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Opening lecture with Ursula Keller

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With thank good morning everyone says thank you good morning ladies and gentlemen and the risk of cells plagiarizing let we welcome you all of you the great great many of you warmly to this conference it is in the heartwarming to see so many of you about 1800 is approximately the same number as last year always a seal physicists and their friends who fled according solve every year this is the form playground this is where you made your friends but even more so we can meet the new kids on the block what brings you here you're all very busy the writer engaged in a struggle with Mother Nature were trying to get that proposal out there the paper out writing proposals against a tight deadline I'm probably all that at the same time and physicists are not exactly known for their herding instincts so there must be a rationale that brings you here you voted with your feet 36 of those what's so important so attractive so much fun about this conference that makes you take 2 full days out of your full calendar well I won't answer that question coming two-a-days show what cannot be put into words than those of a vibrant communities I said you were probably writing proposals they consisted of a tight deadline probably and life is becoming more and more complex on that front the numerous sources where an individual researchers can find them can apply life and find budget for research has increased tremendously in the past years used form used to be 1 of those steady sources of income for years but under the influence of the new structure funding of science in the Netherlands now form itself has become part of the network we call finances older parties this private parties was ministries was ordered fields with universities so life has become more complex presented that thing we probably from more physics research than ever before and excellent research at and yes all those interactions do we bring new inspiration no expertise to connect us with new people with new knowledge Anderson our benefit but at the same time the budget that we can offer for you and for our community the budget as you know it the instruments as you know that those have less urgent and entries you have to live with that this is a complex world and it's important that form that we as a community wouldn't do not lose ourselves in financial regulations and policy instruments and government structures but keep up asking the question what is it that we really want to do what will bring us signs further what our strength where do we see the most exciting physics the best opportunities for progress and here's how can we contribute to solving those grand challenges and how can we contribute to increasing competitiveness and with whom but always starting with the scientists so this conference is entirely science and it's about science it's about our signed by your scientists it's about who we are what makes would rises what tickles our imagination here we can sample feels that we do not know so well here we can link with people in other fields here academics can meet with companies and brainstorm about ideas so I'd like you to think of this conference is a place of inspiration rather than work a busy days you're rattles probably spend tomorrow more often than that and hopefully on Thursday on the weekends you have a quiet moment in U.S. views and experience when you know what it is you really want because that is in the end the question that we as a community will have to answer collectively what is if we really want to do we interact in all directions this private parties with politics with other disciplines but you can only do we can only do that effectively if we What is the what we wanted and there are a myriad of funding schemes but we have to put the signs 1st in picking the best science that is where nobody can debtors that is our field you have to put up the signs 1st or we have no right to speak this conference Science and is brought it offers very much and I can I want to ask you to do just 1 thing don't be polite don't sit in on the talks of your next-door neighbor all for your colleagues you know that you know the work already and yorker occupied a seat for others who do want to go to those talks so follow my request to go to anything
but urine specialization mingle sample get-to-know-you people sparkle this this convention is a former playground so Is this reforms playground and play on a playoff but just for a minute please stay put because stock was a great plenary lectures but it was like Keller and then we will be with us will introduce a new villa in custody for the few years migrated great pleasure and honor to introduce to you the 1st plenary speaker of which because of the color of the light should the usual fluency insulation as you know it she is there a research group lot research with an ultra-fast physics and Segers was most instituted a program of ultrafast science and physical started at ETH wouldn't she left after receiving a diploma as the call of Switzerland and shouldn't be Stanford University about physics and then she moved on for several years to develops when there still was a flourishing laboratory and she was also a visiting professor at the UC Berkeley and then also evident Institute of Technology and apart from doing basic science shows was a cofounder of 2 companies 1 of which is the optics laser-based company time bandwidth with products um a receives research interests lie in exploring the different shows that you can do with lasers ultra-fast science and technology and everything you can do without them all try not only deal trip with short balls generation frequency combs and you removal harmonic generation extreme ultraviolet lights X-rays and what you can do there and in particular she 1 of the pioneers of artists and that's what she will speak about today about the production of about 2 seconds and I want to do experiments with rats and she goes back to a very old experiments which is actually the experiment afford electron spectroscopy that Einstein clarified to us but there's always seems to finding for the elections because on hole electron moves away from an atom of size and that'll be the topic of rhetorically on very much forward to it before circular logic to give you a lecture on it good morning everybody ranges of all I would like to thank the organisers invited me to this and I'm just simply overwhelm you know I thought I'm going to Kansas sleepy annual meeting over national basic conference and here I am there's so many physicists I haven't seen on 1 sport ever and I think we need to do something similar in Switzerland them in this is amazing I mean it's an honor to be here itself and luckily I didn't know how to act as talk of the familiar people otherwise it wouldn't have slept itself the top kiss about the up the clock and with the other clubs can begin actually explorer Mary fundamental processes in quantum mechanics actually the questions you normally ask as a student and then you learn quantum mechanics which you then learn to not Oscar anymore and now in doubt the 2nd spectroscopy we can go back and actually ask exactly those questions and I can tell you everybody has an opinion and there are different and it is an exciting field as an experimentally because the theory kitchens are huffing and puffing after the Ospreys our measurements so of course amendment is never done alone and let me just 1st introduced my co-workers 17 would be invented the technique the upper clock technique I actually had tried to reach me try to explain and understand an experiment that didn't work and so I couldn't I couldn't even give it to a because it was in such a bad shape I came back from my sabbatical took over the years and the graduate student and I worked directly with the graduate student Patrice act a call try to figure out what the the heck is going on and after we figured it out we actually realized what this is beautiful this can do more I added more people and so the group grew we suppose stock then there is another graduate student more postal and also benefited from a very a good collaboration from my colleagues and I are kind heart donor who actually the report also helped to build up a Caltrans apparatus than I had a collaboration with harmless from Amsterdam to do that and penetrating integration which then because he stopped unfortunately and then was taken over by lot the work continued to be improved our measurements because they initially could not resolve and expand that the team even further it added more instrumental techniques the VMI yes and also the theory to explain finally our results but that we measure so when you give you a little bit of
an introduction about the short pulse generation as you know there's a the 1st time stopped at the 2nd pulses were generated in the time in the 70's missed the dying and you know all the pioneering work has been done in the style places where all the techniques have been demonstrated pump rope and so on and and the shortest pulses in the 80's 6 and the 2nd have been produced by Chuck sharing at Bell Labs that's why that was also might be place go and work the breakthrough came as a surprise laser and within a very short time be produced much shorter pulses than before With more average power and the pushed the limits so far down that we only had wanted to optical cycles underneath the pulse and below which means that we have basically when you have a near-infrared piles that 800 metered optical cycle is only 2 . 7 4 and the 2nd so if you wanna move into the upper 2nd you obviously have to to increase the center frequency and this was actually done with the so-called high harmonic generation and high harmonic generation again was an experimental discovery and an explanation came later so people have more more powerful lasers and when you have these later you shoot into something and see what happens and so what happened if you shoot into gasses is a very high intensity in the range of 10 to the 13 to attend to the 15 bucks per square centimeter that you actually produce harmonics so we all know from long nonlinear optics that if you increase your intensity you brew produced 2nd harmonic 3rd harmonics and on but what was special about these high harmonics is that you have this plot toll so instead of Taylor expansion perturbation theory that you're efficiency went down as you go up in harmonics you actually reach the plot toll and the was the 1st time really nicely shown by unruly and you know people were wondering why do we have to spot or we can have this but all going from 1 DVD on energy to 200 EV so wary overall efficiency to minus 6 but you start with a lot so we still have enough you still have nonmetal pulses you know so how does it work and it took a while so the 1st discovery of the blocked or by a meeting was basically 1988 and it took a while to understand it and there
and basically to date we have um In the light of ultrafast pulses going from the you leave a simple idea are made I terahertz and we can go into these high harmonics which of course are banned in them in the higher frequency regime which is absorbed in in air and therefore you need to actually reduce Europe Europe your lab space into vacuum ,comma chamber which is shown here as an example the alkaline now through the whole process of generating a short pulses actually we came up with a different technique which actually gives right now the behind time resolution that any measurement has been done in the time domain but it actually doesn't even use opposite compulsive and this is the optic so may seek out the clock we were able 2 addressed the question how long does it take to pull an electron out of an active so we normally distinguish between the different machines so if you are in their fault on energy which is much lower than ionization potential you can either have multifocal absorption Oregon this tunnel ionization if their intensity is strong enough which um and so that basically the goal potential furor have them get spent through the laser field so strongly that the electron can tumble out but if your foot on energy is higher than the ionization potential then of course you can have a direct admission of a single uh through the absorption of a single photon and half the the emissions so how long does this process stake there were a number of measurements so we basically any the October flocked to resolve the tunnel ionization and it took quite some I mean it was a measurable delay and I will show you offer works have been measured and then other people for example measures a measured the photo emission delay between 2 states and also measured at the lake the funniest thing most actually had that the tunnel ionization where you not only bring the electron out into the continuum you actually have to spatially more freedom than this were many out of atomic units actually most much faster then the single it seems the singer Liam me ionization of a single photon and of course the question still remains does the scale between 1 photon absorption too 3 to 4 to 10 full-blown absorption right so these are all good questions which gets everybody excited and some hardcore quantum mechanics physicists say any model is wrong anyway but you know I'm an experimentalist Ising models worked really well and the same a classical models are actually extremely successful because then we become very creative and come up with a whole bunch of ideas if you just do numerics you lose your creativity story for that I'm always open for discussions afterward right for now you have to listen to me at that so now final ionization so the tunnel ionization they have been papers going on 1 of them is from television and Kelly's also proposed time in his paper from 1965 and basically he predicted as so-called tunneling time for an electron to go through the tunnel barrier that was induced by the laser field and for the intensity that we have been typically working you know like 10 to the 14th into the 15 what per square centimeter being under a pundit amid the center wavelengths that on all time he predicted would have been for 200 to 400 of the sector so this is rather slow right in the foot of the 2nd domain so we thought we can measure so how the do we need to stop the clock recorded the optical and basically what we used is um a short a few cycle infrared policy centered around 800 on we chose circular polarized so you'll know when you have a circular polarized light the electric a field where there is a rotating at the optical frequency around in a circle so that means when you compare when you take a look at the electric field as the hand of a clot you actually have a plan reference right because the way the major normally time with the watch right here laughter our hands said at the meeting hand the 2nd hand so the thought that the faster it rotates the more accurate time mission so now we still this circular polarized light 3 in principle have hand of a clock that is a rotating moralizing offensive 2nd and so we can easily held up the 2nd resolution you know you can easily measure 1 degrees accuracy fraction of degrees so what do we measure recently so it's these electric field we basically have a time reference that is something we can the measure microscopically and is the same time and the same time reference this is also acting microscopically on the Single Act and so you have a defined time and then what do you measure in addition you measure basically also using the simplest way of using this out the clock you actually use this time reference also to induce the tunnel so and then at the end you measure the electron that is coming out and you mentioned the vector Of the electoral momentum in what direction it comes out depending on the direction yeah it gives you the time delay of the tunnel so I'll give you for the
rest of the talk more details but let me then 1st if you did result solely originally started off with helium and you know this 1 figure on the left and shows you with the feeling there are over a large intensity range and basically this solid line would have been dead a that of the electron coming out of the electron momentum assuming it tumbles out with 0 delayed instantaneously and you can see it that underlies a little bit shift that but you know I wear a Boris went actually through this Europe so actually we could put an upper limit on the tunneling delay which was in the range of 35 up the 2nd so far away from the 200 or 400 that killed each predicted we then continue you know when you do measurements which don't agree with theory you keep measuring right that's the best you can do so we changed pocket went to Argonne and are goal we be also did over a large intensity range and um you can see all only in the lower intensity range here the data was more about half the solid line which would have been instantaneous tunneling and an otherwise it's pretty much tracks there the solid line um and but when the it took us a while to understand are gone off the heel because argument turned out to be much more messy and I would like to explain that as as well and so at the end to really resolve the tunneling delayed time been actually back to heal and and these are the measurements that we make us an improvement and now look at the quality of these measurements so um Bluel and alone section is basically blew away ordered the uh basically which gives to the pummeling the lady at Umm at this time of ionization process the scale goes from 0 to 200 of the 2nd and if you compare that to any other prediction of tunneling time because tunneling time has been a heated debate the topic in theoretical physics with many different to predictions so about half you see a whole bunch of different predictions for as many of you know the names you know and you their ranging from 800 to basically a sup 100 up the 2nd to predictions so it's played on the right and basically in a 1 of these stumbling times from Bookmiller BT Colombo work is very similar to the killed this time than and then you have eyes and would weaken then the law more and you can see that our daily life is very similar to the law more tunneling time and then the theoretician in my group Dr. Alexander allowance money used the firemen path integral formalism to actually explain how would the obvious this triangular tunneling barrier and basically brought their could explain it was this 1 as well and if you then look at what is the tumbling time as a function of barrier which you can see on the lower it's not arbitrary units it's upon units so it's great to trade so this is basically together from going out pretty far away from the center of the Act them and you can see it pretty much follows more or less a straight line and it's not a and it's lower than the speed of light and it's much faster than just letting an electron propagate all would be saying distant with their Natick energy of the binding energy all if you just right away would move away the body so I hope I have that this on our latest deal that we still try to get published actually it's on archives and I would like to explain to you a little albeit in more detail how we measure it because people really get very emotional about this kind of measurements will women's Aristide's American Uncertainty Principle how can he do this let me answer these questions let me also emphasize before I go on we actually used the other clocked at technique also to resolve the timing or in the double ionization you nowhere on the circular polarized light you ask you know you can bring if you increase the intensity you cannot only take 1 electron can take 2 of these there are these 2 coming independently circle life or when is the 2nd 1 coming in comparison to the first one and there again we basically showed that the 2nd 1 comes much sooner than the first one which was not predicted and actually showed some correlation which was also predicted that you know when you looked at the ratio of the 2 electronica going in the opposite direction versus into the same direction if you circular polarized you have nobody scattering beats kicks out the electron so you would predict equal distribution result and oscillation was not present was not predicted and theory irritations are still trying to understand exactly what is going on under the sink so that we now go to the opera clock and explain that ,comma ionization experiment so Media I mean generally people there I have long discussions about and the delays in quantum mechanics because time is not an operator and so you have to be very careful to define what are you were all observables right so what we are doing with the at the clock we do too independent measurements 1 is the polarization of the line and 1 is basically the electron momentum and we all know the electoral momentum I can measure his very high accuracy I don't lose any officer compulsive here at this
point of course I can
combining show just that you would get get used to it I know not everybody here is an expert so I use the short policy around 5 and the 2nd in the short pulse the maximum of the electric field rectum goes up in a circle goes down again so if you look at the matter 2 of the electric field it goes slowly up and then slowly down and rotates in the space and when you look into the direction of the propagation you have this hand of the clock at going around and because the panel ionization is such a highly nonlinear process everything happens we've seen that around the maximum because only there you have the necessary intensity to ionized tunnel ionized the at so you take basically and then there is a circular polarized light and because you use short pulse it's actually very hard to do a perfect circle of polarized light actually you can't even do it and you know initially I thought that was a problem but actually at the end it's solved our problem with the time Cyril Collard variations because you don't wanna have a perfect supplies polarized POV because if you take a little bit of electricity then the maximum of your electric field like the war is given by the electricity the main axis of your elliptical paralyzed life so too 210 early to say times 0 is them face the moment where we have their their maximum of the electric waste wrecked this is time 0 because that initiates the tunnel ionization spend most probable trajectory the most from the signal so this is actually the nice thing about the at clock you have a well-defined starting point in the tunnel Prosser of the most probable trajectory so to make sure the elliptical over and over of light policies vary it's just parliamentary and it will not change when you go into the experiment we actually have a sanity check so this gives you times Europe and then they're fast rotating electrical field is spend your time reference so let
me know show you a so you can go for two-step model the 1st step based you have tunnel ionization from both home and then gets Oxalis keeps being accelerated by the electric field of the remaining part of the policy and so would I show you know Is there a rotating electric field wrecked or at the maximum of the electric field you have to tunnel ionization Yuri it see around the lake and then the electron is speed that semi classically you know it's pretty far away from the call you know from scattering theory that this works really well we know from harmonics the December classical pictures very well a describing harmonic generation so we treat than these electron the words in the remaining part of the laser pulses classically and you can in the simplest model you assume new denigration with the elected a least laser field alone no other interaction for the time being I'm coming back to that 1 so I let this moviegoer I hope it works yeah electric field that but I look at the most probable .period maximum electron comes out instantaneously keeps being accelerated by the remaining part of the electric field and while policy is done the electron comes out into a special directions with a certain momentum and you can actually show mathematically very easily is if you just assume during the strong field approximation you neglected going direction actually electric at electron comes out exactly at 90 degrees removed from the maximum so if there would be no tunneling delayed the electron would come out at 90 degrees C but of course there is also the glowing direction and active little bit of a correction and that it's actually was also a very heated debate a debate how do you include correction into this dynamic I'll address that as well and so basically how do we measure the electron momentum there is actually a very nice instrument that has been developed by nuclear physicist the so-called frames and that 1 measures to lead the electron momentum rectories very high accuracy so let me show you that uh so you
have basically an instrument wearing the middle you have um year you have DOS chess as various helium then you come in here with your a laser pulses normally you don't use focusing lens right you've picked the soul into account but it's just a show so you idolize you know every every Everything was imposed on ionizes 1 act so it's really coincidence measurement you don't measure and the electronica simultaneously and
it's every event is a single event you can measure it basically on the both sides you have about a time of flight and the position detectors which give you the Wecht of the idea and the electron so if you have only 1 ionization event you Candida measured Allianz or you can measure the electrons and to get the um the electron momentum now in the
reality we don't have only a laser field under the circleup arise light so when the circle polarized light comes ionizes the act you of course also have the electronica am interaction which in the view is mainly the global potential so you actually really have to add an additional term into your
equation In the regulation which shifts a little bit the magnitude of your distribution so you have here this is your elliptical axing of your life so the maximum is here and here and there on the Nolte interaction the electron will come out in 90 degrees C that's where you have the highest count of course have a certain distribution rights for the tunnel ionization if even take into account the glowing direction it shifts at the little better it and it changes the direct direction would there be a delayed it would shift even more so depending on the angle you would actually be able to resolve that tunneling time and as
I say the elliptical polarization give me the time 0 so would you do
if you use a quorum I've played before you go In through the Caltrans apparatus to set your polarization and then you before you go in you can do also you were at the full characterization of your polarization so all you have to do you insert after your work played before you go into the Caltrans a polarized and you corrupt the rise and basically the polarization of 0 Europe uh policy depending on the angle of view "quotation mark played using you set the electricity and the taxis all 50 of the main polarization and another contrast gives a gift to the electricity and we normally work with electricity of about 2 . 8 not respond because the main 1 is is undefined and also you with this program and uh pulses it's basically impossible to get perfect for polarization and then you need to get from this angle measurement which is the Times Herald accommodation between the laboratory frame angle and the electoral and measurement right you need a combination so how do you do with this so you'll basically I 1st the at the miscellaneous polarization where you don't have the streaking and the direction of these linear polarization is where the electrons will go out and you basically get a colleague accommodation between your polarization measurement and your Caltrans measurement and you said that want to see Iraq and then you go to the electricity and look at the angle of attack from the maximum of your time CEO right so it's a very straightforward way
and you can then take into account the global correction over time
you know we actually improved I was signal to noise you know these measurements are coincidence measurements you measure and electron at the same time so it matters a few workers wanting laser persistently laser so um I got the money to improve my laser after the original an experiment and this just shows you the quality of the data when you go from 1 to the limits to 10 kilohertz right the peak search because at the end of what you do is a peak search of Europe the electron distributed up cumulated over many many many single measurements and of course the speeches becomes better
but if not that nice thing about the upper clock just to make sure that there is a sense check and this is you can actually make the light left and the right see color so you can actually change the orientation of your clock and this is very nice because you can easily show that aired this school ,comma action will give you either that reduction tonight degree C or an addition to 90 degrees C so you can actually have a very sensitive and measurement for days complex electron I interaction um um industry can process and if everything is right and you're not doing making a mistake you should actually measure blows error of of left and right circular polarized light you should measure their disdain offset bundled with regards to the 90 degree streaking angle which would neglect this electronica iron interaction and you can see let me get that and what you can see below disease the results that I showed you at the beginning with the improved laser system and extending the measurement to lower intensity so that actually this tunnel ionization delay becomes a more measurable entity you can see that if you increase the intensity the era bars our kind of touching this 0 pummeling delay time but it's clearly a ball and this as we lowered the intensity the barrier race becomes larger and larger the pummeling the ladies look longer and lower and you can see this offset is increasing and Bluel and there are clocks or on the clock which is a very nice way that we know that there is no systematic error in our angle measurement than just to emphasize these
more you know albeit doing so we have here this is the cultural area the Caltrans opera this year is the gasses focus right so we coming and focusing too at the half of Indo here but for the polarization measurement we insert here a polarizing and the power meter and do all this polarization and then all the ghosts when then sets the quarter with played it goes through this window and if the surrender would do some funny saying we wouldn't get the offset plus minus 90 degrees in the correct way right so this is not a very accurately and you know we understood at a quarter wave plates you know it makes sense the Soviet just the and along the "quotation mark away from the switch between on the clock and clockwise and up to clock operation to measure those angles all the time so it's a very simple and easy way and so these Alsip angle to 90 degrees C turned out to be a very a sensitive mentioned observable measurement to actually understand the complex dynamics of the electoral moving away from the idea right and Joe you can take into account the cool long and so on and as it turned out in there is many more terms that you actually have to take into account you can't stay in the single active electron approximation Yukon actually have to take into account that all the evidence and then think about when you remove an electron from the molecule there is going to be dynamic summed up the 2nd time scale on the molecule right here as it turns out we can treat the moldy electronification of argon and liking this tactic they also fast that they are the same as in a stoppage as experiment so how do we take into account the interaction actually in um at that time and I started most people actually use the one-dimensional model to describe them ionization potential and in the tunnel ionization which is basically to call on potential rise and the electric field here a fuller 4 days then go along so you have to call our boss the electric field in 1 dimension but this is actually not really the correct way because you can actually go into quantum mechanics textbook and you can show that you can actually solve the core of the shredding their creation correctly if you go to the parabolic minutes if we go to the park football accordance with the goal of potential you actually get through potential and effective potential in that it got caught here which is slightly modified from the field as we call it now the future direction modeled his one-dimensional model it has sent them some additional perks it changes the exit polling all of the good are some of the electron and it changes and their energy here so it really goes into the semi classical model but this is the correct mechanical solution for a 46 problem and if we take this into account that basically we can actually it gets the good um correction very accurately to .period Indiana are gone it's actually more complicated than that because the current correction alone did not explain the result so this the figure tells you um this month shows you the tunnel takes .period as a function of the field strengths or intensity and you can see that there mean be tunnel exit increased electric field is going down sold solid line is the field direction model this one-dimensional model and you would actually predict over barrier ionization much earlier but if you actually use them parabolic on its you correctly described it and you actually don't even reached over a barrier the intensities um over there that the electric field strength that we have been working on so when you look down at the end of the electron coming out assuming instantaneous tumbling you know the future action would actually give you and then of course here and at the moment them when you reach over barrier but over a barrier in the realities never reached and you can see bills under the obvious is continuously decreasing and the Concorde action gives this lines at the call correction wasn't really enough so we have do pieces was the contribution from last month options group we have to take into account in argon that you actually have a stock which is under the electric field which is well known and has been described before so we took those staying again as a correction
but then also have an induced Apple which is well known in our bond with their left over electrolysis they have rearranged and if we take this into account we get the agreement and no measurable tunneling time at this really high intensity this look at their this Parliament that here and only at the lower intensities see something like going up and it appeared he was clear to us OK if you really want to concentrate on the tunneling delayed we really need to go back to the room and just with the measurement more accurately and that's what we did uh by going to tend to be lowered pulse repetition rate and going to lower intensity knowing you go to lower intensity the proper line is a probability of ionization is coming lower and lower the count on the Caltrans becomes even attend over it's negligible the smaller mean you end up into noise and so we actually expanded the measurement by going to wear VMI yes and what you're seeing here is um um an overlap so we make sure that our and the overlapping part the date of the solid data points here order vehement yesterday which are overlapping here was the Caltrans and and this article terms stayed which we could expand to lower intensity because we simply
didn't get enough counts anymore so they realize this is at a velocity that a meeting as of also the electron momentum it's it's basically through an Opel but projection going up into the air to to the detector it's a little bit don't have time to explain this in more details has been um has been described the here extensively and is the and but you lose a little bit of of information because you make a projection so you need to have some tomographic reconstruction to ultimately get the 3 D E distribution but you can do about because instead of turning the whole apparatus all we did is just turning the elliptical axis right there in in space which we did presentational halfway plate and make sure but you know that irritated the incoming elliptically polarized light before we go in and make sure all these different projection and out of all these different
projections we ultimately can go through the tomographic uh the construction there has be distribution and
therefore their maximum and direction of the electron and this shows you um for example there and the top graph shows you to integrate the counts you gradually integrate the count of the electrons and you clearly can see in what direction you have the maximum of the electron uh accounts which is the most probable electron tube trajectory and it's the peak search that you use for the delay so I missed this we could able really we're able to get the is and all of that with regards to the 90 degrees C and then of course as we want to get out of this unwanted at the tunneling delay right how do we do this so b we have the frequency omega towel is basically the offset angle from 90 degrees C because the 90 degrees then we have basically there to action monitors the streaking which I explained to you which is the not correction for the loan which is wary well described theoretically so we can do that 1 and then there is an additional correction that has been discussed in the literature extensively and this is the correction assuming this this upbeat about take approximation that the electron comes out with 0 velocity at the exit of the tunnel or does it have some of the most probable trajectory of doesn't have some other velocity sell all bunch of theoretical um predictions you know so but where is the starting point for the salad from what is the initial velocity and then we take into account all the theory that has been published so far you know what we're here and we can get only a small correction so this would be a lecture on its own to explain to you all the different correction but you know and basically down here I am now into the graph I show you what would be that angle this assuming 0 tunneling the where would be the Allstate angle with all the different correction that have been predicted so far taking into account all possible theories so basically that will be 1 another 1 another 1 and another 1 and as you
can see only small correction the offset is still there right so if I take this
into account and then for the tunneling delay time putting it all in and put things for example the record it's me this up than the black 1 which is on the other side of all the theoretical predictions gives you down tunneling delay time right and if I and of course if if I haven't signed by pummeling delay time then the outcome doesn't come out at the maximum of the electric field but actually a little bit later so I need to take this into account in the streaking gifts also small correction but you can see it's always in the air a bar and it doesn't really change the message we have offset so is the that now tunneling if you have a different suggestions ,comma to me let's talk about it we actually have a young theoretician my group and to use the firemen past formalism which has been developed over the years to actually explain all the different predictions of tumbling time and if she applies it to the triangular potential as she can actually explain our so the solid line is the theoretical prediction for determining the late time using firemen path integral formalism and define past formalism has the advantage that that 1 is well defined it's kind of like a deterministic trajectory so each time you can clearly define at times over the winter during which an electron is within the barrier and defined that 1 as the pummeling time and as I showed you before I mean this tunneling time is less than a minute is definitely is lower than the speed of light it's not instantaneous and it's is faster than the speed to Colombo were detailed this time and the time it would take if you would just leave the electron propagators the kinetic energy um over the same distance which would be the upper limit and so I hope With this I I could give you a pretty as a clear description of how we measure at the it's uh this up the 2nd process and defined to you observables that we have the measure of momentum and the air at the time that this product is the location of the Act and that has been ionized which is a macroscopic focus of delays so that no I can measure momentum risk as many as much actress yes I want fraction of the degree which means up the 2nd time resolution but that the interesting thing is affirmed that the furious correct with the firemen pumped integral we Wheat that's theory would also predicted that actually there is a fundamental uncertainty how fast the whole can be created so it is a statistical process and you would have Arezzo you cannot say that instant when the electron was ionized you would have an uncertainty of the whole and dynamics which can be significant and would have to be taken into account it's a very asymmetric Adelaide which goes into the range for all of 100 of the 2nd which would give you a very fundamental uncertainty when you wanna look at the dynamics of pulling an electron out and see how the holes already arranging in there In the solely or in the molecule and these days I would like to conclude and I think you very much for your attention thefts thank you very much for physical for this exciting and or
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Metadaten

Formale Metadaten

Titel Opening lecture with Ursula Keller
Serientitel Physics@FOM Veldhoven 2014
Autor Keller, Ursula
Lizenz CC-Namensnennung - keine kommerzielle Nutzung - keine Bearbeitung 3.0 Deutschland:
Sie dürfen das Werk bzw. den Inhalt in unveränderter Form zu jedem legalen und nicht-kommerziellen Zweck nutzen, vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen.
DOI 10.5446/18027
Herausgeber Foundation for Fundamental Research on Matter (FOM)
Erscheinungsjahr 2014
Sprache Englisch
Produzent OpenWebcast.nl

Inhaltliche Metadaten

Fachgebiet Physik
Abstract Novel time-resolved attosecond streaking techniques are currently being applied in an attempt to answer a very fundamental questions in quantum mechanics, such as how fast can light remove a bound electron from an atom or a solid? Furthermore, the question of how long a tunneling particle spends inside the barrier has remained unresolved since the early days of quantum mechanics. The main theoretical contenders, such as the Buttiker-Landauer, the Eisenbud-Wigner (also known as Wigner-Smith), and the Larmor time give different answers. Yet recent attempts at reconstructing valence electron dynamics in atoms and molecules have entered a regime where the tunneling time genuinely matters. We used the attoclock technique to measure the tunneling delay time in strong laser field ionization of helium and reveal a real and not instantaneous tunneling time. The matching theoretical model predicts a strong implications on the investigation of electron dynamics in attosecond science, because a significant delay must be taken into account about when the electron hole dynamics begin to evolve.
Schlagwörter Lasers
Metrology

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