jewelry store yellow diamond

thanks everybody for coming. so today, i'd like to share with you a few thoughts that engineers and scientists have on diamond. you all may be familiar with the statement that diamond is a girls best friend. but what i'd like to convince you actually they're not only a girl's best friend but actually an engineer's best friend. especially, scientists and engineers like myself are very much excited by diamond because of the wonderful properties that it has.

that can solve many interesting problems for example, it can enable secure communication over long distances. it can advance computation via quantum computation. and also it's an interesting material that can enable breakthroughs in the medical sciences especially sensing. also a bio-compatible material, it's chemically inert so it's good for industrial applications, as well.

but what i'd like to start with first, maybe just having the audience say a few words that you guys know about diamond. what are the properties of diamond that you guys are familiar with? just shout. hard, is one. excellent. anything else? hardest natural material, that's excellent.any other thoughts? shiny. hard, shiny. good.

sparkles! somebody said "sparkles"? excellent. so, diamond is hard. it's actually one of the hardest materials, as the young man in the front mentioned. and its used to cut many other materials. for example, here's a diamond scribe that you can use to cut glass. but actually you can scale this up, and use bigger pieces of diamond, this is industrial diamond, that then gets mounted on a big drill bit that

the oil industry uses to cut huge holes into earth's crust. so that's how diamond's hardness is explored. we'll come back to shininess and sparkliness in a few moments but before we go there, actually i'd like to get a volunteer to help me discover another property of diamond. anybody? come up here. want to come here? okay, so, what is your name?

andrew. where are you from, andrew? framingham, massachusetts. excellent. did you enjoy the snow? happy it's over? he says "yeah", okay.then, andrew, i'll give you some ice, because you like snow so much. i'd like you to take a piece of diamond, hold it like this. bring it to the ice and tell me what happens. say it nice and loud so everyone can hear you.

it melts! did your fingers get really, really cold?really fast? isn't it amazing? ok, good! thanks, andrew. please give a hand for andrew from framingham. alright, he really likes this. excellent. okay, so what andrew justhelped us discover is the fact that diamond is the best thermal conductor.

so, basically what has happened,and you can try this experiment downstairs, we have many talented students, like anna who's in the audience, who can show you this first-hand, that heat from your fingers is channeled through this very sharp edge and melts the ice on the spot. in fact, in the industry like people who make chips, the micro-electronics industry,have discovered is that for example diamonds are now being explored as a material for heat-spreading,so that your computers don't heat up so much. so, that's a nice application of diamond that goes beyond shininess and sparkliness. but let's look at sparkliness a bit.

again, so diamond sparkles, and here i have not quite diamond, this is zirconia. it has very similar properties to diamond. i don't know if you guys can see that itsparkles as you twist it. so, the reason why diamonds sparkle is because diamond is very good at bending light. so, when i point this to you light from this light source gets into the diamond, gets reflected, and goes back to you.

ok? diamonds are cut in such a way to achieve this. in fact, diamonds can bend light beamsmuch more effectively than water or glass. that's the property that's used in jewelry to make very nice sparkly diamond rings. but also, another nice property of diamond is that it can disperse light. so, we know that white light, the light that we're using, is white light, consists of many different colors. diamond has a nice property to separate this light into its colors. and that's what gives it extra sparkliness.

alright, so now that we understand that there's so many different beautiful properties of diamond, what are diamonds made of? what gives this material such unique properties? anybody know? diamond is a mineral, but what is it made of? okay, how about you? yes? coal.

it's a very interesting point, diamond is not made of coal, but call it its sibling. it's like a younger or older brother. anybody else wants to give it a shot? carbon! okay. so, diamond is made of carbon. excellent. and what else is made of carbon is coal. right? and, what else is made of carbon is... graphite!

this young man knows all the answers. excellent. okay, carbon also makes up graphite. so, how come that diamond, graphite, and coal, all have the same, they're made of the same material? the same ingredients - but they actuallyhave very different properties. so, that shows you that when nature cooks these different materials it's not just enough to use atoms, to use the ingredients, but you need to know how to cook them, how to prepare these materials.

so, basically diamond has carbon atoms packed very, very densely. okay? in this crystalline lattice that's shown above. actually, here's a example of such a lattice. here we have, lets ignore the blue guy for a moment, we have carbon atoms very tightly packed in a lattice, whereas graphite, on the other hand, consists of layers of carbon, that are reasonably well packed

but these layers are separated by quite some distance. ok? in fact downstairs you can explore some demos that show you how you can separate each of these individual layers into a sheet that's called graphene, that actually won the nobel prize a few years ago. alright, so this is excellent, we know what carbon is made of, diamonds is made of, it's made of carbon. we know it has unique properties but we really don't want to

spend a lot of time digging for it, right? if you've ever played minecraft, like my son does, yeah? we all know diamond is very, very rare. right? very rare. so, if scientists and engineers want to make devices out of diamond, well, they certainly don't want to dig in the mines for a long time. we would like to actually make it in a lab. okay? so the question, can we make diamond in a lab? and the answer is yes.

otherwise, i wouldn't be standing here. a lot of actually nice research in diamond technology has been done with natural diamonds, before people figured out how to makenice quality diamonds themselves. so, the first approach that actually is used quite a bit is so-called high-pressure high-temperature approach. this is exactly the same way as nature uses to compress carbon atoms very tightly. well in this case, what you have is a huge press

that is heated up to very, very high temperature. so, the pressure that's applied is roughly one eiffel tower upside down on a little coke can. that's a lot of pressure. and you cook it up at very high temperature, a lot higher than your oven at home. and then you turn graphite you turn this guy, into this. that's amazing.

actually, i have here some of these diamondsthat are synthesized this way. this is diamond sand. there is about, uh, probably 20 carats of diamonds, but it's not very valuable, please don't run away with it. i'll ask luke to maybe pass it around, give it to people so they can take a look at it. okay. another way that scientists have developed to synthesize diamond, that yields much purer diamond, is so called chemical vapor deposition method.

in this case, what scientists do they start with some substrate could be a little bit of diamond, and then they bring in different atoms, different gases. in this case, it's ch4 gas. but then...the dark balls are acarbon atoms and white balls are hydrogen atoms. so, what happens as these atoms, molecules of the gas come close to the surface, they get deposited and the structure grows.

in fact, this was a cartoon. if you don't believe me you can take a look at our next slide that shows you if you pay attention, the top layer is moving slowly up. this is diamond being grown in this chemical vapor deposition furnace. so, actually using this method people can grow diamonds of this size without any problem today. so, they can be very, very pure.

they can be as good as natural diamonds in some cases, even better. but what's interesting actually, that we're here we're not so much interest in the pure diamond. we're very much interested in impurities. why? because impurities can make diamond sparkle even better, have color. okay, so behind me is an example

of nice piece of jewlery from themuseum of natural history at harvard. and what you see is a brooch. i guess that's the word. i'm not an expert in jewelry,but i sure know something about diamond. so, here's a golden setting and there you can see a bunch of different pieces of diamond inside. what's interesting when you put this piece of diamond this piece of jewelry under ultraviolet light, you see that it glows.

okay? so, this is the same piece of jewelry that has diamonds that have nice beautiful color, you put it under a blacklight and you can see all of these different colors coming out. there's a little bit of blue, there's a little bit of green some violet, and so on and so forth. so what gives diamond these colors and what actually makes it glow so nicely

are impurities. so, people intentionally make diamond flawed okay, by adding impurities to color them. for example, if i add a little bit of the atom, boron, in my matrix of carbon, my diamond becomes blue. if i add some nitrogen, like the ones that are being passed around, they're yellow.

and if i actually stick in some nitrogen & some defects then diamonds become pink. and these pink diamonds are actually very expensive, they're natural, because they're very rare. here we have an example of pink "diamond". okay, this is a piece of glass, really. but here i have an actual pink diamond, so can you guys see it? what i'm going to show you

that indeed these guys do glow. so, diamonds do glow. and it's actually this glow of diamond, these impurities in diamond that make diamond so interesting we are very much interested in these defects and we would like to build someimportant communication systems out of them, as well as memory for computers. before we go there, i'd like to introduce and explain to you how light gets emitted.

so, here's a very simple model of one nitrogen atom just like this guy but in free space, without diamond lattice. the atom has its core, its nucleus, and it has a few electrons around it. i'm focusing on only one electron. when i applied my green laser pointer, what i did, i added a kick of energy to this electron, and i promoted him to a higher energy level.

after some time, this electron that was excited, decided to be de-excited and went back to its original energy, and emitted a red photon. this is pretty cool. but what's really interesting and unique to these impurities in diamond, is that not only these atoms, these electrons, can emit light,

but they can store information. electron can spin one-way and we call it spin 1. just bear with me for a moment, or it can spin the other way, we call this spin 0. spin up. spin down. and it turns out that you can store information in the way which electron spins. if it spins this way, or it spins that way. okay?

you can use this as memory. and this is very, very interesting, because you can, for example, encode this as one, and this as zero. so, what we need to do is take our nitrogen friend and put it in a diamond lattice. like so, like this one. okay? so, here is nitrogen. we jammed it inside the carbon

and this carbon is now keeping this nitrogen in place. it's very tightly bound and it cannotescape from carbon lattice. and what's really unique about diamond that this this cage of diamond, this cage of carbon does not disturb the properties of this nitrogen atom a whole lot. that's why still maintains its emission properties and also it can be used as memory. so, this is sort of the the punchline

is that nitrogen-vacancy color centers in diamond can be used as atomic-scale memory. each of these little atoms is one memory site which is way, way smaller than what you have today in your computers. what we would like to build out of these things we would like to use a piece of synthetic diamond, like the one shown here, make a lot of these defects, and then like i show here with this pink array,

and these defects would be able to store information in spin up, or spin down. electron spin up, or electron spin down means 1 or 0. and what's really cool is that i can come with my green laser, as i showed you earlier, and read this information simply because spin up emits a little bit less light,

spin down emits a little bit more light. okay, so by shining light on diamond, i can read information. so, this is how the basic components that you could use to build very dense memory that is based only one atom - in this case nitrogen. but there's a problem, okay... as i told you earlier, diamond has a very high refractive index, which really means it bends light very, very strongly.

basically, light that gets emitted in diamond does not escape from diamond very easily. so this is the problem - i have my color centers my nitrogen color centers in diamond. i would like to use them as a memory. in order to read the memory, i need to shine a laser at it and i need to collect the light these guys are emitting. so this is what i need to do, the problem is due to the diamond's ability to bend light

very little light comes out. so, only about 3% of light comes out. which means i have beautiful dense memory, but it's really slow - it takes me a long time to read it. so that's not very good. so, we would like to make very fast memories that are very, very dense as well. so, a solution to this would be really to just simply to shave off the surfaces where these beams are hitting

the diamond surfaces where beams are hitting, as shown here we would basically somehow like to remove this little bit of diamond - erode this away - okay? so what's left is this pillar and now these yellow beams are not trapped anymore. they are actually guided, okay? light now gets trapped inside this diamond pillar, and this can be used to transmit light very effectively

towards the user. so, here's an illustration that shows for example on the right you have nv center in bulk that doesn't emit a whole lot. and in these pillars of diamond there are color centers that emit quite a bit of light, that are excellent memory. but the question is - we knew that this could be done, we did some theory on it

but we didn't know how to make these devices, okay? so, how do you etch, how do you remove the hardest material on earth? there was actually quite a bit of challenge. how do you make something like this? so, we took inspiration from nature many of you may have seen these systems that are very impressive, eroded structure sculpted by nature over many many many thousands millions of years.

i don't want to say something incorrect here geologically but the way this is made is you have very hard material on top some very solid rock and then over time water and air keep eroding the soil around it and what you have is this pillar. so this top layer masks the particular region underneath it,

and the rest is washed away and you have this nice pillar. well, we figured out how to do exactlythe same with diamond. you can see these diamond pillars that we have made they're very tiny. we have put little rocks that are even smaller roughly the size of a virus, little bigger than a virus. these little rocks on top of the pillars, and then we eroded away, eroded away diamond.

okay? and what's left is only diamond underneath these rocks, and you can compare how good we are compared to nature, it took us about one minute to make this thing, nature took many many many years, okay? ours are much smaller - roughly 1 micron tall, whereas natural systems are on the order of i guesstimate 100 meters - i'm not an expert on this. so, our structures are about 100 million times smaller

than what nature does and they have a different function, different purpose. the purpose of our device is to traplight emitting from our defect our nitrogen defect in diamond, these impurities. and collect it somehow from both top and bottom. and when this is done, basically what we can finally start dreaming about using this technology to start building some very interesting memory elements. here is one array. it's a cartoon - but we have demonstratedthis experimentally as well.

i'm not showing you these data, what we have here, we have diamond substrates, there are some on display downstairs, you can see them by the way, maybe i can show you here these are some of these artificial diamond substrates that we use - they are pretty big. you can build serious memory elements in it. we'll use these large pieces diamond fabricate devices in it,

and some of them, they have these color centers i was talking about, these impurities and we can store information in them. for example, i stored 1 in the diamond pillars that are glowing and the way we did it in the experiment is very cool, we not not only used diamond, we used silver, sometimes even gold, to use it as a mirror. silver is a very nice mirror as you probably know because every morning when you wake up

perhaps you look in your mirror in the bathroom. well actually similar layers around diamond can reflect light and helps us get even more light out of the impurities. okay? so we made very tiny mirrors, in very tiny pillars of diamond which helped us make very dense memory. after many years, after my students have been working diligently in the lab - this is sort of the result.

millions of diamond nanowires fabricated a single crystal diamond substrate and that allows us to collect light from them very very effectively and now we are exploring various applications. for example, one application that i mentioned originally was secure communication. perhaps you're aware if you have fios internet at home maybe that you certainly know that when you watch movies

these movies come to your homethrough optical fibers. so, optical communication is a dominant technique, dominant approach to communicate lot of information very very effectively. but the problem with optical communications, the way this works roughly is you have basically, at one end, you have a laser and the laser gets turned on and off, like so. "on" means 1, bit of information 1. off means bit of information 0.

1- 0 - 1 - 1 - 1 - 0 and this is how you communicate over long distance but the problem is if somebody wants to listen to your communication and spy on you, they just need to take a little bit of light outand you'd never notice this and they can get access to your information. however, if you use defects in diamond they emit one photon at a time - as illustrated above me. one particle of light at a time so if somebody steals it away rom you

you know immediately that something'swrong and stop your communication channel. this is of great interest for the dept of defense to private communications, security, banks, whatnot. so this is one possible application. alright, so hopefully i convinced you so far that diamond is not only a girl's best friend but it has many interesting properties and i certainly like it and many of my colleagues who are engineers and scientists like a lot.

and hopefully, the next time you see a diamond ring you'll think how to damage it to make some wires in it... i don't encourage you to do that, it's very, it can be expensive. alright, so with that i'd like to thank you i'd like to thank people who supported this presentation, in particular, center for integrated quantum materials at harvard as well as my department, school of engineering and applied sciences at harvard. and the center for nanoscale systems which has a big clean room where we make these devices.

also, i'd like to acknowledge my students who did most of the work that i showed to you so, thank you very much and i'm happy to take any questions that you have.