Category Archives: Quantum Physics
Orford 17-year-old is among brightest young minds in north west – Warrington Guardian
A 17-year-old boy from Orford was invited to an online celebration of some of the brightest young minds in the region thanks to his competition essay on the theories of quantum mechanics.
Thomas Shaw, who studies A-Level Biology, Chemistry and Maths, entered his 2,000-word essay on the fundamental theory in physics in the Pembroke North Essay competition
The competition is run by Pembroke College in Oxford, aiming to support and inspire the next generation of undergraduates as they consider their university choices.
Thomas said: I found the event interesting and I particularly enjoyed being able to ask questions to students about life on campus within the current COVID-19 restrictions.
Although I didnt win the prize I was able to further develop my writing style in anticipation of completing my Extended Project as well as gain a deeper understanding about quantum mechanics.
The former Cardinal Newman RC School pupil entered the competition over summer after hearing about it through Priestley Colleges Graduate programme, which is designed to improve students chances of securing places at the UKs top universities.
Ian Hughes, who helps Priestley students who are aiming for the most competitive universities, said Thomas was on his way to achieve his goal of studying Chemistry at Oxford.
He said: The dedication, knowledge and skills he has shown in producing this essay proves he has the calibre to achieve whatever he sets his heart on.
All participants received feedback from the postgraduates who marked their essays.
The online celebration covered Oxford admissions as well as a lecture from Peter Claus, who is the access fellow at Pembroke, discussing the history of Eugenics.
Priestley College is part of The Challenge Academy Trust in Warrington, offering a mix of A-Levels and vocational options and soon to be one of the first colleges in the country to offer T-Levels.
Priestly was also the first sixth form college in the country to be awarded STEM assured status, meaning it provides some of the best Science, Technology, Engineering and Maths education in the country.
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Orford 17-year-old is among brightest young minds in north west - Warrington Guardian
Meet the kaon – Symmetry magazine
All Clifford Charles Butler and George Rochester knew for sure was that theyd discovered something new. Photographs from their cloud-chamber experiments at the University of Manchester revealed the tracks of two particles that behaved unlike anything theyd seen before.
When the two physicists published their results in 1947 in the journal Nature, they could have had only the dimmest notion that their discovery would in time upend the worlds understanding of elementary particle physics.
Observations of kaons, as the particles came to be known, and other similar particles led physicists on a path toward the discoveries of new quantum properties of matter, new particlesincluding quarksand the downfall of a once-sacrosanct construct called CP symmetry, an exact relationship between the laws of physics for matter and those for antimatter. Today, high-precision experiments with kaons are helping researchers probe the limits of the same Standard Model the particles helped usher in.
But back in Butler and Rochesters day, physicists were mostly left scratching their heads, says Helen Quinn, an emerita professor of physics and astrophysics at the US Department of Energys SLAC National Accelerator Laboratory.
Kaons didnt fit any picture physicists had at the time, she says. In fact, when physicists realized they needed a new quantum property to describe the particles, it was called strangeness, because the particles had always seemed a bit strange.
By the start of the 1940s, it seemed like physicists were getting a handle on the fundamental particles and their interactions. They knew about electrons, protons and neutrons, as well as neutrinos and even positrons, the antiparticles of electrons Paul Dirac had predicted in the 1920s. They understood that there were forces beyond gravity and electromagnetism, the strong and weak nuclear forces, and were working to better understand them.
But puzzles emerged as unexpected new particles appeared. Physicists discovered muons in cosmic rays using a cloud chamber experiment in 1936. (The name cloud chamber comes from the fact that electrically charged particles travelling through water vapor form tiny trails of clouds in their wake.) They found pions by similar means in 1947.
That same year, Butler and Rochester announced theyd found particles they called V+ and V0. From a set of unusual fork[s] in their data, they inferred the existence of two fairly massive particles, one positively charged and the other neutral, that had broken apart into other particles.
The particles had a number of curious features. For one thing, they were heavyaround five times the mass of a muonwhich led to another puzzle. Ordinarily, heavier particles have shorter lifetimes, meaning that they stick around for less time before decaying into other, lighter particles. But as experiments continued, researchers discovered that despite their heft, the particles had relatively long lifetimes.
Another odd feature: The particles were easy to make, but physicists never seemed to be able to produce just one of them at a time. Smash a pion and a proton together, for example, and you could create the new particles, but only in pairs. At the same time, they could decay independently of each other.
In the 1950s, Murray Gell-Mann, Kazuo Nishijima, Abraham Pais and others devised a way to explain some of the curious behaviors kaons and other newly discovered particles exhibited. The idea was that these particles had a property called strangeness. Today, physicists understand strangeness as a fundamental, quantum number associated with a particle. Some particles have strangeness equal to zero, but other particles could have strangeness equal to +1, -1, or in principle any other integer.
Importantly, strangeness has to remain constant when particles are produced through strong nuclear forces, but not when they decaythrough weak nuclear forces.
In the example above, in which a pion and a proton collide, both of those particles have strangeness equal to 0. Whats more, that interaction is governed by the strong force, so the strangeness of the resulting particles has to add up to zero as well. For instance, the products could include a neutral kaon, which has strangeness 1, and a lambda particle, which has strangeness -1, which cancels out the strangeness of the kaon.
That explained why strange particles always appeared in pairsone particles strangeness has to be canceled out by anothers. The fact that theyre built through strong interactions but decay through weak interactions, which tend to take longer to play out, explained the relatively long decay times.
These observations led to several more fundamental insights, says Jonathan Rosner, a theoretical physicist at the University of Chicago. As Gell-Mann and colleagues developed their theory, they saw they could organize groups of particles into bunches related by strangeness and electric charge, a scheme known today as The Eightfold Way. Efforts to explain this organization led to the prediction of an underlying set of particles: quarks.
Another important feature of the strangeness theory: When scientists found that strange kaons could decay into, for example, ordinary pions, they surmised that the weak nuclear interaction, unlike the strong nuclear interaction, did not need to keep strangeness constant. This observation set in motion a series of theoretical and experimental developments that physicists are still grappling with today.
Building on theories that suggested the neutral kaon ought to have an antiparticle with opposite strangeness to the standard neutral kaon, Gell-Mann and Pais reasoned that the neutral kaon could, through complex processes involving weak interactions, transform into its own antiparticle.
The scheme has a significant consequence: It implies that there are two new particlesactually different combinations of the neutral kaon and its antiparticlewith different lifetimes. K-long, as its now called, lasts on average about 50 billionths of a second, while K-short lasts just under one-tenth of a billionth of a second before breaking apart. The prediction of these particles was among Gell-Manns favorite results, Rosner says, because of how easily they emerged out of basic quantum physics.
One of the important things about K-long and K-short, at least in Gell-Mann and Paiss theory, was that they obeyed something called CP symmetry. Roughly, CP symmetry says that if one were to switch every particle with its antiparticle and flip space around into a sort of mirror-image universe, the laws of physics would remain the same. CP symmetry holds in all classical physics, and it was CPs quantum variant that motivated Gell-Mann and Pais. (Technically, Gell-Mann and Pais were originally motivated by C symmetry alone, but they had to update their theory once experiments determined that weak interactions violated both charge conjugation and parity symmetrybut in such a way that CP itself seemed to remain a good symmetry.)
Ironically, a result motivated by CP symmetry led to its downfall: In 1964, James Cronin, Val Fitch and collaborators working at Brookhaven National Laboratory discovered that the K-long couldvery rarelybreak up into two pions, a reaction that violates CP symmetry. Kaon decays did violate CP symmetry after all.
By the early 1970s, Quinn says, physicists developing the Standard Model needed a way to incorporate CP violation. In 1973 Makoto Kobayashi and Toshihide Maskawa, building on work by Nicola Cabibbo, proposed the solution: The Standard Model needed an extra pair of quarks beyond what they had already theorized. They also predicted that certain quarks could decay through weak interactions into other quarks in ways that violate CP symmetry. Throughout the 1980s and 90s, kaon experiments such as KTeV at Fermilab and NA48 at CERNalong with B-meson experiments such as BaBar at SLAC and Belle at KEKprobed how such interactions led to CP violation.
Over the years, theorists had also made ever more precise predictions about the various ways kaons could break apart. So precise are these predictions, says Yau Wah, a physicist at the University of Chicago, that searching for rare kaon decaysremains among the best ways to test the Standard Model.
The merit of [these tests] is because the Standard Model is too successful, says Wah, who works on the K0TO experiment, a Japanese project to search for neutral kaons decaying into a pion, neutrino and antineutrino.
In the next five years, Wah says, K0TO will likely be in a position to say whether the Standard Models tight predictions related to that decay are correct. If not, it could indicate new sources of CP violation beyond the Standard Model.
Such studies are also a good way to probe physics at extremely high energy scales, since any deviations from current predictions would require new particles with enormous massesperhaps a million times that of the proton, says Cristina Lazzeroni, a physicist at CERNs NA62 experiment, which focuses on rare decays of charged kaons.
Lazzeroni says NA62 has already found some evidence of positively charged kaons decaying into positively charged pions and two neutrinos, and that in the next five years they plan to probe Standard Model physics to a level of accuracy that will allow them to see whether there is new physics to be found. What started in a simple cloud chamber three-quarters of a century ago is continuing in some of the most precise experiments ever done, and kaons are likely to keep on giving for years to come.
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There Are Places in the World Where Rules Are Less Important Than Kindness by Carlo Rovelli review – The Guardian
We live in a golden age of science writing, where weighty subjects such as quantum mechanics, genetics and cell theory are routinely rendered intelligible to mass audiences. Nonetheless, it remains rare for even the most talented science writers to fuse their work with a deep knowledge of the arts.
One such rarity is the Italian theoretical physicist Carlo Rovelli who, like some intellectual throwback to antiquity, treats the sciences and the humanities as complementary areas of knowledge and is a subtle interpreter of both. His best-known work is Seven Brief Lessons on Physics, which was a bestseller, most notably in Italy, where he is also well known for his erudite articles in newspapers such as Corriere della Sera.
He writes on subjects as varied as classical philosophy, the meaning of science, the role of religion, the nature of black holes and the sociopolitical revelation of reading Hitlers Mein Kampf (fascism grows from fear, not strength). His new book is a collection of his newspaper articles, a series of finely wrought essays that draw on an impressive hinterland of cultural and scientific learning.
A common theory in anthropology is violence is not intrinsic to human nature but grew out of the agricultural revolution
There is, for example, a fascinating exploration of Dantes understanding of the shape of the cosmos, which, says Rovelli, anticipated Einsteins brilliant intuition of a three sphere universe by six centuries. And a rather moving meditation on the nature of an octopuss consciousness that could make even the most devoted pescatarian hesitate before ordering a dish made from our shockingly underrated eight-limbed friends.
Rovelli asks what it must feel like to be an octopus with a brain that is spread throughout its body and with arms that can think independently. And he wonders that if evolution could come up with such a radically different form of intelligence on this tiny planet, then what more complex entities might inhabit other parts of the universe? If nothing else, an encounter with a life form with such a different sensory and information processing system, he says, should help clarify what is essential and what is an accessory to what we call consciousness.
The essay format makes for an entertaining and enlightening journey through a wide field of disciplines, which, thanks to Rovellis authoritative voice and clarity of thought, never seems random or disjointed.
What also holds the pieces together is Rovellis perspective as a classic European liberal leftist humanist. Its an attractive political sensibility, particularly in these strange days, and provides a welcome moral framework to much of the writing. But sometimes it lapses into eloquent or even just plain platitude, particularly when the author states his beliefs in bald terms: collaboration is better than conflict, social inequality is bad and war should be avoided.
Set against his almost effortless appreciation of ideas, this stripe of prefabricated idealism can seem politically simplistic. Its a tendency that becomes apparent in an essay about an archaeological find four years ago at Nataruk in Kenya, where the remains of 27 people were unearthed who were killed in a massacre dating back ten millennia.
A common theory in anthropology is that violence is not intrinsic to human nature but, rather, grew out of the agricultural revolution. But as the Nataruk find predates agriculture in the area, it would suggest that warfare is more deep seated than current anthropological thinking would have us believe.
Does that mean, as Rovelli puts it, that we are more akin to our close relatives and prolific warriors, the chimpanzees, or to our other relatives and promiscuous lovers, the bonobos? Well, he says, Nataruk could still prove that violence is a recent arrival in the human story, triggered not by agriculture but a less nomadic lifestyle in which land defence became more important.
The disgust for war that many of us feel may be rooted in the instinctual mental fabric of our species, he writes.
It may indeed, but its also possible that warfare has played its counterintuitive part in the extraordinary proliferation of humanity. Thats an unpalatable thought in almost every way, but the truth is there are many places in history where kindness has been less important than progress.
There Are Places in the World Where Rules Are Less Important Than Kindness by Carlo Rovelli is published by Penguin (20). To order a copy go to guardianbookshop.com. Delivery charges may apply
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Digging into the 3D Quantum Hall Effect – Physics
November 9, 2020• Physics 13, 170
Theorists invoke electron-phonon interactions to explain the recent observation of the quantum Hall effect in a 3D electronic system.
In February 1980, Klaus von Klitzing made a discovery that opened up one of the most exciting chapters in physics history. He had prepared a semiconductor device containing electrons confined to a single layer. This so-called 2D electron gas was already well known to physicists. But when von Klitzing subjected it to very low temperature and very high magnetic field, he found that an intrinsic electronic property, the Hall resistance, occurred only at quantized values that were integer multiples of he2 [1]. The exceptional precision of those values, and their observed insensitivity to sample impurities, ultimately led to the quantum Hall resistance being used to redefine a unit in terms of fundamental constants (see Kilogram Untethered from Early Objects). A perhaps lesser known fact is that physicists have been pursuing a 3D version of the quantum Hall effect (QHE) for 30 years. Experiments achieved success in 2019 [2]. Now, theorists are explaining those results with a model that involves a wave-like electron density. Their picture could help expand the realm of the QHE in 3D [3].
Like a box of chocolates, the QHE comes in many flavors [4]. The behavior seen by von Klitzing is known as the integer QHE. Physicists have since discovered a fractional version, a version that doesnt require a magnetic field, and even a light-induced version. In all cases, the effect is fundamentally tied to the systems two dimensionality. The Hall resistance measures how easily charges moving in an applied electric field can be bent by a perpendicular magnetic field. This resistance, which depends on the occupancy of available electronic states, varies continuously with magnetic field in a typical material. But in a very cold 2D system in a strong enough magnetic field, the Hall resistance only rises in steps (plateaus) because the field forces electrons in the bulk of the material to lie in flat bands with a quantized energy (Landau levels). As long as the Fermi energy, which characterizes the maximum energy of the electron distribution, lies in the gap between the levels, the Hall resistance is stuck at a plateau.
The QHE is difficult to achieve in 3D because the Landau levels spread out in energy along the direction of the magnetic field. As a result, no matter where the Fermi energy lies, the Landau levels (or, more accurately, bands) contribute states, filling the gap and destroying the Hall-resistance plateaus. But in 1987, Bert Halperin proposed that these problems would go away if some intrinsic instability of the materials electronic structure opened a gap in its electronic structure [5]. This instability could, for example, be an induced lattice potential or it could be a charge-density wave (CDW), where electrons form a standing wave pattern instead of being evenly distributed throughout the solid (Fig. 1). This clustering leads to an energy gap, and Halperin predicted that two concrete effects would result from the Fermi energy lying within this gap [5]: the resistivity along the electric field (the longitudinal resistivity) would be dissipationless and drop to zero; and the Hall resistivity would be restricted to the value he2. Here, is set by the period of some internal potential along the direction of the magnetic field, such as the lattice itself or a CDW. These predictions are precise hallmarks for distinguishing the 3D QHE from its 2D counterpart.
Several groups have attempted to see the 3D QHE [69], but none observed Halperins hallmarks. One experimental challenge is the need to find a material with the right kind of instability. Another is that tried-and-true tools for manipulating 2D systems, such as using an electronic gate to tune the carrier concentration and the Fermi level, dont necessarily carry over to 3D. Researchers have tried to build a 3D system from stacks of 2D materials [10]. But the resulting shape of the Fermi surface indicates that the system is still 2D in nature.
The 2019 experiment that succeeded in observing the 3D QHE was performed on the compound ZrTe5 by Fangdong Tang of the Southern University of Science and Technology (SUSTech), China, and colleagues [2]. The researchers used a magnetic field of around 2 T and cooled their material samples to 0.6 K. Crucially, these samples had high electronic mobilities and the Fermi level could be tuned to the extreme quantum limit, where only the lowest Landau level is occupied. Under these conditions, the experiments showed suppressed longitudinal resistivity and a Hall resistivity plateau that existed between 1.7 and 2.2 T. Moreover, for the plateau was equal to half the Fermi wavelength along the magnetic-field direction for all samples. Since the Fermi wavelength in these experiments was much larger than the lattice constant along the field direction, the researchers concluded that the observed 3D QHE arose from some long-wavelength potential (like a CDW) and not from any crystal potential.
Physicists have puzzled over two points about these new results: the precise mechanism behind the observed 3D QHE and why the Hall plateau exists only within a certain magnetic-field range. The theory from Fang Qin, also of SUSTech, and colleagues addresses both problems [3]. In their model, a magnetically induced CDW is behind the 3D QHE. They find that unlike CDWs that are driven by an electron-electron interaction (which would require very strong magnetic fields), CDWs driven by electron-phonon interaction can explain the experiments. They show that this interaction can create the required instability at the relatively small field of 1.7 T. Their model also predicts that fields above about 2.1 T depin the CDW, making it incommensurate with the crystalline lattice. This feature explains why no resistance plateaus are seen above 2.1 T. The theorists picture thus shows the dual function of the magnetic field: it induces an order parameter (CDW) in one direction and a topological phase (the QHE) in the perpendicular direction.
Decades after the discovery of the QHE, the family of related phenomena continues to spread in new directions. Experiment and theory on the 3D QHE open many possibilities that researchers have yet to tap. As Qin and colleagues suggest [3], the race is on for prospective materials hosting the 3D effect. Finding such materials is a must for this area to bloom. With a suitable handcrafting of the crystal structure and of the electron interactions, researchers may achieve a 3D QHE effect under less stringent experimental conditions, such as at room temperature or perhaps even without an external magnetic field. Chances are that condensed-matter physicists beloved chocolate box is going to offer up more treats.
Luis E. F. Foa Torres is an Associate Professor at the Faculty of Physical and Mathematical Sciences of the University of Chile. Previously, he worked in Argentina, Germany, France, and Italy. His topics of research interest include quantum transport, two-dimensional materials, topological insulators, electron-phonon interaction effects, and the physics of driven systems. He received the International Centre for Theoretical Physics (ICTP) Prize in 2018.
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Physicists Circumvent 178-Year Old Theory to Cancel Magnetic Fields – SciTechDaily
The ability to cancel magnetic fields has benefits in quantum technology, biomedicine, and neurology.
A team of scientists including two physicists at the University of Sussex has found a way to circumvent a 178-year old theory which means they can effectively cancel magnetic fields at a distance. They are the first to be able to do so in a way that has practical benefits.
The work is hoped to have a wide variety of applications. For example, patients with neurological disorders such as Alzheimers or Parkinsons might in the future receive a more accurate diagnosis. With the ability to cancel out noisy external magnetic fields, doctors using magnetic field scanners will be able to see more accurately what is happening in the brain.
The study Tailoring magnetic fields in inaccessible regions is published in Physical Review Letters. It is an international collaboration between Dr. Mark Bason and Jordi Prat-Camps at the University of Sussex, and Rosa Mach-Batlle and Nuria Del-Valle from the Universitat Autonoma de Barcelona and other institutions.
Earnshaws Theorem from 1842 limits the ability to shape magnetic fields. The team were able to calculate an innovative way to circumvent this theory in order to effectively cancel other magnetic fields which can confuse readings in experiments.
In practical terms, they achieved this through creating a device comprised of a careful arrangement of electrical wires. This creates additional fields and so counteracts the effects of the unwanted magnetic field. Scientists have been struggling with this challenge for years but now the team has found a new strategy to deal with these problematic fields. While a similar effect has been achieved at much higher frequencies, this is the first time it has been achieved at low frequencies and static fields such as biological frequencies which will unlock a host of useful applications.
Other possible future applications for this work include:
Dr. Rosa Mach-Batlle, the lead author on the paper from the Universitat Autonoma de Barcelona, said: Starting from the fundamental question of whether it was possible or not to create a magnetic source at a distance, we came up with a strategy for controlling magnetism remotely that we believe could have a significant impact in technologies relying on the magnetic field distribution in inaccessible regions, such as inside of a human body.
Dr. Mark Bason from the School of Mathematical and Physical Sciences at the University of Sussex said: Weve discovered a way to circumvent Earnshaws theorem which many people didnt imagine was possible. As a physicist, thats pretty exciting. But its not just a theoretical exercise as our research might lead to some really important applications: more accurate diagnosis for Motor Neurone Disease patients in the future, for example, better understanding of dementia in the brain, or speeding the development of quantum technology.
Reference: Tailoring Magnetic Fields in Inaccessible Regions by Rosa Mach-Batlle, Mark G. Bason, Nuria Del-Valle and Jordi Prat-Camps, 23 October 2020, Physical Review Letters.DOI: 10.1103/PhysRevLett.125.177204
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Physicists Circumvent 178-Year Old Theory to Cancel Magnetic Fields - SciTechDaily
A Modem With a Tiny Mirror Cabinet Could Help Connect The Quantum Internet – ScienceAlert
Quantum physics promises huge advances not just in quantum computing but also in a quantum internet a next-generation framework for transferring data from one place to another. Scientists have now invented technology suitable for a quantum modem that could act as a network gateway.
What makes a quantum internet superior to the regular, existing internet that you're reading this through is security: interfering with the data being transmitted with quantum techniques would essentially break the connection. It's as close to unhackable as you can possibly get.
As with trying to produce practical, commercial quantum computers though, turning the quantum internet from potential to reality is taking time not surprising, considering the incredibly complex physics involved. A quantum modem could be a very important step forward for the technology.
"In the future, a quantum internet could be used to connect quantum computers located in different places, which would considerably increase their computing power!" says physicist Andreas Reiserer, from the Max Planck Institute in Germany.
Quantum computing is built around the idea of qubits, which unlike classical computer bits can store several states simultaneously. The new research focuses on connecting stationary qubits in a quantum computer with moving qubits travelling between these machines.
That's a tough challenge when you're dealing with information that's stored as delicately as it is with quantum physics. In this setup, light photons are used to store quantum data in transit, photons that are precisely tuned to the infrared wavelength of laser light used in today's communication systems.
That gives the new system a key advantage in that it'll work with existing fibre optic networks, which would make a quantum upgrade much more straightforward when the technology is ready to roll out.
In figuring out how to get stored qubits at rest reacting just right with moving infrared photons, the researchers determined that the element erbium and its electrons were best suited for the job but erbium atoms aren't naturally inclined to make the necessary quantum leap between two states. To make that possible, the static erbium atoms and the moving infrared photons are essentially locked up together until they get along.
Working out how to do this required a careful calculation of the space and conditions needed. Inside their modem, the researchers installed a miniature mirrored cabinet around a crystal made of ayttrium silicate compound. This set up was then was cooled to minus 271 degrees Celsius (minus 455.8 degrees Fahrenheit).
The modem mirror cabinet. (Max Planck Institute)
The cooled crystal kept the erbium atoms stable enough to force an interaction, while the mirrors bounced the infrared photons around tens of thousands of times essentially creating tens of thousands of chances for the necessary quantum leap to happen. The mirrors make the system 60 times faster and much more efficient than it would be otherwise, the researchers say.
Once that jump between the two states has been made, the information can be passed somewhere else. That data transfer raises a whole new set of problems to be overcome, but scientists are busy working on solutions.
As with many advances in quantum technology, it's going to take a while to get this from the lab into actual real-world systems, but it's another significant step forward and the same study could also help in quantum processors and quantum repeaters that pass data over longer distances.
"Our system thus enables efficient interactions between light and solid-state qubits while preserving the fragile quantum properties of the latter to an unprecedented degree," write the researchers in their published paper.
The research has been published in Physical Review X.
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A Modem With a Tiny Mirror Cabinet Could Help Connect The Quantum Internet - ScienceAlert
Quantum Technology: Harnessing the Power of Quantum Mechanics – Analytics Insight
Over the years, quantum mechanics has paved the way of humans understanding of the physical world. From the interaction of light and matter to pervasive inventions like lasers and semiconductor transistors, it provides an account of the physical properties of nature at the scale of atoms and subatomic particles. In todays digital age, every business and even country is racing to achieve quantum supremacy. Last year, tech giant Google claimed that it has achieved quantum supremacy by developing a quantum computer called Sycamore. It has the ability to perform a test computation in just 200 seconds against the most powerful supercomputers that likely to take thousands of years to accomplish.
Despite decades of research, the quantum world still remains enigmatic and far away from the human imagination. Quantum technology refers to an emerging field of physics and engineering, relying on the principles of quantum physics. It was first delineated in a 1997 book by Gerard J. Milburn. After that, the technology has accepted immensely from the influx of new ideas from the field of quantum information processing, especially quantum computing.
When it comes to technology, advancements in both business and technological applications have always progressed hand in hand. The field of quantum technology which has been around for decades promises dramatic applications such as the creation of novel materials, advanced metrology, secure communication, and more. Many organizations realize the benefits of quantum technologies to society, industry and academia. Governments are also investing in research and commercialization of these technologies, while universities are exploring implausible applications.
China, for instance, recently demonstrated secure quantum communication links between terrestrial stations and satellites. In the journalNature, the team of 24 scientists reported new progress of successfully testing the transmission of a secret key for encrypting and decrypting messages between a satellite and two ground stations located roughly 700 miles apart. The method enlisted quantum entanglement, an idea of modern physics that seems ridiculously at odds with common sense.
In anarticle, Paul Martin, Quantum Technology Expert noted that with the latest feats of engineering harnessing more of the potential of quantum mechanics, quantum technology is gaining new hype 50 years later it became a part of human lives through nuclear power. According to him, we are now starting to control quantum entanglement and quantum superposition. That means quantum technology promises improvements to a broad range of everyday gadgets, including more reliable navigation and timing systems; more secure communications; more accurate healthcare imaging; and more powerful computing.
Along with private companies capital investments, government support of quantum technologies has created an optimistic environment for the future of this technology. For example, the UK Government has invested around 400 million in the UK National Quantum Technologies Programme to develop the countrys strong research capabilities in Quantum Technologies. The programme is a collaborative initiative to advance technology and provide long-term benefits to society. Within the programme, four quantum technology hubs were created, each with a particular focus.
On the other side, the Indian Government in the recent 2020 budget announced plans to invest US$1.12 billion in quantum computing research over the next five years. The US, China, Japan, Germany, and Canada have already announced ambitious schemes to bolster quantum computing programs.
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Quantum Technology: Harnessing the Power of Quantum Mechanics - Analytics Insight
Will the Universe Remember Us after We’re Gone? – Scientific American
Im a compulsive journal-scribbler. This habit, which goes back to my teens, has proved useful to my career. All my articles and books start as journal entries. But my motivation is not merely professional. If I dont record my thoughts, I wont remember them, and they wont matter. So I fear. This feeling has grown as Ive aged.
Compounding my concern is the possibilityno, probabilitythat one day humanity and all its residues will vanish. Our works of science, mathematics, philosophy, art, music and, yes, journalism will slip back into the void whence they came. Everything we have thought and done will be for naught. If nothing about us endures, if nothing is remembered, we might as well never have existed.
No wonder so many of us, even in this age of scientific materialism, still believe in God. An immortal, omniscient being watches over each and every one of us, and not just celebrities like Einstein and Beyonce. He/she/it/they also surely remembers us after were gone, like a cosmic backup device with infinite storage capacity. Supposedly. If this divine entity does not exist, and someday all traces of us disappear forever, in what sense do our lives matter?
Scientists are not immune to such anxieties. Existential angst, I suspect, accounts for physicists belief in conservation of information. I first heard about this proposition years ago, but Ive only given it serious consideration over the last few months, which Ive spent trying to learn quantum mechanics.
Two of my main texts are The Theoretical Minimum books on classical and quantum mechanics by Stanford physicist Leonard Susskind (with two co-authors). Susskind imparts what you need to know to start doing physics. One thing we definitely need to know, according to Susskind, is that information is never lost. This law, Susskind asserts, underlies everything else.
Conservation of information is more fundamental, he says, than Newtons first law (motion is conserved); the first law of thermodynamics (energy is conserved); and what is sometimes called the zeroth law of thermodynamics (if systems A and B are in equilibrium with C, then A and B are in equilibrium with each other). Hence Susskind calls conservation of information the minus-first law.
The minus-first law encompasses the principle of determinism, which holds that if you know the current state of a system, you know all of its past and future. The French polymath Simon-Pierre LaPlace famously spelled out the implications of determinism over 200 years ago:
An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.
This omniscient intellect has come to be known as LaPlaces demon. Susskind insists that quantum mechanics, although not deterministic in the same way as classical mechanics, still conforms to the minus-first law. In a 2008 interview he said the minus-first law underpins everything, including classical physics, thermodynamics, quantum mechanics, energy conservation, that physicists have believed for hundreds of years.
In the 1980s Stephen Hawking challenged the minus-first law, claiming that black holes destroy information. Hawkings hypothesis touched off a crisis in physics, a clash of basic principles like no other since Einstein was young, Susskind said in 2008. He rebutted Hawking in papers and a popular book, The Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics.
All the information sucked into a black hole, Susskind argues, is preserved in its outer membrane, or event horizon, where space and time undergo bizarre distortions. In a review of Black Hole War, journalist George Johnson bravely takes a stab at explaining Susskinds thesis: A description of everything that falls into a black hole, whether a book or an entire civilization, is recorded on the surface of its horizon and radiated back like imagery on a giant drive-in movie screen.
Susskind, as you might guess from Johnsons review, is fond of theories that cannot be empirically tested and hence potentially falsified. In his 2005 book The Cosmic Landscape, Susskind contends that our universe is just a hillock in an infinite landscape of universes. This proposal is pure speculation, and hence arguably unscientific, because we have no way to prove or disprove the existence of other universes.
Perhaps Susskind and other physicists dont want us lay folk to take ideas like the multiverse or minus-first law too seriously. Maybe these are just metaphors, poetic fancies, like the Holy Ghost in Catholicism. But physicists seem to pride themselves on saying what they mean. So, Im going to take Susskind at his word when he declares that information is never lost.
Let me tease out the implications of that remarkable statement. First, as I have argued previously, the concept of information doesnt make any sense in the absence of something to be informed, that is, a mind. Information requiresit presupposesconsciousness. So, if information is conserved, so is consciousness. If consciousness exists now, it must always exist. Or so the minus-first law implies.
In fact, many scientists and philosophers have proposed that consciousness is as fundamental as matter, or even more fundamental. Ive lumped these speculations together under the label neo-geocentrism, because they resurrect the ancient, narcissistic notion that the universe revolves around us. Neo-geocentric theories represent attempts to sneak a consoling religious assumptionthis universe is all about usback into science, and so does conservation of information.
If I had to rank laws of physics, Id go with the second law of thermodynamics, which holds that disorder, or entropy, always increases. Our expanding cosmos is headed toward heat death, a state of terminal boringness, in which nothing ever happens. The second law of thermodynamics, evidence for which I see whenever I look in the mirror or read the news, trumps the minus-first law.
Actually, Im suspicious of all laws of physics, which strike me as manifestations of scientific hubris. Scientists take an assumption that applies under certain very tightly controlled conditions, usually with lots of qualifications, and transform it into a cosmic principle that applies to all things at all times in all places. But Im especially skeptical of the minus-first law.
Never mind Hawkings conjecture that black holes destroy information. Im worried about far more mundane processes. Three years ago, strokes severely damaged my fathers memory, making it hard for him to recognize me and my siblings. Last June he died, at the age of 96, and my stepmother had his body cremated. My father persists, sort of, in the fragmentary, fading recollections of those who loved him. Polymath Douglas Hofstadter coined the heartbreaking phrase soular coronas to describe our memories of those eclipsed by death. But one day well die too.
The minus-first law implies that the universe will bear the imprint of my fathers life forever. Long after our sun and even the entire Milky Way have flickered out, aliens with the godlike powers of LaPlaces demon could in principle (that handy, all-purpose hedge) reconstruct the lives of my father and every other person who has ever lived.
Thats a nice thought (which inspired the 1996 book The Physics of Immortality by physicist Frank Tipler.) But I dont buy conservation of information any more than I buy reincarnation or heavenor a god who cherishes us. These propositions, scientific and religious, represent understandable but finally unpersuasive attempts at consolation. My contemplation of the inevitable loss of everyone and everything I love unsettles me. But Id rather face death squarely than take refuge in false assurances from priests or physicists.
In The Black Hole War, Susskind strikes a rare (for him) note of humility: Very likely we are still confused beginners with very wrong mental pictures, and ultimate reality remains far beyond our grasp. (I found this quote in a blog post by physicist Peter Woit.) On this point, Susskind and I agree.
Meanwhile, as my end looms, I keep frantically filling up notebooks.
Further Reading:
The Twilight of Science's High Priests
The Delusion of Scientific Omniscience
Multiverse Theories Are Bad for Science
Can Mysticism Help Us Solve the Mind-Body Problem?
The Rise of Neo-Geocentrism
Why information can't be the basis of reality
Quantum Escapism
My Quantum Experiment
See also Strange Loops All the Way Down, a chapter in my free online bookMind-Body Problems.
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Will the Universe Remember Us after We're Gone? - Scientific American
Threat of Quantum Computing to Bitcoin Should be Taken Seriously, But theres Enough Time to Upgrade Current Security Systems, Experts Claim -…
LocalBitcoins, a leading peer to peer (P2P) Bitcoin exchange, notes that with the advent of quantum computing, there have been concerns that this new technology could be a threat to existing online protocols. Some experts claim that powerful quantum computers might become a legitimate threat to the security of Bitcoin (BTC) and the current encryption algorithms that it uses.
According to LocalBitcoins:
While the threat of quantum computing to Bitcoin is to be taken seriously, experts believe that Bitcoin [and other cryptocurrencies] have time to adapt to the quantum age without compromising [their] security in the process.
As explained in a blog post by LocalBitcoins, Bitcoin or BTC and its blockchain-based network is secured by cryptographic algorithms, which is why its called a cryptocurrency. Cryptography allows developers to protect certain sensitive data and communication on a platform so that only the parties authorized to view the information can access it. The LocalBitcoins team notes that cryptography uses several different algorithms, and Bitcoin depends on them to function properly.
At present, these algorithms are almost impossible to break, but quantum computers may spell trouble to these algorithms in various ways, according to LocalBitcoins.
They explain that the idea or concept behind quantum computing is to go beyond the power of traditional computers by leveraging quantum mechanics, a field in physics that describes behaviors on a subatomic scale. They also noted that when unobserved, subatomic particles can exist in multiple places at once, however, when [they have been] detected, they collapse into a single point in space-time.
They further explain:
Traditional computers operate with bits which encode either a 0 or a 1, while quantum computers use quantum bits, or qubits, which can be both a 0 or a 1 at the same time. This phenomenon is known as superposition which allows a huge amount of calculations to be carried out simultaneously.
They continued:
Bitcoins algorithm most at risk from quantum computing is its signature algorithm that uses ECDSA (Elliptic Curve Digital Signature Algorithm) [which] is used to generate the public/private key pair to sign Bitcoin transactions securely (sending and receiving coins). ECDSA uses asymmetric encryption, and the reason for it being secure comes from the need to factor multiple large prime numbers to break the algorithm. Breaking ECDSA and deriving a private key from a public key using current computers would take such an astronomical amount of time that it wouldnt even be realistic to try it out.
But with quantum computers that support parallel calculation, this same process can be carried out a lot more efficiently, and multiple types of attacks then become possible, the LocalBitcoins team noted.
They explained that the first one of these potential attacks aims to target re-used addresses. When a transaction is performed, your public key becomes visible on the blockchain or a distributed ledger technology (DLT) network. The LocalBitcoins team adds that knowing your public key, an attacker whos using quantum computers may then use your public key to derive your private key. After theyve determined what your private key might be, they can begin signing transactions on your behalf which means they can also spend your Bitcoins or any other cryptocurrency.
LocalBitcoins clarifies that addresses that have not been used to send transactions are quantum-safe because quantum computers cant read their public key.
LocalBitcoins further noted that another possible attack is the double-spend attack. This measures how fast a quantum computer can derive your private key from the already visible public key. They pointed out that if an attacker can do this before your transaction is confirmed multiple times in a block, you are essentially both trying to spend the same bitcoin, and the attacker wins.
They also mentioned:
Bitcoins hashing function used in the block creation is even more robust in the face of a quantum threat than its signature algorithm. The algorithm Bitcoin uses in its mining process is called SHA-256. When a miner solves a block and receives the right to add it to the blockchain, that miners transactions become confirmed, and part of the ledger.
They further explained:
To solve a block, a miner needs to guess a nonce, or a value that after a hash is applied, results in a number that has a certain number of leading zeroes. As a miner, you cant start from a valid result and then generate the correct nonce from it. You have to randomly guess it. This takes a lot of computing power and is behind the proof-of-work securing Bitcoins network. If the SHA-256 was broken somehow, an attacker could mine new blocks at will and earn all Bitcoin block rewards.
LocalBitcoins notes that existing quantum computers are only operated in labs and still appear to be a long way from becoming a legitimate threat to Bitcoin and other cryptocurrencies. According to estimates, a quantum computer of around 4000 qubits would be required to break Bitcoins code, while the most powerful quantum computers available right now operate with only about 50 qubits.
Industry experts predict that quantum computing machines may begin to break binary based encryption algorithms within the next decade unless theres an unexpected mathematical or physical breakthrough before that.
The LocalBitcoins team added:
When the quantum threat becomes more imminent, cryptography will have moved to more quantum-proof algorithms. In the process, Bitcoins algorithms would have become quantum-resistant as well. This can be achieved by hard-forking (backwards incompatible upgrade) the Bitcoin blockchain by consensus among the Bitcoin nodes, so it will be secure from quantum attacks.
They continued:
As long as multiple users have access to a quantum computer, no single entity will be able to gain dominance over Bitcoin mining. Perhaps in the future Bitcoins blockchain will be operated completely by nodes running on quantum computers.
Original post:
Pablo Jarillo-Herrero receives the Lise Meitner Distinguished Lecture and Medal – MIT News
Pablo Jarillo-Herrero, the Cecil and Ida Green Professor of Physics, was awarded the Lise Meitner Distinguished Lecture and Medal, for his groundbreaking work on twistronics, a technique that adjusts the electronic properties of graphene by rotating adjacent layers of the material.
His breakthrough research in twisted bilayer graphene research discovered unique electrical properties with the potential to create innovative superconducting materials and novel quantum devices for advanced quantum sensing, photonics, and computing applications.
The medal, sponsored by theRoyal Swedish Academy of Sciences through its Nobel Committee for Physics, recognizes the work by Jarillo-Herrero and his group that helped launch a new field: strongly correlated physics in 2D moir superlattices.
Pablos work has really changed the way physicists think about materials and it has created a great opportunity for theorists to develop new ideas, says Peter Fisher, professor and head of MITs Department of Physics.
Jarillo-Herrero will give his lecture and receive his medal at the annual colloquium-style event at AlbaNova University Center in Stockholm, at a date to be determined next year. The lecture commemorates Lise Meitner, an Austrian-Swedish physicist who contributed to the discoveries of the element protactinium and nuclear fission.
The list of previous recipients is very distinguished, Jarillo-Herrero says, noting fellow recipients including Nobel Prize winners Frank Wilczek, the MIT physics professor who was the first recipient of the prize,in 2015, and Princeton Universitys Duncan Haldanein 2017. So for me it's a great, and humbling, honor to see my name in the same list!
TheJarillo-Herrero Groupexplores quantum transport in novel condensed matter systems such as graphene and topological insulators.
A native of Valencia, Spain, Jarillo-Herrero joined MIT as an assistant professor of physics in 2008, where he received tenure in 2015, and was promoted to full professor of physics in 2018.
In October he received the RSEF Medal, the highest scientific recognition of the Spanish Royal Physics Society. Other awards include anAlfred P. Sloan Fellowship; a David and Lucile Packard Fellowship; a DoE Early CareerAward; a Presidential Early Career Award for Scientists and Engineers; an ONR Young Investigator Award; a Moore Foundation Experimental Physics in QuantumSystems Investigator Award; ThePhysics World2018 Breakthrough of the Year; the 2020 Oliver E. Buckley Condensed Matter PhysicsPrize; and the 2020 Wolf Prize in Physics. In 2018, Jarillo-Herrero was elected a fellow of the American Physical Society.
See more here:
Pablo Jarillo-Herrero receives the Lise Meitner Distinguished Lecture and Medal - MIT News