So it's a real pleasure to have. My friend and colleague Professor and he me with us today. Because I got his a bachelor's degree in electrical engineering from Sharif University and then continued to work as a design engineer in Iran before coming to Georgia Tech to get his master's and Ph D. in electrical computer engineering He then worked as a research engineer at the M I R C For those of you who remember the precursor precursor of the I even. Before becoming a faculty member in the C.E. in two thousand and eight where he's now a full professor also a associate director for and in C.R.I. the national and technology coordinate infrastructure for computation and modeling he's won a number of awards including the S.F. career Ward as well as awards from S.R.C. Tripoli and Georgia Tech for teaching he last gave a presentation and then I went Tech in two thousand and nine so there are probably very few of you who remember that I was there. But I'm sure this will be very different stuff so I'll turn it over to a zone. Thank you for the night and thank you very much for coming. My pleasure. Couple of years and so. Without giving too much introduction we've seen all of the talk about moves law and how everything has been scaling down to smaller and smaller dimensions and the level of complexity constantly increasing one of the things that I sometimes like to look at is the looking at chart which was in the log scale who looking at the chart in the lean years scale it sometimes gives us a better picture of how rapidly things are evolving and at the heart of all this exponential growth has been. It. Has been the. Metal oxides semiconductor transistor where you marginally the. Potential barrier in a device in order to control the flow of electrons going from source to drain. So when you applied no voltage to the gate the energy Bear year is this high and therefore you block all the electrons as you increase the gate will to you push the energy bare your down and then you allow electrons to go from source to drain but in reality this doesn't work like. Complete an ideal switch because of the the way that energy of electrons is distributed so if you look at the distribution of probability of the states in the source it follows this very distribution and tours this side the probability drops exponentially so this becomes almost like an exponential which means that as you gradually bring down the the energy bare year the number of electrons that have enough energy to groove or this barrier increases exponentially rich means that if you look at the current that you get as a result of this modulation of the energy bill year it increases. In an exponential fashion so for every sixty million that you shift here you get one order of magnitude increase in dream current So this picture looks very nice and you have a really good energy Bear year it's relatively flat inside the channel no matter how much will drain you apply this valid for a big divide. But gradually as people have scaled down the dimensions of the device things have changed because the control that gate has on the channel is through this capacitance but there are other capacitance is involved as well there is some capacitance to ground to do this substrate and source and there is a capacitance between the channel and the drain which means that the this potential height or this energy profile is not controlled purely by the gate but also by the drain so for a small device for a short channel the wise the picture looks something like this now if you look compare this carefully with the case over here first of all the peak of this energy barrier is now smaller because of the effect of the drain over there so more electrons can go over to bear years of the leakage increases also right at the top here you see that the length of the energy barrier is small so some electrons can tunnel through and go to the other side so both of these effects increase the leakage. And the other thing is that because these other capacitors are also involved the change in gate world just doesn't directly translate here so that means that sixty million per decade is constantly increasing as you make the device smaller so. With this to summarize this affects what happens is that this device becomes more and more leak so the only solution to this problem is to increase this capacitance and make the control that gate has on the channel better and better and that's has been what industry has been doing for many years so if you look at the evolution of and was transistor. Started by playing or playing. Structure then and it was using silicon dioxide as the insulating layer then in order to further increase the capacitance without making the oxide too thin this switched to high K. dielectric materials to change the gate material to metallic gates and they kept improving this device then they went to three dimensional geometries so that instead of trying to reach to the channel only from one side in the Fin FET structure which is a three D. structure you try to reach the gate from three sides and moving further people are thinking about nano wires the channel is surrounded by the gate from all sides to a gate all around type configuration either in a horizontal fashion ordinary vertical fashion to the good thing about the vertical sorry this one is the vertical This is the ladder or so the good thing about the vertical dimension is that you can actually make the channel lengthen longer without making the footprint of the device larger So there's all these changes that are happening and this has been the evolution and probably these will come into production in the next few years and the industry has a clear roadmap for the next five or ten years and people are now talking so if you look at this geometry this is for something like fourteen nanometer this is the dimensions that people are dealing with these are really really tiny dimensions. And the push is to go down to five nanometer or three nanometer but at some point you have to change the paradigm you cannot keep scaling things and trying to do the same thing that brings us to the research that they want to talk about today which is trying. To think about completely new ways of doing computation and try to use state variables other than electronic charge or try to reinvent the device and also try to come up with new way of. Building circuits and systems out of the same devices or out of new devices so to motivate that if you look throughout the history been there multiple times so. All the days there were computers based on mechanical switches then. Electro mechanical sutures you know relays will be very used to do computation then vacuum tubes then transistors individually and then integrated circuits and from bipolar junction transistors to mosques and we've been working with this for many years and this mean this much scaling but it doesn't mean that this should go for ever so there may be new devices that can can can continue this trend for the years to crawl. Now when we want to do research on new devices and new circuits then many things will change at all levels of abstraction and if you look at the options that are out there and people are studying there are a vast. Number of options at each level of abstraction at the very bottom layer which is the materials that are being used people are looking at one dimensional materials that are carbon nanotubes or looking at to do materials like Graffy like other to the materials that have come out in the in recent years people are thinking about using fair magnets to do computation and I'll be talking a lot about federal magnets or spintronic for doing computation and recently people are even interested in magnets because thirty magnets have. A aura switching time constant around one or two or three nanoseconds But if you are able to grow to enter for magnets they can switch really really fast. There's a push to use federal troops and there's a lot of interest there there are even people thinking about using strain taking advantage of peas or electric devices and apply string and make switching happen that way and I would be talking about these devices in the consequence of spintronic devices and it's making all sorts of. Mr devices and so forth so the number of options at the material is quite. Elaborate and there are many options out there but then once you look at all these materials there are so many physical phenomena that you can potentially you do computation. In the past it was this field effect. And the effects that are being used there are well known but now people are talking about joy in magnitude resistance effect basically if you have two magnets and the two magnets are aligned the resistance is lure then the case that the two magnets are and so that the giant magnitude exists if you put a tunnel layer in between the two magnets then you can even. Further enhance the change in resistance when the two magnets are versus the two magnets being anti per. And the important concept that is being used is Magni to many of the magnetic materials when you are price strain to them their magnetic properties change so you can have a magnet that is in plane so the two stable conditions are in play but as soon as your prize strain this magnet may go out of play so this condition may become out of play again I will be talking about this effect and how one can potentially use this for. For doing computation fair electorate existence in fair electric devices if you put two metallic contents of different kinds and sandwiches a year depending on the orientation of the layer you may have higher resistance or lower resistance so that's a fundamentally new concept and a new. Way of doing computation or new way of storing information because computation has to parse doing the computation and storing information so both of them are really important so I'm not going to go through the rest of the physical phenomena that people are looking at but do number of options are quite. Large. Then once you have. A nominee on a new material that you can utilize then different ways that you can make a device out of it you can do the computer using these new physical concepts and some of them are still Field Effect devices evolutionary type of improvement over what we half and some of them are completely new like magnet to magnetic tunnel junction devices for memory applications or. Junctions negative capacitance devices are the case when you insert a for electric between the gate and the normal insulator then you may use some. Spinning wave type computer which I would be talking briefly of so there are many options at the device level and then once you have new devices you have many options how to use these devices to build the circuit and do the computation. The way that we do competition is usually through functions and you make an adder. You do computation that way but with many of these devices it may not be the best way of doing things you have some new options you can make majority against with them you can make new type circuits with them and as you will see some of these devices perform much better if you go to these nontraditional types of circuits and then at the system level both traditionally we had C.P.U. use the G.P.U. but now people are trying to break the barrier between the computation part and the storage part so instead of doing competition here and trying to fetch data and restore data into memory what if you bring memory and computing into the same place or. New ways of doing competition with approximation or shine inspired computing and at the end software and operating systems have to look at everything and that's the higher level of abstraction now. You can't really do research any of these years on any of these topics and not look at what is above and what is below. Real comprehensive study is needed if you want to come up with something that is completely revolutionary and can change the computing paradigm so in our group we try to cross the boundaries of these levels of abstraction and obviously we cannot do everything but if you look at this chart this the size of the boxes here is how much effort we put on each of these so we do the smaller amount on materials mainly trying to develop compact physical models with captured to keep parameters and the key properties of various emerging materials and it's not just emerging materials even materials that we are very familiar with like silicon if you try to transport spin through Silicon That's a new phenomenon that is not understood so you need to develop new models there as well. And for devices try to develop compact physical more those that capture the physics of the devices and also try to come up with better devices understand whether the limitations and how they can be overcome and how we can improve them and then once we have these compact more of those and sit at level models we try to analyze some circuits based on these devices try to find what is the best circuit for each kind of device and benchmark them and compare with each other and try to see at the city level what are the limits that devices are imposing and how we can try to mitigate those limitations and at the system level we try to come up with methods that in a fast way you can take from materials and devices and could go to the system level and see what is the performance of the of the system what is the to. Just the number of instructions per second that you may be able to execute. So. You can't do all of this on your own and the key for us has been collaboration so we've been collaborating with many people on the industry's side. Being part of S.R.C. working closely with the sponsors within S.R.C. we have close collaboration with Intel over the past five years we have published a lot together and we've been working with some of the colleagues at Intel and we have a close collaboration with I'm Eric that's a big institute in Belgium which most of the semiconductor companies you know. Tool vendors material suppliers are collaborating there so working with them has been very instrumental in our research. We have started some new collaboration with our especially at the system level and also with Micron and memory devices but another big effort within our group in the past three years has been this benchmarking research because there are all these centers that are funded by Sarsi and NIST which are working on new materials. This frame and new devices these centers and these centers and also try to come up with new circuits so working with these. Investigators gives us axes to real experimental data many tourists within these centers so this has been a very productive collaboration try to benchmark various materials and devices and compare their performance at the circuit and system level. So this you know they've been. Marking effort that we took over about three years ago before that was led by. And in young intell and this is a summary charge with shows you if you execute the thirty two bit edition using different different device concepts what would be. The energy and what would be the delay associated with that so there are many device options here and I'm not going to go through those just some highlights one is this reference point and this is based on the projections for the future size of fifty nanometer this is this was for the eighteen technology year this is a relatively optimistic data point because the international technology for semiconductors used to be quite optimistic. The the other device is this the most go voltage This is based on theoretical projections four point three wart get all around. India arsenide nano Warrior do wise and it's based on atomicity quantum transport simulations so these two basically Sure what's the competition that we have in terms of seam OS can do and then we're trying to. Look at other devices and see where they stand and this is not about ranking these devices and see which one is the best it's because because these are all at the very early stages of research. It's too soon to say which one is the winner which one is the loser but it's the Google of this approach is to understand the general behavior of these devices and to understand what is limiting their performance why some of these devices are in the bad corner. And how we can improve them and try to push them to the right corner and try to do to make them competitive so that's the goal so this is what was done. Back in two thousand and fifteen and then since then we've been working on this and I'm going to show you more of the results. So after this long introduction the presentation will be on spintronic materials and devices. And then we'll be talking about one form of the room or fix their kit basically networks and you see that some of these devices that were performing very poorly brilliant function is can potentially do much better if you go to something that takes advantage of the physics of the device and finally summarize. So for Sprint tronic device is just a very. Brief Introduction is that when you pass current through a conductor the electrons have random spin orientation and as a result there is no net spin in the current So there is no spin Porter. But when you pass electrons through a magnet depending on the orientation of this magnet the electrons get polarize around. Depending on that magnetic. So the majority of electrons not all of them but the majority of the electrons coming out of that magnet will become aligned with the magnet and then if you pass this spin porous current on another magnet you and if this current is strong enough then you can actually rotate your intuition of this magnet because these electrons have. Angular momentum that they can transfer to the magnets and reoriented and make it aligned with the spin for ization overlap. It's so here it. Is happening and here spin transfer torque is happening now. One advantage that these devices have is that this can be all metallic and therefore you can have the low voltage operation and also magnets can be nonvolatile can store information even if you remove power so these are some of the benefits but the question is how would you use this to do computation with it and how would be what would be the performance of it and I will use this as a case study where you see how going through the levels of hierarchy starting from materials to devices to circuits will give us some insight into the operation of these devices one of the proposed devices was not was all spin logic by. Purdue and the idea is that you pass electrons through this magnet and polarized electrons and and inject them into non-magnetic material here like copper so here spin accusation is generated because elections coming from this magnet gets put get poor as according to your intuition of this magnet so then this is electrons real diffuse and. Move to the other side and then on this side they will inject a torque on this magnet and will flip this according to this so this would behave like a buffer Now if you connect three of these together then you can make a majority because these spin poor areas ation of electrons that are going to appear here will depend on the majority of the inputs and then this one can drive the next stage so this can potentially be computing pair of them where this would be the building block the majority gate communication happens the same way as the computation and. The channel materials that you can use here are any material any metal like copper or aluminum or in some cases even graphing. To analyze this you need to look at the dynamic of the magnets so the creation describes this and you need to look at the interface between the magnet and the channel of the mixing conductance matrices you need to look at Spindrift diffusion in the channel and then look at the dynamic here and you can write all these equations in matlab and try to solve themselves consistently which would be time consuming and it would be very messy and you need to worry about convergence and if these are going to work at the at what as electrical engineers we are much more comfortable with circuit inspires and do simulations there so we took all of these physics and for each one we came up with a circuit model where or basically subcircuits which exactly replicates the function of each. Each block So here are this is the dynamic of the magnet stimulated by these by this sub circuit and. These are the interface matrices and then within the channel you need to have electrical signal because this is a conductor and has a like a normal in a clinic you have a distributed R.C. circuit but at the same time you need to account for X. Y. and Z. components of the spin porous current so you have these branches which account for the X. and Y. Z. and then you can just set it up inspires and then Spice will handle this on its own you don't need to worry about the. The convergence issues and at the same time it gives us some insight because we are very familiar with these circuits these are distributed R.C. networks so we know how they behave so well as a sick a designer when you see some elements like this you can get much more intuition rather than some Matlab codes that are solving some equations. But at the material level you also need to be careful because material parameters highly dependent on what kind of dimensions you're dealing with it what kind of interfaces you're dealing with what kind of impurity and dropping you're dealing with so part of our work has been to develop a compact more of those for some important primary like spin diffusion land spin relaxation and we've been calibrating these models read a lot of experiments so that will give us some important. Some confidence in the results one thing that I want to mention is that for example if you look you can go and look it up and see that what is the spin diffusion Lenten copper in materials around five hundred or six hundred nanometer but you can't use it in a real circuit because at nano scale electrons get scattered at the surface at the ground boundaries manage scale you need to worry about the size of facts so this model captures size effect and based on that gives you the spin relaxation. Another way of doing computation is wave computing and one approach is to use spin waves so if you have a magnetic layer you can create spin waves on it basically these magnets will start oscillating and you can generate wave and then you can potentially do interference and based on interference you can make a majority cage if the phase of the inputs are the same there's going to be constructive interference if they are out of phase you're going to have destructive interference and there's been proposals to do this week computing based on spin race so there are some issues about these the proposals that spin waves are weak and you need to regenerate them every time you need to have gain. If you just want to use conversion back and forth between electrical signals and spin of waves then you need to have complicated since amplifiers thermal noise must be accounted for and these spin waves are nonvolatile whereas magnets are volatile and one advantage of magnets is non-relativistic How can you use spin waves and build circuits that are still nonvolatile so to do that our approach has been to use magnet to stricture and to use. Piers to electrics to create spin create strain and reorient magnets based on that so the idea is that. You have a magnet to electric So when you apply normal to the magnet is in place there is no string so the magnet is in play and it has to stable conditions in positive or negative effects as soon as you apply to the peers electric you create string and then the magnet may go out of plane if the design has been done right so with this approach what we can do is we can take the state variable of this magnet being. So the orientation of the magnet would be our state so it can be either in positive or negative X. in order to read the stage variable what we do is we apply the magnet to electric So now the magnet wants to go out of place but depending on the initial condition if it's positive or negative X. the spin wave that you create is going to have one hundred eighty degree fish. Now you have generated this spin with you have read your state here and now the receiver needs to detect the phase of this coming spin if the where did we do it is the opposite so on the receiver side. Where you want to do the right operation really. Initially put the magnet in the out of planes. But when the spin with arrives we turn this world. Now the magnet wants to fall in place but the direction that it's going to fall really depends on the defeat of the spin that it's coming so this way we have generation regeneration every time the circuit is nonvolatile and we can control the direction of flow of information by clocking in the right way. So one of the things that we did was try to see if this is reliable on the thermal noise and one thing that you would see is that on the if you put the magnet initially at the high energy and now the spin rate wants to fall this in either positive or negative X. you will see that this is not reliable but the reason is that when you put the magnet in a high energy state it's going to make many oscillations before it damps and it falls on positive or X. directions but you can use Exchange spring system or use the built in string to change the energy profile here and by changing it you change the profile here such that this because this zero point becomes the other point now this is going to be a very damped switching and as soon as it goes into one port it's going to converge around that port so it's not going to make so many switches between positive and negative X. which you do here and here it's going to have a deterministic stitching so this is the simulation that we did try to see what would be the error rate and it seems that we can get to really good error rates for this circuit so and this is one that we did with I. Became interested in this proposal and they wanted to simulate an entire. Majority gate and recall aberrated with them and did the simulation and this nano scale majority get based on spin waves under simulation side is work. So this is the summary of the benchmarking results for spintronic devices so these are this is the spin rate logic it's very low energy it's low because you're dealing with magnets and magnets or that they have time constants in demand of can't reach it so this is a low energy relatively slow device this is a magnet to electric M.T.G. device for the sake of time I'm going to skip to the main vol device this is using spin Hall effect of devices that can be made out of that and one of the things that you see here is that how we started from this original device and gradually try to make it better this is the all screen logic that there showed and depend if this is the in plain version of it this is the out of plain version of it and if. It's become available at room temperature then this would be to perform the potential performance of this device but what you see is that these devices are very energy hungry Compared to see Mars and that's a problem that we need to solve and we can try to make these materials better to make it better or we can try to use this materials for something other than bullion logic that would be talking about so. So feel defective Weiss's there are many options again I have to skip the details of these devices and I'll just show you the latest benchmarking that we have. These are the so this is the most lowered the most high performance are shown here but a few highlight devices this is a theme this is to lose of to dematerialize and you make it tunneling device out of them the potential to tunneling happens between the two layers and you module that kind of searching. This is base fit which based on the boards on condensation and the efforts to demonstrate this has not been successful this was supposed to be done by and by layer graphene So at this point this is just theory and has not been physically demonstrated. This is negative differential resistance device based on tunneling between two to delay years again but this new kind of circuits didn't require special clocking to do that and also we need to keep in mind that CMOs itself is a moving target it's going to become better and better one up one example is as I mentioned looking at nano warriors and either in the lateral case or the vertical case and we've been collaborating with benchmarking these and and evaluating their potential performance and this is at the level of a processor an ARM processor and the conclusion was that the lateral device was better for high performance because you can still apply the strain and get higher mobility whereas the vertical device was better for power applications. Now said that building CMOs in brilliant applications it's very difficult and that takes us to places where we try to take advantage of the physics of the device and make circuits that are more efficient so to do this kind of benchmarking for nontraditional circuits we had to. Have some requirements the circuits should have many applications it shouldn't be a very niche kind of circuits it should be something that can be used to implement many beyond CMOS devices efficiently so that you can have a meaningful benchmarking and it should have well defined boundaries and specs so for that purpose networks are a good candidate because they can do many times it's a universe of computers so it can do any it's a complete. Function it can do anything that you want with it and it's very efficient in doing image processing and associative memory and tracking targets and. And at the heart of it is dot product which is used in many other circuits. So the way that cellular neural networks work is that it's a two D. at a very. Cells where cells are connected to each other. And the dynamic of each cell is dictated by a equation like this so this is the state variable of J. and there is a feedback factor and there is a linear combination of all the inputs to the circuit and the linear combination of the states nearby and some biasing condition so did the normal way of implementing this by making by using our power amps for the neurons and all the synapses which determine what is the weight is dictated by the. Operational transconductance. So basically you can use mosfet or you can use to fret Superman these amplifiers on. Steps Up there should devices would be good because they're going to give you better gain lower power but at the same time you could do a sixty and you can do digital. Design and for each you have on a six circuit which does exactly the same so the digital option is also there and then we wanted to do spin tronic implementation of this in a more efficient great and if you look at the L.G. equation which dictates the dynamic of a magnet it's very similar to the dynamic of the C.N.N. So the same kind of equation is applied and if you think about it if you look at this. Cell the current that you pass through this will generate spin current ritual Suge this magnet now this behaves like an integrator and you see that as you increase this current you are going to get faster searching but the key is that this equation is very similar to. This equation and we can take advantage of that so. You can. Put a reference resistance years so this is an empty J.D. orientation of this magnitude determine the resistance of this device there is a reference point here and then there is a normal CMOS inverter rich amplifiers the signal and drives the nearby cells and then this is the driving circuit and the size of this or is this is the true means what is the weight of each synapse and this is the output voltage versus Magna's magnetization direction. This is how one cell one completes looked like and here is the simulation result taking account of thermal noise and here we are showing one function which is noise filtering. Here is an associative memory application so it's supposed to correspond one to two and three to four and here you see how one is being transferred to two so these are the simulations of all the magnets within the circuit now to do the benchmarking the case study that we looked at is this very simple associative memory case these numbers these digits must be corresponded or transferred to these digits and we look at various way of doing this so this is the benchmarking result this is this network benchmarking. One of the things that they want to highlight is this light blue data points does the spintronic devices so for example this is something similar to. Spin diffusion or all spin logic this is spin hall device and these devices now can perform better than C. MOS whereas if you remembered the brilliant functions these devices were many orders of magnitude worse than c mass and the reason here is that we are taking advantage of the physics of the device to do. The actual circuit which is that. The the dynamic of the neural networks so to benchmarking result is completely different when you do it for this particular saloon or network applications compared to the boolean case that we talked about before. Now one other. Explanation of why these. Spintronic devices can do much better than this is that if you look at the circuits here each of these synapse you're going to be. With many transistors and this is an analog circuit is going to dissipate power all the time. There is this which is a much more complicated circuit and it's going to be dissipating power whereas here each synapse is just two transistors and a magnet and the neuron is just these two M.P.G. and just two inverters. So one other thing about the lunar new network is that people have shown that you can use similar neural networks to efficiently implement convolution or neural networks and convolutional neural networks are much more used these days for many applications that requires. Machine learning and inference from a big large set of data so this is the work that our collaborators. And Sharon who are at Notre Dame have done and be sure that all the leaders in a convolutional neural network they can be done. With. That works and that So these are for example an example of those circuits that can be done via it cellular and it works so the results that we have over there are quite come can be translated here and we're working with it to benchmark their results for four convolutional neural networks based on this so. Throughout the benchmarking what Observateur is that as you are more those become more and more accurate than you. For more limiting factors then the benchmarking results become more pessimistic but at the same time if you really think about what are the issues whether the problems or the devices and try to modify and reinvent these devices the data points gradually move to the right corner but still it's going to be quite challenging to be. In. A brilliant domain and novel system and circuit concepts are quite necessary to utilize the new properties of these devices and one example is the cellular neural networks that have been implemented these beyond Sue Moss devices. So. Before I and I want to acknowledge the people who have done the work. Research engine in my group he's done a lot of work here the current and former Ph D. students some of the names are listed here and they've done a lot of the work and the results that you saw mostly from them we have some collaborators that Intel which we have been working very closely the the benchmarking effort is guided by you know representatives from the four major. Sponsor companies and all the. Students within the Star net assets so thank you very much for your time and I would be happy to answer any questions thank you very much. Questions. But the answer. Is. I would say most of them we have major material challenges So for example all the devices. The. Street did suffer through suing are much of what the theory predicts and in most cases is due to the traps so those trap states are limiting the minimum current so you can't go be long below that. Due to the material as the D. fabrication a material product which is all very strange and some of the magnetic devices still the the materials are not as mature. So I think most of them are suffering you know they need a lot of improvement in the material part. Yes I. Think it was. Guys yet the. Process. Is there. So. That. Works. Out OK. So I'm trying. To. Change. You guys. In many cases nothing has been fabricated completely you know for example if you look at this C.S.L. device. Pieces have been demonstrated the physics is well understood but to integrate the entire device we're still not there so most of the changes that you see over these trends is redesigning the device itself it's not restarted from this experimental point and we said what if we can make this part but there what if we can make this material but that it's basically starting from this original proposal and looking at OK when you put it in the circuit what is really limiting you for example for this case was that the size of the magnets had to be big because of the two contacts that you had to make and now is there a way to break this device into smaller pieces and reuse the current that is coming and therefore not. Needing as much current so that. Takes you may be here or for you to for example here you. You add another layer to funnel electrons into the magnet saw So you clicked more spins and funnel them into the device So these are not. These are the result of a redesign of the device after learning what is limiting them. Yeah so. It's become. Actually nothing more than not and not always so sometimes because you are coming up with a better design. And you actually make it better and the error bar should get smaller so it depends if you become to speke So if the trend here is just to become too speculative and say that what if I have a. Spin relaxation that can be ten microns then yes that's that's true but when you are making this device better by coming up with a better design and in many cases actually you make the device simpler then know the error bar is not going to increase. At. This. Point. What with. The rise right I think that's a very good point I think for some of these devices would be great because some of these devices have larger error rates so that would be one factor. Another factor can be complex city of the device how difficult it would be. So.