Hey guys, this is Nate, AKA The Foot Account, and welcome back to the channel. It is Monday, you know what that means, market outlook time for your next week in FIFA 21 Ultimate Team. Kind of an interesting week this week. A lot of question marks, we're not entirely sure what's going on with the Rule Breakers promo. With Rule Breakers set two, are they gonna be just out of packs on Tuesday, tomorrow, are they just gonna be done and over with then? Are they gonna get re-released back into packs, both sets, are we gonna get road to the final? A lot of question marks this week. So we're gonna talk about it, talk about the market as well. And it's another Champions League week. So that's something that we have to kind of take into account as well. And also talk about what happened just a few hours ago with squad battle rewards and some of the market movements that we are seeing happening on the market right now. So let's actually start with that. Just a few hours ago, we did have squad battle rewards. I did mention in the video yesterday that there were gonna be some buys around that time because some stuff was going to rebound. Player like this Lucas card, really met a card very popular to invest in. Some of the stuff did rebound a little bit from rewards. Couple out-of-packs informs and really met a golds did in fact deal up because as you can see, Lucas is about 45,000 coins before rewards and it was now back up at 50K and still rising. And probably will continue to rise into the morning a bit today on Monday. Looks like hats it's up a little bit, Varan is up a bit, but some of the stuff is still down a lot lower than it was. Joe Gomez is 123K out-of-packs, interesting. Interesting, interesting, but I would expect some of the stuff to rise up a little bit into the day on Monday. But again, gold cards are just not as much the name of the game anymore. In FIFA, we're starting to get to a place where a lot of special cards coming out, SBCs, promo players are coming out in the game and there's just more demand for those cards instead of the gold. So I think especially for Thursday flipping this week and when we have things happening during the week from now on in FIFA, I think even just trading in general myself, I'm gonna be steering away from gold cards a little bit more and going a lot more towards once-to-watches, informs, and other specials in the game because there's a bit more of a consistency with those cards and just because they're out-of-packs and there's more fluctuation with those, whereas there's not as much demand for some of the gold cards. There's still a lot of demand for gold cards. We're only a month into the game, but not as much as there will start to be on the out-of-packs, informs, and team of the weeks and stuff like that. So wow, Renato is absolutely flying from where he was this weekend. That's interesting right there. But let's take a look at again what some of these rule breaker cards are doing on the market because some of these cards got slammed today with supply. They're going down a lot and this is the one card that's really sticking out to me, Alex Tashara, who I think was overpriced to begin with, but this dude's down like 100,000 coins literally today. He was almost at 400K earlier today on Sunday and the dude is now under 300,000 coins on the market. Royce is back down at 400K. Pugba's 920, the dude was selling at 1.5, first hour or so of Friday on the promo. That's crazy. And I think these cards are coming down to a lot better prices and it makes sense, right? Because we're actually realizing that the pack weight on the second team of rule breaker cards is a lot higher than the first. He was down right around 900K. So he's dropped off 600,000 coins. Even some of the cards from rule breakers team one have reached not low points to where they were in packs almost, but they're pretty low, right? Like Douglas Costa is back to 435. He was almost 500K. Mertens is down at 488. Llorente is down, Laporte is down at 478. Kane is even down like 60K. So a lot of these cards are just getting low after the week and they sell off. Now the biggest question is when this rule breakers promo finishes on Tuesday? Because I believe it is Tuesday. Yes, one day 12 hours from now. So it'll be Tuesday at 6PM UK. These rule breakers go out of packs. And that's very interesting to me because that's a Tuesday, right? So it's Tuesday. What is gonna happen after that? Is EA on that Tuesday gonna start dropping Champions League content? And are they gonna drop like loading screens on Wednesday and Thursday for road to the final? Or are we just gonna have no promo this weekend? Or are they gonna put all rule breakers back in packs for a couple of days? It's kind of weird because this is ending on Tuesday. We haven't really heard anything about this. But one thing that I was a bit interested in today was this denayer SBC that came out. I was not expecting an SBC because usually what they do is for a promo. And I know the Bellarabi is going after the promo date but a lot of times for promo SBCs they end at the end of the promo. So if in fact we are gonna get rule breakers cards in packs again, it would almost make sense because of the way that SBC is out for six more days. So we'll see, right? Again, I would not say that you have to sell your rule breaker cards but I don't think I would really invest in anything yet. If you're buying anything right now maybe it's just because you've got a few games of rivals left to play for your weekly allotment of 30 rivals games where you're just trying out some cards for fun. But there's really not a lot to do on Monday to Wednesday in this game except for objectives. Now there are some objectives right now that I'm gonna have to be grinding myself too. I can fend for and still finishing off rule breaker Mukielle which I'm very close to being done with. But other than that, there's really not a lot of stuff to do on Monday to Wednesday this week. So again, just like we saw last week on the market I would expect to see stuff not really move around too much in price. All the hype is gonna be based around people trading and people investing and also with team of the week there's gonna be some interesting movements this week. Of course with Gareth Bale scoring today his once to watch was like 220K. He got subbed on, went up to like 250 or 260 went back down to 230 after the game and is now back up to 250. I don't know if this guy gets an inform. I don't think he does to be honest but EA could very easily slide him in. So there's a lot of possibility with team of the week this week to be very interesting with once to watch cards. So you're gonna see a lot of hype build up on those. Wednesday is gonna be another day of probably like leaks and all sorts of crazy things happening with that. And then yeah, there's just again a lot of question marks on what's gonna happen though after Tuesday. Now probably Tuesday since it is a UCL week we will see the UEFA market matchups and that has dropped the market both of the last two Tuesdays that we've had because we've had that SBC come out on Tuesday past two weeks with tradable pack supply and what that has done is it's dropped the market some stuff has rebounded from it but a lot of people last week bought their Thursday flips during that timeframe which wasn't a terrible idea if we're being completely honest but this week I think if you're gonna be buying your flips on that day the only flips that I'll be buying that early on Tuesday would be if there's any sort of panic selling with out of packs cards. And again, like I mentioned at the beginning of the video a lot of things that you're gonna see me doing on this game now it's gonna probably revolve around out of packs, informs and special cards just because I think that's where a lot of people are starting to upgrade their teams with because they've played with these gold cards, right? Or they've got gold cards in their team that there's not a feasible card yet in the game they can upgrade with but maybe they have instead of gold Jay Zeus at Striker they wanna upgrade to somebody like this Zaha so this card is gonna fluctuate out of packs in my opinion because it's a prem striker five star skills which is very desirable this year in FIFA. So you're probably gonna see me stick to more special card trading and if you're gonna buy out of packs stuff for your Thursday flips which we'll talk about on Tuesday night into Wednesday. Tuesday could be a decent day to look at that stuff if you get in early, right? Now of course you're thinking no content on Wednesday if you're gonna buy your Thursday flips the only risk is they put something on a Wednesday that makes the market go down then you're probably losing some coins but again, let's talk about UCL before we we'll get into Thursday flipping later this week as the market does move and change but let's talk about Champions League for a bit because there are Champions League games on Tuesday and Wednesday again of this week and I think Europa League on Thursday as well but we have to start talking about road to the final cards because some people think that road to the final will be the promotion coming this Friday because of rule breakers ending on Tuesday people are thinking that road to the final cards will be released this Friday. So let's take a look. A lot of people were also saying they think it might be too early for road to the finals last year road to the final team number one was released on November 8th and team two was released a week later on November 15th so it was a two week promo last year November 8th and November 15th. Last year match day four was on November 5th and 6th match day fifth was in the 26th and 27th of December now of course this year 2020 were a bit further behind and they're playing a lot of games kind of scrunch together just because of the way things are with the late starting of the seasons and stuff like that. So we are on this Tuesday we're on match day three, match day three. Now I would not be, I'd be fine if EA put out road to the final this early and they put it out during match day three and four that'd be actually kind of sick I think before Black Friday but I could also see them waiting until almost after Black Friday because match day five looks like if I could click on it it's on December 1st that'd be kind of right after the Black Friday promo this is Tuesday November 24th so I honestly think that if they're going to drop road to the final they, if it makes sense for the FIFA calendar I think they have to do it either this week and if it's a two week promo they have to do it this week and next week and then we have Black Friday after that almost so I would honestly think that's how this kind of schedule will work out with the road to the final cards and with the promo coming this weekend now we'll see if it actually does happen but again, match day three this year for road to the final cards last year they were released on match day four that just means more possibility for people to lose coins so from an EA standpoint that's even better for them more people could lose coins with fluctuations on which cards are going to make it from the group stage to the knockout stage if roads to the finals are active in game and that'll be more coins that we can make from trading as well so that'll be fun but just kind of watch out for that this week I don't know if it's coming but we will see so again, you away from our key matchups this week Real Madrid inter looking like a very possible matchup or Atalanta Liverpool could be in the SBC with possibly maybe PSG and Leipzig looks pretty popular maybe Zenit and Lazio possibly Chelsea and Renee we'll see man but again, I would expect that supply SBC on Tuesday and then honestly after Tuesday Thursday flipping on Thursday is like the only thing that's really guaranteed we can make rewards on Thursday we really don't know what's coming in the second half this week it's really kind of just all questions up in the air if I'm being completely honest now of course we did mention the rule breakers cards possibly coming back into packs EA has not said anything about that we don't really know if that's happening or not for sure but they of course could spring that on us in a moment's notice and put these guys in packs until Friday if they wanted to or even for even a whole another week if they wanted to do that as well so if I were you guys I would not really go and panic sell a lot of those cards a lot of these have been over invested in but I was mentioning in yesterday's video a guy like this Kamara who was over invested in he was kind of chilling at like 50K all day today and of course today with the denier center back coming out looks like he did go up a little bit which helped some but he was kind of chilling at almost his lowest price ever today on PlayStation 52K and in the low fifties on the Xbox as well before the denier SBC came out today he was looking very very investable because a lot of people were finishing week in week and they were selling their investments and that was kind of like dipping him down lower to a price that he had like his lowest price ever even out of packs so just be careful with these I would say they're gonna be great for trading great for flipping like this Douglas Costa of course we have Player of the Months right it is now November so we're probably gonna see some Player of the Month voting start to pop up on Twitter and on the socials because that those awards they're probably gonna be given out here in a decent amount of time I think the order if we take a look at the live SBCs for Player of the Months we have them live which one expires first Ansu Fathi expires in six days Calvert Lewin expires in seven Krammich in 14 and then Neane is in 20 days so probably I would expect La Liga and the Premier League Player of the Month SBCs to be released first and I would expect that voting to come out here pretty, pretty soon because of that so just keep an eye out for that voting later this week a lot of people are saying it could be Kain or Sun for Premier League Player of the Month that would be a big SBC I'm kind of hoping for Sun we'll see and then of course Lewin Dotsky is the favorite again this month or not again but he's the favorite this month of October for the Bundesliga Player of the Month so a lot of SBC stuff is in the future I'm gonna be making some videos here in the future about maybe getting your club ready for Icon SBCs and a lot of big player SBCs that could be coming because still, right now in foot if we take a look at the cheapest players by rating 84s are cheap man 84s at under 3,000 coins are very cheap 85s at 6K are cheap these cards are gonna boom at some point but it's gonna take a big SBC for that to happen 83s at 850 to 1,000 coins is very cheap as well so again one thing you're gonna hear me recommend in the next couple of weeks is just do a club stock once you have a lot of coins club stock 82s to 86 is 87s I know the prices are pretty cheap to just throw one or two of each card in the club throw a couple in the transfer list if you really want to and you can honestly chill with those cards and just wait for the SBCs to come out because at some point those cards will go up with SBC demand it's just a matter of when does that actually happen but again if you're trying to trade and make some coins this week probably the out of pack specials are gonna be the best way to go and actually to end this video I have my pre-order pack so let's rip these at the end of this video and see if we can get anything but this week with trading wise I'm gonna be looking at icons out of packs, informs and special cards because they are out of packs and they're popular so they're gonna fluctuate around in price and that's gonna be a great opportunity to make some coins this week just in case let me check on some informs right now Firmino is 227 that's pretty cheap that's a card that I like to look at to flip Kyle Walker is 570 Kyle Walker's center back cards gonna be an interesting watch this week with the possibility of him getting a right back inform of course we have multiple ones to watch cards that are inflated right now too no man, back to back non-boards from the pre-order packs oof, racket-titch nice but anyways let me take a quick look at these and talk to you guys about these we'll look at these more in the week Partet was like man of the match for the Arsenal game so he is inflated at the moment Zietsch is extremely overpriced possibly getting an inform this week I would sell him in the hype on Wednesday Bale I would sell into the hype on Wednesday as well it's gonna be crazy if he gets into team of the week but we have three guys here three guys from team of the week number or once to watch set one that could get into the team of the week which would be very interesting if that happens I think Leeds play tomorrow or in a couple days oh, Samedo, Samedo's another one this guy is probably gonna get into team of the week as well he was man of the match in his game so once to watch this could be kind of crazy to trade with this week as well something to kind of keep an eye on if you're doing anything in the game this week if you wanna get a little risky with it there's gonna be a lot of eyes on once to watch cards and their fluctuations heading into Wednesday with team of the week so that's gonna be an interesting watch as well but again kind of like a big question mark on what's gonna happen later this week just watch the rule breakers kind of trade with those if you want to out of pack specials and icons are gonna be the best way to go of course if we do have SBCs come out trade will pack supply SBCs then you will have a good opportunity to trade with gold cards just make sure you're trading with meta ones very popular cards that bounce around a lot in price cause they're just desired for a lot of people's teams so that's kind of the market outlooks this week boys just a lot of question marks right this week can literally be summarized with what the heck is gonna happen we don't know EA sports let's see what you got all right boys if you enjoyed this video smash the thumbs up on it comment down below if you have any questions subscribe to the channel if you're new I will catch you guys later peace out


Okay, so first why quantum information? So this is a small classical computer. In 2019, I remember Professor Mazari had said that you can run quantum espresso for silicon on the phone. So this is our very small computer now. And this is what a quantum computer might look like. So why bother to move from our small classical computers to this quantum computer that looks very cumbersome and inconvenient? Well, the answer is that quantum computers can potentially provide new solutions to unsolved problems and also simulate quantum phenomena faster than the classical computers. So for example, quite long ago in the 1980s, Peter Shaw had proven that you can use quantum computers to find the prime factors of large integers. And this is something that a classical computer cannot do. And it's also the basis of the RSA cryptography that is the most widely used public key cryptography now. So now if the quantum computer can solve this problem, it means that there's a problem with the cryptography that we use now. So we also have quantum cryptography that will allow secure transfer of information across long distances. And even a more interesting quantum teleportation where you transfer the wave packet from one place to another using quantum methods but still within the speed of light. And how do they do this? Well, here on the left you see the classical bit of zero or one. And the qubit, which is the quantum bit, is a superposition of two states, zero and one. So you can see that here that the qubit has a lot more information than the classical bit. But a lot of this information is hidden in the sense that you can't measure directly what the coefficients of zero and one are. Once you measure it, the state is destroyed. So quantum information is about how one can manipulate this hidden information to perform amazing tasks. So one example here is the bell state, which is the basis of quantum teleportation. So the bell state is what one might call an entangled state because you can't factorise it into a direct product of two different states. So that's entanglement in your title. And how do you physically realise the qubit? So you saw that humongous a quantum computer on the first slide. Well, it's not easy. So these are some conditions that would have to be satisfied. The first you need to have a robust representation of quantum information, which typically means you have a finite number of possible levels, such as in a spin three-half particle. Then you need to be able to control the quantum states, and this is very tricky. And you need to be able to prepare initial states with sufficiency long lifetimes. So this is challenging if you are not in the ground state or not in the completely random states. And also you have to measure the output result. Most of the commonly studied qubits nowadays involve either spin, charge, or photons. And in this session, we are going to focus on spin where we look at localised spin centres in atoms, molecules, or condensed phase. So what's the role of first principles calculations here? Well, we can elucidate the quantum state in localised spin centres. And the challenge would be to look at, understand the excited states. And also because localised spins often have strong correlations that you have heard in the second session. We would typically might need to go beyond DFT using a DMFT for fluctuating spins and to capture intracite correlations. And as you saw in the previous slide, lifetimes are very important so it would be good if you can predict the lifetimes of excited states as the first speaker would be talking about. And we also want to be able to predict experimental observables for measurements and understand how the system interacts with the environment so that we can control it. So without further ado, I would like to introduce the first speaker for this session. Prof. Christian Van Dual from the University of California at Santa Barbara who is telling us about modelling points defects for quantum information science. Thank you. I am very pleased to be here at this excellent conference and I'd like to thank the organisers for giving me the opportunity to speak here. It's the first time I have a chance to speak at the Total Energy Workshop and it's a real honour for me. So, let's see, we need to switch over to my computer somehow. So I'd first like to acknowledge the people who have been involved in this work first and foremost Aldrius Alcauskas and various other people who are currently or formerly members of my group. A number of these people have moved on to other positions in the meantime and I'd like to thank David Afshalom who used to be at UCSB for introducing me to this field. And by the way on the programme it lists my first name as Christian. I don't know who put the programme together. They must have had access to government files or something like that because that's the only place where my name is actually spelled as Christian. I'll go by Chris, okay. So, our chair introduced the topic very nicely. We want to manipulate quantum information and kind of in the simplest possible picture of that. What you would like to do is take localised wave functions the way you have them in an atom, the way we study them, for instance, in the hydrogen atom in the introductory quantum courses and manipulate those wave functions. Okay, so you would want to somehow trap that atom and then address those wave functions somehow. And some implementations of qubits or single spin centres actually try to do that with trapped ions or molecules or you can think about quantum wells or quantum dots but actually a very attractive way of simulating such a trapped atom is to do it with a point defect in a semiconductor or insulator, okay. Point defects used to be referred to as colour centres. They were widely studied in alkali halides but of course in the context of semiconductors they have been widely studied because they are usually bad objects that degrade the performance of a device but here we are actually going to be using them to design single spin centres or in the case you want photons, single photon sources. So these will form our solid state system where quantum information can actually be manipulated at room temperature. So in my talk I will actually not so much talk about the actual quantum computing aspects or the manipulating the quantum information but the actual implementation in the context of materials of these single photon sources or single spin centres. And the prototype of this of course as you probably all know is the nitrogen vacancy centre in diamond which I will talk about as an example. So just to elaborate a bit on the importance of this if you actually have access to such single spin centres or single photon sources you can create, control, manipulate non-classical states of light and matter and that will really enable us to go beyond classical limits. Not just in computing but also in quantum information science for instance with quantum cryptography and another very interesting application is actually to do extremely sensitive imaging and sensing. So in the case of single spin centres such as the NV centre in diamond where you want to manipulate a spin it turns out that to initialize and to manipulate that spin you want to use light. So that's already one manifestation of the fact that you want to really understand fundamentals of light absorption and emission. Another way to use these atomic centres is to generate single photons which are then used for for instance quantum key distribution and again clearly you need to understand fundamentals of light absorption and emission in such centres. So as I said in the NV centre in diamond this has already been widely studied in diamond you can remove a carbon atom create a vacancy if you have a nitrogen atom next to that you create a point defect that has extremely interesting properties it can function as a qubit at room temperature or even at elevated temperature it has a long coherence time it's optically addressable and so it has come to serve as kind of a prototype for such single spin centres and the electronic structure is actually reasonably straightforward on the left hand side I illustrated in a single particle picture you have a wide band gap which means that the defect levels associated with the centre which occurs somewhere in the middle of the band gap are well separated from the band edges which is important for the coherence and then these levels in the particular symmetry of the NV centre are A1 levels and E levels they are occupied with electrons in this way in the particular charge state that you want for this centre which is actually a negative charge state you have an S equal to one ground state and then by exciting an electron optically out of this A1 level to an E level you can actually get it into an excited state as is illustrated on the right hand side here and the energy of that optical transition is 1.945 EV and of course then you get also luminescence around that energy now if you look at this in more detail and look at the magnetic structure you actually find that there are a number of possible transitions between these magnetic sub levels possible and it turns out that there is actually another possibility instead of this optical transition to go from the excited state to the ground state via this intermediate level this is referred to as the inter-system crossing and these transitions actually are non-radiative transitions and they are very important because they actually enable you to initialize the system in this MS equal zero ground state so to have a particular spin state for the centre so I'm using this as an illustration to show that both non-radiative and radiative transitions need to be thoroughly understood on the radiative side here's a luminescence spectrum measured for the NV centre this 1.945 EV actually corresponds to the so-called zero phonon line which I will tell you a little bit more about soon but as you can see there is actually a very wide sideband which is caused by vibronic coupling coupling to phonons which you need to thoroughly understand to really understand the properties of this system so that's what we set ourselves as a goal to study these line shapes and also to understand non-radiative recombination so we use our formalism that we developed some time ago and this is actually a review article that can kind of serve as a manual for how to do these first principles calculations for point defects in solids we calculate the formation energy of the defect I won't say much about that but that obviously gives you information about how likely it is that a certain defect can actually be formed in the solid in case you're looking to design new types of single spin centres the specific example I'm giving here and that I'm going to be using throughout the talk is actually not for diamond but for gallium nitride which is a semiconductor that we have studied in a lot of detail partly for the quantum information science applications but also because it is the main material used for solid state lighting which is an extremely important technology in its own right so for this particular example my quote-unquote point defect is actually an impurity I use the word point defect in a generic sense it could be an intrinsic native defect or it could be an impurity the formalism is general I focus here on carbon sitting on a nitrogen site in gallium nitride this is the definition of the formation energy and this can be generalized for any point defect or impurity so we can calculate this we use density functional theory we don't use the traditional LDA or GGA functionals because they have severe shortcomings the most widely known one is the band gap problem if you're interested in calculating defects levels in the band gap obviously if you have underestimation of the band gap it becomes very difficult to get quantitative information and we have been using hybrid functionals particularly the screened hybrid functional of Heidskusserie and Enzerhoff to overcome that problem I'd like to point out that there is actually another major advantage to using this hybrid functional namely that you get a much more accurate description of charge localization which LDA and GGA fail to provide and particularly when you're looking at point defects where particularly the wave functions of holes tend to be localized on particular orbitals the hybrid functional turns are to give an accurate description of that as we have verified in a number of benchmark studies so coming down to the issue of calculating radiative and non-radiative recombination so in the examples that I'm going to give, I'm going to assume that we have a recombination process between a carrier in a band edge, either the conduction band or the valence band and a localized defect level everything I'm saying can also be applied to so-called internal transitions where you would have a transition between two levels that are localized on the defect in a radiative process obviously the energy that you gain by recombining for instance an electron with a hole on the defect level is emitted as a photon in an non-radiative process the energy will be dissipated in the form of phonons so how do we calculate line shapes then we will know how to calculate the strength of an optical transition by calculating the dipole matrix element but these very broad line shapes that in the case of carbon and gallium nitride were already measured back in 1980 this requires a description of the interaction with the lattice interaction with phonons so I briefly want to show you the underlying principles of this which are very general we think about this problem in the context of a so-called configuration coordinate diagram we can do a calculation for carbon sitting on a nitrogen site in gallium nitride in a particular charge state and when we just let our modern electronic structure codes run we would immediately optimize the structure and give us the minimum energy position as a function of the atomic positions but in reality atoms move even at zero temperature zero point motion and when transitions are going to take place the atoms are going to move so we can actually map out around the minimum energy surfaces illustrated here in one dimension as a function of what I call a configuration coordinate which is kind of a common term for describing a whole set of atomic coordinates so I do that for one particular charge state, I can do it equally well for another charge state for instance the neutral charge state and I've added an electron here between these two transitions and then if we look at this curve here it has a similar shape but its minimum may occur for a different set of atomic coordinates because you've now changed the charge and so the atoms may want to assume different positions optical transitions will take place for instance absorption out of this defect level and putting it into the conduction band would take energy vertical transition would occur with this amount of energy and that vertical transition will probably be the strongest signature that you will have in an optical line shape after the transition has taken place the system of course relaxes to its minimum and then you can subsequently have emission or luminescence and you immediately see there is a difference in energy between where you expect the peak of absorption and the peak of emission to be so that's the well known stoke shift so that's the principle of it, we can calculate that in practice again carbon and gallium nitride we see what the energies are of these various transitions the transition that would take place between the minima of these two curves is the so called zero phone online as I said before the most prominent peak in an optical emission process would occur for this vertical transition which for this carbon impurity would be at about 2.1 EV now if we want to get the actual optical line shape out of this we need to couple this description to a description of vibrations in the system and here's our configuration coordinate diagram again and then we need to take into account that for each of these curves for the ground state and for the excited state since they describe the energy function of atomic position there will be vibrational modes in a one-dimensional picture and if these would be roughly parabolic you can think of it as simple harmonic oscillators with equally spaced energy levels which actually turns out in many cases to be a remarkably good description of what's going on so these horizontal lines illustrate these vibrational levels and then it immediately becomes obvious that the transitions in the space are not just from these solid dark curves here but are actually going to be transitions between these various vibrational levels which then ultimately leads to a luminescence spectrum that can be quite broad okay the energy that needs to be dissipated after making a luminescence transition and going back to the ground state will be dissipated in the form of vibrations and a very common measure for that is the so-called one risk factor which is basically this relaxation energy divided by the typical vibrational frequency for these transitions okay if the two curves for ground and excited states are pretty much aligned with each other in terms of where their minimum is then this one risk factor will be very small okay that's the case for instance if you have transition metals in oxides chromium and aluminum oxide in that case all of the energy of the transition is essentially concentrated in the so-called zero phone online most transitions are not that way in many cases you have significant relaxation energy, significant coupling to vibrations and in addition to the zero phone online you have this fairly wide phone on sideband which may have significant structure if the one risk factor becomes very large in case the relaxation energy is really much larger than the typical vibrational frequency for instance in f-centers and all cal halides you mostly get to see this wide sideband and the zero phone online becomes actually very hard to detect now from the point of view of computations this last case is actually the case that is most readily described because for that case we have shown that a one-dimensional model in which we describe the vibronic states in terms of a single coordinate actually does a remarkably good job and then we can we can just calculate a normalized luminescence intensity within the Frank Condon approximation calculate these vibronic overlap integrals in one dimension and for instance for our carbon impurity and gallium nitride we've done this for a number of examples but you can see the agreement between our theoretical description and experiments which are the circles is very very good which really gives us a benchmark for saying that we can do very well in terms of describing these line shapes particularly in the case of large lattice relaxations large one grease factors we can also do it in the case of intermediate values of the one grease factor and that's what we've tested in the case of DNV center in diamond where you see this structured phone on sideband is a configuration coordinate diagram for DNV center in diamond here's the electronic structure once again and based on that configuration coordinate diagram again we can put all the vibrations into it but we can't do it anymore in a one dimensional model we would not be able to match the details of the experimental line shape we actually are forced to take three dimensional picture digital phone on's into account both the lattice phone on's as well as more localized phone on's in the vicinity of the defect in order to be able to reproduce the experimentally observed structure of this phone on sideband this was the status of these calculations in the meantime has actually been able to optimize the description even further such that the overlap between the theoretical curve and the experimental curve is essentially perfect so this gives us a very important tool for helping identify single photon centers in materials and also for designing single photon centers the NV center has gotten a lot of publicity but it's really not an ideal center the zero phone online is the line that you're going to use in the quantum applications but as you can already see just by visual inspection of this spectrum the zero phone online has quite a low overall intensity it's only like less than 3% of the overall intensity of the emission here so you're basically working with a very inefficient emitter from the point of view of using it for quantum information so the search is currently on for centers where most of the intensity is concentrated in the zero phone online so the ability to calculate these line shapes is really very valuable so let me switch gears and talk about non-radiative recombination we're going to be using the same ingredients the same principles but now not for optical transitions but for transitions that are mediated by phonons so the context in which non-radiative recombination is often discussed is once again for defects in materials where the defects are playing a detrimental role and are trapping carriers either by trapping electrons from the conduction band or trapping holes from the valence band this was a problem that was recognized shockly and read and whole in the early 50s and flagged as an important obstacle for making highly efficient electronic devices so while it was flagged as an obstacle in terms of doing quantitative calculations of these rates of capture that hadn't really been possible until recently with the advent of highly accurate electronic structure calculations but also calculations of phonons as well as electron-phonon interactions so we want to calculate these rates for instance how an electron gets trapped on a defect level like this it's a product of these three factors obviously the number of electrons that are available the number of defects that are present in the particular charge state that will capture an electron and most of the information is in this capture coefficient which is what we are actually going to to be calculated and again we do that with the aid of these configuration coordinate diagrams so there are three curves here because ultimately you first want to capture an electron and then go to a state where you can capture a hole that has been completed so the transitions between these various curves here are now not transitions that are mediated by photons but what we are going to do is for instance if we start in the upper curve make a transition to the curve below it by using energy provided by lattice vibrations to cross over between these two curves so if this were a classical picture we'd immediately know what the barrier for that process is it would be a thermally activated process whereby you really have to go up this amount of energy to be able to cross over but this is quantum mechanics and we don't need to go all the way to that crossing point we can have a quantum mechanical process to make these transitions and that's what we can explicitly calculate the formula we use for that is essentially for a means golden rule where you recognize a matrix element squared there should be a density of states which is included in this energy conserving delta function which when sum or integrated over all of the possible electronic states that reflects the density of states the electron phonon coupling is what enters into this matrix element and calculate that very accurately formula is actually on the right hand side here this is the matrix element that we need to calculate and with some simple manipulations you can actually reformulate that in terms of an overlap between a wavefunction and a wavefunction at a different set of atomic positions and we have extracted these matrix elements based on different possible codes with the help of Georg Kresser we were recently able to also obtain this in FASP so we combine this information with the information about the configuration coordinate diagrams that we already have and again as our benchmark because it has been so well studied I'm plotting here the capture coefficients for holes onto a carbon level in gallium nitride plotting it as a function of temperature the red curve is what we calculate the blue diamonds are experimental values and you see the agreement is really very good so if I have a few more minutes no okay I want to make one more point which is about conventional wisdom in terms of the position of defect levels in the bandgap to give you maximum non-radiative recombination going back as far as Shockley and Reid and Hall when people have thought about centers that are going to be highly efficient non-radiative centers they've usually thought about levels that need to be in the middle of the bandgap the reason for that is it's kind of intuitive the rate with which you can capture for instance an electron from the conduction band becomes lower and lower and further away this defect level is from the conduction band and conversely the whole capture rate becomes lower if the defect level is further away from the valence band so combining those two principles you immediately say well if you want to have a center that can capture both electrons and holes it needs to be somewhere in the middle of the bandgap we recently found an important exception to that very relevant for identifying centers for quantum information we looked at transitional impurities in gallium nitride looking at iron for instance the iron level is very close to the conduction band it's within half an EV of the conduction band so you would say very strong non-radiative capture of electrons that's obvious you would think the non-radiative rate for capturing holes would be very low or even non-observable experimentally however it was found the rate for capturing holes was as high as the rate for capturing electrons I don't have time to go through the complete story but we've been able to explain this based on taking into account that a transitional impurity such as iron has excited states very easy to see to see within the D state manifold you can put electrons in excited states that correspond to higher line D states and if you take those excited states into account you can actually calculate rates that are very close to the experimentally observed rates so that's the context in which we came across this but we find this to be a very general issue for instance this is an example for a gallium vacancy complex in gallium nitride that careful consideration of excited states and you may notice that this sort of picture is actually very similar to what we calculate for the NV center in diamond these excited states can play an extremely important role in non-radiative recombination and going beyond quantum information in our opinion also explains why defects can still be important non-radiative centers in extremely wide bandgap materials or even insulators where the traditional picture based on energy difference between defect level and bandage would tell you non-radiative recombination would not be important so I'll just put up my conclusion slides here and I'll actually leave you with a slide of references in case you're interested in more details and I'll stop here and be happy to answer any questions Thank you


I'm here today to announce some changes in the Defense Department's policies regarding transgender service members. Our mission is to defend this country. And we don't want barriers unrelated to a person's qualification to serve, preventing us from recruiting or retaining the soldier, sailor, airman, or marine who can best accomplish the mission.


Hello and welcome to International Daily Roundup from People's Dispatch, where we bring you the top news items from across the globe, our headlines. Saudi rights activist Lujayn Al-Hathool released from prison. Burmese security forces escalate crackdown as anti-coup protests continue. Philippine Supreme Court holds second day of hearings against anti-terror law. Student protests continue across Greece ahead of vote on contentious education bill. Prominent Saudi rights activist Lujayn Al-Hathool has been released from prison. Al-Hathool was released on February 10th after spending nearly three years in detention. However, her family has reported that Al-Hathool will be placed under probation for three years and is banned from traveling outside the country for five years. Her family and rights groups also repeatedly stated that Al-Hathool was subjected to severe physical and psychological forms of torture while in prison. In prison, activists including Al-Hathool were reportedly subjected to electric shocks, flogging and sexual assault. However, Saudi courts have dismissed the claims on multiple occasions, including as recently on February 9th. The special criminal court had sentenced Al-Hathool to five years and eight months in prison in December 2020. She was convicted on charges relating to seeking to change the Saudi political system and harming national security. The court suspended two years and ten months of her sentence in addition to the time already served since her arrest in 2018. Al-Hathool had extensively campaigned for the women's right to drive and had publicly opposed the Saudi law of male guardianship over women. News of Al-Hathool's release was first announced by her sister Lina on Wednesday night, local time. Lina Al-Hathool went to say, quote, Lujen isn't home, but she's not free. The fight is not over. She also demanded the release of all political prisoners. At least a dozen of other women's rights activists had been detained along with Al-Hathool amid a widespread crackdown in 2018. For our next story, we look at Myanmar where daily protests against the military coup have continued as tens of thousands of people continue to step out into the streets. Teachers, industrial workers, government employees, and healthcare workers are participating in the civil disobedience movement in large numbers. As the protests continue to grow, the military has started implementing a series of restrictions across cities and townships. These include a ban on public gatherings of over five people and motorized processions as well as a curfew from 8 p.m. to 4 a.m. Security personnel have also escalated the use of force during protests. Police have deployed tear gas, water cannons, and rubber bullets at protest sites. Reports of police firing, warning shots, as well as live rounds have also been circulated. A woman has also been hospitalized after being shot in the head during a protest in the capital city on February 9th. Maya Thwe Thwe Khayyong is currently in critical condition and has reportedly lost significant brain function. Amnesty International has verified reports of shootings and has stated that Burmese security forces deployed machine guns against protesters. Amid domestic and foreign calls for the restoration of the civilian government, individual countries have also initiated a series of measures against the military leaders. New Zealand announced a suspension of high-level political and military contact with Myanmar on February 9th. The country will also impose a travel ban on Myanmar's military leaders and exclude projects associated with its military from its aid program. U.S. President Joe Biden has also approved an executive order to impose sanctions on military leaders responsible for the coup. Biden announced on February 10th that the sanctions would also extend to their family members, as well as business interests. The U.S. government is also taking steps to block the military from accessing $1 billion of Burmese government funds held by the U.S. The second day of hearings against an anti-terror law were concluded in the Philippines on February 9th. 13 lawyers are representing 37 petitions against a contentious law in Philippine Supreme Court. The second day of hearings focus on how the new law removed protections previously afforded to those accused or convicted of a crime. Lawyers argue that the language of the new law would render the writ of habeas corpus ineffective. This is because the law allows for a person to be detained for up to 24 days without a warrant. Law enforcement agencies will only require authorization from the Anti-Terrorism Council, which would have to be an extrajudicial body. Petitioners also argued that the law does away with monetary compensation provided to those acquitted of terror charges. The Anti-Terror Law supersedes the Human Security Act, which had set a compensation of around $10,000 for every day spent wrongfully imprisoned. The Supreme Court also rejected a plea made by two people from the Indigenous Eta community to be included in the petitions. Jaipur Gurung and Junior Ramos were the first people charged under the Anti-Terror Law and have been in prison since August 2020. According to reports, they are arrested while trying to evacuate from their ancestral lands, which have been subject to continuous military operations. The third day of hearings has been scheduled for February 16. For our final story, we go to Greece, where students are continuing their protests against a contentious education bill proposed by the conservative, new democracy-led government. The bill will implement increased surveillance measures on university campuses, including police patrols. The Greek Parliament is due to vote on the bill on February 11. In the meantime, here is a video feature on the protests. Funding for our schools, we say no to police. We say that no students will be cut off educations. We say that we will continue fighting and we accept no police brutality and threats. Thank you for watching People's Dispatch and check out our website at peoplesdispatch.org.