good evening i'm yvonne step for science for the public and i welcome you to tonight's contemporary science issues and innovations our subject is quantum computing and quantum biology and our distinguished guest is seth lloyd one of the pioneers in quantum computation seth lloyd is the naam peace professor of mechanical engineering at nest two sets institute of technology in addition he is principal investigator at the m research laboratory of electronics and director of the center for extreme quantum information theory x at mit he's also an adjunct professor at santa fe institute and is on the editorial board of quantum information processing dr lloyd was already an emerging star in quantum computation before he received his p h d in theoretical physics from rockefeller university in one nine hundred eighty eight he went on to cal tech to work with nobel laureate marie gilman where he developed the first viable design for a quantum computer and the first demonstration of quantum algorithms when dr lloyd joined the faculty at mit in one thousand nine hundred four he was in the stablished leader in the development of quantum computation physics of information and complex more recently he's made an important contribution to the emerging field of quantum biology as well in addition to his contribution to an awards for quantum computation dr lloyd has been an educational innovator training the next generation of mit geniuses and he's also written a book for the general public programming the universe in which he outlines his concept of the universe as a cow quantum computer he'll discuss all of this tonight it's a great pleasure and an honor to welcome dr seth boyd welcome sir thank you very much yvonne it's great to be here ok i have to start with computation just generally please could you help us out here with the difference between digital computers that we use now and quantum computers what's the difference so digital computers of which almost everybody has a very powerful one even in their smartphone are very common and they process lots and lots of information for us and the way they process information is they chop up that information into tiny pieces called bits now a bit is just the distinction between two possibilities yes or no zero or one yeah true or false and then in a conventional digital computer this bit is represented in physically by having a little capacitor a kind one and all of the fancy things that ordinary classical computers do simply involves flipping bits in a systematic way now part of computers are also computers and they process information and they chop up the information to the very tiny pieces and they flipped it but the difference is that the bits in a quad a computer are represented at the most tiny level the very small sample you could have say rather than having a whole bucket full of electrons representing a one you could have a single electron here representing or you would have an electron there representing a zero so far around once he was at a concert somebody asked him james what are going to play next and he said i don't know but whatever it is it's got to be funky so quantum mechanics is kind of the james brown i so so  central funkiness of quantum mechanics comes because particles like electrons have waves that are associated with them so wave over here a means electron pretty much over here wave over there means electron pretty much over there but it's totally ok for an electron to have a wave which is here and there at the same time this means that the single electron is both over here and there simultaneously which means considered as a b cuban that is in some funky quantum sense that nobody really understands registering both zero and one simultaneously it's weird it's strange i don't understand it i don't know anybody who does but that's the way it is but it's fast and it's mighty is that the i do yes well quantum computers don't get their power so much from being faster though than classical computers though they could be much faster it's really from this quantum weirdness this quantum funkiness so if i have an electron that can be here and there at the same time zero one and zero simultaneously and i feed this quantum bit into a quantum computer as a program let's suppose that it was zero says do this like add two plus two one says do that add three plus one so if i put this single quantum the quantum computer then just in the same way that this bit is both zero and one of the same time the quantum computer is now doing this and that at the same time adding two plus two and three plus one simultaneously in some funny quantum set so quantum computers can do this kind of strange quantum multitasking that classical computers can't and this is this ability to do multiple things at once not just two but for  another technical term and a way to do a good zillion things at once that allows them to solve problems that you can't solve on a classical computer so even a very small quad of computer with only say hundred quantum bits could do some things that classical computers could never ever do and just at a time when we need that kind of capacity i suppose given the kinds of data and amount of data that we deal with if i have a quantum bit like this electron that's here and there simultaneously and then somebody comes along and looks at it to say hey are you here or are you there then what will happen is that the electron will spontaneously appear either to be here or to be there no longer here and there simultaneous so if somebody looks at the electron they disturb it and then this means you can also detect to see if somebody has peaked so you can detect eavesdroppers and hackers who are looking at your quantum bits and this means for instance you can make quantum computers that are effectively immune to hacking in fact  a major thing i'm sure right right there that will be a major advantage right there unless you're a hacker well ok that means it's the end of that career and the hacking careers are over but that's quite interesting the other thing is that are they they are difficult to create you were the first person that came come up with a viable model of the of a quantum computer so why is it difficult to they're very small yet they're very sensitive it's hard to get them to do what you want them to do you have to ask them very very badly and they still may not do what you ask no matter how nicely you do so but if you if you massage these electrons in just the right way ask them extremely nicely learn how to speak their language and to try to convince them to compute then you can and my colleagues and i and many other people throughout the world have been working for the last two decades to build quantum computers and we actually have succeeding first and building very simple ones with just a couple of quantum bits and then ones with five or ten quantum  we're now working on ones with twenty to fifty quantum bits and we hope that in the near future we'll have quite a computer say with a hundred to a thousand clocks and of course you know compared to your smartphone this is an e of bits but because quantum computers have this capacity to do so many things simultaneously then even a small quad a computer with a few hundred quantum bits could do things that no classical ok so if this becomes standard then you need a lot less to replace the digital computers that we have so much power now that have so much power now is that the idea we need a lot less quantum side to replace this well or not aiming to replace digital cars a list of all we don't want to make enemies about of people who make them and also it's not the case that everything that ordinary digital computer can already but minecraft is already perfectly fine it's not clear that a word processing program such as microsoft word i that you need to have a quantum computer but there are some problems particularly problems for example in finding patterns in very large amounts of data where quantum computers could potentially provide an advantage over the most powerful class and there are quite a few fields today astronomy is one of them of  course but just many fields where you have enormous amounts of data and you have to make these decisions about what you're going to pick for data and throw stuff out in this case that is very powerful if you could have a quantum them well for data analysis and yeah analyzing big data and quantum machine learning there are a whole variety of different problems where quantum computers might be quite helpful just the last couple of days my call they can i have been talking about the quantum netflix our prism so you know if you have a company such as netflix or any other such company that that wants to take your ratings of a few movies and then provide you with a set of movies that they think would be a good set of movies for you then it turns out that doing this in a quantum mechanical fashion would be much more powerful you could you could use you could analyze the data from many many more users who have many more movies and you would have a more subtle analysis of how to present recommendations to actually ironically while wall looking around this is i found so there are a bunch of very standard classical algorithms for doing image processing they're very sophisticated and they do a pretty good job but if you take these classical algorithms and you visioning building in the next five to ten years so three hundred quantum bits could could deal with two to three hundred power pieces of data and this is a large number and i pick it because  three hundred happens to be the number of elementary particles in the universe also but all of all of their herd of three hundred of them and and so in order to have a classical computer that could handle that same you also have developed that you're the first one out the gate on this on the idea that the universe is actually a quantum computer and you happen to have a book that you  wrote for the general public for general readers on the subject so why is the universe a quantum computer so if i think i came to this idea because i was looking at ways of building  computer so what kinds of pieces electrons atoms photons are hoarding most of light what kind of pieces you could you put together to actually construct a computer that would process information in this funky quantum mechanical mattia and i came to the realization that pretty much anything would do because it bottom everything is quantum mechanics all quantum mechanical things atoms molecules photons store information so for instance a photon that's polarized like this so it's a little electric field and we're going back and forth you would call that zero photon polarized like this you could call one or an electron spinning around  call one so so i realize that not only could we take almost anything and make it compute i think i actually said at the time that you know you could make a cup of coffee compute for you if you shine you know massaged it in the right way and convinced it to work to process information in the way we ask you to well it's because these things elementary particles atoms and molecules we're already computing are already registering information you know every atom carries with it bits of information every time two atoms bounce off of each other in the air in this room that information is transformed and process and so they are already processing information the pieces of the univers processing information at the most microscopic level so when we actually you know tickle them with lasers or microwaves to make them do a quantum computation to solve some hard problem what we're doing is not just taking something that was not computing and making it compute instead we're taking something that was computing all along and kind of hacking into its program i think to convince it to compute something different from what it was doing so i came to this realization that you know everything is computing from trying to build these quantum computers but then of course once you realize that then you ask well what is going on in the universe as a whole yeah all of its pieces are processing information  it's processing information in a way that allows what's called a universal computation which is a kind of thing that you know ordinary computers and smart phones and human beings do all the time so the universe is a computer from not from a  metaphorical perspective but from the actual technical definition of a computer moreover because at bottom it's quantum mechanical and this most microscopic information processing is taking place at this quantum mechanical level where everything is completely weird computer it's processing information every and doing it in a way that universal and we can understand a lot about the universe by accepting this realisation what i ask you what we can understand about the universe with this but two things first of all everybody has asked you this i am sure but we have had models of the universe it's a clock at so this it's a digital computer about a quantum computer fine fine so there is there that another very important point that you make in your book is that that's that information is physical and i think even you mention we're not used to thinking that information is something physical but it makes sense as you explain this that yes you know in the in the sixteenth century galileo not only invented the pendulum clock but started to talk about the mechanics of the way the world worked in terms of things like clockwork which became a very common metaphor in the seventeenth century in the early sixty's hundreds and and of course he was you know had a particular model for how things worked and he was applying this mechanical system as a metaphor for the sort of mechanical system what's interesting about that is that in some sense he's right that is that you know he used this notion of trying to understand for instance how pendulum swing back and forth on a regular fashion which to first extent is independent of how far they're swinging to develop the laws of motions which were the precursors to newton's laws of motion so he was in some sense the first modern and he was discovering these mechanical laws for how the universe was working by thinking at the same time about clocks and the universe itself so of course a computer is itself a mechanical object and you know what it's processing information physical things are happening inside them in fact it has a very precise clock monitors how things move back and forth and so when i guess i would i don't take umbrage but i would say yes indeed you know i'm guilty of saying a we're building quantum computers so the universe is a quantum computer but in some sense i mean galileo was also right saying that the universe is essentially a clock in some mechanical system that's performing certain functions in a regular fashion so that's true and it's also  them so the information mate is always physical or whatever that's as i say that's a different thing a different way of looking at it from ation than we usually have but you're feeding you're telling you're giving the computer the commands you're setting it up but this is different so if it operates as it can be cuter then where does that take us in terms of the universe how how does it work if it's a quantum computer moving across through through the air from my mouth to your ears or neural signals i process in the brain that information is always represented by the state of some physical system you know if i raise my voice from down here to up here yeah you know i'm changing the frequency of the waves that are going through the air so that information is conveyed by the actual physical and of the system that's conveying this in for sense that that even when one talks about more sophisticated forms of information processing such as you know what computers are doing when you're playing grand theft auto or what's going on in our brain as we're processing language which the universe set as a quantum computer in terms of what the universe is or does where it's going what started does it tell us anything about that well of course it is already bought us the ability to that well there is one very important feature about the universe which human beings have wondered about for thousands of years that this this fact of the universe is computing explains and that is why is the universe complex yes ok so this is quite bizarre some level it's almost gotten more bizarre as time has gone on because it's become clear over the last few hundred years that the extra so you have a very simple initial state for the universe with almost no information and very simple laws that have you know of the t shirt they have almost very little information so how can you possibly from this simplicity come to the complexity of living systems of human societies of the arrangement of stars and planets and galaxies in the universe everywhere you look things are stunningly complex and the fact that the universe is in fact a computer explains this a ha and this comes from a again this is not a a metaphor it comes from a branch of  mathematics called algorithmic information theory which is how to talk about information in terms of computation and one of the results from this theory this mathematical theory says suppose you have something like the universe which is capable of computation but hasn't yet done anything credibly imply and suppose you start you know programming it here and there at random now what happens is that these little random seeds are like little random programs that are instructing with a part of the universe to do something it's something that looks kind of random instructing this part of the university something else i are very complicated things that have rather simple programs that can generate them what this says is that the fact that the universe is capable of computation and that it's being programmed here and there random means that if you go so more far enough out there you're going to find any complicated thing that you can imagine existing in the universe and moreover these complex things will come into existence with quite high probability aha so so this this fact that the universe is at bottom computing and actually being programmed by weird little quantum randomness which are what are their programming the universe that explains why the universe is complex such a universe that is capable of computation must necessarily generate all forms of complexity including things as complex as human life so you're saying it could not possibly have been static from the get go i think that  given to become complex as long as it's capable of computation that it will compute so even if you try to make it very simple i the existence of these little tiny so called yellow fluctuations of program the universe are you wandered into this i think by accident quantum biology did you not that you were at first amused that anybody would come up with this idea that was in photosynthesis the quantum biology has been left out quite the way but they keep finding very interesting things and as i think as it turned out you came up with one of the real insights on this how did you get into quantum biology basically taking a piece of the photosynthetic system inside green sulfur bacteria it was zapping it with lasers and seeing what happened and what happened was that they got very strong evidence that this kind of quantum weirdness of things being in two places at once was this bacterium is a sector is essentially performing a quantum computation and this was reported in the new york times i read this in the new york times and a bunch of my colleagues read it we had our weekly theory group meeting and everybody thought this was the craziest thing th ever heard but that you know they figure somebody ought to look at it so they delegated me to go look and luckily at that same meeting was my colleague from harvard along us produce it was a professor of chemistry at harvard and he knew a lot about this this material in the experiments that were behind this this claim and so we put together our heads and we looked at the claim and by the way it turned out that the kind of quantum were claiming this green sulphur backed her was performing it wasn't doing it because they were claiming that essentially well i mean photosynthesis works you get a photon particle of light comes in from the sun molecule within the leaf until it gets to a place where its energy can be turned into chemical energy this is called the reaction center we're in this energy in the x aton it's turned into chemical and it's been known for quite a long time that this process was very efficient almost one hundred percent efficient once the light is absorbed this exit on this particle the energy finds this reaction center and can be and is trying to do energy with almost one hundred percent efficien asperger's and i were able to show right away that this wasn't doing a quantum search but instead it was doing another kind of quantum process called a quantum law now quantum walk is a quantum version of the classical random walk where you know if you're had too much to drink you know you want to randomly wander around and you diffuse through this process so if this x autonomy were performing a random walk through this process it would just be through this photo complex it would just be you know jiggling around and eventually hits upon there the reactions that are by accident in a quantum walk because quantum particles such as electrons or x or tongs can be two or three or four or more places at there's lots that we don't understand about it and there is there's ongoing arguments between theorists and experimentalist about the exact form in which this quantum mechanical coherence takes but the fact that these other exa tonnes are here and there at the same coming out left and right in the last few years there's a great interest in this is a long way to go however nobody else that i know of has pointed out something that you sort of solved  and that is the issue of coherence decoherence could you explain this quantum state and why this is so delicate and how you solve for x well so first of all it wasn't just me it was a lot of us produce  interpretive modern dance that explore what i say which you can find one you tube of your warning so so the idea is the following so if you have something that corresponds to medium so you can think of this wave wiggling along and it's just moving along just completely fluidly throughout this meeting and that's of course a very efficient way from getting from point a critter point b but there's a problem which the wave tends to get stuck so it will propagate along and gradually these these rather than having nice way fronts that you know are regularly moving along these little irregularities gradually subtract from this regular eventually the wave gets completely stuck and the particle does well so in these photosynthetic systems which do have these irregularities these exit times the they move along this way of like past but then they get but now an interesting thing happens which is that these mediums have some kind of disorder just from the fact that they're you know not assembled perfectly but they're also jiggling around some because they're at you know finite temperature and everything localized place and the wave can then probably it again will get struck again but then the wiggling will you know free it to propagate again and so what happens in our theory and i'm trying to do this dance with my fingers  sock puppets here but what happens is that over short times these particles of energies xa tang's are taking this kind of quantum walk where they are exploring all the different places around them quantum mechanical fashion then they get stuck because they're waves have got messed up and localized but then they're free get fried by the noise and decoherence and they're free to propagate in a wave like fashion again and so the noise is good for them the noise is good so in fact when we first did our calculations we said oh well this will work much better at low temperature and we modeled this system this so called f m o complex where these original plumbing experience had done we made a very very approach a model that had no free parameters all the parameters were taken from experiments so we were and we modeled in the quantum mechanical fashion we're quite confident that this was going to give us a very good picture of what's going on because we knew a lot about this this complex and so but we found rather strangely that in fact at low temperature we're quantum coherence should play the most important role not only knock it wasn't going anywhere and it's only one in our model we raise the temperature we found oh when we raise the temperature it goes from you know very low efficiency is actually making its way to the reaction center to an almost one hundred percent efficiency making its way through reactions and in fact we found  characteristic curve which said that if we raise as we started raising the temperature the efficiency went up and up and up and up but then it's when we're at it too far it went down and down and down and down and what this means is to much decoherence is bad because you you know instead of having this situation we're localized and then you get to propagate your localized again you get to propagate again so you have a very significant quantum mechanical component of what's happening then if you get make it too noisy what happens is you're just like we're going we're at crazy all the time an between static disorder and dynamic disorder and quantum coherence converge is that this sweet spot that's goldilocks point where you get almost one hundred percent efficiency and all the other photo complexes we've looked at bit careful about these claims so there's indirect evidence that avian migration employs quantum mechanical effects and there's also indirect evidence that the sense of smell yes you have quantum mechanical effects that you do this quantum mechanical effects to detect the vibrational frequency of the molecules that you're smelling so maybe you could like you know have somebody smell like a rose by playing the right sound that it has and like that biology so thank you for your input in that in our few minutes i'd like to get your background tell us about how you got into this field just generally as indeed i read lots of books about science and yet when i got to school when i started learning about physics in school which i guess was around when i was eleven or twelve then i was fascinated by this apparent simplicity of the mathematical laws governing how physics worked it seemed amazingly that every simple laws that govern so much of what's going on arrays of the world yeah that's right at that point i  set of ideas about ideas and information in quantum mechanics rather ironically this is all based on work that i did for from my master's degree my m phil in history in philosophy and science at cambridge univers yeah that must have been addressed yeah so i mean it's actually based on my degree in humanity yes so and in fact if you look at my my master's thesis was entitled the spread of ignorance all that work the spread of ignorance then a lot of the ideas for how you describe these complex systems in a quantum mechanical fashion how you describe them in terms of information because so many people in research are really very narrow you know that this is a problem in general today and here's this you know you've got this humanities aspect and it made it identity black in an ancient greek and i was always interested in literature and music you know a lot of music as well as math and science writing which is my life yeah in actually i think in science in general you can you know there's always a danger if you work on too many things have been just to dilla todd so you have to pick and choose i mean i actually when i started what i did the same phil which was one hundred eighty three to eighty four that's what convinced me that i actually did want to go to graduate school because i had such a good time doing it under the supervision under the supervision of jeremy butterfield who's now the head of the philosophy department and it was great and i just enjoyed playing around with the idea and then when i went to graduate school to do a ph d in physics turned out that you know i had this conception that oh you being a graduate student you come up with novel and interesting ideas that you think are interesting and then you work them out and then everything is ok well that turned out to be wrong because in fact at that time in the mid eighties these ideas about working ideas about information and quantum mechanics and foundations of quantum mechanics that was a very years they said they three professors came into office and said ok lloyd we don't know we don't understand what you're working on and we don't care so if you want to keep working on it you can leave i'll say they were kicking me out and if you if you wish to stay you can work on these two very technical quantum field theory problems which we're going to resign you so there was a it was a bad experience right isn't that interesting though but you had mentioned and i'm sorry that we're almost out of time because that's your story is so fascinating and instructive for many young people who are starting to melt it and what something is not popular at the moment you have to perseverance you as you did i would actually  especially now with huge funding cut backs and so on feel the pressure to conform and so i like your message to you know go ahead try it out anyway and you had mentioned just kind of for a while and i wish that we had more time to talk about it in any case i thank you so much for talking with us and giving us all this wonderful background thank you thank you very much yvonne it's been a great pleasure