1 00:00:08,960 --> 00:00:11,919 Hello, and welcome to the Physics World weekly 2 00:00:11,919 --> 00:00:12,419 podcast. 3 00:00:12,794 --> 00:00:15,535 In this episode, we meet Hannah Earley, 4 00:00:15,914 --> 00:00:17,774 a mathematician and physicist 5 00:00:18,155 --> 00:00:21,375 who's cofounder of a company that is commercializing 6 00:00:22,154 --> 00:00:22,654 reversible 7 00:00:22,954 --> 00:00:23,454 computing. 8 00:00:24,154 --> 00:00:25,935 This paradigm has the potential 9 00:00:26,300 --> 00:00:28,879 to use less energy than conventional 10 00:00:29,339 --> 00:00:29,839 computation, 11 00:00:30,539 --> 00:00:33,579 something that could prove very useful for power 12 00:00:33,579 --> 00:00:34,079 hungry 13 00:00:34,460 --> 00:00:35,600 AI applications. 14 00:00:36,619 --> 00:00:39,979 Hannah talks to Physics World's Margaret Harris about 15 00:00:39,979 --> 00:00:40,640 the physics, 16 00:00:41,164 --> 00:00:42,704 engineering, and commercialization 17 00:00:43,725 --> 00:00:45,265 of reversible computing. 18 00:00:54,200 --> 00:00:56,280 My guest today is Hannah Early, the chief 19 00:00:56,280 --> 00:00:58,920 technology officer and cofounder of a startup called 20 00:00:58,920 --> 00:01:01,000 VerComputing that aims to build a new type 21 00:01:01,000 --> 00:01:03,899 of computer architecture based on reversible operations. 22 00:01:04,280 --> 00:01:05,979 Hello, Hannah. Welcome to the podcast. 23 00:01:06,734 --> 00:01:08,594 Hi, Margaret. Thanks for having me on. 24 00:01:09,295 --> 00:01:11,295 We talk a lot about quantum computing on 25 00:01:11,295 --> 00:01:13,534 the Physics World Weekly podcast. But while I 26 00:01:13,534 --> 00:01:15,855 understand that Ver's work is in some sense 27 00:01:15,855 --> 00:01:17,234 based on quantum principles, 28 00:01:17,614 --> 00:01:19,855 you're not building a quantum computer in the 29 00:01:19,855 --> 00:01:20,834 usual sense. 30 00:01:21,269 --> 00:01:22,629 Maybe you could start out by giving our 31 00:01:22,629 --> 00:01:25,209 listeners just a quick introduction to what reversible 32 00:01:25,269 --> 00:01:26,409 computing is. 33 00:01:27,189 --> 00:01:29,670 Yeah. Of course. So, in fact, actually, there's 34 00:01:29,670 --> 00:01:32,469 not very much similarity to what we're doing 35 00:01:32,469 --> 00:01:34,629 in quantum computing at all except for the 36 00:01:34,629 --> 00:01:37,134 reversible principles at at the core of it. 37 00:01:37,134 --> 00:01:37,875 So, obviously, in 38 00:01:38,254 --> 00:01:41,055 quantum computers, it's very necessary that all the 39 00:01:41,055 --> 00:01:44,414 operations are unitary. And as a consequence, if 40 00:01:44,414 --> 00:01:47,055 you're doing any classical computation on a quantum 41 00:01:47,055 --> 00:01:47,555 computer, 42 00:01:48,174 --> 00:01:50,939 that means that it is logically reversible, which 43 00:01:50,939 --> 00:01:53,500 means that you can always from once they 44 00:01:53,500 --> 00:01:55,819 get back to the previous state. And that's 45 00:01:55,819 --> 00:01:58,060 very necessary in quantum computing because otherwise, you're 46 00:01:58,060 --> 00:01:59,040 going to get decoherence. 47 00:01:59,980 --> 00:02:02,799 In what we're doing in classical reversible computing, 48 00:02:03,340 --> 00:02:05,935 it's not kind of a physical necessity, 49 00:02:06,394 --> 00:02:08,235 but what it lets us do is, 50 00:02:08,634 --> 00:02:10,875 if we can not only make this computer 51 00:02:10,875 --> 00:02:11,854 logically reversible, 52 00:02:12,314 --> 00:02:14,414 but also also physically reversible, 53 00:02:14,715 --> 00:02:17,134 then that in principle lets us access 54 00:02:17,650 --> 00:02:19,909 significantly lower energy operations 55 00:02:20,210 --> 00:02:22,870 than than conventionally. So this dates back to, 56 00:02:23,250 --> 00:02:24,310 some work from 57 00:02:24,849 --> 00:02:26,849 Rolf Landau and if you trace it back 58 00:02:26,849 --> 00:02:29,189 even further to Leo Szilard and, 59 00:02:29,569 --> 00:02:30,710 Maxwell himself 60 00:02:31,055 --> 00:02:31,555 on 61 00:02:31,935 --> 00:02:34,594 what the energy costs or thermodynamics 62 00:02:35,694 --> 00:02:37,955 are when it comes to information processing. 63 00:02:38,574 --> 00:02:39,314 And so 64 00:02:39,694 --> 00:02:42,014 whilst we're not necessarily trying to break what 65 00:02:42,014 --> 00:02:43,854 is has become known as the Landau limit, 66 00:02:43,854 --> 00:02:46,360 it turns out that there is this limit 67 00:02:46,420 --> 00:02:47,640 when you want to 68 00:02:48,020 --> 00:02:50,580 erase information on on the energy cost of 69 00:02:50,580 --> 00:02:52,580 that. And this turns out to be a 70 00:02:52,580 --> 00:02:53,560 pretty small number, 71 00:02:54,260 --> 00:02:56,840 k t log two, k being Boltzmann's constant, 72 00:02:56,900 --> 00:02:58,040 and t being temperature, 73 00:02:58,504 --> 00:03:00,264 which is something like 10 to the minus 74 00:03:00,264 --> 00:03:02,824 21 joules. So it's a very small amount, 75 00:03:02,824 --> 00:03:05,224 but it turns out that, one, we're actually 76 00:03:05,224 --> 00:03:07,064 kind of closer than you might expect to 77 00:03:07,064 --> 00:03:08,284 this limit, but, two, 78 00:03:08,585 --> 00:03:10,840 even without trying to break this limit, by 79 00:03:10,840 --> 00:03:14,060 making your operations physically reversible, you can significantly 80 00:03:14,199 --> 00:03:18,219 reduce the energy cost of general operations even 81 00:03:18,360 --> 00:03:21,159 just when applying it to what we currently 82 00:03:21,159 --> 00:03:22,460 can do today in competing. 83 00:03:23,240 --> 00:03:25,180 Why is it that you have this 84 00:03:25,775 --> 00:03:26,275 incredible 85 00:03:26,574 --> 00:03:27,875 improvement in energy 86 00:03:28,175 --> 00:03:30,514 efficiency, I guess, if you have 87 00:03:30,814 --> 00:03:31,875 reversible operations? 88 00:03:33,134 --> 00:03:35,634 Yeah. So, it really depends on 89 00:03:36,495 --> 00:03:39,294 the computational medium you're talking about. So for 90 00:03:39,294 --> 00:03:42,150 example, in in CMOS computing, computing, which is, 91 00:03:42,389 --> 00:03:44,090 what we're doing at Ver computing, 92 00:03:44,870 --> 00:03:45,610 when you 93 00:03:46,550 --> 00:03:49,510 do an irreversible operation in a CMOS logic 94 00:03:49,510 --> 00:03:50,010 circuit, 95 00:03:50,469 --> 00:03:52,490 what this corresponds to is, 96 00:03:52,870 --> 00:03:55,365 so you take your logical circuit, and you 97 00:03:55,365 --> 00:03:57,604 have some inputs that are currently supplied to 98 00:03:57,604 --> 00:03:59,764 it and some output. And then later when 99 00:03:59,764 --> 00:04:01,625 you want to change that input, 100 00:04:01,925 --> 00:04:04,165 you're pretty much just you know, there might 101 00:04:04,165 --> 00:04:06,344 be some latch upstream or or some register. 102 00:04:06,724 --> 00:04:07,944 You change that input, 103 00:04:08,270 --> 00:04:09,729 and it's going to then 104 00:04:10,030 --> 00:04:12,449 kind of propagate through that circuit. 105 00:04:12,909 --> 00:04:15,729 And as it propagates through, it's going to 106 00:04:16,110 --> 00:04:18,990 change transistor connectivity, and it's going to then 107 00:04:18,990 --> 00:04:21,709 end up effectively flushing all of these signal 108 00:04:21,709 --> 00:04:22,209 energies 109 00:04:22,555 --> 00:04:24,095 into ground or into VDD. 110 00:04:24,474 --> 00:04:25,454 And as a consequence, 111 00:04:25,834 --> 00:04:26,495 you get 112 00:04:26,954 --> 00:04:27,774 this characteristic 113 00:04:28,794 --> 00:04:30,254 c v squared dissipation. 114 00:04:30,794 --> 00:04:32,794 And so this is kind of just taken 115 00:04:32,794 --> 00:04:35,615 as most axiomatic in in CMOS computing. 116 00:04:36,474 --> 00:04:38,370 And for a very long time, this was 117 00:04:39,009 --> 00:04:41,410 kind of negligible. And for the amount of 118 00:04:41,410 --> 00:04:42,930 computation we wanted to do, we had more 119 00:04:42,930 --> 00:04:45,169 than enough energy, and so it wasn't really 120 00:04:45,169 --> 00:04:46,310 seen as an issue. 121 00:04:46,850 --> 00:04:49,649 But when you change, at least the CMOS 122 00:04:49,649 --> 00:04:51,189 logic circuit to operate reversibly, 123 00:04:52,204 --> 00:04:54,044 what that corresponds to is adding in a 124 00:04:54,044 --> 00:04:56,524 step before you change the input, and that 125 00:04:56,524 --> 00:04:57,664 step is to 126 00:04:57,964 --> 00:05:00,524 first recover that signal energy that is stored 127 00:05:00,524 --> 00:05:01,904 in the gates of transistors. 128 00:05:02,764 --> 00:05:04,685 And you so you recover that, 129 00:05:05,389 --> 00:05:07,949 probably storing it generally in in some kind 130 00:05:07,949 --> 00:05:08,689 of reservoir, 131 00:05:09,069 --> 00:05:12,269 maybe even in inductors magnetic field. And then 132 00:05:12,269 --> 00:05:14,430 once you've recovered that technology, you've put that 133 00:05:14,430 --> 00:05:16,110 circuit into a neutral state, and then you 134 00:05:16,110 --> 00:05:16,850 can supply 135 00:05:17,310 --> 00:05:19,329 new inputs into that circuit. 136 00:05:19,709 --> 00:05:22,085 And when you do that, you're no longer 137 00:05:22,464 --> 00:05:24,225 there's a little bit more complexity to it, 138 00:05:24,225 --> 00:05:26,545 but effectively, you're trying to avoid setting up 139 00:05:26,545 --> 00:05:27,045 these 140 00:05:27,665 --> 00:05:30,805 quite significant potential differences that lead to dissipation. 141 00:05:31,665 --> 00:05:33,425 This is dissipation of heat. Right? You know, 142 00:05:33,425 --> 00:05:35,264 this is this is heat heat that is 143 00:05:35,264 --> 00:05:36,629 generated when you erase 144 00:05:37,110 --> 00:05:39,509 a register of bits and just dump that 145 00:05:39,509 --> 00:05:40,009 information 146 00:05:40,389 --> 00:05:41,930 to the environment. 147 00:05:42,870 --> 00:05:43,689 Yes. Exactly. 148 00:05:44,230 --> 00:05:46,970 How does reversible computing solve that problem? 149 00:05:48,149 --> 00:05:50,230 Reversible computing really solves that problem by just 150 00:05:50,230 --> 00:05:52,085 not generating that heat to begin At the 151 00:05:52,085 --> 00:05:54,965 same signal energy is flowing through the circuit, 152 00:05:55,205 --> 00:05:57,705 at least when you're doing reversible CMOS. 153 00:05:58,165 --> 00:05:59,685 But because you're able to 154 00:06:00,485 --> 00:06:01,944 in principle, you can recover 155 00:06:02,405 --> 00:06:04,324 a large amount of that energy. The amount 156 00:06:04,324 --> 00:06:06,740 of that energy that you can recover depends 157 00:06:06,740 --> 00:06:08,759 on how much you slow down the computation. 158 00:06:09,779 --> 00:06:11,779 I I probably want to revisit that a 159 00:06:11,779 --> 00:06:13,779 bit later in what that means because it 160 00:06:13,779 --> 00:06:16,339 sounds like our computation is much, much slower, 161 00:06:16,339 --> 00:06:19,665 and, that's actually not necessarily the case. 162 00:06:20,125 --> 00:06:21,504 But depending on 163 00:06:21,805 --> 00:06:24,545 this factor by which you slow it down, 164 00:06:24,685 --> 00:06:26,384 that kind of linearly, 165 00:06:26,845 --> 00:06:29,884 proportionally reduces the amount of energy that gets 166 00:06:29,884 --> 00:06:31,264 dissipated in that operation. 167 00:06:32,439 --> 00:06:35,319 There's also other circuit components that enable this 168 00:06:35,319 --> 00:06:36,839 whole thing to work and those have their 169 00:06:36,839 --> 00:06:39,240 own dissipation. But as long as you optimize 170 00:06:39,240 --> 00:06:41,819 those and optimize the the slowdown, 171 00:06:42,520 --> 00:06:43,160 you can save 172 00:06:44,375 --> 00:06:45,355 I I won't say arbitrarily 173 00:06:46,055 --> 00:06:48,215 much energy, but really in CMOS, the limit 174 00:06:48,215 --> 00:06:50,154 seems to be about 4,000 times. 175 00:06:50,615 --> 00:06:52,455 And, you know, you still have the same 176 00:06:52,455 --> 00:06:54,615 currents flowing through. It's just that instead of 177 00:06:54,615 --> 00:06:55,675 having those currents 178 00:06:56,134 --> 00:06:58,615 dumped to ground when when you start a 179 00:06:58,615 --> 00:07:01,459 new computational cycle, you much more carefully manage 180 00:07:01,459 --> 00:07:02,600 that energy flow. 181 00:07:03,620 --> 00:07:05,139 And you mentioned you wanted to talk a 182 00:07:05,139 --> 00:07:06,740 bit more about it's not that this is 183 00:07:06,740 --> 00:07:09,060 a really slow computation, because that's the traditional 184 00:07:09,060 --> 00:07:10,360 way you do things without, 185 00:07:10,660 --> 00:07:13,139 exchanging heat. You do things adiabatically. It's a 186 00:07:13,139 --> 00:07:15,245 really slow process. It doesn't sort of disturb 187 00:07:15,245 --> 00:07:16,764 the system in any way. Is that not 188 00:07:16,764 --> 00:07:17,664 what you're doing? 189 00:07:18,524 --> 00:07:20,925 It actually is, but I'll explain why that's 190 00:07:20,925 --> 00:07:22,704 not surprisingly slow. 191 00:07:23,084 --> 00:07:25,564 So adiabatic operations are kind of the core 192 00:07:25,564 --> 00:07:27,964 of what we're doing. So usually your signals 193 00:07:27,964 --> 00:07:30,629 in in regular CMOS are as close to 194 00:07:30,629 --> 00:07:32,790 a square wave as you can get. And 195 00:07:32,790 --> 00:07:34,790 we change those waves to be more what 196 00:07:34,790 --> 00:07:36,709 we like to call trapezoidal. So you have 197 00:07:36,709 --> 00:07:39,449 kind of flat regions where signals are stable, 198 00:07:39,509 --> 00:07:41,990 and then you have these linear ramps over 199 00:07:41,990 --> 00:07:45,134 a relatively long rise of full time. And 200 00:07:45,134 --> 00:07:47,394 that's where you kind of get the adiabaticness 201 00:07:47,615 --> 00:07:48,834 of what we're doing. So 202 00:07:49,375 --> 00:07:51,214 our approach is really a combination of both 203 00:07:51,214 --> 00:07:53,474 adiabatic computing and reversible computing. 204 00:07:54,495 --> 00:07:56,974 The reason why this is not horrendously slow, 205 00:07:56,974 --> 00:07:58,754 and this was really the worry 206 00:07:59,214 --> 00:07:59,954 back in 207 00:08:00,319 --> 00:08:02,720 the nineties when people were kind of first 208 00:08:02,720 --> 00:08:03,599 trying to build, 209 00:08:04,000 --> 00:08:06,319 these reversible computers. And and then it actually 210 00:08:06,319 --> 00:08:08,399 was more of a problem. The reason why 211 00:08:08,399 --> 00:08:10,579 this isn't a problem now is that 212 00:08:10,879 --> 00:08:12,019 this rise time 213 00:08:12,334 --> 00:08:14,115 is measured as a fraction of 214 00:08:14,574 --> 00:08:16,754 or as a sorry, as a multiple rather 215 00:08:17,134 --> 00:08:20,274 of the transistor's intrinsic switching time. 216 00:08:20,654 --> 00:08:23,055 And for modern processes, these can be on 217 00:08:23,055 --> 00:08:24,895 the order of picoseconds or even less than 218 00:08:24,895 --> 00:08:25,259 picoseconds, 219 00:08:26,139 --> 00:08:28,080 I e, terahertz frequencies. 220 00:08:29,020 --> 00:08:31,900 We obviously do not run our computers at 221 00:08:31,900 --> 00:08:33,980 terahertz frequencies, and there are very good reasons 222 00:08:33,980 --> 00:08:35,580 for that. And this kind of dates back 223 00:08:35,580 --> 00:08:37,580 to the end of de noid scaling back 224 00:08:37,580 --> 00:08:38,540 in 2005 225 00:08:38,540 --> 00:08:41,465 when before then, computational frequency seemed 226 00:08:41,924 --> 00:08:43,845 to double with a cadence similar to Moore's 227 00:08:43,845 --> 00:08:45,845 law, and and then afterwards, it kind of 228 00:08:45,845 --> 00:08:47,545 stagnates that a few gigahertz. 229 00:08:48,165 --> 00:08:50,884 But the transistor switching frequency kept kept going 230 00:08:50,884 --> 00:08:53,065 up. And so as long as we are 231 00:08:53,339 --> 00:08:56,459 significantly slower than this hundreds of gigahertz or 232 00:08:56,459 --> 00:08:57,199 even terahertz, 233 00:08:57,819 --> 00:08:59,360 then that's enough to get reversible 234 00:08:59,899 --> 00:09:02,319 efficiency. So we could operate in the gigahertz 235 00:09:02,379 --> 00:09:04,379 range, and that's still gonna give you 50 236 00:09:04,379 --> 00:09:06,639 or a 100 times energy saving 237 00:09:07,214 --> 00:09:09,855 in principle. I I did also mention that 238 00:09:09,855 --> 00:09:12,274 there are other circuit components that enable adiabatic 239 00:09:12,414 --> 00:09:13,394 switching, and 240 00:09:14,014 --> 00:09:16,274 those are pretty difficult to get good efficiencies 241 00:09:16,414 --> 00:09:18,654 on. And so those kind of end up 242 00:09:18,654 --> 00:09:19,154 dominating, 243 00:09:19,534 --> 00:09:21,920 but we can still get quite significant energy 244 00:09:21,920 --> 00:09:22,420 savings. 245 00:09:23,840 --> 00:09:26,100 But this sounds like, you know, really fascinating 246 00:09:26,240 --> 00:09:28,720 sort of concept in academic research. What is 247 00:09:28,720 --> 00:09:30,480 it that made you decide a few years 248 00:09:30,480 --> 00:09:32,399 ago now that now is the time to 249 00:09:32,399 --> 00:09:34,420 actually start commercializing this technology? 250 00:09:35,564 --> 00:09:38,684 Yeah. Great question. So it was kind of 251 00:09:38,684 --> 00:09:42,125 a almost serendipitous encounter between me and and 252 00:09:42,125 --> 00:09:44,225 my cofounder, Rodolfo Rustini. 253 00:09:46,605 --> 00:09:49,029 So I was doing a PhD in a 254 00:09:49,029 --> 00:09:52,549 number of unconventional computing topics, but, reversible computing 255 00:09:52,549 --> 00:09:54,169 being being one of the primary 256 00:09:54,789 --> 00:09:57,610 ones in that. And I had 257 00:09:58,070 --> 00:09:58,889 one of the 258 00:09:59,509 --> 00:10:01,684 topics I was looking at was what was 259 00:10:01,684 --> 00:10:04,245 the ultimate future of computing. And I kind 260 00:10:04,245 --> 00:10:05,865 of became very convinced 261 00:10:06,485 --> 00:10:06,985 that 262 00:10:07,365 --> 00:10:09,544 all future computers had to be 263 00:10:09,845 --> 00:10:12,264 at least involve a significant amount of reversibility 264 00:10:12,565 --> 00:10:15,440 if you wanted to keep increasing the performance 265 00:10:15,659 --> 00:10:17,839 of your larger and larger computers. 266 00:10:18,299 --> 00:10:18,959 Like, certainly 267 00:10:19,419 --> 00:10:20,940 in the long future, if you are thinking 268 00:10:20,940 --> 00:10:21,679 about building 269 00:10:22,459 --> 00:10:25,579 matrioshka brains and and other huge computers, then 270 00:10:25,579 --> 00:10:27,019 there's really no way to deal with the 271 00:10:27,019 --> 00:10:29,504 heat unless they use reversible computing. What's the 272 00:10:29,825 --> 00:10:31,024 sorry. I'm gonna stop you there. What's a 273 00:10:31,024 --> 00:10:32,164 matrioshka brain? 274 00:10:32,704 --> 00:10:34,945 Yeah. So I I might be mixing this 275 00:10:34,945 --> 00:10:37,184 up with Jupiter brains, but the idea is, 276 00:10:37,184 --> 00:10:40,084 you know, maybe these very advanced civilizations 277 00:10:40,625 --> 00:10:42,884 far beyond what what we are at 278 00:10:43,345 --> 00:10:44,404 might start to build 279 00:10:44,759 --> 00:10:45,740 computers the size 280 00:10:46,120 --> 00:10:48,860 of moons or planets or even larger astronomical 281 00:10:48,920 --> 00:10:49,420 systems. 282 00:10:50,120 --> 00:10:50,620 And 283 00:10:51,000 --> 00:10:53,160 the scaling laws turn out that if you 284 00:10:53,160 --> 00:10:54,220 just want to build 285 00:10:55,240 --> 00:10:58,084 a computer using irreversible techniques, you can only 286 00:10:58,084 --> 00:11:00,884 really cover the surface of some system in 287 00:11:00,884 --> 00:11:04,245 in computational matter. And that's purely because of 288 00:11:04,245 --> 00:11:05,065 the thermodynamics. 289 00:11:05,764 --> 00:11:06,664 If you're generating 290 00:11:07,204 --> 00:11:08,644 a certain amount of heat and you want 291 00:11:08,644 --> 00:11:10,644 to radiate that, then you're going to get 292 00:11:10,644 --> 00:11:13,160 some kind of area metric scaling law. If 293 00:11:13,160 --> 00:11:15,080 you want to go above that scaling law, 294 00:11:15,080 --> 00:11:17,320 then you really need to get this control 295 00:11:17,320 --> 00:11:18,620 over heat, and the only, 296 00:11:19,160 --> 00:11:21,500 approach that gives you that is is reversible 297 00:11:21,559 --> 00:11:22,059 computing. 298 00:11:22,680 --> 00:11:24,759 So I was looking maybe a little bit 299 00:11:24,759 --> 00:11:27,595 longer term, back then than what is maybe 300 00:11:27,595 --> 00:11:30,154 commercially practical right now. But I could also 301 00:11:30,154 --> 00:11:31,455 see that kind of 302 00:11:32,315 --> 00:11:33,835 it may be the case that in the 303 00:11:33,835 --> 00:11:36,235 nearer future, this might be relevant. And my 304 00:11:36,235 --> 00:11:36,735 cofounder 305 00:11:37,274 --> 00:11:39,115 was coming from a different direction. He was 306 00:11:39,115 --> 00:11:41,340 coming from very much looking at 307 00:11:42,139 --> 00:11:44,379 the growth of AI. And and this was 308 00:11:44,379 --> 00:11:45,899 back in 2021. 309 00:11:45,899 --> 00:11:48,860 So, you know, AI was becoming increasingly relevant, 310 00:11:48,860 --> 00:11:49,759 but we hadn't 311 00:11:50,300 --> 00:11:52,220 quite seen the explosion that we have in 312 00:11:52,220 --> 00:11:54,254 in the last couple years. It's been very 313 00:11:54,254 --> 00:11:56,254 fast how much this has increased. It feels 314 00:11:56,254 --> 00:11:58,595 like it's been around forever now. But 315 00:11:59,055 --> 00:12:00,274 he saw that 316 00:12:00,815 --> 00:12:02,975 we were potentially going to get a crisis 317 00:12:02,975 --> 00:12:05,795 in hardware, not least because there were 318 00:12:06,254 --> 00:12:08,195 increasing signs that Moore's Law 319 00:12:08,970 --> 00:12:10,409 is being predicted a number of times in 320 00:12:10,409 --> 00:12:12,169 the past, but perhaps this really was the 321 00:12:12,169 --> 00:12:13,450 time that Moore's law was going to come 322 00:12:13,450 --> 00:12:15,690 to an end. And so these combination of 323 00:12:15,690 --> 00:12:16,190 factors 324 00:12:16,730 --> 00:12:19,289 and a serendipitous meeting between us through a 325 00:12:19,289 --> 00:12:21,789 mutual friend led us realizing that maybe 326 00:12:22,605 --> 00:12:23,904 the solution to 327 00:12:24,285 --> 00:12:24,785 AI's 328 00:12:25,165 --> 00:12:28,524 upcoming energy problem would be reversible computing. And 329 00:12:28,524 --> 00:12:30,524 I wanna link back to what Feynman was 330 00:12:30,524 --> 00:12:33,165 saying in the nineteen eighties about reversible computing, 331 00:12:33,165 --> 00:12:34,065 which was that 332 00:12:35,085 --> 00:12:36,304 as long as you are 333 00:12:36,750 --> 00:12:39,470 significantly above the Landau limit, above a 100 334 00:12:39,470 --> 00:12:42,269 or 300 times the Landau limit, there's no 335 00:12:42,269 --> 00:12:44,669 need for you to ever consider reversible computing 336 00:12:44,669 --> 00:12:45,169 because 337 00:12:45,470 --> 00:12:47,470 we've got back in the eighties, we've got 338 00:12:47,470 --> 00:12:50,184 so much energy available, and our computation is 339 00:12:50,184 --> 00:12:52,985 already so inefficient, etcetera, and we're not really 340 00:12:52,985 --> 00:12:54,445 doing all that much computation. 341 00:12:55,225 --> 00:12:58,264 But now it's forty, fifty years later, and 342 00:12:58,264 --> 00:13:00,424 it turns out that we are actually at 343 00:13:00,424 --> 00:13:02,345 a few 100 times the landau limit. And 344 00:13:02,345 --> 00:13:02,845 so 345 00:13:03,490 --> 00:13:05,250 while it may not have been right in 346 00:13:05,250 --> 00:13:07,730 the nineties back when MIT built some reversible 347 00:13:07,730 --> 00:13:09,409 chips, it it looks like now might be 348 00:13:09,409 --> 00:13:10,069 the time. 349 00:13:10,929 --> 00:13:12,690 Okay. You talk about a chip. Right? Let's 350 00:13:12,690 --> 00:13:15,089 just get quite physical. What do logic gates 351 00:13:15,089 --> 00:13:17,144 look like in this technology? What do circuits 352 00:13:17,225 --> 00:13:19,004 look like in reversible computing? 353 00:13:20,024 --> 00:13:20,504 Yeah. 354 00:13:20,904 --> 00:13:23,004 So this is a great question. And 355 00:13:23,545 --> 00:13:25,144 it can be kind of hard to figure 356 00:13:25,144 --> 00:13:27,804 out what this is from the literature. And 357 00:13:28,264 --> 00:13:30,329 in a sense, this is because it really 358 00:13:30,329 --> 00:13:32,570 depends on on what you're building. So, obviously, 359 00:13:32,570 --> 00:13:33,850 I'm going to talk a lot about what 360 00:13:33,850 --> 00:13:36,329 this means in CMOS. But, traditionally, when you're 361 00:13:36,329 --> 00:13:38,509 looking at reversible computing, you see that 362 00:13:38,889 --> 00:13:42,169 relevant gates are gates or gates. And it's 363 00:13:42,169 --> 00:13:43,389 asking if you're building 364 00:13:43,894 --> 00:13:46,855 classical computations in a quantum computer. These are 365 00:13:46,855 --> 00:13:48,615 the gates that make sense. What are those 366 00:13:48,615 --> 00:13:51,174 gates? Yes. Those those terminologies our listeners might 367 00:13:51,174 --> 00:13:53,754 not have heard of before. Sorry. Yes. In 368 00:13:53,815 --> 00:13:56,394 computers, when you're doing reversible classical computing, 369 00:13:57,509 --> 00:13:59,269 your gates need to be need to have 370 00:13:59,269 --> 00:14:01,129 the same number of inputs as outputs. 371 00:14:01,509 --> 00:14:02,250 And so 372 00:14:02,629 --> 00:14:03,529 whilst in 373 00:14:03,830 --> 00:14:04,970 irreversible computing, 374 00:14:05,509 --> 00:14:07,750 the universal gate might be, say, the NAND 375 00:14:07,750 --> 00:14:09,769 gate, which is two input, one output. 376 00:14:10,149 --> 00:14:10,649 In 377 00:14:11,134 --> 00:14:14,174 reversible computing, this universal gate might be something 378 00:14:14,174 --> 00:14:16,894 called the Tefoli gate. This was discovered in 379 00:14:16,894 --> 00:14:19,294 the nineteen eighties. It's well, you could argue 380 00:14:19,294 --> 00:14:21,054 it was discovered earlier, but it wasn't named 381 00:14:21,054 --> 00:14:22,975 in the nineteen eighties at least. And this 382 00:14:22,975 --> 00:14:25,879 is a three input, three output gate. And 383 00:14:25,879 --> 00:14:28,279 what it does is quite simple. Its first 384 00:14:28,279 --> 00:14:30,920 two inputs are just copies across, so let's 385 00:14:30,920 --> 00:14:32,600 call them a, b, and c. The first 386 00:14:32,600 --> 00:14:34,059 two outputs are a and b. 387 00:14:34,360 --> 00:14:36,379 The third output, we just XOR, 388 00:14:36,920 --> 00:14:39,184 the third input c with the product 389 00:14:39,965 --> 00:14:41,565 of both the logical and of a and 390 00:14:41,565 --> 00:14:42,065 b. 391 00:14:42,845 --> 00:14:45,404 And in quantum computing, you might also see 392 00:14:45,404 --> 00:14:48,045 this referred to as controlled controlled not or 393 00:14:48,045 --> 00:14:48,945 CC not. 394 00:14:49,565 --> 00:14:50,065 So 395 00:14:50,540 --> 00:14:52,379 a lot of the reversible circuits you see 396 00:14:52,379 --> 00:14:54,620 out there make use of of these kinds 397 00:14:54,620 --> 00:14:55,279 of gates. 398 00:14:55,740 --> 00:14:58,700 But seamless, it is interesting, and it actually 399 00:14:58,700 --> 00:14:59,200 deviates 400 00:14:59,580 --> 00:15:01,600 quite a bit from from this paradigm. 401 00:15:01,980 --> 00:15:03,679 And the reason for that is 402 00:15:04,985 --> 00:15:07,465 unlike in, say, a quantum gate where kind 403 00:15:07,465 --> 00:15:09,725 of as you put information 404 00:15:10,504 --> 00:15:12,205 into the inputs, it gets 405 00:15:12,585 --> 00:15:15,004 directly transformed in place to outputs. 406 00:15:15,384 --> 00:15:16,764 It's not really how 407 00:15:17,225 --> 00:15:18,809 switching based logic works. 408 00:15:19,210 --> 00:15:20,730 So if you look at, say, a NAND 409 00:15:20,730 --> 00:15:22,570 gate well, actually, let's take a NOT gate 410 00:15:22,570 --> 00:15:24,490 in CMOS. Right? Because that seems like an 411 00:15:24,490 --> 00:15:27,950 intrinsically reversible gate, and logically, it is. But 412 00:15:28,490 --> 00:15:30,350 physically, it's not necessarily 413 00:15:30,649 --> 00:15:32,634 reversible in CMOS. And the reason for this 414 00:15:32,634 --> 00:15:35,514 is you supply the input, to one side 415 00:15:35,514 --> 00:15:36,894 of of your not gate, 416 00:15:37,274 --> 00:15:39,295 and the output gets generated. 417 00:15:39,995 --> 00:15:42,394 But you haven't consumed the input. You haven't 418 00:15:42,394 --> 00:15:44,730 transformed the input into the output. And so, 419 00:15:44,730 --> 00:15:46,970 actually, you should more think of the not 420 00:15:46,970 --> 00:15:49,769 gate in CMOS as a one input, two 421 00:15:49,769 --> 00:15:52,590 output gate because it kind of intrinsically 422 00:15:52,970 --> 00:15:54,669 keeps around a copy of the input. 423 00:15:55,529 --> 00:15:56,684 And in that sense, 424 00:15:57,085 --> 00:15:58,544 actually, all CMOS gates 425 00:15:59,884 --> 00:16:00,945 just conventionally 426 00:16:02,284 --> 00:16:04,304 have the ability to be used reversibly. 427 00:16:04,845 --> 00:16:07,404 And so the gates we use at fair 428 00:16:07,404 --> 00:16:10,230 computing are not that different from the conventional 429 00:16:10,230 --> 00:16:12,389 gates you'd find in in any standard cell 430 00:16:12,389 --> 00:16:12,889 library. 431 00:16:13,590 --> 00:16:14,409 Rather, we 432 00:16:14,870 --> 00:16:17,750 operate them quite a bit differently from how 433 00:16:17,750 --> 00:16:18,570 they're conventionally 434 00:16:19,029 --> 00:16:21,509 driven. And so we take a lot greater 435 00:16:21,509 --> 00:16:23,750 care of how signals propagate, and we add 436 00:16:23,750 --> 00:16:25,705 a little bit of extra circuitry around so 437 00:16:25,705 --> 00:16:26,445 that we can 438 00:16:26,825 --> 00:16:29,465 kind of both compute a gate, so generate 439 00:16:29,465 --> 00:16:31,865 its output from its input, and also decompose 440 00:16:31,865 --> 00:16:34,264 a gate so that whilst holding its input, 441 00:16:34,264 --> 00:16:35,085 you can actually 442 00:16:35,465 --> 00:16:38,460 ungenerate the output. And so adding this control 443 00:16:38,600 --> 00:16:41,399 lets us transform pretty much any regular gate 444 00:16:41,399 --> 00:16:44,200 into a reversible gate. There's a little bit 445 00:16:44,200 --> 00:16:47,240 more implementation complexity, but but actually the gates 446 00:16:47,240 --> 00:16:49,160 and the logic itself are not not very 447 00:16:49,160 --> 00:16:51,384 much different from how you would build a 448 00:16:51,384 --> 00:16:51,884 conventional 449 00:16:52,264 --> 00:16:53,245 C West chip. 450 00:16:53,785 --> 00:16:55,144 And I think I read that you sort 451 00:16:55,144 --> 00:16:58,024 of store the energy in some sort of 452 00:16:58,024 --> 00:17:00,184 resonator in order to do the uncomputation to 453 00:17:00,184 --> 00:17:02,264 do the reverse operation to make the gate 454 00:17:02,264 --> 00:17:03,965 reversible. How does that work? 455 00:17:04,690 --> 00:17:05,170 Yeah. 456 00:17:05,570 --> 00:17:08,470 So this is the other critical component. So, 457 00:17:08,529 --> 00:17:10,210 you know, it's not enough to just make 458 00:17:10,210 --> 00:17:10,869 your circuit 459 00:17:11,170 --> 00:17:13,650 theoretically logically reversible. You need to add in 460 00:17:13,650 --> 00:17:16,470 some extra circuitry so that you can actually 461 00:17:17,424 --> 00:17:19,924 operatively reverse the the operations. 462 00:17:20,464 --> 00:17:23,184 So one of the simplest approaches is so 463 00:17:23,184 --> 00:17:24,644 as you mentioned, you know, 464 00:17:25,105 --> 00:17:27,825 most of these implementations use a resonator. So 465 00:17:27,825 --> 00:17:29,744 one of the simplest could be, say, an 466 00:17:29,744 --> 00:17:33,029 LC resonator like you might encounter in first 467 00:17:33,029 --> 00:17:34,950 year physics, so just an inductor and a 468 00:17:34,950 --> 00:17:35,450 capacitor. 469 00:17:36,150 --> 00:17:37,610 Now one of the key 470 00:17:39,269 --> 00:17:40,809 developments of the, 471 00:17:41,269 --> 00:17:44,230 MOSFET transistor of, the kind of transistors that 472 00:17:44,230 --> 00:17:45,285 came before is that 473 00:17:46,484 --> 00:17:49,705 its gate is effectively a capacitor. 474 00:17:50,404 --> 00:17:54,105 And so when you supply inputs to a 475 00:17:54,244 --> 00:17:55,625 seamless logic cell, 476 00:17:55,924 --> 00:17:58,164 what you are doing is storing energy on 477 00:17:58,164 --> 00:18:00,720 the capacitors of the gates of of that 478 00:18:00,720 --> 00:18:03,839 logic cell, and then the logic cell will 479 00:18:03,839 --> 00:18:06,259 then generate outputs, and those outputs will 480 00:18:06,720 --> 00:18:09,059 then drive additional capacitive gates. 481 00:18:09,920 --> 00:18:12,579 And so if you can arrange your circuit 482 00:18:13,105 --> 00:18:13,684 so that 483 00:18:14,065 --> 00:18:15,444 these capacitive gates 484 00:18:16,304 --> 00:18:16,884 are effectively 485 00:18:17,265 --> 00:18:18,484 one big capacitor 486 00:18:19,024 --> 00:18:21,505 and then you tie that to an inductor, 487 00:18:21,505 --> 00:18:22,005 then 488 00:18:22,625 --> 00:18:24,544 you're already most of the way there because 489 00:18:24,544 --> 00:18:27,444 now you've built an LC circuit. And so 490 00:18:27,720 --> 00:18:29,319 at some points in time, that, 491 00:18:30,119 --> 00:18:33,319 inductor will have all of the energy stored 492 00:18:33,319 --> 00:18:35,079 within it, and the capacitors will be in 493 00:18:35,079 --> 00:18:37,400 some well, they will have no energy stored, 494 00:18:37,400 --> 00:18:39,339 and they will be computationally neutral. 495 00:18:40,085 --> 00:18:42,404 And then at a later time, that energy 496 00:18:42,404 --> 00:18:44,484 from that inductor can move onto the capacitive 497 00:18:44,484 --> 00:18:45,625 gates of those transistors. 498 00:18:46,005 --> 00:18:48,884 And then those gates are computationally active and 499 00:18:48,884 --> 00:18:50,265 you can generate an output. 500 00:18:50,805 --> 00:18:51,464 And then 501 00:18:52,190 --> 00:18:54,029 because this is an oscillatory circuit, they can 502 00:18:54,029 --> 00:18:55,549 then pull that energy back. And so that's 503 00:18:55,549 --> 00:18:57,170 kind of the fundamental principle. 504 00:18:58,509 --> 00:19:01,630 That's not enough because, you know, you need 505 00:19:01,630 --> 00:19:02,130 to 506 00:19:02,589 --> 00:19:05,309 then control how the outputs are generated. And 507 00:19:05,309 --> 00:19:06,990 so really you have kind of a number 508 00:19:06,990 --> 00:19:09,125 of these, not too many, but a number 509 00:19:09,125 --> 00:19:11,785 of these LC circuits. And so kind of 510 00:19:11,845 --> 00:19:13,704 you divide your computation into 511 00:19:14,085 --> 00:19:15,304 a few different stages, 512 00:19:15,605 --> 00:19:17,525 and then each of those stages has their 513 00:19:17,525 --> 00:19:18,025 own. 514 00:19:18,404 --> 00:19:19,684 Yeah. We we do it a little bit 515 00:19:19,684 --> 00:19:22,500 more compactly, but as a first order, you 516 00:19:22,500 --> 00:19:24,259 could imagine that each of these stages has 517 00:19:24,259 --> 00:19:25,240 their own inductor. 518 00:19:26,579 --> 00:19:29,299 Okay. What stage is Vericomputing at now? I 519 00:19:29,299 --> 00:19:30,899 think you're in the process of building a 520 00:19:30,899 --> 00:19:31,399 chip? 521 00:19:32,419 --> 00:19:35,444 Yeah. So we last year, we got our 522 00:19:35,444 --> 00:19:37,684 seed funding. We built our team, and we 523 00:19:37,684 --> 00:19:38,184 actually 524 00:19:38,644 --> 00:19:41,204 fully taped out our first well, we taped 525 00:19:41,204 --> 00:19:43,125 out our first test chip. It's not come 526 00:19:43,125 --> 00:19:45,704 back yet. So hopefully, we'll be able to 527 00:19:45,924 --> 00:19:48,164 announce that and its results in in the 528 00:19:48,164 --> 00:19:50,009 future. But yeah. So we've 529 00:19:50,650 --> 00:19:52,910 developed our first test chip. And what 530 00:19:53,369 --> 00:19:54,670 that chip does is 531 00:19:55,049 --> 00:19:55,549 really 532 00:19:56,089 --> 00:19:57,710 kind of bring together 533 00:19:58,329 --> 00:19:59,630 all of the different aspects 534 00:20:00,170 --> 00:20:03,769 of what a potentially commercially viable reversible chip 535 00:20:03,769 --> 00:20:05,994 would look like. So back in the nineties 536 00:20:05,994 --> 00:20:09,115 and more recently, people have made purely reversible 537 00:20:09,115 --> 00:20:11,515 chips and that the logic is reversible, but 538 00:20:11,515 --> 00:20:14,335 it doesn't actually have the capability to recover 539 00:20:14,394 --> 00:20:16,875 signal energy. And so our test chip, when 540 00:20:16,875 --> 00:20:18,710 we get it back and announce it, should 541 00:20:18,710 --> 00:20:20,710 be able to actually recover that energy within 542 00:20:20,710 --> 00:20:21,369 the system. 543 00:20:21,910 --> 00:20:23,830 And then we should be able to, well, 544 00:20:23,830 --> 00:20:25,930 measure how much how much better it is. 545 00:20:26,070 --> 00:20:28,710 And then what we're doing now is so 546 00:20:28,710 --> 00:20:31,190 so we want to commercialize this technology as 547 00:20:31,190 --> 00:20:32,570 quickly as possible. And 548 00:20:33,234 --> 00:20:35,234 really within the next few years, we think 549 00:20:35,234 --> 00:20:36,214 that there's 550 00:20:36,595 --> 00:20:39,154 a urgent demand for more energy efficient computing, 551 00:20:39,154 --> 00:20:41,954 but also energy efficient computing that doesn't look 552 00:20:41,954 --> 00:20:43,554 that different. Obviously, there are a lot of 553 00:20:43,554 --> 00:20:44,054 different 554 00:20:44,434 --> 00:20:47,650 various approaches to kind of making computing more 555 00:20:47,650 --> 00:20:50,929 energy efficient, but reversible computing's advantage, and this 556 00:20:50,929 --> 00:20:53,329 was actually something it was criticized for in 557 00:20:53,329 --> 00:20:54,309 the past that 558 00:20:54,690 --> 00:20:56,549 changes have been made, is that 559 00:20:56,929 --> 00:20:59,984 so reversible computing as we implement it has 560 00:20:59,984 --> 00:21:00,644 the same 561 00:21:01,505 --> 00:21:02,005 programming 562 00:21:02,625 --> 00:21:04,085 approach as conventional. 563 00:21:04,384 --> 00:21:06,464 And we, you know, have a little bit 564 00:21:06,464 --> 00:21:06,964 of 565 00:21:07,345 --> 00:21:09,744 extra complexity in in the logic to account 566 00:21:09,744 --> 00:21:11,125 for this. But effectively, 567 00:21:12,065 --> 00:21:14,404 you know, if you build, say, an inference 568 00:21:14,545 --> 00:21:15,045 accelerator, 569 00:21:15,390 --> 00:21:17,630 you should be able to just plug this 570 00:21:17,630 --> 00:21:21,230 into a server, launch PyTorch, and have it 571 00:21:21,230 --> 00:21:23,630 run. And so what we're doing this year 572 00:21:23,630 --> 00:21:24,130 is 573 00:21:24,430 --> 00:21:25,650 we are trying to 574 00:21:26,190 --> 00:21:28,430 take the print source we implemented in our 575 00:21:28,430 --> 00:21:31,170 test chip and really make them 576 00:21:31,505 --> 00:21:34,065 scalable so that we can build powerful chips 577 00:21:34,065 --> 00:21:34,565 and 578 00:21:34,865 --> 00:21:37,345 improve the efficiency of all the individual components. 579 00:21:37,585 --> 00:21:39,745 So last year was more making a proof 580 00:21:39,745 --> 00:21:42,384 of concept or proof of viability, and and 581 00:21:42,384 --> 00:21:44,005 now we're trying to get it to be 582 00:21:44,144 --> 00:21:46,679 actually something that people would want to buy. 583 00:21:47,299 --> 00:21:49,139 And what does success look like for you 584 00:21:49,139 --> 00:21:50,279 in the next few years? 585 00:21:51,299 --> 00:21:54,359 Yeah. So in the next few years, particularly 586 00:21:54,500 --> 00:21:56,259 by, you know, 2027, 587 00:21:56,259 --> 00:21:57,399 2028, 588 00:21:57,460 --> 00:21:58,359 starting to 589 00:21:58,819 --> 00:21:59,720 sell actual 590 00:22:00,194 --> 00:22:00,694 reversible 591 00:22:01,315 --> 00:22:01,815 chips 592 00:22:02,194 --> 00:22:02,694 that, 593 00:22:03,234 --> 00:22:04,615 you know, you could, say, 594 00:22:05,075 --> 00:22:05,815 put in 595 00:22:06,274 --> 00:22:08,994 a data center or put in a mobile 596 00:22:08,994 --> 00:22:10,515 device. You know, there are lots of different 597 00:22:10,515 --> 00:22:12,839 applications. Right? You can make this much more, 598 00:22:13,319 --> 00:22:15,980 obviously, it's intrinsically more energy efficient. But 599 00:22:16,839 --> 00:22:18,200 what that means, you know, whether you want 600 00:22:18,200 --> 00:22:19,720 this in a low power device or whether 601 00:22:19,720 --> 00:22:21,400 that just means you want to do even 602 00:22:21,400 --> 00:22:23,480 more computation for the same amount of energy, 603 00:22:23,480 --> 00:22:25,659 that's that's something you can play around with. 604 00:22:25,960 --> 00:22:27,765 So success would look like we want to 605 00:22:27,765 --> 00:22:29,765 be selling products in a few years. We 606 00:22:29,765 --> 00:22:31,065 want this to actually be 607 00:22:31,605 --> 00:22:33,445 to move out of the lab, out of 608 00:22:33,445 --> 00:22:35,384 academia. We want this to be something 609 00:22:36,005 --> 00:22:37,465 that is commercially viable. 610 00:22:38,404 --> 00:22:40,164 And then we want to build off that 611 00:22:40,164 --> 00:22:42,805 and keep improving the energy efficiency of this 612 00:22:42,805 --> 00:22:45,420 and really get to a new scaling law, 613 00:22:45,420 --> 00:22:45,920 something 614 00:22:46,460 --> 00:22:48,380 akin to Moore's law, something not going to 615 00:22:48,380 --> 00:22:51,599 be identical. You know, scaling down of transistor 616 00:22:51,660 --> 00:22:55,200 size pretty much hitting its its limit, but 617 00:22:55,914 --> 00:22:57,914 we think that, you know, at least energy 618 00:22:57,914 --> 00:23:01,355 efficiency, you can keep doubling that every cell 619 00:23:01,355 --> 00:23:01,855 phone, 620 00:23:02,234 --> 00:23:04,634 maybe all throughout there every two years, but, 621 00:23:04,955 --> 00:23:07,214 that could be ambitious, could be unambitious. 622 00:23:07,994 --> 00:23:09,295 And we want to then, 623 00:23:09,950 --> 00:23:13,150 effectively in twenty years time, have computation that's 624 00:23:13,150 --> 00:23:15,869 a few thousand times more energy efficient than 625 00:23:15,869 --> 00:23:16,690 it is today. 626 00:23:17,150 --> 00:23:20,190 And the ultimate success would be if this 627 00:23:20,190 --> 00:23:23,309 becomes kind of a fundamental part of how 628 00:23:23,309 --> 00:23:23,970 you build 629 00:23:24,484 --> 00:23:26,484 most computing systems. There's always gonna be a 630 00:23:26,484 --> 00:23:29,924 need for traditional irreversible computing, and the reason 631 00:23:29,924 --> 00:23:30,744 for that is 632 00:23:31,125 --> 00:23:32,744 that reversible computing excels 633 00:23:33,045 --> 00:23:36,244 at parallel tasks. But for very serial tasks, 634 00:23:36,244 --> 00:23:36,569 it's 635 00:23:37,529 --> 00:23:38,669 this slowdown 636 00:23:39,210 --> 00:23:41,609 becomes more more significant. So there's always gonna 637 00:23:41,609 --> 00:23:43,549 be a need for kind of a CPU 638 00:23:43,609 --> 00:23:47,069 type architecture, but perhaps anything which is parallel, 639 00:23:47,450 --> 00:23:49,769 might lead to a more reversible architecture. And 640 00:23:49,769 --> 00:23:53,125 maybe in ten, twenty years' time, every computer 641 00:23:53,125 --> 00:23:54,484 you buy might have a little bit of 642 00:23:54,484 --> 00:23:56,964 reversibility or maybe a lot of reversibility in 643 00:23:56,964 --> 00:23:57,464 it. 644 00:23:57,845 --> 00:23:59,525 That's fascinating. We'll have to check back with 645 00:23:59,525 --> 00:24:01,045 you in a few years. It'll be interesting 646 00:24:01,045 --> 00:24:03,444 to see particularly how this develops in parallel 647 00:24:03,444 --> 00:24:05,924 with quantum computing, which I think, likewise, people 648 00:24:05,924 --> 00:24:07,065 who work in that field 649 00:24:07,410 --> 00:24:09,410 recognize that quantum computers are not gonna do 650 00:24:09,410 --> 00:24:09,910 everything, 651 00:24:10,289 --> 00:24:11,970 but they may do some things well. It'll 652 00:24:11,970 --> 00:24:13,029 be interesting to see 653 00:24:13,570 --> 00:24:16,150 an evolution maybe beyond the sort of monolithic 654 00:24:16,369 --> 00:24:20,130 CMOS technology and monolithic irreversible CMOS technology that 655 00:24:20,130 --> 00:24:22,365 we have at the moment towards this quantum 656 00:24:22,424 --> 00:24:23,625 area and towards this, 657 00:24:24,184 --> 00:24:25,404 reversible computing 658 00:24:25,865 --> 00:24:26,365 paradigm. 659 00:24:27,304 --> 00:24:29,224 Yeah. It'd be really interesting to see where 660 00:24:29,224 --> 00:24:29,724 heterogeneous 661 00:24:30,184 --> 00:24:30,684 architectures 662 00:24:31,065 --> 00:24:32,904 end up going. And so obviously, we've had 663 00:24:32,904 --> 00:24:34,924 a huge amount of success in the traditional 664 00:24:35,650 --> 00:24:37,750 digital programming model, and 665 00:24:38,529 --> 00:24:40,049 there were a lot of advances that and 666 00:24:40,049 --> 00:24:42,470 that will probably never go never go away. 667 00:24:42,690 --> 00:24:43,190 But 668 00:24:43,650 --> 00:24:45,250 we've made a lot of progress in the 669 00:24:45,250 --> 00:24:45,750 last 670 00:24:46,609 --> 00:24:50,244 few decades in quantum and analog and photonic 671 00:24:50,384 --> 00:24:52,644 and and all of these other computational paradigms. 672 00:24:52,944 --> 00:24:53,684 And so 673 00:24:54,464 --> 00:24:56,625 I I can very much see that maybe 674 00:24:56,625 --> 00:24:58,085 in in the future, you'll 675 00:24:58,384 --> 00:25:00,865 not just have a CPU and a GPU, 676 00:25:00,865 --> 00:25:02,464 but maybe all of these other, 677 00:25:02,865 --> 00:25:04,369 types of computation 678 00:25:04,910 --> 00:25:07,869 embedded. Maybe not into your into your cell 679 00:25:07,869 --> 00:25:09,329 phone, but maybe into 680 00:25:09,710 --> 00:25:10,210 supercomputing 681 00:25:10,509 --> 00:25:12,369 clusters and data centers at least. 682 00:25:13,390 --> 00:25:15,390 Hannah Early, thank you much for joining us 683 00:25:15,390 --> 00:25:16,210 in the podcast. 684 00:25:16,829 --> 00:25:17,809 Thank you, Margaret. 685 00:25:27,164 --> 00:25:30,525 That was Margaret Harris in conversation with Hannah 686 00:25:30,525 --> 00:25:31,025 Earley, 687 00:25:31,349 --> 00:25:31,849 cofounder 688 00:25:32,230 --> 00:25:32,970 of VerComputing. 689 00:25:34,069 --> 00:25:36,650 You can find out more about Hannah's journey 690 00:25:36,789 --> 00:25:40,789 from getting a PhD in applied mathematics and 691 00:25:40,789 --> 00:25:42,089 theoretical physics 692 00:25:42,549 --> 00:25:44,089 to becoming the cofounder 693 00:25:44,549 --> 00:25:46,089 of a start up company 694 00:25:46,585 --> 00:25:47,884 in the career section 695 00:25:48,184 --> 00:25:49,485 of Physics World. 696 00:25:50,025 --> 00:25:51,325 Just look for the headline, 697 00:25:51,705 --> 00:25:52,924 Ask Me Anything. 698 00:25:53,305 --> 00:25:56,904 Hannah Earley. I love theory, but seeing an 699 00:25:56,904 --> 00:25:59,965 idea get closer and closer to reality 700 00:26:00,345 --> 00:26:01,164 is great. 701 00:26:01,730 --> 00:26:03,570 I'm afraid that's all the time we have 702 00:26:03,570 --> 00:26:06,369 for this week's podcast. Thanks to Hannah and 703 00:26:06,369 --> 00:26:08,070 Margaret for a fascinating 704 00:26:08,450 --> 00:26:10,549 introduction to reversible computing, 705 00:26:10,930 --> 00:26:13,730 and a special thanks to our producer, Fred 706 00:26:13,730 --> 00:26:14,230 Isles. 707 00:26:14,690 --> 00:26:17,585 We'll be back again next week. See you 708 00:26:21,484 --> 00:26:21,984 soon.