# Quantum computing with Chad Rigetti

**Author:** Chad Rigetti
**Type:** Video
**URL:** https://www.ycombinator.com/library/7S-quantum-computing-with-chad-rigetti
**YouTube ID:** GzMvG8UO6Eg

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Chad Rigetti, founder of Rigetti Quantum Computing (YC S14), talks about quantum computing and Rigetti's founding story.

## Transcript

everybody our next speaker is Chad retti from retti Quantum Computing retti Quantum Computing went through YC in the summer of 2014 um at that point they had nothing uh they are now one of the leading Quantum Computing companies in the world and next year well I don't know exactly when they are getting close to a Quantum Supremacy machine uh I have a particular love for the startups where they're trying to do something it's not clear if it's technically possible but if they do

uh it changes the world and it just goes nothing nothing nothing nothing and then everything is different uh these companies are super fun to work with uh and I think they're super fun to work on which is why I'm so excited Chad's here to tell us about retti and also hard technology startups in general um and why it's okay if you don't have a growth graph every week uh sometimes you just work and work and work and then everything comes together um Chad come out here because I have a question for you so Chad and I met on the streets uh of San Francisco

in uh walking around the financial district in 2014 and Chad had not yet started his company but was thinking about it and Chad and I have actually never spoken about this again but I think I hope you remember this um I think Chad thought I was really crazy because we got into a long conversation about this simulation hypothesis and if a building a quantum computer was actually really bad because it would use a lot of resources uh to emulate and shut down the simulation did you think I was really crazy it was a very interesting

conversation is that like a really nice you can say yes I didn't think you're crazy but I had just moved to San Francisco into Silicon Valley from New York City and that is not a conversation you can have in New York City without people thinking you're crazy uh but I'm an open person and I you know I like to learn so I was very interested in this hypothesis and it was an amazing conversation it was very fun all right well I hope the company works and I hope the simulation does not shut down um great thank you that will help all right

so Chad is going to talk to us about retti thank you for coming Chad awesome thank you so much Sam all right I'm incredibly excited to be here today and to talk with you guys um I'm also incredibly honored so thank you very much Sam and Cat and YC for having me uh giving me the opportunity to talk with you guys so this uh as Sam mentioned when we joined Y combinator in summer 2014 we had nothing uh we had not

built a single Cubit the fundamental like building block of a computer we did not know how we were going to build cubits uh I knew what they needed to look like and I knew uh what the fundamental requirements were in fact I'd been working in the field for already about 10 or 12 years in Quantum Computing um and uh this is a 5 Cubit quantum computer that we have built at retti computer uh it's less than 2 years later and uh

we're about 35 people in a warehouse in Berkeley uh about 20 some phds and we're building cor computers and we're in a race uh to Define this technology for the next 20 30 40 years and it's incredibly fun it is a kind of thing that gets you up in the morning and is worth spending your life on humans are building humans have been building tools and Technology to store and process information for Millennia uh

I like to think of the Sund dial as the original computer it takes an input and it tells does something useful with it and tells you the time uh from the Sundial to the Abacus uh and then things like the babage Difference Engine which you can go see at the Computer History Museum it's amazing and you should do it um to Punch Cards those are all systems based on Newtonian mechanics and every time our understanding of nature Evol evolves and develops further we had a deeper level of understanding our technology progresses as well so uh many

great companies were born of this first transition that I'm talking about on the slide uh IBM started as a Computing tabulating and recording company they made punch punch cards and time clocks uh they were kind of born out of this first transition into the microchip era and uh they they you know they blossomed and evolved and survived through the through this time to grow into a very very large company other companies that drove that first transition uh who was it Fairchild Intel and then what's been born in the era of the microchip well

almost everything we see around us it's driven the global economy for the past 50 or 60 years that's incredible the amount of Leverage you can get from a Computing technology is massive and you know what we've known since 1905 that beneath uh there's Newton's laws on one hand and then beneath that there's kind of Maxwell's equations and we've known since 1905 that there's a fundamental description of Nature and that's quantum mechanics uh at rietti Computing we're driving this next transition from microchips to those systems based on

individual atoms or artificial atoms that we build in in in the lab uh and that that's a very exciting opportunity for for us so why is it worth doing this this sounds incredibly hard why is it worth uh trying to build quantum computers in the first place well the kind of problems that these machines will solve are incredibly impactful they fall into two broad categories we think of them in in kind of two broad categories on the one hand you have a class of

applications that we think of as quantum chemistry so what you're doing in this case is using the quantum mechanical the the quantum computer as a tool to investigate other quantum mechanical systems it turns out that that's almost everything uh in science uh medicine Material Science this is stuff that's going to lead to better drugs uh better materials better nuclear reactors highly impactful technology why are we doing this because if you can you you build a Quant computer you can do simulation driven design of new

catalysts Catalyst to capture carbon or nitrogen from the atmosphere it can help solve global warming this is an incredible incredibly broad technology uh the other bucket of applications uh is is machine learning and artificial intelligence so in this case what you do is learn to embed a learning problem on a classically intractable physical model that you can simulate on a quantum computer that's a mouthful what it means is quantum computers are going to lead to fundamentally more powerful forms of artificial

intelligence so when I say more powerful what do I mean uh does anyone recognize this H it's on the slide so this is ton he 2 uh this is until about three months ago was the most powerful computer on the planet it cost about $400 million it burns about 20 megawatts of electricity you guys know how much electricity that is it's enough to it's enough to power

about it's enough to power the town I grew up in about 20,000 households it's about half the size of a football field it's based on 3.2 million Intel cores so there's two problems with this ultimately our approach to building large scale computers is starting to break and there's two problems the first is that Moors law is ending that's been happening for a long time lateral transistor scaling the fundamental measure of Moors law has sort of leveled

off for the past eight years the other thing is something that I hope you've all heard about in your computer science class is called omd's law omd's law talks about the limiting benefits or the diminishing returns of parallelization these are massively parallel machines 3 2 million cores running in parallel only problems that can be parallelized run fast on these kinds of machines uh there's a fundamentally better way now President Obama has shown some significant Vision in uh sort of driving

uh a return of American leadership and high performance Computing and he has said said that America is going to build an exascale computer something about 30 times more powerful than ton 2 by 2020 that machine will cost about a billion dollars with current technology and it would require a nuclear power plant to run it we're going to do it and we need to but there's another path ultimately when you can compute with quantum physics you have a faster and cheaper path to that level of of

computing power how is that possible well these are two developmental systems in our lab in Berkeley these are what you see in the big white cans are cooling systems every high performance computer has a cooling system these ones are very powerful these runs at low temperature uh inside each of those cooling systems is a single chip when this picture was taken we had a 5 Cubit processor in that machine a single chip with about 60 or 70 cubits on it would be more powerful than that entire half a football field

side size machine that's what Quantum Computing unlocks uh so this is a true hard tech startup and one of the challenges that hard tech companies I'll talk about this more in a moment brings is this challenge of operating in in an arena that is not well- defined that does not have a welldeveloped supply chain you know what you want to do but the capabilities to do it do not exist or not commercially or or easily accessible we've had to develop all of the building

blocks the entire supply chain for this technology what does that mean for us we have developed new new simulation driven design methods to actually devel design these Quantum chips uh we had develop our own Fab our own microfabrication capability uh We've developed advanced electronics that allow you to control these these chips you can think of a quantum computer something like a nuclear reactor where you have the core the N you know where where the reaction's happening that generates all the power but then there's this really complex traditional engineering system around it that stabilizes it and

extracts a computational capability and that thing is very expensive and it requires very Advanced control electronics and then ultimately uh we serve access to these machines over the cloud and so we have to have Cloud software and applications and that's a lot of work there's a lot of different things you got to tie together in one organization to do this uh this slide is frankly a synthesis of the past 15 years of my life I've been working on this problem my entire adult life uh I was a junior in college in Saskatchewan Canada

and really that's amazing where are y'all from oh wow moja here Mo um I was I I was a junior at the University of reg Regina in Saskatchewan Canada and a physics major I was incredibly frustrated I was very very frustrated because I didn't understand two basic things that I thought every human on the planet should understand what's quantum physics and how do computers actually

work how do they actually store process represent information about the same time I read about a field called Quantum Computing I like to synthesize things I thought this was amazing there's one field that I can learn instead of having to learn two this makes life so much easier I've been working on that ever since and that was in 2001 uh I heard about these people at Yale University that had an idea for building quantum computers uh you can

build these things out of real individual atoms or ions that's really hard because individual atoms or ions are extremely tiny and very very hard to control they said why don't we build these things out of special electrical circuits based on superconductors that have no dissipation and build them in such a manner that they mimic real atoms build an artificial atom out of an electrical circuit I like that that's amazing that's such a great idea because what's going to happen is you're going to be able to leverage all of traditional semiconductor manufacturing capabilities

you're going to be able to build a scalable T chip technology someday based on those superc conducting cubits I spent about seven years with those uh with that group at Yale I was a PhD student at postto uh I spent about three years in doing further research at IBM in Quantum Computing and in 2013 I started retti Computing to develop Quantum integrated circuits and that's what we've done so this is the jump on my second slide this is the leap from

Newtonian plus Maxwell's equations to Newtonian plus Maxwell's equations plus Short's equations quantum physics and uh ultimately I want to offer you a work working definition if there's any physics majors in in the audience I want to give you a working definition of a quantum computer quantum computers store and process information in individual photons that's it um your iPhone the iPhone 7 uses about 100 billion photons per bit processed it

may be as much as 10 the 17 uh and 100 billion photons per bit transmitted this is far more efficient technology okay so I want to talk for a moment about the distinction between a hard tech company and a tech company first of all when I say hard tech I don't mean it's harder although it feels harder what we mean is every company and look at the company on this slide these are incredible

organizations incredible incredible organizations incredible companies incredible products incredible Founders these are all incredibly hard things there's one distinction a hard check company has to deal with in includ in addition to all of the tech execution Market risk all the standard things all the gauntlet that you have to steer your organization through to survive fundamental questions of possibility you have to deal with that when you're a hard tech company that is the that is the signature of a hard tech

organization now there's two things I want you to take away from this the first is that well with all of that risk we're saying it might not even be possible why the hell are you going to do that why the hell is anyone going to invest in your company if it might not be possible to even do it why is it worth it if you're not sure it's possible well there's two things you get from my perspective the first

is if and when you are successful you create Monumental leverage and defensibility I think of the Manhattan Project as a canonical hard tech organization look at the leverage they created that's incredible the Apollo missions when President Kennedy said in 1961 as a nation we're going to put a American on the surface of the Moon and return him safely to Earth by the close

of this decade that was an epocal moment for mankind that's the kind of story that isn't written in quarterly reports and spreadsheets that's written in heroglyph on Cave walls that's the kind of stuff that stirs the heart that's what you get when you do a hard tech company and that is so powerful I want you to notice something

on the slide look at these amazing companies at some point the defensibility and leverage that hardtech provides and the incredible passion that you engender uh by working on problems of that scope and impact leads organizations on the left to pushing into the into hard tech in order to access those things think of uber moving into self-driving cars think of Google with now 100 seedlings hoping

to turn something into a long-term defensibility Microsoft buil software and has started working on Quantum Computing that's what you get with a hard tech company now there's also significant challenges and I want to talk about three of them for a moment team communication and integration so first of all building an organization that has world's experts in XY Z all of the things that you need to

master as an organization is incredibly hard it comes with its own set of challenges you're going to have to interface to the best scientists and Engineers on the planet in those various Fields you're going to hire them you're going to have to bring them all into one company and you're going to have to find a way to impedance match them to allow them to talk to each other and under the roof of one organization and that leads into this integration challenge integrating an organization that does all these disparate things we have people on the team uh we have a

road scholar uh who's been doing research in Quantum Computing for 10 years and is 27 years old uh we have tenured physics faculty we have someone teaching a course at keltech who built the communication systems on the Mars rover missions we have an incredible organization and one of the problems we've solved that that we we have people who can all have a conversation together because they all have developed a shared language that level of integration becomes a long-term weapon for your organization huge amount

of uh value can be created by it now communication we're not doing this because Quantum Computing is interesting we're doing this to cure cancer and to solve global warming how you talk about what you do as an organization is incredibly impactful I encourage you to spend a lot of time thinking about it I did this a few years ago and I decided that our mission as an organization when there were three people in the company was we're on a

mission to build the world's most powerful computer it gives you something to sink your teeth into it's a little more tangible than photons we did this exercise again in the in the past month uh with with the team fully built out well partially built out at this stage and uh we got to the same thing it's really amazing why are we doing it we're bu we're building the most powerful computers in the world to solve Humanity's most important and pressing problems that's a rallying cry

that can be very impactful for your organization now the other thing you get with integration is the opportunity to create all this defens ability so the chip the quantum integrated circuit is one part of it that gives you an Intel kind of business for the quantum Computing era we're not stopping at that because no one is competing at all these different levels today and we have an opportunity to build Moes around the entire thing the next layer up is to build the system become do Master System integration that's an IBM style business and then ultimately to own the software and platform uh add in the Microsoft

style business ultimately I want to go full stack and also include the Google style business of applications and and designing new drugs to to save people's lives all right so before I move on to this I want you all to do something for me I want you to do this one thing for me I want you to take 10 minutes today after this at the break when you go home today during your meditation whatever you want to do I want you to take 10 minutes and look in your heart and I

want you to ask yourself the question what kind of company do I want to join or found what kind of organization resonates with me and when you do that spend that 10 minutes when you do that some small fraction of you it won't be many some small fraction of you will say you know what I want to do the thing that stirs my heart I want to do the thing that calls to me that is worth spending your life on one last thing so one of the special

challenges that a hard tech organization faces is the capabilities to do what you need to do don't exist if they existed it wouldn't be a hard tech organization so there's this tension that exists in all companies but is especially accentuated in hard tech a tension between developing the product take your product from concept to Market get the product built ship the product with the things you need to do to enable that at each successive stage of evolution company development build the

capabilities and create organizational Clarity that's your job as a founder and a leader what should you work on well I found that there's a useful framework I thought about this problem for a really long time because I was spending every day trying to balance these two competing tensions ultimately these are both processes of pumping entropy out of the system you have an idea for the product I know what this quantum computer wants to look like it's all you know we we but it doesn't exist it doesn't exist yet there's all these questions we have to

answer think of when Elon started SpaceX he had an idea for what this rocket was going to look like there's a gazillion micro decisions that have to be made to actually manifest that thing in the real world that is a process of pumping entropy out of the vision same with company development creating this organizational Clarity building the capabilities answering the question are we going to do our own Fab are we going to Outsource Fab are we going to partner with IBM to do the Fab are we going to how are we going to do the Fab we have to answer that question ultimately that is a process of pumping ENT of the system there's a lot of things that this leads you to one is it tells you who you should

hire some people create order and Clarity in their wake they create systems they execute systems they reinforce systems they train other people how to use those systems other people generate entropy know what you're looking for hire people who pump entropy out of your vision for your organization it's incredibly powerful so this is one of my favorite pictures I've ever seen this is a picture of the Control

Data Corporation 6600 machine what I love about it is look at howy it is there's wires hanging out of this thing everywhere you can see the pumps down in the corner this machine was the is widely considered the first supercomputer the United States blocked the export of one of these things to our allies in France it was incredibly impactful at a geopolitical

level and who built it a group of 34 folks in the woods of Wisconsin 34 people built the world's most powerful computer I can't even read the memo it's too powerful ultimately 34 people out competing a giant Behemoth that is what happens in high performance Computing that is what happens with a lot of hard tech organizations and it's an incredible opportunity for you if this pulls at your heartstrings thank you

very much
