The world that quantum physicists study with a trained eye is the same world that we non-scientists navigate every day. The only difference is that it was enlarged to incomprehensibly small and large scales.
However, quantum physics remains a largely obscure topic – even to scientifically adept readers. News@Northeastern spoke to Gregory Fiete, professor of physics at Northeastern University, about some of the broad applications of quantum research, ranging from developing Renewable energy sources And build more powerful computers, to enhance humanity’s pursuit of discovering life beyond the scope Solar System. Vieti’s comments have been modified for brevity and clarity.
To get started, let’s give our audience an insight into the nature of your business, by looking at a very small world. What are some misconceptions about the work that quantum physicists like you are involved in – and why is it important?
You mentioned Quantum and the Small World. This is what most people think of when they think of quantum mechanics and the way some of the early foundations of quantum theory developed, which looked at the hydrogen atom and how it contains discrete energy levels, which you can observe experimentally by looking at its spectra, or how it absorbs and emits light, on the for example.
[The hydrogen atom] It absorbs and emits certain frequencies, and we now understand that because of the quantum nature of the atom – how there are only specific permissible orbits of the electron around the nucleus. So we tend to think of quantum mechanics in terms of this very important early example of the hydrogen atom, and therefore we are biased towards thinking that the quantum is small. But in fact it is not at all about the small.
Take the sun for example. The sun is very large – it is the largest body in our solar system; Our planets revolve around them in orbits due to their gravity.
The way the sun works is by burning hydrogen. Its gravity is so great that it fuses hydrogen into helium, and then helium into other elements. They fuse atoms together and this fusion process is a quantum phenomenon, and it’s behind one of the great energy challenges being undertaken here on Earth, known as continuous fusion. That’s just taking hydrogen and fusing it into helium – if we could do that on Earth within a magnetic confinement, then we’d have a clean, renewable energy source.
There are unlimited amounts of hydrogen that can be combined, and helium is not radioactive. So we can produce a lot of energy from things that are more or less infinitely abundant without producing waste in the form of radioactive material. This is a dream physicists are working towards. So, some of the biggest things in the universe are definitely quantum mechanics, including supermassive black holes that can lose energy through a quantum phenomenon known as Hawking radiation.
The second point is that one often thinks that quantum transactions have very low temperatures. Again, let’s take our Sun as an example – it’s extremely hot, but it is quantum mechanical. Low temperature does not work as a requirement for you. This example of a star and the amount of the fusion process and the high temperatures associated with that – I just want to broaden my view of what quantum mechanics is and how ubiquitous it is.
When we write about the work that you and your colleagues do, there are always real-world applications. Can you talk about some of the ways quantum physicists are spurring technological progress outside their field?
I will list some of my favorite techniques. One of the things that really excites me about quantum physics is its use of what I think of as “forensics”, or quantum forensics, if you will.
Since things like atoms have separate energy levels associated with them, it turns out that this can be used to identify atoms. If you compare the permissible energy levels for hydrogen and the permissible energy levels for helium, or any other element, they are different. If you have any gas out of anything, you can determine which atoms are in the gas by looking at how it absorbs and emits light. This is of great practical value if you are interested in something far away, such as a planet orbiting a star that is not ours.
There is a wonderful field of exoplanets that we are discovering with powerful telescopes, and we are discovering these planets moving between the stars and our Earth. Our telescopes – some in space connected to satellites with incredible frequency and sensitivity – are so powerful that we can look at the thin layer of the atmosphere around these planets, and how the light from the star passes through them. Then we use spectroscopy technology and see how the planet’s atmosphere absorbs light from behind it, which can be thousands of light years away. So we can detect the atoms in the atmosphere.
This is very interesting. But it goes further than that. We can detect molecules that are present, too. For example, are two hydrogen atoms bonded to one oxygen atom? In other words, is there water in the atmosphere? Molecules have their own spectral signature. So we can actually detect if there’s water in the atmospheres of some of these planets, and that’s really exciting.
However, we can go a step further. When there are temperatures involved, these spectral lines, as they are called, expand these specific frequencies. There is a type of frequency where you see absorption and emission. And the amount being expanded tells you about the temperature of the molecule – in other words, the temperature of the atmospheres of these planets.
It’s really amazing that we can determine what’s in the atmospheres of these planets – planets that would be impossible for humans to visit. That, and we can look for fingerprints of life, like, are there particles that we associate with life floating in these planets, at least if life is similar to Earth; Then we might be able to identify some possibilities that some planet is out there that no human can visit, harboring life. Or maybe we can discover other life candidates. This is a very inspiring example, ultimately based on quantum physics and spectroscopy technology.
One other example that I think also gets widespread attention is that quantum physics produces energy sources that are out of the reach of solar energy. So when you send a deep space probe to look at the outer planets of our solar system, let’s say Pluto (technically no longer considered a planet). If you want to look at Pluto, you send a deep space probe – it takes years to get there. You may ask, what kind of power source can you get for the computers on this probe so they can send the beautiful pictures we see? Well, you can put a battery in there. It will take years to get there, space contains a lot of radiation and batteries can be damaged; They may not function properly when they are released by all the thermal variations emerging from the atmosphere, the coldness of space, etc. This is not very practical. There isn’t enough sunlight that you can collect using solar panels to power your computer systems and send back images.
So how do they power the computers on these deep space probes? What they use is radiation. They use a radioactive substance, and radioactivity is again another quantum process, where heavier elements decay into lighter elements. When they do this, they eject portions of their nucleus. But these ejected portions of the nucleus carry energy that can be captured.
There are materials, some very close to the things I’m working on, that are called thermoelectric materials. They take areas of high temperatures and connect them to areas of low temperatures, converting this difference in high and low temperatures into a voltage, which then acts as a battery. Once you have voltage in an electrical system, you can now drive currents and operate a computer or electrical circuits in the somewhat normal way.
Everything is very interesting. Quantum physics really appears to be the foundational work that goes into transforming our energy infrastructure, among other technologies. Is this the correct way to think about it?
Yes that’s right. This is a great point – to think about climate change, renewable energies and also technologies that do not pollute our environment.
If we just think about energy for a moment, like when we discussed the example of fusion, it’s a green technology – assuming we can turn it on. If we move away from fusion, there are other technologies in place now and they are green. Take a wind turbine. What is the relationship with wind turbines Quantum physics? The way wind turbines work is that they have magnets attached to the propellers while the wind runs them, and the rotation of the magnets generates an electric current. This is how you generate electricity: you wind a magnet inside a coil of wire.
But the question is: Which magnet should you use? That’s where the basic research — actually research that I’m involved in somewhat at Northeastern University — comes in: thinking about magnetic systems that would have desirable properties for applications like wind turbines.
You need a very strong magnet that needs to survive high temperatures, which means well above room temperature, because it can heat up there with the sun shining on it. It must also have properties strong enough to survive whatever the strains and stresses as it winds into this turbine system. Those are the so-called hard magnets. So how do you develop better magnets? This is a quantitative question.
As a final thought, I wonder what your high hopes are for your research and in this field. What would you like to see happen during your life, and are there any developments we are on the cusp?
This is a tough question everyone in the field is asking: What developments are we really on the cusp of? A well-cited example is quantum computing. Having a quantum computer won’t solve every computing problem anyone can dream of. It turns out that quantum computers are particularly adept at certain classes of problems, where they can provide what’s called a “quantum advantage.” There are some specific problems for which quantum computers are most useful; But other problems may be better solved by traditional supercomputers.
So one of the questions in this field is to try to provide a little bit more clarity about the specific problems that quantum computers will help us solve. It’s an evolving area, like what a real specialized problem for a quantum computer is. I think all of us who work in this field feel that there will be some specific applications, where quantum computers really outperform everything else – and everyone wants to be involved in this; Every person means every developed country. Everyone wants to be a part of this upcoming quantum revolution, which is not just about developing quantum mechanics as a new science, but transforming quantum mechanics into very broad applications. And computing is only one area in the foreground.
the quote: How quantum physicists search for life on exoplanets (2022, September 16), retrieved September 18, 2022 from https://phys.org/news/2022-09-quantum-physicists-life-exoplanets.html
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