A New International System of Units in 2018!? How my Nobel Prize Contributed to this Development
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Transcript: English(auto-generated)
00:14
Yes, yesterday already when Professor Feldman got his birthday presents, I was confused
00:22
and I expected that there's no secret at all, so they will give me also some birthday gift and I'm not smoking, so I expected something to eat or to drink or so, therefore last night I changed a little bit some of my slides because I want to show you the picture at the time of the discovery of my Nobel Prize winning research.
00:42
This is a picture. So this is a true story. Now I have not always photographed with me if I'm doing some experiments in the lab, but when I got the Nobel Prize five years
01:03
later after this experiment, journalists wanted to have really a picture of the real situation and it's very close to reality. So I can confirm we had such a situation, you see at two o'clock in the morning in Grenoble I made the discovery at night and we met always with all the scientists in the lab and then
01:22
we had some baguettes, some cheese, and some red wine and so this was natural wine. So since then I have the image that I'm a drinker of wine, so that I always drink red wine and even at once these Branclet sink, the special wine, you see
01:42
also the Nobel Prize mentioned there, this Appelachian Nobel Controllée, it's a nice ombudté eau d'Aumain, Klaus von Klitzing. So my students rented for one year a vineyard, so I collected all the grapes and this is an official wine. And if you want to read the story you could see von Klitzing, there's a chapter
02:04
in the book of Bob Laughlin, he has written a book, a different universe, and the discovery of the quantum Hall effect, Bob Laughlin got the Nobel Prize in 98. Okay, but now let's go really to the work. I started 30 years ago with my first
02:26
Nobel lecture here at Lindau and very often the discussion students ask me, okay, how to get a Nobel Prize? And it's not easy to give an answer, so one answer is don't believe what the boss is telling you, be independent,
02:40
do what you want to see and to do. But today, for the first time, I have two answers to the question how to get a Nobel Prize. The answer number one, just cross Lake Constance and eat chocolate. Perhaps you know this picture, there's the picture,
03:09
and then you have to go not to Austria, to Switzerland this time, just crossing the Lake Constance. Okay, but you know, such graphs, you can manipulate this in all kinds of things.
03:22
Yesterday I learned, in Germany you have to also eat a lot of chocolate, but only the probability is half of the... But if you put it against fish consumption and Nobel laureates or football finalists, then Iceland will be the winner. Okay, but this one,
03:44
another one is just a question of money. Okay, the Nobel Foundation will not be happy about this, but all Nobel laureates got perhaps a letter from this auction house. If you don't need a medal anymore, just give them on the auction. And for example, Leon Ledermann's Nobel Prize was sold last year at this auction,
04:06
and so if you have enough money, but unfortunately scientists have not enough money, but if you want at least to touch Nobel Prize, so this is the Nobel Prize, yes?
04:21
So come to my... So come to the afternoon to the session. Now I have not a certificate with me, but this is a certificate if you get the Nobel Prize, and I will speak about my Nobel Prize and new application of this.
04:43
So this was discovered, as mentioned before, in 1980, but I will go back because this year we are celebrating 50 years of the anniversary of quantum Hall physics because already 1966, if you look at the literature, you can see quantum Hall signs in the publications.
05:02
And this was basically a search on silicon field effect transistors. So you know the principle of a field effect transistor, we have a capacitor, one metal plate on one surface, the other one a semiconductor, there's a positive gate voltage, one introduces a thin layer of electrons.
05:22
And these are two-dimensional electrons because particle in a box gives you a zero-point energy for this electron, they cannot move to the particular, they are quantized. So this is a two-dimensional system, and a lot of research has been done in this field, and the interesting point is the magnetic field is perpendicular to this two-dimensional system,
05:40
you can quench the kinetic energy of the motion of the electrons in this plane by the strong magnetic field. Then we have discrete energy levels. So this was known already for a long, long time, more than 50 years. And this is the very first picture filling up these discrete energy levels in a strong magnetic field with electrons.
06:01
So this is a gate voltage, you're increasing the number of electrons, and you see in the conductivity going up and down, filling up the discrete energy levels. This was from the IBM group 50 years ago, the publication. And exactly at these positions, we are with the thermal energy and the energy gaps,
06:21
and this is the interesting point, this is already quantum Hall physics. A system, a two-dimensional system, discrete energy levels, and the thermal energy in the energy deck. So these experiments published 50 years ago started the field of quantum Hall science. Now today there's a lot of more activities, and if you hear something about topological insulator,
06:41
spin Hall effect, quantum anomalous Hall effect, composite fermions, n-gons, non-abelian statistics, super fluidity, fractional sharps, fermions, bubbles and stripes, everything you can do with a two-dimensional system in a strong magnetic field. So it's a wide field, but I cannot cover this, so there's a whole lecture series. I will just concentrate on two publications, two books, published in 2015,
07:03
Introduction to Quantum Metrology and Quantum Metrology. So the name metrology will be in the focus of my talk today. And in all these books, there's about atomic clocks, but also quantum Hall effect plays a very important role in these books. And you know metrology, metrology, the science of measurements.
07:24
And all scientists know that all measurements can be expressed by our seven base units, in biology, in chemistry, in high energy physics. In principle, you can go back to these seven base units, second for time, meter for length, kilogram for mass, kelvin for temperature, ampere for electric current,
07:40
canela for luminous intensity, mole for the amount of substance. So these are the bases for all measurements, all experiments can express this in these. And the kilogram, you know, remember perhaps it's a prototype, the kelvin, triple point of water, ampere, force between wires. These are very good realizations of these units.
08:01
And we will perhaps have a change in two years' time for all these base units. And today, I will give you some idea about the change we expect. And the Phillips team made already some public relations for my talk, because this picture is also from NIST. And some months ago, I got the email,
08:22
do you intend to talk at the Leno meeting about the new SI in your lecture? As you get closer to the adoption of the new SI, it seems that it becomes even more important. So we agreed that I will cover this, because on this card, so everyone will get this gift, yes? But Bill showed only the front side, I showed you the back side.
08:40
The back side, there's the Josephson constant, the Van Gritten constant, therefore, I will make some public relations for these two constants, because they were the origin of the change we expect in the future for our SI system. OK, Josephson effect, quantum Hall effect, the driving force for the expected change in the SI system. And we heard already about the Josephson effect,
09:03
two superconductors, we can couple them without microwave radiation, we have the super current here, and this microwave radiation, we have steps in the voltage, which are extremely accurate, independent of the superconductor, with 15 digits or more, you have exactly a voltage
09:21
which depends only on the fundamental constant h over 2e and the frequency. So this was the first very important effect from metrology, and then the conventional value for the Josephson constant was introduced in the list of fundamental constants, because everywhere in the world used this effect for the realization of a volt.
09:42
And one should call this a volt 1990 with the index 90, because this was introduced in the year 1990. You can buy such equipment, closed cycle, cryogenic systems, to have your voltage standard at home. And the same happens with the quantum Hall effect. The quantum Hall effect, a current through a device,
10:02
and the important thing is, you need these two-dimensional electron systems to dominate fields, and you measure the Hall effect and then the current and the voltage, and in the ideal case, the Hall effect is not a linear function, it's also a step-like increase. So this is a real experiment, and these plateaus, they have something to do with h over e squared.
10:25
Once more, with many, many different materials, different samples, you have reproducibility with ten digits for different materials. Something very stable. Therefore, we have like for the Josephson constant, also the conventional value, also from the Klitzing constant,
10:41
a fixed value without any uncertainty just for calibration outside our present international system of units. And once more, this Ohm is not our official Ohm in our international system of units. It should be called Ohm with the index 990. And Oxford Instrument will sell at the end of this year
11:01
a system, a quantum Hall system, and this was a publication last year, Operation of Caffeine Quantum Hall Resistance Standard in a Calogen-Free Tabletop System. And today, this caffeine on silicon carbide, you can have a situation, this is an experimental curve of the Hall effect and the longitudinal resistance.
11:21
And you have Hall plateaus starting at two Tesla, going up to 60 Tesla, just the plateau, with a value of 12,906.4035 Ohms for the negative magnetic field, this value, for the positive magnetic field, this value. So this Hall effect is a quantized Hall plateau
11:41
now for these devices from three Tesla to 60 Tesla. So one can use such device for magnetic fields in the range between here three Tesla and here about 14 Tesla in temperature range up to 10 Kelvin at currents up to 500 microamps
12:02
to be in the accuracy of one part in 10 to 9. This is now graphene, and there's a lot of activity now in graphene. Originally, we used gallium arsenide. In gallium arsenide, we have much smaller plateaus. So you see in this space, we have only very small temperature
12:20
range, small currents, and the small magnetic field range. The accuracy is wonderful, but is much smaller than the range. And the other system, the graphene, is insensitive. So therefore, we have this comparison. And therefore, a lot of groups are now in the Metrology Institute on graphene. One can combine this. You have this strange value of 12,908 Ohms.
12:42
You can produce also one Mac Ohm. This is a very recent experiment from the Japanese group. Some array of quantum Hall devices in order to produce a nice plateau exactly at one Mac Ohm. This is a combination of different quantum Hall devices. And you can combine this in such a way to go very close to the value of one Mac Ohm
13:04
within three parts in 10 to 8. So these are today the modern arrays of quantum Hall devices for metrology. And as mentioned, you can combine them parallel in CAS. And for practical application, it's no doubt that the use in voltage quantum Hall resistance
13:22
are fixed by fundamental constants, the H and E. Now, we have now these quantum units. The voltage, the Ohm, if they combine this, you have the ampere, coulomb, inductance, watt. Everything can be expressed or measured experimentally with very high accuracy now using these quantum units.
13:44
But on the other hand, we have our official SI units. With these base units, you can express all the other quantum units. But today, for practical application, we are using the quantum units. And these were adjusted in 1990. So 1990, there was an agreement.
14:00
But today, it starts to deviate from each other. And the new international system of units will unify these two worlds. So the idea is to integrate now the electrical units, which are artificial units, these conventional values. One will integrate this in our new international system of units.
14:20
And there was a very important meeting in 2014 at the General Conference on Weights and Measures. And they discussed the future vision of the international system of units, the SI. And they decided to complete all work necessary for the General Conference at the next meeting, 26th meeting, to adopt a resolution that would replace the current international system
14:43
with the revised one. And the next meeting will be in 2018. And there's a very high probability that in 2018, we will change our international system of units. At present, all the people which can do high precision measurements of fundamental constant using the old SI system
15:01
to determine the value of the fundamental constant. And then you have to submit this to a committee. The deadline is 1st July of next year. And if there's an agreement between the different groups, different countries, then one will change the direction. One will fix the values of the fundamental constant. And then on this basis, you have to realize then the units.
15:22
So don't worry. The new units of our international system will be defined in such a way that nothing will change in our daily life. So you will not see this. The kilogram will stay a kilogram. But it will be more stable, more universal, and mainly the kilogram that Amperes own, the Royal Kelvin Mole, will be influenced by these new definitions.
15:43
And I had recently a conference, Coton Hall Effect, and the former director of the International Bureau of Weights and Measures in Paris, in France, Terry Quinn, he presented a talk and said, key to the new SI will be the redefinition of the kilogram in terms of a fixed numerical value of the Planck constant.
16:01
And such a definition only became possible with the discovery of the Coton Hall Effect. At the time of the discovery of the effect, I never believed that this has some influence on the kilogram. And I will tell you a little bit about the old kilogram. This is our kilogram. The kilogram is a unit of mass. It's equal to the mass of the international prototype
16:20
of the kilogram. That's the definition. This was the year of the first Nobel Prize. They fixed this. And they added later a little bit, as I said, after clearly using the BIPM method. So this is our official definition. If a kilogram disappears, nobody knows what a kilogram is. And if you want to see the kilogram,
16:42
you have to go to the BIPM in Paris. They have a very nice garden there, a nice institute. And if you want to see the kilogram, you have to go into this building and to look at the safe. And I have here a video. Once a year, there is a conference, and there are three different organizations which are interested in the kilogram.
17:01
They have the key to the safe. And the director of the BIPM has the code of the safe. Once I had the offer to be the director of this institute. But the contract says you have to live in the building to take care of the kilogram. So the one key, second key, and then they open the safe.
17:24
And everyone is happy if the kilogram is still there. So no, they're clapping hands.
17:45
So this is a important kilogram. Now from time to time, one compares this prototype against the copies. Each country has a copy. And then they discovered there's a drift,
18:01
a drift between the prototype and the mean value of all the other ones. So you can say, okay, the prototype becomes lighter or other becomes heavier. Today we have the feeling that the prototype becomes lighter because the melt was slightly different.
18:21
And one has the impression that the gas is diffusing out of the prototype. This is today the scientific experience. So we have a kilogram definition which is not stable. This is terrible, I think. And a new problem appeared in 2014, the reference kilogram at BIPM which is used for the dissipation of the unit of mass has been damaged.
18:41
There was some scratch at the bottom. If you put it on the balance, there's a danger that you scratch there. And there was a jump in the mass of these by 37 micrograms. So you have something which is not stable. And then you can see official pull time of kilogram is seriously losing weight.
19:01
Or I dumped the lump for radical cancer. And already in 2005, mainly at the NIST, one discussed some ideas to an electronic kilogram. And for this electronic kilogram, the Josephson effect and the quantum Hall effect is important.
19:21
And you can build it by yourself. So this is the Lego so-called watt balance. So in principle, just the balance on one side, the force by mass, and here the force by some electric current. And you have to balance them. And the electrical quantities, if they are measured in quantum Hall effect and Josephson effect,
19:43
finally, you end up with a Planck constant for the product of voltage and current, which is important in this experiment. So if you want to do this, the Planck constant has a one-to-one relation to the mass. And up to now, very accurate values for the Planck constant are obtained
20:02
using such type of experiments. And in the archive, you can find this Lego watt balance and a part of the mass based on the new SI. So once more, in the future, the Planck constant will be fixed. And then you can do your experiment with the mass.
20:21
And I got this video from NIST when they built up the new kilogram. So this is the new kilogram. And Bill knows this. He just goes to his office. This is a new kilogram there. And just last week, there was a publication, precise instrument, Planck constant, the future kilogram from the NIST group.
20:41
And the uncertainty is three parts in 10 to 8 at present for these experiments. This is good enough to change already the direction. But the question is whether the other countries, the other groups, the other experiments will give in the same uncertainty the same value. So you see the BIPM, all over the world,
21:01
this watt balance I have here in Korea, it's a watt balance. Or in China, they have also an electronic kilogram here. And these are the points in the world where they have built up now these so-called watt balance to have their own kilogram if you have the new definitions. Then you have not to go to Paris to know what the kilogram is.
21:21
Now the interesting point is do all the different experiments give the same value? And you see the collection of data now. And the request is to be in this red bar for the final definition. So if you have this collection of data OK,
21:40
you may move it somewhere here in this range. And I think in the future, one will agree somewhere perhaps in this range. Now the interesting point is not only the watt balance, there's another experiment which gives you a very good value for the Planck constant. And I will mention this. This is so-called Avogadro project. The Avogadro project gives you also value
22:02
for the Planck constant. You see the green points and they have even sometimes a smaller uncertainty and they are very close to this value. And I'm very optimistic that they will agree in 2017 or 18 and they will fix the value somewhere in this range. Now I will just explain how you can determine
22:21
the Planck constant by the Avogadro project if you have this equation for the Rydberg constant. The Rydberg constant is very well known and you have then the fine structure constant which is known as 10 digits. The velocity of light is a fixed value. The only question is, do you have electron mass?
22:41
And in order to have a connection between atomic and macroscopic masses, you need the Avogadro project. So the Avogadro project is just to have the bridge between atomic quantities and macroscopic quantities. And this was the world project, the Avogadro constant counting atoms
23:01
of a single crystal in a silicon sphere. And just last week I was at a conference at the round and ready decimation of the kilogram via the SI sphere. Because if you fix Planck constant and elementary charge velocity of light in principle from the de Broglie wavelength, you can say, okay, you have some connection
23:21
between mass and fundamental constants. It's not done in this way. But in principle, by fixing fundamental constant, we have access to atomic masses. And then we need the Avogadro project in principle to transfer this microscopic mass to macroscopic mass.
23:41
So as a scientist, I had the feeling the better way would be to define the mass of a silicon atom or some atom, but then we will not fix the Planck constant and we cannot integrate the electric unit. So we will have not a new definition that a certain number of atoms is a kilogram. This will be not the definition.
24:01
It will be the Planck constant. So we have here now the old kilogram, the silicon sphere or the watt balance, and all of them give then access to the Planck constant. So this is the idea starting from the old system going to a reference new system of constant of nature,
24:22
the Planck constant, the magnetic charge, Boltzmann constant, Avogadro constant, velocity of light will be fixed numbers and this will form the basis for the new SI. So the Avogadro project and watt balance is low high precision measurements of the Planck constant. And at present, I have the feeling the watt balances are built up in many countries and seem to be the best way to realize the unit of mass
24:41
on the basis of a fixed value for the Planck constant. Quantum Hall effect anyway will play an important role in our new international system. And this new development was triggered by basic signs on a silicon field effect transistor. So you never know in which direction you suddenly find some explanations. If you want to have the quantum Hall effect fundamental constant,
25:01
I have a video on my home page called a universal language showing the connection between fundamental quantum Hall effect, fundamental constant and the new SI. And thank you for your attention.