Edinburgh and Dr. Sabien who is one of the famous physicists in Pakistan I'm really grateful to him for his mentorship it actually it's he who has inspired me to do outreach activities in optics in nearby schools because he himself is perhaps one of the best outreach activities in Pakistan where he's organizing a lot of seismolars and several outreach activities for a wide variety of audience and at the last but not the least I am really grateful to my current and former students who have done most of the work that I have shown here so with this I would like to thank you for thank you very much for the floor is open for questions anybody got a question yes this is not a really a question is something for the students what is called here surface waves is also called evanescent waves and some of our students already saw them in the laboratory so evanescent waves or surface waves are the same kind of waves thank you that that's great thanks for that comment so you guys in the labs you've already seen this all right another any questions other this is probably maybe more curiosity has anybody explored the effects of non-linearity in this I mean non-linear surface plasma polarity yes actually there has been a lot of work in non-linear surface phosphonics which is mostly with the homogeneous material you have a homogeneous isotropic metal and a homogeneous isotropic dielectric medium but the dielectric medium is non-linear and actually the non-linearity with phosphonics is much easier to work with than with free space because when you have a light passing through let's say a dielectric medium its intensity is whatever you put in but in plasmonics when you couple light to the surface wave the field isn't extremely enhanced near the interface and because of that the non-linear effects magnify I haven't done myself but there's a lot of work that's been done on this area okay any other questions comments thanks for your presentation I have no question but I have a comment I think it's would be nice if you could all of these theories by experiment to to see the agreement between experiment and also theory just a comment yeah thank you very much we actually have done some experimental work and some of them is being still done at Penn Strait since I moved to Pakistan as I mentioned our university is only 30 years old and in 2014 when I joined LAMS the department of physics which I was part of was only six years old and still there is there were empty lab spaces so we are now establishing the labs and hopefully in six months to one year my lab would be ready so we will definitely be doing experimental yeah okay any other comments questions let's thank Faria again for a great great talk congratulations so now we're going to move to Christian Thomas Smigolo and he's going to give us a talk on spectroscopy with twisted light or how ions learned to stop worrying and love the twist I learned that when I was four I was actually an expert at the twist it was chubby checker you remember chubby checker right area in the meantime I'm while they're sitting it up I'm actually I'm on the phone I'm arranging for the band so I think we we're just negotiating the final terms so that's tonight seven o'clock so all our guests anybody that sorry we're negotiating that too to be announced okay so Christian you're all set ready to go thank you very much can you hear me well first of all thank you very much to the International Center for Theoretical Physics and to the International Commission for Politics for choosing me for this prize I would especially also like to thank the people who proposed me for this prize that were two professors Alex Feinstein and Gaston Giribet to them I'm very thankful as they considered I was worthy for it and also to the convention for finally choosing me and there's something more about thanks at the end but I'll get so the order of my presentation is a little bit the other way around I'm going to so that's the title which was already read to us so I won't get into it so there are three parts to the presentation as I said at the end I'll be telling you a little bit more about my university my current status and so and the first two parts so the first part which is the biggest and longest part is a bit of history on how do we get to the experiments that I did at the University of Mainz and that we are continuing now at Buenos Aires and I take now the opportunity to say also I'm very very thankful to Ferdinand Schmidt Keller who was my director in Mainz who with whom I thought these experiments since they were a little baby and a little flick over of an idea now in both our heads then I'll shortly go through the results which are actually kind of simple and I hope you understand them in a blow and finally I'll rant a little bit about what I'm doing now other things I've done and so so without further ado let's go into the history and I tried in the history to connect a little bit with the school and the techniques that I think you didn't directly see in the school but are connected very very connected to the use of optics in food industry and one of the things I learned as a kid when I used to visit the vineyards an uncle of mine was administrating is that they use something called a refractometer and they use also something that somehow had to do with polarization rotation to measure the quantity of sugar and water this technique was very very old and it came to be after Malus discovered the optical properties of polarization from terpentine and Iceland spar which we later learned to know or as calcite that with these techniques you could polarize light and not later after that there were four discoveries that I would like to point out and which are a lot of connection with what happens then which were the following so in 1811 Argo discovered that quartz crystals would rotate polarization and but and later later years Biot discovered that not only quartz crystals but also some organic compounds would rotate polarizations between them sugar but most interestingly Herschel a couple of years afterwards discovered that there were some quartz crystals that would rotate polarization in one direction and others that would rotate polarization in another direction not only that that when you cut the quartz crystals there was one of the angles of the cutting planes of the quartz crystals that would would be either right-handed or left-handed and that would correlate with whether the crystals would rotate the polarization in one direction or the other one these findings let all of these guys past their van hoffen level in the later years to search for the same things in the organic compounds and actually found that depending on the kind of sugar that you have you can have sugar that it's chiral in one direction or in another direction and that's actually is what produces and the rotation of polarization so here of course this is very simple diagram of the idea you have oops wrong button a beam passing through some cell with something and the polarization rotating and now I'm going to the next slide which is the slide that we're going to be filling up through this history and it has on the vertical axis it has the kind of effects that light have on matter so here we're filling up so mechanical effects of on light so something so when lights and matter interact different things can happen either light can change matter can change or matter can change in different ways you can change internal structure you can change the center of mass that's why I've just discerned these two here and we're going to try and fill in this table with different kinds of ways of interaction so the one that I've just talked about is spin angular momentum and we call basically optical activity I just very quickly mentioned at the beginning the refractometers that would be the changing of the direction so changing of the linear momentum and that's what we call refraction it's also dependent on frequency we can click this both out they're probably the two oldest one of them and the next one came up actually as an application of the refraction when friend hoffer and actually wallstone earlier discovered so wallstone discovered that if you put sunlight through a prism they were missing lines and then from hoffer discovered that this same missing lines were the missing lines that would appear if in the middle of a ray of light you would put some kind of gas and depending on which gas you would put they would change which missing lines would be and then they would start it classifying and this missing lines and this was the beginning of optical spectroscopy and of course of the idea of the atom that we have right now not much later seaman discovered something very interesting that if you put a magnetic field you put a magnetic field on the atoms then actually what happens so this is an idea of atomic levels that your atomic level splits so where wherever you had one line actually if you put a magnetic field then more lines appear and this was not the discovery by seaman but that actually came later that which lines would absorb would depend on the polarization of the beam that you would come into so I'm representing with this blue thing a polarizer and whether you're coming in with blue polarized light or yellow polarized lights red or left or right you would either excite one of the lines or the other lines this was actually noted by a couple of guys that whose name you've been hearing a lot in the school it was raman actually and it was actually in the in the study of the same kind of raman lines that you're seeing today that raman and castler realized that there was a transfer of the there was an angular momentum associated with the spin or with the polarization of the photon and so the observation was done by Hanley and Beyer at the same time in Germany and not long after actually the the time span between the first publication and the second publication seems very crazy for that time how did they anyhow look this is July 31 and this is it's May 31 anyhow they all came up with the explanation that was okay there must be a spin associated to the photon and very funnily castler had published at the beginning of the year something saying there wasn't a spin to the photon this is how things how quickly ideas were changing at the moment and actually he was then awarded the Nobel prize for not only this explanation but for other other applications of the idea of spin actually castler is a the third guy there on the on the photos over there if you want to take a look at his face and on this there the third one counting from down up and so we can go back to our charge chat and we can say okay the internal motion of the atoms can be changed by light also the internal twisting motion of the atoms can be changed by light that was discovered by Hanley and bear now let's look a little bit whether we can actually change the center of mass of so you know not just the relative motion of the electron with respect to the nucleus but also can we move atoms as a whole and well yes we can and very funnily and this was for one of the cases it was discovered before and before the idea before the idea the idea of atomic spectroscopy and the other one was actually motivated by the discoveries of Hanley and bar and the interpretation of ramen and castler so let's go to it but before that and so up to now the only explanation that we have that we need of a wave is basically something that have polarization and an oscillating field for all of what we've seen up to now and well it could have some spatial dependence but we really don't care about it and for what comes next we will need to complex make this a little bit more complex so Beth actually heard about the discovery of the fact that there has to be an angular momentum associated with the polarization of the photon and went and carried out this wonderful and beautiful experiment so it's a Cavendish like type of experiment is an experiment where so in a vacuum chamber you hold a little piece of there that I'm trembling the little piece of quartz glass which is here assumed and you shine in light up that then shines down and depending on the polarization of the light that goes up and down this little piece of quartz which we know that rotates polarization should either feel a torque in one direction or the other one and that's exactly the torque that and that Beth measured proving that there was also a mechanical effect on the macroscopic motion or on the center of mass motion of the atoms and so that has to do with the turning with the twist but of course before that so there's a very beautiful experiment more much more recent experiment done by Halina Rubinstein Dunlop in Australia where she actually makes so this is a frames of a video these are calcite particles in an optical tweezer and they're turning you see frame by frame they're turning because they're they're being shown by a circular polarized light or if they're shown by linearly polarized light the angle of the crystal can be decided so this is done with a very focused beam on a microscope an optical tweezer and it's actually a quite simple experiment and these are micro sized little pieces of calcite so continuing with the with the mechanical effects of course the linear momentum is something that we've known for a long long time this was first observed actually by Kepler when he saw the comet tails and he realized that the comet tails were not following the trajectory but were always pointing away from the Sun and then Nikols actually at more or less at the same turn of the century did the radiometer which was very similar to the one of the that I just described by Beth and then during the whole of the 20th century we've seen many a plethora of experiments where we actually see atoms recoiling because they emit a photon I won't go into the details of that and also we've learned for the design of satellites and spacecrafts that if we don't take into account radiation pressure they end up somewhere else where that we expect please don't confuse the crux radiometer the crux radiometer I don't I didn't put an image it's the one that's a ball with some little stains that are black and white on one side on the other one that's not radiation pressure what change what makes it rotate and what makes it rotate is heating of the surfaces so let's go back to our chart and so we can finally very happily say we understand the energy momentum part of the transfer of of motion from from light to matter and also we can understand the spin angular momentum but there's more to this and how is there more to this well so to to understand the transfer of of momentum we we first have to add actually something else to our wave so we actually have to say our wave is not just a global field it's a traveling wave but this is not the most general solution to to the equations to the equations of freely populating fields actually if you there are many ways to solve and to find the equations but if you solve the equations in the paraxial approximation so beams that are more or less traveling in one direction the general the most general case is something that looks like this and so something that has this part and then that has a big spatial part here which i will describe in a second but the most important part so the simplest solution is the gaussian beam so it's a gaussian beam that we get out of lasers that we get out of fiber optics and very typical for monochromatic lights but there are some other solutions that have look at this phase factor so this is a revolving phase factor and actually it produces beams that are donut likes beams which we call either vortex beams or chiral beams or they have many names twisted beams and and this is the kind of beams that became kind of popular a couple of years ago because of this very nice paper that was published in 1992 where the authors basically took this beam so took the solution for for the wave equation and basically calculated said they took the pointing rate vector but they said let's actually calculate the angular momentum of the pointing vector and if you integrated and divided by average power you actually see that the angular momentum that this vector has has two components one corresponding to the spin and another one proportional to l l the phase factor here so there's an extra angular momentum at least at that point it was discovered theoretically first that there's an extra angular momentum associated and with the with this turning of the face that's why we have an extra line here so this extra line is up for this extra orbital angular momentum that was discovered in 1992 and actually here's again Halina Rubenstein Dunlop that did the first demonstration that you could actually transfer this optical orbital angular momentum to trapped particles and here this is the same kind of experiment where you see frames of a particle rotating it's kind of difficult to figure out which of the particles is rotating and I normally try you to make you to guess and to pick up hands for one particle another one I'll just say which one it is it's this one here it's very slightly rotating but you see the the axis is clearly more horizontal like here and more vertical like here and this was then demonstrated in many many ways and this is where we do a video intermission from some videos that I took from YouTube that were published by the people from the University of Southampton and let's see if this works well so basically if you shine this kind of beams over there we go over this is not the one I want to start with sorry this one here so if you start do you have an optical tweezer again that will trap particles as you see they're starting to trap the particles in the bright part of the beam and as soon as there are sufficient amount of particles trapped they start turning because the optical force is stronger than the friction in the liquid that these particles are in and then they turn and in this other video and you actually see them turning in one direction and the other one as you change the chirality of the beam okay as you change the chirality of the beam from one direction to the other one so the bottom part is the representation of what the beam is doing the top parts are the particles rotating in one direction and the other one so this is just to say they have been many many many demonstrations that this is so but in all of these cases yeah here we are all of the demonstrations are on the center of mass of particles it took us a long time to actually cover this other little hole but before that little hole let me show you something so people tried and failed unfortunately to observe optical dichroism so like optical activity the same kind so a lot of people tried to do rotation of so rotation of polarization or rotation of angular momentum in optically active material and unfortunately they failed but very fortunately they published their results and I go this was very interesting for me and that was very motivating when looking at what to do that people actually publish negative results it's very important and it's very healthy for our community to publish negative results and the two first titles are a bit tricky they don't really say the negative results they say circle dichroism of cholesterol polymers and the orbital angular momentum of light and if you read the abstract it immediately says we saw nothing this one is a little bit more sincere negative experimental evidence and so up to now what we know is there are no materials we know of no materials that actually have optical activity in the spatial structure of light we don't know that they won't be that we won't find but coming from atomic spectroscopy and quantum optics we thought that we somehow had this thing in mind and we thought let's look and see if we can actually see something in atomic spectroscopy and there were many people saying this is impossible and I'll tell you why so this is an image of a very strongly focused beam and a trapped ion it's fake right so it's really an image of an ion and it's really an image of a beam but they're super post one on top of the other one so the beam has roughly three microns and the ion here is not the normal one amson that one would expect this is about 10 or 20 nanometers which is the spread of the motional wave function that you would expect for a trapped single at ion and what people said is like okay if you just put an ion in the center of one of these beams you'll see nothing and if you put it on the side well you see a force but you will be seeing the same thing as you saw with an optical tweezer and well we thought about this for a long time and we realized something very important which is forget about that and so there are different kinds of atomic interactions there are atomic interactions that are what we call dipole interactions that are mediated by the intensity of the field and so that would be what you call electric dipole interactions where the only thing that matters really is the intensity of the field and the frequency of oscillation and those are interactions where you change your orbital angular momentum in one but actually if you if you feel or a gradient so if your field has some spatial structure then you can do transitions of a bigger order at what what we call quadrupole transitions and the interesting thing is that these fields in the middle have a very strong gradient so we set ourselves to first ask ourselves can we excite an atom in the dark can we excite an atom just by putting it in the center of one of these beams where there is a very strong gradient and so I'll just skip this and the answer fortunately was yes so what you see here is iron position so we are moving a single trapped iron across this beam as I was showing like this so we can deterministically place an iron where we want in this beam and we measure the the the excitation probability of the ion as a function of the position and depending on how we choose the polarization of our beams we can either decide the ion to be excited by the longitudinal gradient so the gradient has to do with the with the with the traveling wave and there you see the red curve which is the intensity profile or you can change the polarization of your fields so that the geometry excites the atoms with the transverse gradient and here you see actually excitation of the atom in the center of the beam in the dark center of the beam we had done the calculations for this a couple of years earlier so we were actually very happy to see this finally coming out in an experiment two years four years later and you can do this for different kinds of beams and you you can see how with a Gaussian beam you actually can measure the the the transverse gradient so the fact that the the intensity is going to zero you see these little humps to the side this is a result I just showed you or beams with a higher order and but now let's go to the original question which is can we twist the ions with this I'll skip this and how how do we prove that we twist the ions so and so this is the the energy level scheme for calcium which is the ions that we were using and so normally if you would have everything collinear and you would just have polarization your two alone allowed transitions would be sigma plus or sigma minus say your ion is initially in this state you can only transition to this state and this state so if you tune your laser to this transition or tune your laser to this transition as we were seeing this morning in the lectures where you tune a laser to a transition and you see if that transition is allowed or not and in principle if you tune to all of the other transitions you should see nothing if you just have polarization the question is what happens if you add orbital angular momentum can you combine spin plus orbital angular momentum to get a change in magnetic number of two or anti combine them to get a change in magnetic number of zero so we did this experiment and the answer is yes the results of this experiment are here so what let me spend a minute explaining the axis so this is interaction intensity so the the probability of excitation of the atom and what you have in this axis is the angular momentum of the photon and this is the change in angular momentum of the ion so in principle if you have a strong selection rule you should have only excitation in the middle and that's exactly what you have so these two big peaks which are the stronger excitation are the two um transitions that are mediated solely by polarization and this smaller things in the diagonal are the transitions that are now allowed because of the operation of orbital angular momentum and so this is the graph that proves that that as it says here and I want you to take home photons are not just frequency and polarization they also can have an extra twist so there's more angular momentum to a photon than just the one coming from the polarization and also for many transitions local brightness is not all that matters atoms can't get excited in the dark and so we can finally put a very nice tick here and say yeah we can transfer orbital angular momentum to the atomic degrees of freedom but we still have unfortunately this little bugger here and with this chart I will actually more or less hop into the end of my presentation where I tell you in which directions we're going so the first direction that we're going is actually in a crude and brutal way thinking out of the box which is thinking out of this box and so can we use this for applications I'll tell you in a second a little bit more about this but basically we're trying to apply this to high precision spectroscopy so the kind of spectroscopy that we use with single trapped atoms and ions is very important for optical clocks for maintaining the best frequency standards in the world actually the way we defined our second might change in the next years from the cesium standard to an optical standard and if you're able to make this spectroscopy better with hollow beams we might do a nice contribution there and we want also to see if there's a regime where one actually is in the middle between exciting motional modes of the atoms and exciting internal modes of the atom so that one can entangle this kind of motion and create what we call in the quantum community shredding or cat states which has entangled the entangled states of motion and internal so external internal motion and there's still the big open question which I leave for you is is there any material is there any possibility to observe optical activity angular chirality so let's hope at some point somebody comes with a brilliant idea and and can fill this gap I'm confident it should be filled in at some point there should be some kind of molecule that is sensitive not only to the polarization but also to the spatial structure of the beam and so with that I go into the third part I think I'm doing good with time then and so and it's a bit about thanks I'm about telling you what I'm doing in my current institute and a little bit about how my career was and I was asked by the organizers to tell a little bit about my trajectory and how I've seen things up to here so here it goes I'm right now at the University of Buenos Aires I don't know why the the curious world of Balboa came into the into the program there's no Balboa in Buenos Aires and this is our physics department it's a bit older than 10 years and that's where I came back to set up a new lab and to set up this lab I've received enormous support from other three faculty members and actually two of them were my old PhD advisors so Juan Pablo Paz is a theoretician Miguel Aratonda is an experimentalist but it's working on another lab actually outside of the university and Augusto Rogales is also a theoretician and the four of us together decided to start an ion trapping lab in Buenos Aires and we started this three years ago and I'm very happy to tell you that we have our first trapped ions so this is an image of our first trapped ions which we trapped one week ago so that's the first sign of a working lab and in the lab we're not too many we're actually only four for people so me and three students but the nice thing and this goes to to the kind of recommendations and ideas so this is the whole group this is the joint group it's a big group that thinks of quantum physics experimental atomic and photonics and we get together we discuss papers periodically we tell each other what we're doing and that actually is part of what I think gives us a lot of strength I'm missing a slide okay I hear this this one this one here and so just to tell you very very quickly about my trajectory I studied my undergraduate studies at the University of La Plata that's a little bit south of Buenos Aires and then I moved to a PhD at the University of Buenos Aires but mixture between the University of Buenos Aires and a Center for Research for Defense where I did my PhD thesis then after that I spent some years in in mines in Germany as a postdoc and now I'm back at the University of Buenos Aires and there are a couple of things that were always very important and determined and determined in choosing where to go and what to do the first of all is work environment and friendship so I always prioritized the idea that or the feeling that I was going to get into somewhere where I would understand myself with the people I was going to spend time with them and you spend more time with your colleagues than with your family choose your colleagues wisely that's my first recommendation then another thing collaborators local and international so when I went back to Argentina the first thing that I tried to to push forward was having a big network of collaborators I saw that one of so spending some time working in Europe I saw that the real big potency of doing science in Europe is that you have many centers nearby and where you can ask colleagues or friends about something that you've been thinking about and probably that thing has been solved somewhere else so keeping yourself talking to different people all the time helps always a lot and the last one work hard play hard and so not only in your free time but also take work as something that you play with and that's I think one of the keys of doing nice and good science and so just to just to close two more things so okay now I did a bit of mess with the slides I definitely did miss one slide okay that's a slide of things other things I worked on but but but did not talk about today so all of these techniques were thought for quantum computing with single trapped ions but that we applied to some other idea to study basic science and in that direction in the next years in our lab we are not only going to look into the structure of light and how that changes light matter interactions but also on some interesting problems that have to do with so this has to do with structure of light so light can also be not uniformly polarized as the beams that we use up to now but also can have polarization dependent of the position these are called vector beams we want to study the how vector beams change the way they interact with matter and also we have a very nice project which is called a nanocryostat where we want to cool levitated nanoparticles sympathetically with a cloud of ions so the idea is that we trap a cloud of ions and a nanoparticle in the middle and by laser cooling the ions we can cool the nanoparticle and finally also on thermodynamics and cooling we want to understand thermodynamics of small systems very close to the quantum regime and possibly in the quantum regime and for that our workers will be different kind of ion change that we can cool or hit heat on one side or the other one with lasers that will also allow us to measure the temperature of the ions and study how heat transport happens in the systems where in principle the ergodic condition is not met where non-linearities may not be present where the conditions that lead to the normal assumptions of thermodynamics are not present and so with all of that I thank you very very much for your attention and if you have any other further questions I'd be happy during the evening to receive them thank you very much thank you very much for that floor is open for some questions thank you very much for a nice presentation so I was just wondering if the ion is at a place where the field is dark so like have you thought what what are the possible mechanism with which it's interacting with all the light that's around and which is not at the position of the ion so I skipped one slide and so not one slide actually one animation and I will go back to that and so these animations let's see if they work nicely okay what you see here that would be like our s orbital and this would be the transition between an s orbital and a p orbital neither at the beginning or at the end there's dipole moment but in the transition during the transition there's a dipole moment there's there you can think of what you have as an oscillating field and what you really need for that is a field that turns on and off and instead for a quadrupole field for a quadrupole transition you get something like this so if you start in s and you want to go to a d state you need stretching in one direction and stretching in the other direction and this is exactly the kind of things that you are that you feel when you're in the center of the beam so if you're in the center of the beam so I'm not going to do a funny thing but so a dipole interaction to me is like doing like this yeah you need to start jumping but a quadrupole interaction is more like starting to do like that and it really doesn't matter if you're not going up or down you really just have to turn sideways and this is what happens in the center of the beam it's not that the atom is totally in the dark if it was totally in the dark nothing would happen but the atom feels that there's more light and so a positive field in one direction and a negative field in the other direction and that changes through time and this shakes the atom in a special way that allows for quadrupole transition another question yeah thank you for the nice presentation I'm going to take this mind nubbing sorry I'm going to take this mind nubbing thing for a mirror face yes so vortices besides in light fields were also generated in electron microscopy and it was shown that they increased the they increased the resolution of the microscope do you expect that the ions with orbital angular momentum will also increase the resolution in spectroscopy actually um this kind of hollow beams were already used for one of the super what's called a super resolution imaging technique stead is based basically on this kind of hollow beams they're not using in any sense the angular momentum from the beam they're just using the idea of a hollow beam yes yes and I don't know of any techniques that actually use the angular momentum specifically but um stead and many other related things techniques of super solution do use this kind of hollow beams actually they use normally um the radially polarized beams because those beams focus better um so the vector beams that I was talking about not not the normal twisted beams but the vector beams focus better um um like a half times or the square root of two better than the other one so it's not only that you want to use a donut beam that but if you tailor your polarization in the right way you can have a strongly focused beam so you plan to work with polarization vortices in future yes okay thank you okay thank you another question I have an extra video yeah we're gonna be watching that tonight uh no okay so no more questions why don't we why don't we thank christian and and uh faria both our speakers uh winners uh give them another round of applause congratulations to both of you um so tonight uh in in your honor both of your honors we uh we have uh from courtesy the ico we we have a reception uh and that's going to start at nine o'clock sorry seven o'clock seven o'clock down at the Adriatico everybody here is invited we'll have live music I just I just got the word so we got the the photonically fat foobars are going to come they used to be called Balboa from Buenos Aires but no nobody could figure out where Balboa was so any rate uh tonight seven o'clock there'll be lots of food there's going to be dancing it'll it'll be fun so everybody's welcome and with that thank you very much and we'll see everybody tonight