Category Archives: Quantum Physics
Backscattering protection in integrated photonics is impossible with … – EurekAlert
image:The figure shows a scanning electron microscope image of one of the photonic waveguides studied by the DTU researchers. The waveguide is formed at the edge between two photonic topological insulators (blue and red) which are realized in nanoscale silicon membranes. It has been predicted that light propagating in such topological waveguides is immune to backscattering on structural defects, but this was never investigated experimentally. For the first time, the DTU team checked this in an experiment and found the opposite: strong backscattering. Credit: C. A. Rosiek. view more
Credit: Credit: C. A. Rosiek.
The field of integrated photonics has taken off in recent years. These microchips utilise light particles (photons) in their circuitry as opposed to the electronic circuits that, in many ways, form the backbone of our modern age. Offering improved performance, reliability, energy efficiency, and novel functionalities, integrated photonics has immense potential and is fast becoming a part of the infrastructure in data centres and telecom systems, while also being a promising contender for a wide range of sensors and integrated quantum technologies.
Significant improvements in nanoscale fabrication have made it possible to build photonic circuits with minimal defects, but defects can never be entirely avoided, and losses due to disorder remains a limiting factor in todays technology. Minimising these losses could, for example, reduce the energy consumption in communication systems and further improve the sensitivity of sensor technology. And since photonic quantum technologies rely on encoding information in fragile quantum states, minimising losses is essential to scale quantum photonics to real applications. So the search is on for new ways to reduce the backscattering, or even prevent it entirely.
A one-way street for photons is impossible today
One suggestion for minimising the loss of photons in an integrated photonic system is to guide the light through the circuit using topological interfaces that prevent backscattering by design.
"It would be very nice if it were possible to reduce losses in these systems. But fundamentally, creating such a one-way street for photons is a tough thing to do. In fact, as of right now, it is impossible; to do this in the optical domain would require developing new materials that do not exist today," says Associate Professor Sren Stobbe, Group Leader at DTU Electro.
Circuitry built from topological insulators would, in theory, force photons to keep moving forward, never backward. The backwards channel would simply not exist. While such effects are well-known in niche electronics and have been demonstrated with microwaves, they have yet to be shown in the optical domain.
But full topological protection is impossible in silicon and all other low-loss photonic materials, because they are subject to time-reversal symmetry. This means that whenever a waveguide allows transmitting light in one direction, the backwards path is also possible. This means that there is no one-way street for photons in conventional materials, but researchers have hypothesized that a two-way street would already be good enough to prevent backscattering.
"There has been a lot of work trying to realise topological waveguides in platforms relevant for integrated photonics. One of the most interesting platforms is silicon photonics, which uses the same materials and technology that make up todays ubiquity of computer chips to build photonic systems, and even if disorder cannot be entirely eliminated, perhaps backscattering can," says Sren Stobbe.
New experimental results from DTU recently published in Nature Photonics strongly suggest that with the materials available today, this likely will not happen.
State-of-the-art waveguides offer no protection
Although several previous studies have found that it may be possible to prevent backscattering based on various indirect observations, rigorous measurements of the losses and the backscattering in topological waveguides were so far missing. The central experiments conducted at DTU were performed on a highly well-characterised state-of-the-art type of silicon waveguide, showing that even in the best waveguides available, the topological waveguides show no protection against backscattering.
"We fabricated the best waveguide obtainable with current technologyreporting the smallest losses ever seen and reaching minute levels of structural disorderbut we never saw topological protection against backscattering. If the two-way topological insulators protect against backscattering, they would only be effective at disorder levels below what is possible today," says PhD-student Christian Anker Rosiek.
He conducted most of the fabrication, experiments and data analysis along with postdoc Guillermo Arregui, both at DTU Electro.
"Measuring the losses alone is crucial, but not enough, because losses can also come from radiation out of the waveguide. We can see from our experiments that the photons get caught in little randomly located cavities in the waveguide as if many of tiny mirrors had been randomly placed in the lights path. Here, the light is reflected back and forth, scattering very strongly on those defects. It shows that the backscattering strength is high, even in a state-of-the-art system, proving that backscattering is the limiting factor," says Guillermo Arregui.
Waveguide-material should break time-reversal symmetry
The study concludes that, for a waveguide to offer protection against backscattering, you would need the topological insulator to be constructed from materials that break time-reversal symmetry without absorbing light. Such materials do not exist today.
"We are not ruling out that protection from backscattering can work, and absence of evidence must not be confused with evidence of absence. There is plenty of exciting research to be explored within topological physics, but moving forward, I believe researchers should take great care in measuring losses when presenting new topological waveguides. That way, we will get a clearer picture of the true potential of these structures. Suppose someone does indeed develop new, exotic materials that allow only propagation in one direction, our study has established the tests needed to claim real protection against backscattering.," says Christian Anker Rosiek.
Observation of strong backscattering in valley-Hall photonic topological interface modes
10-Apr-2023
The authors declare no competing interests.
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Backscattering protection in integrated photonics is impossible with ... - EurekAlert
Great Mysteries of Physics: will we ever have a fundamental theory of life and consciousness? – The Conversation
Whats the difference between a living collection of matter, such as a tortoise, and an inanimate lump of it, such as a rock? They are, after all, both just made up of non-living atoms. The truth is, we dont really know yet. Life seems to just somehow emerge from non-living parts.
This is an enigma were tackling in the fifth episode of our Great Mysteries of Physics podcast hosted by me, Miriam Frankel, science editor at The Conversation, and supported by FQxI, the Foundational Questions Institute.
The physics of the living world ultimately seems to contradict the second law of thermodynamics: that a closed system gets more disordered over time, increasing in what physicists call entropy. Living systems have low entropy. A messy lump of tissue in the womb, for example, can grow into a highly ordered state of a foot with five toes.
We maintain this high sense of order for many, many decades, explains Jim Al-Khalili, a broadcaster and distinguished professor of physics at the University of Surrey in the UK. Its only when we die that entropy and the second law of thermodynamics really kicks in.
Quantum biology is one approach to understanding how living matter is different from inanimate matter. It is based on the strange world of quantum mechanics, which governs the microworld of particles and atoms. The idea is that living systems may use quantum mechanics to their advantage promoting or halting quantum processes.
Evolution has had long enough to fine-tune things or to stop quantum mechanics from doing something that life doesnt want it to do, explains Al-Khalili, who carries out research in the area. Its a newish area of science.
One example, albeit still controversial, is photosynthesis, the process in which plants or bacteria absorb particles of sunlight, photons, and convert it to chemical energy. Some physicists believe a quantum property known as superposition allowing a particle to be in many possible states, such as taking different paths, simultaneously enables this process.
A lump of energy [such as a photon] just randomly bouncing around should just be lost as waste heat, explains Al-Khalili. Theres a quantum mechanical explanation for how that photon follows multiple paths simultaneously.
Al-Khalili and his colleagues are now using quantum biology to try to understand DNA mutations a core part of life and theyve made some intriguing discoveries already. And while he isnt convinced the approach will ever be able to explain consciousness, he argues we cannot rule it out.
Sara Walker, an astrobiologist and theoretical physicist working as a professor at Arizona State University in the US, favours another approach, however. She is trying to create a new physical theory of life based on information theory which takes information to be real and physical.
Information seems to be crucial to life. Living organisms have an inbuilt set of instructions, DNA, which non-living things simply dont have. Similarly, when living beings invent things, such as rockets, they rely on information, such as knowledge of the laws of physics, stored in their memory.
We can use the current laws of physics to predict how a planet evolves over time, for example whether and when nearby objects are likely to crash into it. But we cant use the laws to explain how and when intelligent beings arise and decide to build rockets and satellites which they launch into orbit around the planet.
I do think that there are laws of physics that are yet undiscovered that explain the phenomena of life, and I think those have to do with how information structures reality in some sense, explains Walker.
Walker believes that living organisms are more complex and difficult to assemble from fundamental building blocks than inanimate, naturally produced objects, such as simple molecules. And when simple living beings exist, they seem to generate even more complexity either by evolution or through construction.
So Walker believes life generates a sudden boost in complexity which may have a threshold that could be a fundamental feature in the physics of life. Another central part of her theory is time. The deeper in time an object is, the more evolution is required to produce it.
Walker has designed an experiment to look at how molecules are built up by joining smaller pieces together in various ways. She says the team hasnt found any evidence that molecules with high complexity can be produced by non-living things. The ultimate goal is to pinpoint an origin of life in which a chemical system can generate its own complexity.
Not only could that help us understand how life arises from non-living building blocks, we could also use it to search for life on other worlds in the cosmos.
_You can listen to Great Mysteries of Physics via any of the apps listed above, our RSS feed, or find out how else to listen here. You can also read a transcript of the episode here.
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The quantum world: A concise guide to the particles that make reality – New Scientist
The ancient Greeks speculated that it might be air, fire or water. A century ago, physicists felt sure it was the atom. Today, we believe that the deepest layer of reality is populated by a diverse cast of elementary particles, all governed by quantum theory. From this invisible, infinitesimal realm, everything we see and experience emerges. It is a world full of wonder, yet it can be mystifying in its weirdness. Or at least it can often feel that way.
What youll find below is a concise, clear-eyed guide to the known particles and forces from electrons, quarks, and neutrinos to photons and the Higgs boson as well as the quantum laws and phenomena that give quantum physics its reputation for strangeness, including wave-particle duality, entanglement, and the uncertainty principle. You will also discover the hypothetical particles that could make sense of cosmological conundrums such as dark matter and dark energy, and the stranger things that might lurk beneath the quantum realm. Finally, you will have many of your questions answered, not least what is a theory of everything anyway?
We start with what we pretty much know for sure. Visible matter consists of atoms, and at the centre of atoms are protons and neutrons. But even these arent elementary particles, as detailed by the current standard model of particle physics, our leading description of reality on the tiniest scales. So we begin, deep down, with what matter is really made of.
Electrons
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The quantum world: A concise guide to the particles that make reality - New Scientist
The Universe Isn’t Empty. It’s Filled With ‘Quantum Foam’ Explorersweb – ExplorersWeb
One of humankinds greatest intellectual advantages has been the ability to embrace contradiction to understand that something can be both itself and its opposite at the same time.
That comes in handy when talking about quantum physics. The subject ricochets between illustrations like Schrodingers cats (both alive and dead), and the infamously confusing Heisenberg Uncertainty Principle, which states you cant simultaneously measure the location and movement of a subatomic particle.
If you look at the image above, youll see what looks like a night sky filled with exploding fireworks. In reality, its a subatomic image of the constant creation and destruction of matter and antimatter.
Electrons and antimatter electrons, quarks and antimatter quarks they are created from nothing and disappear back into nothingness, Fermilabs Dr. Don Lincoln explains in the video below. Empty space is actually extremely busy.
These are called virtual particles, which Lincoln likens to the appearing and disappearing bubbles on a foamy root beer. (Regular beer is probably too controversial an example.)
But theres another name for this phenomenon as well: quantum foam.
Thats basically an attempt to offer a memorable image for a much trickier physics concept. Namely, that nothing is still something.
Intrigued?
Watch the full video above from the excellent YouTube channel Fermilab to get a firmer grasp on why empty space might not be empty at all.
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The Universe Isn't Empty. It's Filled With 'Quantum Foam' Explorersweb - ExplorersWeb
Great Mysteries of Physics: will we ever have a fundamental theory of life and consciousness? – Yahoo News UK
Whats the difference between a living collection of matter, such as a tortoise, and an inanimate lump of it, such as a rock? They are, after all, both just made up of non-living atoms. The truth is, we dont really know yet. Life seems to just somehow emerge from non-living parts.
This is an enigma were tackling in the fifth episode of our Great Mysteries of Physics podcast hosted by me, Miriam Frankel, science editor at The Conversation, and supported by FQxI, the Foundational Questions Institute.
The physics of the living world ultimately seems to contradict the second law of thermodynamics: that a closed system gets more disordered over time, increasing in what physicists call entropy. Living systems have low entropy. A messy lump of tissue in the womb, for example, can grow into a highly ordered state of a foot with five toes.
We maintain this high sense of order for many, many decades, explains Jim Al-Khalili, a broadcaster and distinguished professor of physics at the University of Surrey in the UK. Its only when we die that entropy and the second law of thermodynamics really kicks in.
Quantum biology is one approach to understanding how living matter is different from inanimate matter. It is based on the strange world of quantum mechanics, which governs the microworld of particles and atoms. The idea is that living systems may use quantum mechanics to their advantage promoting or halting quantum processes.
Evolution has had long enough to fine-tune things or to stop quantum mechanics from doing something that life doesnt want it to do, explains Al-Khalili, who carries out research in the area. Its a newish area of science.
One example, albeit still controversial, is photosynthesis, the process in which plants or bacteria absorb particles of sunlight, photons, and convert it to chemical energy. Some physicists believe a quantum property known as superposition allowing a particle to be in many possible states, such as taking different paths, simultaneously enables this process.
Story continues
A lump of energy [such as a photon] just randomly bouncing around should just be lost as waste heat, explains Al-Khalili. Theres a quantum mechanical explanation for how that photon follows multiple paths simultaneously.
Al-Khalili and his colleagues are now using quantum biology to try to understand DNA mutations a core part of life and theyve made some intriguing discoveries already. And while he isnt convinced the approach will ever be able to explain consciousness, he argues we cannot rule it out.
Sara Walker, an astrobiologist and theoretical physicist working as a professor at Arizona State University in the US, favours another approach, however. She is trying to create a new physical theory of life based on information theory which takes information to be real and physical.
Information seems to be crucial to life. Living organisms have an inbuilt set of instructions, DNA, which non-living things simply dont have. Similarly, when living beings invent things, such as rockets, they rely on information, such as knowledge of the laws of physics, stored in their memory.
We can use the current laws of physics to predict how a planet evolves over time, for example whether and when nearby objects are likely to crash into it. But we cant use the laws to explain how and when intelligent beings arise and decide to build rockets and satellites which they launch into orbit around the planet.
I do think that there are laws of physics that are yet undiscovered that explain the phenomena of life, and I think those have to do with how information structures reality in some sense, explains Walker.
Walker believes that living organisms are more complex and difficult to assemble from fundamental building blocks than inanimate, naturally produced objects, such as simple molecules. And when simple living beings exist, they seem to generate even more complexity either by evolution or through construction.
So Walker believes life generates a sudden boost in complexity which may have a threshold that could be a fundamental feature in the physics of life. Another central part of her theory is time. The deeper in time an object is, the more evolution is required to produce it.
Walker has designed an experiment to look at how molecules are built up by joining smaller pieces together in various ways. She says the team hasnt found any evidence that molecules with high complexity can be produced by non-living things. The ultimate goal is to pinpoint an origin of life in which a chemical system can generate its own complexity.
Not only could that help us understand how life arises from non-living building blocks, we could also use it to search for life on other worlds in the cosmos.
_You can listen to Great Mysteries of Physics via any of the apps listed above, our RSS feed, or find out how else to listen here. You can also read a transcript of the episode here.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
The Conversation
Jim Al-Khalili receives funding for his research from various bodies: UK funding agencies (EPSRC, STFC), trusts and charities (Leverhulme Trust, John Templeton Foundation). These funds are used to pay for part of his salary, along with those of colleagues and collaborators, postdoc salaries, travel and subsistence for research and to conferences etc. Sara Walker receives funding from John Templeton Foundation and NASA. She is a fellow at Berggruen Institute and External Faculty at Santa Fe Institute.
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Is particle physics the same as quantum? – Rebellion Research
Is particle physics the same as quantum?
Particle physics and quantum physics are related but they are not the same thing. Particle physics is a branch of physics that deals with the study of the fundamental particles and their interactions, while quantum physics is the study of the behavior of matter and energy on the atomic and subatomic scale. Both fields of physics are highly interconnected, and they often use similar tools and techniques, but they have different focuses and objectives.
Particle physics is concerned with the study of the smallest building blocks of matter, such as quarks, leptons, and bosons, and their interactions with each other. Particle physicists use high-energy particle accelerators to smash particles together and observe the particles and radiation that result from the collisions. They also use detectors to measure the properties of the particles, such as their mass, charge, and spin. The goal of particle physics is to understand the fundamental laws of nature and the structure of the universe at the most basic level.
While particle physics and quantum physics have different focuses, they become highly interconnected. Particle physicists use quantum mechanics to describe the behavior of particles at the subatomic scale, and they often use quantum field theory to explain the interactions between particles. Similarly, quantum physicists use the study of particles and their interactions to test and refine the laws of quantum mechanics.
In conclusion, while particle physics and quantum physics are related, they are not the same thing. Particle physics is concerned with the study of fundamental particles and their interactions, while quantum physics is concerned with the behavior of matter and energy on the atomic and subatomic scale.
Lastly, both fields of physics are important for our understanding of the universe, and they often use similar tools and techniques, but they have different focuses and objectives.
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Is particle physics the same as quantum? - Rebellion Research
Universes Greatest Mysteries and Why They are Unsolved – Worldatlas.com
The universe is shrouded in mystery. No matter how much science uncovers about the universe, there always seems to be more to discover. What are some of the greatest mysteries in the universe and why have they gone unsolved?
The currently accepted model that describes the early moments of the universe is the Big Bang. While the Big Bang explains how the universe evolved during its earliest moments, it tells us nothing about how the universe came into existence. Was there anything before the Big Bang, or did the universe simply spring from nothing? As of yet, this remains one of physicss biggest mysteries.
The reason why this question remains unsolved is due to the fact that the two theories that best describe our universe are at odds with one another. These two theories are general relativity and quantum mechanics. Relativity describes the universe on its largest scales, such as gravity and mass, while quantum mechanics describes the smallest aspects of our universe, such as atoms and subatomic particles. While these two theories work well on their own, scientists have yet to figure out how to unite the two under a single, unified theory. Until scientists figure that out, the origin of the universe will remain a mystery.
There is perhaps no better example of mystery in our universe than black holes. A black hole is any object whose gravitational pull is so strong that not even light can escape past a certain point. Every black hole is surrounded by a region known as an event horizon, which is the boundary where the escape velocity of the black hole exceeds the speed of light. Since light cannot escape the event horizon, no information can exit the black hole. This means that no matter how hard we try, there is no way of knowing what happens beyond the event horizon, at least not directly. There is a chance that mathematical models may one day explain the inner workings of a black hole. Yet for that to happen, scientists will need to unite quantum mechanics and general relativity.
Ever since humanity awakened to the fact that the stars are other suns with their own planets, scientists have wondered about the possibility of life existing beyond the Earth. As of yet, the Earth is the only world known that has life. Given the sheer size of the universe and the number of stars and planets out there, it seems unlikely that our planet is the only one with life, yet we currently have no evidence of it. Discovering alien life would be no easy task, and since Earth life is the only form of life we know of, humans are subject to extreme bias when looking for aliens. However, technology has now advanced to the point where it is possible scientists could detect alien life in the near future if there is any to find. The reason why this question has remained unanswered for so long could come down to technological limitations.
While the question of alien life remains unanswered, there is another pressing question related to life: how did it get started? The fossil record and genetics have allowed us to peer deep into Earths history, painting an accurate picture of how life has evolved over the last 3.8 billion years. However, as of yet, it remains unknown exactly how life started.
At some point in Earths history, the right chemicals existed under the right conditions to allow for the development of RNA and DNA, leading to the first forms of life on this planet. How and where that happened remains a mystery. Since there is no way of going back in time and observing the origin of life, humans may never know for sure how life first started. Some form of an answer to this question may eventually come in the form of laboratory experiments that may one day be capable of synthesizing RNA and DNA from non-living materials.
The origin of the universe is one of its biggest mysteries, yet so is its end. The universe is currently 13.8 billion years old, and it will likely continue existing for trillions upon trillions of years more. Relative to how long the universe will likely exist, it is still very much in the early stages of the universe. The universe may one day end in a heat death long after the last stars have burned out, or perhaps the expansion of space will one day run in reverse, causing the universe to collapse inwards. While there are many good theories on how the universe will end, the information scientists do have is far too limited to know for certain.
When matter first formed after the Big Bang, it emerged in two types: matter and antimatter. Models show that the universe should have created equal amounts of matter and antimatter, which would have destroyed one another and left a universe of pure energy. However, for reasons that remain unknown, the universe created slightly more matter than antimatter, allowing for the eventual formation of stars, galaxies, planets, and life. Exactly why the early universe had this discrepancy is a mystery, and according to most models, the universe should not exist in its current form. This could remain a mystery until better models are uncovered, or perhaps it has to do with how the universe came into existence.
The universe is full of mystery, and the questions listed above only scratch the surface of what remains unknown. As science and technology advance, our understanding of the universe will change. Perhaps at some point in the future, the answers to these and other questions will be as basic as knowing the Earth is round. For now, all we can do is continue to search for answers and uncover more about this mysterious universe.
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Universes Greatest Mysteries and Why They are Unsolved - Worldatlas.com
The priest who proved Einstein wrong – Big Think
This is the fifth article in a series on modern cosmology.We encourage you to read installments one, two, three, and four.
In 1929, Edwin Hubble confirmed that the Universe is expanding. With that question settled, a far older one came back to haunt scientists: Did the Universe have a beginning? If so, what was going on before? Was there space, and was there time?
The quest for an answer has a fascinating history, and the search is still very much part of the conversation in cosmology. Maybe there are a few lessons to be learned from the wisdom of our predecessors.
One of the first voices to address the issue of a beginning was the Belgian priest and cosmologist Georges Lematre. Despite his love for physics, Lematre followed his fathers advice (read: pressure). After a degree in civil engineering in 1913, he started to train as a mining engineer.
Sometimes a single factor can change someones course in life. In my case, it was inorganic chemistry labs that convinced me to change my studies from chemical engineering to physics (against my fathers advice as well.) In Lematres case, it was years of exposure to the horrors of World War I. When the war was over, Lematre knew it was time to pursue his dream. By 1920, he had joined both a graduate program in mathematical physics and the Maison Saint Rombaut, an extension of the seminary of the Archdiocese of Malines. There, he would be trained for priesthood.
In September 1923, Lematre was ordained a priest. In October, he joined Arthur Eddington and his prestigious research group at Cambridge as a graduate student. After a year in England, Lematre left for Harvard. He developed a solid foundation in theoretical physics and astronomy, a combination that would anchor his constant efforts to link the theoretical and observational aspects of cosmology.
Creative and independent, in 1927 Lematre wrote a paper in which he basically rediscovered Alexander Friedmanns cosmological solutions predicting an expanding Universe. In the same paper, he showed that these solutions, as well as Willem de Sitters, also led to a linear velocity-distance relation for receding galaxies.
Lematres paper was published in an obscure journal and remained largely unnoticed. He did try to talk to Einstein about his results, but Einstein showed no interest. Vos calculs sont corrects, mais votre physique est abominable, Einstein told him Your calculations are correct, but your physics is abominable. But Lematres fate was about to change dramatically, and within a few years, Einstein himself would be applauding his ideas.
When Hubble made his observations public, many cosmologists, including de Sitter and Eddington, scrambled to find a semi-realistic model of the Universe that could accommodate both matter and the expansion. When Lematre heard of their efforts, he reminded his former adviser that he had solved the problem in 1927. Eddington finally read Lematres paper and managed to get a translation published in Monthly Notices of the Royal Astronomical Society.
His prescient ideas finally vindicated, Lematre pressed on with a more ambitious plan: to develop a complete, even if qualitative, history of the Universe, including its mysterious origin. The purpose of any cosmogonic theory is to seek out ideally simple conditions which could have initiated the world and from which, by play of recognized physical forces, that world, in all its complexity, may have resulted, he wrote.
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In 1931, Lematre published a paper in Nature. In it, he proposed the primeval atom and described the initial evolution of the Universe in terms of the decay of an unstable radioactive nucleus. He thus combined the new science of nuclear physics with the second law of thermodynamics, which says that over time, order tends to give way to disorder. He made no effort to explain where this original nucleus came from. This is how Lematre unleashed his vision of cosmic birth:
This atom is conceived as having existed for an instant only, in fact, it was unstable and, as soon as it came into being, it was broken into pieces which were again broken, in their turn; among these pieces electrons, protons, alpha particles, etc., rushed out. An increase in volume resulted, the disintegration of the atom was thus accompanied by a rapid increase in the radius of space which the fragments of the primeval atom filled, always uniformly.
He then described how, from this prototypical matter, gaseous clouds would eventually form and condense into clusters of nebulae what we call galaxies. With amazing intuition, he even proposed that the debris of these cosmic fireworks is detectable today as fossil rays, which he associated with cosmic rays. Little did he know that such rays indeed permeate the Universe. They are what we now call the cosmic background radiation, but they are not related to cosmic rays.
Lematre was clear that this model was only a rough approximation: Naturally, too much importance must not be attached to this description of the primeval atom, a description which will have to be modified, perhaps, when our knowledge of atomic nuclei is more perfect. Again, he was right. His cosmogonic vision, in a sense a cross between a creation myth and a scientific model, was to become the precursor of the modern Big Bang model of cosmology.
Despite obvious similarities with the let there be light biblical account, Lematre insisted that his primeval atom hypothesis was a scientific model, and was not inspired by religious views on creation. He felt very uncomfortable when, in 1951, Pope Pius XII compared the initial state of the Universe as described scientifically with the Catholic interpretation of Genesis. In 1958, due to the pressure of several colleagues, Lematre felt it was time to justify his position:
As far as I can see, such a theory remains entirely outside any metaphysical or religious question. It leaves the materialist free to deny any transcendental Being For the believer, it removes any attempt to familiarity with God It is consonant with Isaiah speaking of the Hidden God, hidden in the beginning.
Lematre never ruled out the possibility that even the coming into being of the primeval atom could someday be explained scientifically, proposing that the answer may come from applying quantum mechanics to the Universe as a whole. This idea will re-emerge decades later, as Edward Tryon, Stephen Hawking, and others propose a quantum origin for the Big Bang. He left it to the future to determine whether any scientific theory can actually deal with the problem of the First Cause. (Where did the primeval atom come from?) As we will see, the problem remains unsolved.
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Physicists Create Photonic Time Crystal That Amplifies Light – Gizmodo
A team of researchers designed a two-dimensional photonic time crystal that they say could have applications in technologies like transmitters and lasers.
What Is Carbon Capture? With Gizmodos Molly Taft | Techmodo
Despite their name, photonic time crystals have little in common with time crystals, a phase of matter first proposed in 2012 and observed several years later. The fundamental commonality is that both crystals have structural patterns over time, but time crystals are quantum materialsthe atoms are suspended in quantum stateswhile photonic time crystals are artificial materials not found in nature and theyare not necessarily suspended in quantum states.
Researchers have had difficulty building and manipulating 3D photonic time crystals, so the recent team tried something different: slimming down the material to a mere 0.08 inches (2 millimeters) thick. Their crystal amplifies light at microwave frequencies. The experiment results are published today in Science Advances.
By modulating or changing the electromagnetic property of the metasurface over time, we were able to create a 2D photonic time crystal, said Xuchen Wang, a physicist at the Karlsruhe Institute of Technology and the studys lead author, in an email to Gizmodo. Reducing photonic time crystals from 3D to 2D can make them thinner, lighter, and easier to manufacture, just like how metasurfaces improved on metamaterials.
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Photonic crystals are optical structures whose ability to refract light changes periodically (that is to say, over time). In lab settings, the electromagnetic properties of metamaterialscan be fine-tuned to create photonic crystals that are unnaturally good at amplifying light waves.
Photons in such crystals have a repeating pattern that makes them coherent, similar to how laser patterns pulsed at quantum bits help keep them coherent, prolonging quantum states.
In [photonic time crystals], energy is not conserved; hence the states residing in the momentum gap can have exponentially increasing amplitudes, said Mordechai Segev, a physicist at the Technion Israel Institute of Technology who is unaffiliated with the new paper, in a February interview with Nature Photonics. This has a huge impact on the physics involved.
Real-world applications of the discovery involve most devices that rely on photonics. For example, wireless signals could be improved by coating devices in 2D photonic time crystals, making signal strengths more robust.
Though the crystal crafted by the team only amplifies microwave frequencies, Wang told Gizmodo that a slight tweak in the design could allow the crystal to work in millimeter-wave frequencies, like those used in 5G communications.
Time will tell how scaleable the technology is and how well it performs outside a lab.
More: Physicists Got a Quantum Computer to Work by Blasting It With the Fibonacci Sequence
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Physicists Create Photonic Time Crystal That Amplifies Light - Gizmodo
Next Big Thing: Quantum in action – Cosmos
Ive been doing battle in the lab with quantum effects for close on 40 years, and its been mindboggling to see the shift in capability to the point where we can make hundreds of thousands of junctions on a single chip.
A new wave of quantum research was set in train with advances in nanotechnology and the ability to manipulate matter at really small scales, and now quantum has entered the lexicon, not just for people working in the area, and for fans of Marvel movies. Quantum is on the radar of governments, investors and forward-thinking businesses, who understand how transformative it will be in so many areas.
Quantum technologies are already impacting medicine through better imaging. Theyre changing our ability to see through barriers, into structures, into geological formations, as well as into cells. Quantum optimisation is already making a difference in freight and logistics. Governments of advanced economies around the world are focused on the potential of quantum.
Quantum is on the radar of governments, investors and forward-thinking businesses, who understand how transformative it will be in so many areas.
So were certainly in a good place. We dont have people worrying about whether were going to create mini black holes that will grow to swallow the world like the poor scientists at CERN. Were not struggling against entrenched positions, as the climate scientists did in the not-too-distant past.
Were in the sweet spot. This is the part of the quantum odyssey where we should feel optimistic and energised. We have excellent foundations, built on decades of patient, fundamental research funded by government. We have a lively research community and an energetic set of start-ups and multinationals working on some really novel ideas and applications. We have momentum and we have cut-through among decision-makers.
So we want to capitalise on that, and ensure Australia remains a world leader in quantum expertise and clever innovations. Its time now to widen the conversation, so that educators, businesses and researchers in other disciplines understand how these new technologies will impact what they do. We need to add the language of quantum to our kids backpacks, so theyre learning about quantum science and concepts from the get-go. Kids have no problem being in two places at once! They will get this faster than we did. We are even reading our babies books on quantum physics! Education is always the starting point.
We need to add the language of quantum to our kids backpacks, so theyre learning about quantum science and concepts from the get-go.
But were not progressing quantum in a linear fashion. At the same time as we teach young people the science, quantum needs to be on the radar of industry sectors and researchers outside the immediate quantum disciplines.
Were living the quantum revolution as we speak, and its important that the broader community understands that. If youre in a business that handles data, the security issues are not something for the medium-term to-do list. Theyre for attention now, to ensure data cant be harvested today for future decryption. If you use data in your research, you need to be thinking about interoperability and also how current platforms that combine classical and quantum computing will impact your research. You need to be ambitious and think well beyond the ways you have considered data in the past. If youre solving computationally large problems, youll be able to do it faster, and with lower energy consumption.
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If youre in any sector that requires super precise measurements, or need to make decisions where time is everything, then you should be thinking about whether this can help you.
Were living the quantum revolution as we speak, and its important that the broader community understands that.
People who work in finance, in mining and mapping, in measurement, in the transport and logistics sector these are the first cabs off the rank.
But none of us can present the full dance card of quantum applications. This is a task for each sector to consider. And people in industry need to be taking action now.
Specific industries should be asking themselves: What are the killer problems in my day-to-day work that weve never been able to solve? Could quantum be a possible solution? This is the right question, and I encourage everyone who is thinking about the shape of their business, or their research, or teaching over the next few years to turn their minds to it.
Dr Cathy Foley is Australias Chief Scientist. This is an edited extract from a speech she gave at Quantum Australia 2023 in February in Sydney. The full transcript of Dr Foleys speech is available here.
Read Dr Cathy Foleys previous Next Big Thing, from April 2021.
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