Category Archives: Quantum Physics

No matter who you are, where you are, or how quickly youre moving, the laws of physics will appear exactly the same to you as they will to any other observer in the Universe. This concept that the laws of physics dont change as you move from one location to another or one moment to the next is known as the principle of relativity, and it goes all the way back not to Einstein, but even farther: to at least the time of Galileo. If you exert a force on an object, it will accelerate (i.e., change its momentum), and the amount of its acceleration is directly related to the force on the object divided by its mass. In terms of an equation, this is Newtons famous F = ma: force equals mass times acceleration.

But when we discovered particles that moved close to the speed of light, suddenly a contradiction emerged. If you exert too large of a force on a small mass, and forces cause acceleration, then it should be possible to accelerate a massive object to reach or even exceed the speed of light! This isnt possible, of course, and it was Einsteins relativity that gave us a way out. It was commonly explained by what we call relativistic mass, or the notion that as you got closer to the speed of light, the mass of an object increased, so the same force would cause a smaller acceleration, preventing you from ever reaching the speed of light. But is this relativistic mass interpretation correct? Only kind of. Heres the science of why.

Schematic animation of a continuous beam of light being dispersed by a prism. If you had ultraviolet and infrared eyes, youd be able to see that ultraviolet light bends even more than the violet/blue light, while the infrared light would remain less bent than the red light does. The speed of light is constant in a vacuum, but different wavelengths of light travel at different speeds through a medium.

The first thing its vital to understand is that the principle of relativity, no matter how quickly youre moving or where youre located, is still always true: the laws of physics really are the same for everyone, regardless of where youre located or when youre making that measurement. The thing that Einstein knew (that both Newton and Galileo had no way of knowing) was this: the speed of light in a vacuum must be exactly the same for everyone. This is a tremendous realization that runs counter to our intuition about the world.

Imagine youve got a car that can travel at 100 kilometers per hour (62 mph). Imagine, attached to that car, youve got a cannon that can accelerate a cannonball from rest to that exact same speed: 100 kilometers per hour (62 miles per hour). Now, imagine your car is moving and you fire that cannonball, but you can control which way the cannon is pointed.

As shown in an episode of Mythbusters, a projectile fired backward from a forward-moving vehicle at the exact same speed will appear to fall directly down at rest; the velocity of the truck and the exit velocity from the cannon exactly cancel each other out in this take.

This is what we commonly experience and also lines up with what we expect. And this is also experimentally true, at least, for the non-relativistic world. But if we replaced that cannon with a flashlight instead, the story would be very different. You can take a car, a train, a plane, or a rocket, traveling at whatever speed you like, and shine a flashlight from it in any direction you like.

That flashlight will emit photons at the speed of light, or 299,792,458 m/s, and those photons will always travel at that same exact speed.

That speed that the photons travel at will be the same as ever, the speed of light, not only from your perspective, but from the perspective of anyone looking on. The only difference that anyone will see, dependent on how fast both you (the emitter) and they (the observer) are moving, is in the wavelength of that light: redder (longer-wavelength) if youre mutually moving away from each other, bluer (shorter-wavelength) if youre moving mutually toward each other.

An object moving close to the speed of light that emits light will have the light that it emits appear shifted dependent on the location of an observer. Someone on the left will see the source moving away from it, and hence the light will be redshifted; someone to the right of the source will see it blueshifted, or shifted to higher frequencies, as the source moves toward it.

This was the key realization that Einstein had when he was devising his original theory of Special Relativity. He tried to imagine what light which he knew to be an electromagnetic wave would look like to someone who was following that wave at speeds that were close to the speed of light.

Although we dont often think of it in these terms, the fact that light is an electromagnetic wave means:

This was cemented in the 1860s and 1870s, in the aftermath of the work of James Clerk Maxwell, whose equations are still sufficient to govern the entirety of classical electromagnetism. You use this technology daily: every time an antenna picks up a signal, that signal arises from the charged particles in that antenna moving in response to those electromagnetic waves.

Light is nothing more than an electromagnetic wave, with in-phase oscillating electric and magnetic fields perpendicular to the direction of lights propagation. The shorter the wavelength, the more energetic the photon, but the more susceptible it is to changes in the speed of light through a medium.

Einstein tried to think of what it would be like to follow this wave from behind, with an observer watching electric and magnetic fields oscillate in front of them. But, of course, this never occurs. No matter who you are, where you are, when you are, or how quickly youre moving, you and everyone else always sees light move at exactly the same speed: the speed of light.

But not everything about light is the same for all observers. The fact that the observed wavelength of light changes dependent on how the source and the observer are moving relative to one another means that a few other things about light must change as well.

This last part is critical for our understanding, because momentum is the key link between our old school, classical, Galilean-and-Newtonian way of thinking and our new, relativistically invariant way of thinking that came along with Einstein.

The size, wavelength, and temperature/energy scales that correspond to various parts of the electromagnetic spectrum. You have to go to higher energies, and shorter wavelengths, to probe the smallest scales. Ultraviolet light is sufficient to ionize atoms, but as the Universe expands, light gets systematically shifted to lower temperatures and longer wavelengths.

Light, remember, ranges in energy tremendously, from gamma ray photons at the highest energies down through X-rays, ultraviolet light, visible light (from violet to blue to green to yellow to orange to red), infrared light, microwave light, and finally radio light at the lowest energies. The higher your energy-per-photon, the shorter your wavelength, the higher your frequency, and the greater the amount of momentum that you carry; the lower your energy-per-photon, the longer your wavelength, the lower your frequency, and the smaller your momentum is.

Light can also, as Einstein himself demonstrated with his 1905 research into the photoelectric effect, transfer energy and momentum into matter: massive particles. If the only law we had was Newtons law the way were used to seeing it as force equals mass times acceleration (F= ma) light would be in trouble. With no mass inherent to photons, this equation wouldnt make any sense. But Newton himself didnt write F= ma like we often suppose, but rather that force is the time rate of change of momentum, or that applying a force causes a change in momentum over time.

The inside of the LHC, where protons pass each other at 299,792,455 m/s, just 3 m/s shy of the speed of light. Particle accelerators like the LHC consist of sections of accelerating cavities, where electric fields are applied to speed up the particles inside, as well as ring-bending portions, where magnetic fields are applied to direct the fast-moving particles toward either the next accelerating cavity or a collision point.

So, what does that mean momentum is? Although many physicists have their own definition, the one Ive always liked is, Its a measure of the quantity of your motion. If you imagine a dockyard, you can imagine running a number of things into that dock.

A large superyacht, MotorYacht GO, crashed into the Saint Maartens Yacht Club dock. The large amount of momentum in the yacht caused it to crash through wood, concrete, and even reinforced steel as it destroyed the dock. Momentum, for very large masses moving even at slow speeds, can be disastrous.

The problem is, going all the way back to Newton, that the force you exert on something is equal to a change in momentum over time. If you exert a force on an object for a certain duration, its going to change that objects momentum by a specific amount. This change doesnt depend on how fast an object is moving alone, but only by the quantity of motion it possesses: its momentum.

So what is it, then, that happens to an objects momentum when it gets close to the speed of light? Thats really what were trying to understand when we talk about force, momentum, acceleration, and velocity when we near the speed of light. If an object is moving at 50% the speed of light and it has a cannon thats capable of firing a projectile at 50% the speed of light, what will happen when both speeds point in the same direction?

You know you cant reach the speed of light for a massive object, so the naive thought that 50% the speed of light + 50% the speed of light = 100% the speed of light has to be wrong. But the force on that cannonball is going to change its momentum by exactly the same amount when fired from a relativistically-moving frame-of-reference as it will when fired from rest. If firing the cannonball from rest changes its momentum by a certain amount, leaving it with a speed thats 50% the speed of light, then firing it from a perspective where its already moving at 50% the speed of light must change its momentum by that same amount. Why, then, wouldnt its speed be 100% the speed of light?

A simulated relativistic journey toward the constellation of Orion at various speeds. As you move closer to the speed of light, not only does space appear distorted, but your distance to the stars appears contracted, and less time passes for you as you travel. StarStrider, a relativistic 3D planetarium program by FMJ-Software, was used to produce the Orion illustrations. You dont have to break the speed of light to travel 1,000+ light-years in less than 1,000 years, but thats only from your point of view.

Understanding the answer is the key to understanding relativity: its because the classical formula for momentum that momentum equals mass multiplied by velocity is only a non-relativistic approximation. In reality, you have to use the formula for relativistic momentum, which is a little bit different, and involves a factor that physicists call gamma (): the Lorentz factor, which increases the closer you move to the speed of light. For a fast-moving particle, momentum isnt just mass multiplied by velocity, but mass multiplied by velocity multiplied by gamma.

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Applying the same force that you applied to an object at rest to an object in motion, even in relativistic motion, will still change its momentum by the same amount, but all of that momentum wont go into increasing its velocity; some of it will go into increasing the value of gamma, the Lorentz factor. For the earlier example, a rocket moving at 50% the speed of light that fires a cannonball at 50% the speed of light will result in a cannonball traveling at 80% the speed of light, with a Lorentz factor of 1.6667 along for the ride. The idea of relativistic mass is very old and was popularized by Arthur Eddington, the astronomer whose 1919 solar eclipse expedition validated Einsteins theory of General Relativity, but it takes a certain liberty: it assumes that the Lorentz factor () and the rest mass (m) get multiplied together, an assumption that no physical measurement or observation can test for.

Time dilation (left) and length contraction (right) show how time appears to run slower and distances appear to get smaller the closer you move to the speed of light. As you approach the speed of light, clocks dilate toward time not passing at all, while distances contract down to infinitesimal amounts.

The whole point of going through all of this is to understand that when you moveclose to the speed of light, there are many important quantities that no longer obey our classical equations. You cant just add velocities togetherthe way Galileo or Newton did;you have to add them relativistically.

You cant just treat distances as fixed and absolute; you have to understand thatthey contract along the direction of motion. And you cant even treat time as though it passes the same for you as it does for someone else; the passage of time is relative, anddilates for observers moving at different relative velocities.

A light-clock, formed by a photon bouncing between two mirrors, will define time for any observer. Although the two observers may not agree with one another on how much time is passing, they will agree on the laws of physics and on the constants of the Universe, such as the speed of light. A stationary observer will see time pass normally, but an observer moving rapidly through space will have their clock run slower relative to the stationary observer.

Its tempting, but ultimately incorrect, to blame the mismatch between the classical world and the relativistic world on the idea of relativistic mass. For massive particles that move close to the speed of light, that concept can be correctly applied to understand why objects can approach, but not reach, the speed of light, but it falls apart as soon as you incorporate massless particles, like photons.

Its far better to understand the laws of relativity as they actually are than to try and shoehorn them into a more intuitive box whose applications are fundamentally limited and restrictive. Just as is the case with quantum physics, until youve spent enough time in the world of relativity to gain an intuition for how things work, an overly simplistic analogy will only get you so far. When you reach its limits, youll wish you had learned it correctly and comprehensively the first time, all along.

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Does mass increase when nearing the speed of light? - Big Think

You know a story is going to be fun when it starts with a question that makes you laugh: What is the most boring number in the world? It's a legitimate mathematical question, and it turns out there are interesting numbers (prime numbers, powers of 2) and not-so-interesting numbers. You can probably anticipate the paradox: If a number is especially boring, doesn't that make it interesting? Theoretical physicist Manon Bischoff, who is an editor for our partner publication Spektrum in Germany, showshow to sort numbers for boringness and why it matters.

I admit I was skeptical when we first started discussing a story proposal about treating a person with multiple personalities. Weren't some of the classic cases exaggerated or made up? But the fascinating account of Ella by therapist and anthropologist Rebecca J. Lesterexplains how dissociative identity disorder can develop and manifest. It's a hopeful and generous story that takes us inside the therapeutic process and reveals how someone can start to heal from extreme trauma.

When a weather disaster strikes, people want to know whether climate change is to blame. And if so, to what degree? The field of attribution science has advanced dramatically in the past decade. As investigative journalist Lois Parshley writes, researchers are now able to say how much worse or more likely floods, hurricanes, wildfires, droughts, and other disasters were made by the human-caused climate crisis. This knowledge can help people respond to unfolding disasters and plan for future ones.

Drug-resistant hookworms are spreading among pet dogs, and researchers have traced their origins to greyhounds raised for racing. The parasites can kill puppies and occasionally cause nasty infections in people. Science journalist Bradley van Paridon describes how the superparasite evolved and traveled through greyhound racetracks, rescue dogs and dog parks.

Electrons move in mysterious ways. They're too fast to observe in detail as they jump through crystals or perform feats of quantum tunneling that let them escape energy barriers. To understand the bizarre properties of matter, physicists are creating models made of light. Physicist Charles D. Brown II shares how his light-based version of graphene lets him study how particles behave in a crystal lattice. In the author's words, Quantum physics is a trip!

Some of the most distinctive languages on Earth are still spoken, but just barely, by people who live on the Andaman Islands off the coast of India. Andamanese people arrived to the archipelago about 50,000 years ago, and according to genetic and linguistic studies, they were largely isolated until recently. Linguist Anvita Abbi worked with the last speakers of several local languages to preserve and understand their heritage. She discovered that the grammar of Andamanese languages is fundamentally based on the parts of the body, unlike any known language family.

What's the future of fusion? Is it always going to be another 20 or 30 or 50 years away? In our cover story, author Philip Ball examines recent advances in fusion energy, including the first reaction that created more energy than was used to trigger it. Fusion will not be part of our urgently needed transition from fossil fuels to renewable energy. But there's still a chance it could succeed ... in another 20 or 30 or 50 years. Ball cuts through the hype and explores the physical limitations and opportunities of the energy that powers stars.

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Answering Questions about Boring Numbers, Disasters, Fusion, and ... - Scientific American

In theaters June 2

THE PLOT:

Miles Morales (Shameik Moore) a.k.a. Spiderman, is now a household name in Brooklyn NY, saving citizens from those who wish to harm them. Yet, being a superhero is lonely as Miles longs to see Gwen (Hailee Steinfeld) again Spiderwoman from an alternate universe.

As Miles struggles to break free from his parents image of him as a kid, he encounters The Spot (Jason Schwartzman) a local villain hell-bent on getting revenge on Miles for transforming him into what he has become.

With The Spot creating havoc, Gwen and other Spidermen and women from alternate universes work to stop him, but Miles discovers a truth from his allies that, for him, is just as sinister as any villainous plan and he plans to stop it.

KENTS TAKE:

Spiderman: Across the Spider-verse is the second chapter in the ongoing Sony animated Spiderman series and is the first half of a two-part story.

Miles is back and is still working through his feelings and situation. His uncle turned out to be The Prowler and is now dead. He learned that he is not the only Spiderman in the universe and has fallen for Gwen, a Spiderwoman in an alternate universe. Spiderman is also a local celebrity in Brooklyn, and this celebrity comes with pitfalls, such as the guest-hosting of Jeopardy, the failed baby powder endorsement, and his attempt to grow a moustache. Miles is a teenager through and through, pushing back at his parents who still see him as a kid while he fights to be heard and understood.

Directors Joaquin Dos Santos, Kemp Powers and Justin K. Thompson bring us a vibrant, colorful, and wildly creative animated feature. Mixing and matching animation styles, this film will keep viewers attention throughout its 2 hours and 15-minute running time. Using interesting and unusual perspectives, we follow Miles and Gwen as they traverse Brooklyn and the multiverse following their spidey-senses to lead them to a truth that is very relevant to Miles.

Writers Phil Lord, Christopher Miller and Dave Callaham manage to pull off a rare occurrence creating a sequel to a successful film that is as good, if not better than the first film. This film is not political, it isnt preachy, and it certainly isnt your traditional superhero film what it is, is an action-packed coming-of-age story about a regular kid who is special and the struggles he endures as he transitions from childhood to adulthood. This heartfelt, emotional film isnt sappy, its real, real life, real feelings in an unreal setting. A setting with splashes of color, hidden places, dark shadows, freedom, beauty, and wonder. Miles likes Gwen and Gwen likes him back, but this isnt a sappy romance, its the awkward moments, the unspoken words and the silences that define their relationship.

The cast is excellent and adds depth to this feature, but the strength of performance by Shameik Moore as Miles elevates this film and creates an honesty that is vital to its success.

Another notable strength of this film is its soundtrack. From modern rap to classic R&B, this soundtrack covers a diverse musical palette and weaves perfectly into the story helping to define and create moods.

Spiderman: Across the Spider-verse is the first Summer Blockbuster to hit theaters and its recommend that this cool, action-packed, memorable story be seen on the big screen. This is one of those instances where getting caught in a spiders web will be a positive experience.

LYNNS TAKE:

Pop art, quantum physics and pathos collide in a grand superhero spectacle, resulting in this Spider-Man: Across the Spider-Verse, sequel being a mind-blowing amalgamation of next-level animation like but surpassing the 2018 original.

However inventive and clever it is, though, about half of the storyline is incoherent and panders to fan service -- and the sensory-overload-on-steroids style is overwhelming and exhausting. Yet, were all locked in.

This 2 hour and 20- minute eye-popping extravaganza takes place across six dimensions, has 240 characters in it and had over 1,000 animators working on it the most ever.

The Spider-Man mythology, easily relatable for teens who understood creator Stan Lees metaphors for figuring out their place in the world, began as a socially inept high school student who was bitten by a radioactive spider, and thus developed superpowers. That was in 1962, and in fighting crime in his subsequent Marvel Comics issues, Peter Parker would eventually learn with great power comes great responsibility.

Since 2002, there have been eight live-action Spider-Man movies, plus his role in The Avengers franchise, not to mention a past TV series, Broadway musical, video games and books.

The three co-directors Joaquim Dos Santos, Kemp Powers, and Justin K. Thompson mash parts of the old films with elements of the comic books. That comic imagery, added in with drawing and painting styles of the 20th and 21st centuries, results in a visually stunning work. Art historians will be in for a treat.

And comic book fans will be delirious about the Easter eggs no doubt courtesy of cheeky producers Phil Lord and Chris Miller who finally won an Oscar for directing the first movie (previously robbed for The Lego Movie) but only co-wrote this script with David Callaham, a veteran of the first and Shang-Chi and the Legend of the Ten Rings.

I understand their desire to throw in as many gags for the super-fans, but that darn muddled narrative lets the rest of us down. And their need to fiddle with the Spider-Man canon to keep it fresh and interesting. Sure, there are compelling human emotional touches (dead relatives, loved ones in peril), but the hyper-kinetic storytelling weakens the overall effect for those not in the zone.

Another sticking point is that the middle entry in this animated world ends with a cliffhanger, then states Miles will return in Spider-Man: Beyond the Spider-Verse. It is set for a March 29, 2024, release -- frustrating to viewers who like things resolved before waiting for another one, because this one just ends without a resolution.

And if you did not see Spider-Man: Into the Spider-Verse released four and a half years ago, you will be lost here. As a quick recap, Miles Morales, a black Hispanic Brooklynite, was juggling his life between being in high school and a Spider-Man, but when Wilson Kingpin Fisk uses a super collider, he finds out that others from across the Spider-Verse have been transported to his dimension.

This time, 15-year-old Miles remains on Earth 42, but as he discovers more multi-verses, he meets dozens of other Spider-People. In this global take, we meet a Spider-Man India (Karan Soni), a cockney street punk Spidey named Hobie (Daniel Kaluuya), a snarling, hulking vampire Spidey Miguel OHara (Oscar Isaac), and a pregnant Spider-Woman, motorcycle mama Jessica Drew (Issa Rae). Saving the world is tough business, and there are existential crises happening.

Miles mentor, Peter Parker (Jake Johnson), is shown as a young father, married to MJ (Zoe Kravitz), who brings his baby along for the adventures. Sad girl Gwen Stacy (Hailee Steinfeld) is a combo grrrl rocker and a Spider-Girl whose anguished storyline is equal to Miles.

While one can applaud the energy and the dazzling visuals of non-stop action, characters are often frazzled, and the pace is so frenetic that you feel like you are trapped in this parallel universe too. Whos good, whos evil, and who may be both?

Shameik Moore has returned to voice Miles, and hes dandy as the angsty teen who is exasperating to his parents because of his time-management skills (they dont know hes keeping the bad guys in check, at least his neighborhood in Queens).

His parents are voiced by Brian Tyree Henry and Luna Loren Valdez, joining a slate of major talent whose vocal work is solid but does not immediately identify them. Yet, its easy to place J.K. Simmons as J. Jonah Jameson, SNLs Rachel Dratch as the principal, and Jason Schwartman as the revenge-seeking villain The Spot (a standout).

Hyper and hypnotic, Spider-Man: Across the Spider-Verse has pushed forward the genre and is a fun fan experience. The propulsive score by composer Daniel Pemberton is also a plus. I give the animation an A+ but the story a B-.

Its a lot to juggle sci-fi, action, adventure, family, comedy, drama, and fantasy in one animated feature, and this film does display heart, even if the movie cant stand on its own.

After two decades of superhero comics ruling the bombastic blockbuster box office, whats next? Has art opened another dimension? One of the Spider-Verses greatest strengths is that it still surprises, and these multiverses show no signs of maxing out.

One thing is for certain, the enthusiasm for this head-spinning series is not waning anytime soon (even with the grumbling about waiting for the next sequel). Its as if weve hopped on one of the wildest amusement parks rides ever, and we need to see where it leads.

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Spiderman: Across the Spider-verse | Reel World | timesnewspapers ... - Webster-Kirkwood Times, Inc.

Were not getting to absolute zero anytime soon. The temperature at which all energy in an object drops to zero, our inability to reach it is enshrined in the third law of thermodynamics.

One version of the law states that in order to reach absolute zero, wed have to either have infinite time or infinite energy. Thats not happening any time soon, so out the window go our hopes of achieving a total lack of energy.

Or do they?

A team from the Vienna University of Technology in Austria wanted to see if there was alternate route to absolute zero. And they found one in an interesting placequantum computing.

The researchers entered into their research with the intent of trying to generate a version of the third law of thermodynamics that jived cleanly with quantum physics. Because the regular version that so many physicists know and love doesnt quite fit nicely into the quantum world.

Disagreements between classical and quantum physics happen all the timeits why so much time and effort goes into trying to find a unified theory of physics that encompasses both sets of rules. That doesnt mean classical physics is wrong, it just means its limited in ways that we didnt expect when we first were figuring out how the universe works.

The third law of thermodynamics, despite how fundamental it is, is one of those surprisingly limited aspects of classical physics. In saying that we cant reach absolute zero without infinite time or infinite energy, it doesnt fully take a fundamental aspect quantum physicsinformation theoryinto account.

A principle of information theory called the Landauer principle states that there is a minimum, and finite, amount of energy that it takes to delete a piece of information. The catch here is that deleting information from a particle is the exact same thing as taking that particle to absolute zero. So, how is it possible that it takes a finite amount of energy to delete information and an infinite amount of energy to reach absolute zero, if those two things are the same?

It's not a total paradoxyou could take an infinitely long time. But that doesnt tell the whole story. The team discovered a key parameter that would get it done a whole lot fastercomplexity. It turns out that if you have complete, infinite control over an infinitely complex system, you can bring fully delete information from a quantum particle without the need for infinite energy or infinite time.

Now, is infinite complexity with infinite control more achievable than infinite time or infinite energy? No. Were still dealing with infinities here.

But this discovery does emphasize known limitations in the functionality of quantum computers. Namely, once we start saving information on those things, were never going to be able to fully scrub the information from the quantum bits (known as qubits) making up our information storage centers.

According to experts, thats not going to present a practical issue. Machines that operate absolutely perfectly already dont exist, so theres no reason to hold quantum computers to an unreachable standard. But it does teach us a bit more about exactly what building and operating these futuristic machines is going to take.

When it comes to quantum, were just getting started.

Associate News Editor

Jackie is a writer and editor from Pennsylvania. She's especially fond of writing about space and physics, and loves sharing the weird wonders of the universe with anyone who wants to listen. She is supervised in her home office by her two cats.

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There's a Secret Way to Get to Absolute Zero. Scientists Just Found It. - Popular Mechanics

A team at the University of Portsmouth has achieved unprecedented precision in measurements through a method involving quantum interference and frequency-resolving sampling measurements. This breakthrough could enhance imaging of nanostructures and biological samples, and improve quantum-enhanced estimation in optical networks.

A team of researchers has demonstrated the ultimate sensitivity allowed by quantum physics in measuring the time delay between two photons.

By measuring their interference at a beam-splitter through frequency-resolving sampling measurements, the team has shown that unprecedented precision can be reached within current technology with an error in the estimation that can be further decreased by decreasing the photonic temporal bandwidth.

This breakthrough has significant implications for a range of applications, including more feasible imaging of nanostructures, including biological samples, and nanomaterial surfaces, as well as quantum-enhanced estimation based on frequency-resolved boson sampling in optical networks.

The research was conducted by a team of scientists at the University of Portsmouth, led by Dr. Vincenzo Tamma, Director of the UniversitysQuantum Science and Technology Hub.

Dr. Tamma said: Our technique exploits the quantum interference occurring when two single photons impinging on the two faces of a beam-splitter are indistinguishable when measured at the beam-splitter output channels. If, before impinging on the beam splitter, one photon is delayed in time with respect to the other by going through or being reflected by the sample, one can retrieve in real time the value of such a delay and therefore the structure of the sample by probing the quantum interference of the photons at the output of the beam splitter.

We showed that the best precision in the measurement of the time delay is achieved when resolving such two-photon interference with sampling measurements of the two photons in their frequencies. Indeed, this ensures that the two photons remain completely indistinguishable at detectors, irrespective of their delay at any value of their sampled frequencies detected at the output.

The team proposed the use of a two-photon interferometer to measure the interference of two photons at a beam splitter. They then introduced a technique based on frequency-resolving sampling measurements to estimate the time delay between the two photons with the best possible precision allowed by nature, and with an increasing sensitivity at the decreasing of the photonic temporal bandwidth.

Dr. Tamma added: Our technique overcomes the limitations of previous two-photon interference techniques not retrieving the information on the photonic frequencies in the measurement process.

It allows us to employ photons of the shortest duration experimentally possible without affecting the distinguishability of the time-delayed photons at the detectors, and therefore maximizing the precision of the delay estimation with a remarkable reduction in the number of required pairs of photons. This allows a relatively fast and efficient characterization of the given sample paving the way to applications in biology and nanoengineering.

The applications of this breakthrough research are significant. It has the potential to significantly improve the imaging of nanostructures, including biological samples, and nanomaterial surfaces. Additionally, it could lead to quantum-enhanced estimation based on frequency-resolved boson sampling in optical networks.

The findings of the study are published in the journal Physical Review Applied.

Reference: Ultimate Quantum Sensitivity in the Estimation of the Delay between two Interfering Photons through Frequency-Resolving Sampling by Danilo Triggiani, Giorgos Psaroudis and Vincenzo Tamma, 24 April 2023, Physical Review Applied.DOI: 10.1103/PhysRevApplied.19.044068

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Photon Precision: How Quantum Physicists Shattered the Bounds of Sensitivity - SciTechDaily

IN NOVEMBER 1997, a young physicist named Juan Maldacena proposed an almost ludicrously bold idea: that space-time, the fabric of the universe and apparently the backdrop against which reality plays out, is a hologram.

For many working in the fields of particle physics and gravity at the time, Maldacenas proposal was as surprising as it was ingenious. Before it was published, the notion of a holographic universe was way out there, says Ed Witten, a mathematical physicist at the Institute for Advanced Studies in Princeton (IAS), New Jersey. I would have described it as wild speculation.

And yet today, just over 25 years on, the holographic universe is widely revered as one of the most important breakthroughs of the past few decades. The reason is that it strikes at the mystery of quantum gravity the long-sought unification of quantum physics, which governs particles and their interactions, and general relativity, which casts gravity as the product of warped space-time.

Then again, you might wonder why the idea is held in such high regard given that it remains a mathematical conjecture, which means it is unproven, and that the model universe it applies to has a bizarre geometry that doesnt resemble our universe.

The answer, it turns out, is twofold. First, the holographic conjecture has helped to make sense of otherwise intractable problems in particle physics and black holes. Second, and more intriguing perhaps, physicists have finally begun to make headway in their attempts to demonstrate that the holographic principle applies to the cosmos we actually reside in.

Maldacena, now also at the IAS, was originally inspired by two separate branches of

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Do we live in a hologram? Why physics is still mesmerised by this idea - New Scientist

My friend, Richard is a curmudgeonly physicist, who sends me science-y things he finds online. Richard loves making the point that if you dont understand something mathematically, you dont understand it. This claim bugs me, perhaps because I studied literature in college and teach humanities here at Stevens. My rebuttal follows.

Richard is in fancy company when he contends that the deepest truths are mathematical. Pythagoras and Plato both implied as much, and Galileo famously wrote that you can only read the grand book of the universe if you understand the language in which the book is written: mathematics. In 1931 James Jeans, a British physicist, proposed that the Great Architect of the universe, that is, God, seems to be a mathematician.

Richard sent me the Galileo and Jeans quotes, plus similar comments from physicist Richard Feynman. To those who do not know mathematics, Feynman wrote in The Character of Physical Law, it is difficult to get across a real feeling as to the beauty, the deepest beauty, of nature. But heres an irony: Feynmans comments on quantum physics contradict the claim that mathematics illuminates nature.

In a book on quantum electrodynamics, which he helped formulate, Feynman reiterates that you cant comprehend quantum theory without the math. But he adds that you cant understand it with the math either! I dont understand quantum physics, Feynman confesses. Nobody does. He suggests that physicists advanced mathematical tricks, although they make calculations easier, can obscure what is actually happening in nature.

Also, if God is a mathematician, in what dialect does She/He/They/It speak? Quantum phenomena are described with differential equations, matrices and path integrals, a method invented by Feynman. Each of these dialects employs imaginary numbers, which are constructed from the square roots of negative numbers.

Moreover, quantum theory accounts for electromagnetism and the nuclear forces, and general relativity describes gravity. Quantum theory and general relativity are conveyed in radically different lingos that are hard to translate into each other. Some physicists still dream of a unified theory, possibly embodied in a single formula, that describes reality. That is the theme of Michio Kakus recent bestseller The God Equation: The Quest for a Theory of Everything.

But Kakus vision of a mathematical theory of everything seems increasingly quaint, given all weve learned about the limits of mathematics. In the 1930s, Kurt Gdel proved that all but the simplest mathematical systems are inconsistent, posing problems that cannot be solved within the axioms of that system. Extending the work of Gdel, mathematician Gregory Chaitin points out that mathematics, rather than being a unified, logically consistent whole, is riddled with randomness, contradictions and paradoxes.

Philosopher Bertrand Russell, early in his career, revered mathematics, which he thought is our best route to absolute truth. Toward the end of his life, perhaps because of the influence of Gdel, Russell arrived at a darker view of mathematics. I fear that, to a mind of sufficient intellectual power, he wrote, the whole of mathematics would appear trivial, as trivial as the statement that a four-footed animal is an animal.

Thats far too bleak a view. If mathematics reduces to a tautology, 1 = 1, it is a fantastically fecund tautology. Mathematics has led to countless intellectual, aesthetic and material advances, on which our civilization depends. But mathematics, like ordinary language, is a human invention, a powerful but limited tool, not a divine gift. Many mysteries resist mathematical analysis, especially those related to the human mind. And some great scientific advances have been non-mathematical. Charles Darwins On the Origin of Species does not include a single equation.

For all these reasons, we should doubt physicists who say that truth must be expressed in equations. Physicists would say that, wouldnt they? Thats like a poet saying that truth can only be expressed in meter and rhyme, or an economist saying that everything comes down to money.

Back for a moment to my grouchy pal Richard. Although a math-o-phile, Richard does not share the belief of Kaku and others that there ismust be!a single, true mathematical description of the world. Richard adheres to a position called theoretical pluralism. There can be many ways to model nature and to solve a scientific problem, Richard says, and insisting that there must be one correct way can impede scientific progress. On this point, Richard and I agree.

John Horgan directs the Stevens Center for Science Writings. This column is adapted from one posted on johnhorgan.org.

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Is Ultimate Truth an Equation? Nah. The Stute - The Stute

Published on Thursday, May 4, 2023

How can integrating the arts with science and technology cultivate something new and unexpected? This question is one that Nancy Kawalek has been answering in several ways throughout her career most recently, with a suite of engaging games focused on teaching the principles of quantum science and engineering.

Kawalek, a professionally trained actor, brings her unique perspective from a background in theater to explore the myriad possibilities of a different stage: Scientists,Technologists, andArtistsGeneratingExploration.

Aptly shortened to STAGE, the collective laboratory was initially launched by Kawalek during her time at the California Nanosystems Institute at the University of California, Santa Barbara (UCSB). Today, it is embedded in the Pritzker School of Molecular Engineering (PME)at theUniversity of Chicago where Kawalek is a professor and Distinguished Fellow in Arts, Science, and Technology.

A true testament to the interdisciplinary tenant on which the PME was established, Kawalek was encouraged to expand her work at UChicago by a former UCSB colleague, Matthew Tirrell, who has been the dean of PME since 2011. Her team includes distinguished scientists, engineers, professional actors, technology experts, students, and diverse theatrical, visual, media, and performing artists.

At that time I had no idea that the University of Chicago would be such a good place, that the fit was just right, said Kawalek, who stressed that the aim is to explore how to get people to think and work in new ways, in addition to getting them excited about science.

Importantly, we are never going to get everyone excited about science just by sharing the facts. Weve seen this happen in such a bold way recently. I believe the only way to engage the general public in the sciences is to grab them emotionally. And I think the way to do that is always with a good story, said Kawalek. Its critical that we move people or entertain them and thats what the games do.

The Quantum Casino

A betting card game for two to seven players, Chicago Quantem is based on the popular poker variant Texas Holdem. The experiential game immerses players in the world of quantum physics and qubits.

With these concepts superposition, entanglement, operations, and measurement built into the game mechanics, the goal is to collect, change, and arrange the cards into a winning hand. Cards and colors are used to represent these complex ideas. As one example, having more entanglement in the game is better because more entangled qubits are desirable in quantum applications.

For Kawalek, it has been gratifying to see the games out in the world and being enjoyed by a diverse range of players. The STAGE team debuted the games at the 2022 American Physical Society (APS) Annual Meeting and featured them later that year at the South Side Science Festival where five- and ten-year-olds sat down with the game. Its amazing when you can create something that really spans all ages and levels of education, Kawalek said.

In six months, Kawalek and her team, including more than 40 students, created three card games with custom decks and three digital games. The project is aptly called the Quantum Casino and also includes a Quantum Photo Booth, which is used to aid in explaining quantum key distribution, a mechanism for sharing encryption keys between remote parties.

The work drew from three important research papers: Quantum Poker:a game for quantum computers suitable for benchmarking error mitigation techniques on NISQ devices; Quantum blackjack:advantages offered by quantum strategies in communication-limited games; and Investigation of quantum roulette.

But why quantum specifically? Kawalek wants more people to engage with quantum science and engineering an area that promises to provide growing opportunities and jobs, including many that dont require a PhD. To know that you can get some training and have a job that is interesting and that pays well its a huge opportunity to level the playing field for a large swath of the population who might never think they could engage with science, or be a scientist, she explained.

This approach means making the games accessible to schools and teachers. You really cant make an impact unless your work is out in the world, said Kawalek, who is collaborating with the Polsky Center for Entrepreneurship and Innovation to commercialize and patent the Quantum Casino games. We are eager to reach as many people as possible. If you can engage a few people, and they start to talk to others, it creates a ripple effect.

INTERESTED IN THIS TECHNOLOGY?ContactMichael Hinton, Manager, Technology Marketing, who can provide more detail aboutthis technology, discuss the licensing process, and connect you with the inventor.

//Polsky Patentedis a column highlighting research and inventions from University of Chicago faculty. For more information about available technologies,click here.

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May 5, 2023• Physics 16, 75

A new kind of 3D optical lattice traps atoms using focused laser spots replicated in multiple planes and could eventually serve as a quantum computing platform.

Researchers have produced 3D lattices of trapped atoms for possible quantum computing tasks, but the standard technology doesnt allow much control over atom spacing. Now a team has created a new type of 3D lattice by combining optical tweezerspoints of focused light that trap atomswith an optical phenomenon known as the Talbot effect [1]. The teams 3D tweezer lattice has sites for 10,000 atoms, but with some straightforward modifications, the system could reach 100,000 atoms. Such a large atom arrangement could eventually serve as a platform for a quantum computer with error correction.

3D optical lattices have been around for decades. The standard method for creating them involves crossing six laser beams to generate a 3D interference pattern that traps atoms in either the high- or low-intensity spots (see Synopsis: Pinpointing Qubits in a 3D Lattice). These cold-atom systems have been used as precision clocks and as models of condensed-matter systems. However, the spacing between atoms is fixed by the wavelength of the light, which can limit the control researchers have over the atomic behavior.

Optical tweezers offer an alternative method for trapping and controlling atoms. To form a tweezer array, researchers pass a single laser beam through a microlens array (or similar device) that focuses the beam into a 2D pattern of multiple bright spots. Atoms are automatically drawn to the centers of these spots, forming an array in a single plane (see Viewpoint: Alkaline Atoms Held with Optical Tweezers). We take these tweezer arrays to the third dimension, says Malte Schlosser from the Technical University of Darmstadt, Germany.

To obtain a 3D lattice, Schlosser and his colleagues took advantage of the Talbot effect, which is an interference phenomenon that occurs when light strikes a periodic structure, such as a diffraction grating or a microlens array. The light exiting the structure produces a 2D interference pattern of bright spots at some fixed distance beyond the structure but also generates additional planes of spots parallel to the first one. The Talbot effect had long been considered a nuisance for tweezer array research, as it creates extra bright spots that trap stray atoms, which interferes with measurements. The researchers turned this bug into a feature by deliberately tuning their optical system to trap atoms in the extra bright spots, Schlosser explains.

The researchers shined an 800-milliwatt laser onto a microlens array, which produced a 2D square array of 777 atom traps at the focal plane of the lens. But thanks to the Talbot effect, this 2D array was reproduced in 17 parallel planes, giving a total of 10,000 atom traps. These Talbot planes come for free, so we dont have to put in additional laser power or additional laser beams, Schlosser says.

As a demonstration of their system, Schlosser and his colleagues showed that they could load around 50% of the traps with rubidium atoms and induce an optical transition in all the atoms in a sublattice. In the future, the team plans to use a focused laser beam to selectively excite a single atom. Such optical control could allow researchers to read the atoms state or to place it in a so-called Rydberg state that would let it interact with its neighbors. Control of atomatom interactions has been previously demonstrated in 2D tweezer arrays. Schlosser foresees having atomatom interactions in the 3D lattice, but currently the spacing between the planes is too large (around 100 m); a distance of 10 m or less would be required.

Besides squeezing down the spacing of the lattice, the team plans to explore other trap geometries, such as hexagonal patterns that could mimic materials like graphene. The researchers are also working to boost the laser power. More light will increase the number of traps in the lattice. They estimate that doubling the power would provide 30,000 traps and that quadrupling it should produce close to 100,000.

Schlosser and his colleagues are tackling one of the most important challenges any quantum computing technology will face, which is scaling, says Ben Bloom, founder and chief technology officer of Atom Computing, a quantum technology company in California. He says that the new design can create a large number of atom quantum bits at essentially no cost, but there will be challenges ahead in trying to control the atoms within the lattice. Still, controlling so many atoms will have practical benefits. Pushing to large numbers of individually controlled atoms in 3D will allow for the exploration of new quantum error-correction codes, Bloom says.

Michael Schirber

Michael Schirber is a Corresponding Editor forPhysics Magazine based in Lyon, France.

A new experiment follows the trajectories of electrons as pulsed laser light yanks them away from their atoms and slams them back. Read More

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Physics - Tweezers in Three Dimensions - Physics

Less than three decades into the 21st century, the world is at the edge of a second quantum revolution one that integrates with the Fourth Industrial Revolution to create new technologies, new materials, and new, clean energy storage mechanisms.

It is also deepening humankinds understanding of life-generating biological processes such as photosynthesis, said Professor Jeff Murugan in his 19April inaugural lecture, The Future is Quantum How I learnt to stop worrying and embrace chaos.

It was the first in the reconfigured UCT Inaugural Lecture Series.

The term quantum revolution was coined by quantum physicists Jonathan Dowling and Gerard Milburn in 2002. It refers to quantum mechanics, a framework used to describe the dynamics of matter, such as electrons in atoms and molecules at a fundamental level.

The study of quantum matter the kind found in materials such as superconductors, magnets and graphene sits at the nexus of a number of overlapping disciplines, including condensed matter physics.

The title of Professor Murugans lecture was a play on words; chaos referring to both the realm of the everyday and the chaos that exists in realm of quantum particles because of their sometimes unpredictable properties.

The future is quantum

Early examples of quantum inventions include the transistor and laser. Lasers perhaps provide the easiest vehicle to demonstrate the enigma and potential of quantum mechanics. Lasers were developed in the 1950s by optical physicists who found that hitting certain kinds of atoms at the right energy could lead these to emit more photons with the same energy and direction as the initial photons. The effect would cause a cascade of photons, creating a stable, straight beam of light.

Suddenly were talking about material science, computing, batteries, cryptography, and all things quantum.

Harnessing the potential of a second quantum revolution has far-reaching implications, said Murugan, the founder and director of the Laboratory for Quantum Gravity & Strings (QGaSlab) in the Department of Mathematics and Applied Mathematics.

Suddenly were talking about material science, computing, batteries, cryptography, and all things quantum, he said. And in other things, were better able to understand chemistry and biology in terms of quantum mechanics, for example, why photosynthesis is the most efficient energy-harvesting system known in nature is best understood in terms of a property of quantum systems known as superposition.

Quantum computing has led big companies such as Google and Microsoft to invest heavily in quantum technologies,many teaming up with academic research institutions to create partnerships that will advance this technology.

Early developments

Murugan describes the mathematics at the heart of quantum matter as beautiful.

He and his talented young research group at QGaSlab, which corrals researchers in string theory, quantum gravity and cosmology, have made small but important breakthroughs in the field.

Theres been a flurry of activity over the past five to six years, building this up.

The result has been several research papers that explore the properties of these novel quantum systems.

Among these, quantum batteries are perhaps the most exciting possibility on South Africas radar right now: next-generation battery technology that can potentially revolutionise the nature of energy generation and storage.

No South African needs to be convinced that alternative energy storage is a good thing to invest in, said Murugan.

Unlike the batteries we know, such as the lithium-ion battery in smartphones that rely on classical electrochemical principles, quantum batteries rely solely on quantum mechanics.

They have a remarkable set of properties, he explained. Charging an ensemble of quantum batteries no longer scale linearly with the number of cells, but rather, exponentially. The more batteries there are, the faster they charge and the more batteries there are, the more energy you can deposit into that system, but exponentially faster. Remarkably, this quantum advantage of these batteries is because they are quantum chaotic!

In the current era of rolling blackouts and Eskoms uncertain future, the power of quantum batteries holds enormous potential for clean, reliable energy, he added.

Even though the possibilities are manifold, including new portable power sources for electric vehicles, which charge almost instantly, it is the fundamentally quantum aspect of these processes that intrigues Murugan, the mathematical physicist.

Chaos and purpose

But his beginnings as a mathematical physicist were not promising. At school he hated mathematics.

It was boring, uninspired and disconnected from anything. Physics, on the other hand, was amazing. It was curious and made me think about the world around us.

The turning point in his relationship with mathematics came with his introduction to calculus. It showed him that mathematics and physics were inextricably interwoven.

Here was motion; things were happening. There was cause and effect.

Mathematics is really a language to understand the universe around us.

From this, Murugan drew one of several life lessons that peppered his lecture, part of a legacy he would like to impart to his students (he is a 2018 Distinguished Teacher Awardee) and his children, he said.

Mathematics is really the language of nature. And like any language, it can be learnt in two ways. You can learn it like a linguist, understanding the structure of the language and the etymology of its lexicon, or immerse yourself in a population, where you will learn how to speak the language, swear-words and all.

Following undergraduate and postgraduate studies at UCT, in 2000 Murugan travelled to the United Kingdom on a Lindbury Fellowship to pursue a PhD in non-commutative geometry in string theory, jointly at UCT and Worchester College, Oxford. He was co-supervised by UCTs Emeritus Distinguished Professor of Complex Systems George Ellis and Philip Candelas, until recently Rouse-Ball Professor of Mathematics University of Oxford.

Postdoctoral studies followed at the High Energy Theory Group at Brown University in the United States. He returned to UCT in 2006 to join the Cosmology and Gravity Group, founded by Emeritus Professor Ellis. He left to begin QGaSlAB in 2012. In doing so, he had entered a new world of possibilities, perhaps too many, he said.

I am a mathematical physicist with a very short attention span so, unlike many of my colleagues, I dont spend too long thinking about any particular problem. My career has basically been a random walk through interesting problems in mathematical physics that include gravity, condensed matter, neurophysics, and even traffic flow.

This underpinned his final lesson in his lecture: Never stop learning!

Family business

The vote of thanks following Murugans presentation was delivered by his wife, UCT cosmologist Professor Amanda Weltman, the director of the High Energy Physics, Cosmology & Astrophysics Theory group at UCT andSARChI Chair in Physical Cosmology.

He takes very complex mathematical topics and unwraps them strand by strand.

Their three young children also attended the lecture, the littlest charming the audience over her fathers shoulder while another put his mind to bossing a Rubiks speed cube (a love of the abstract runs in the family).

In her address, Professor Weltman said, Theres never any doubt that Jeff was destined to be a professor of mathematical physics. His innate talent and great curiosity for understanding the universe and our world within it are two qualities that have helped him become a leader in the field and one of the most sought-after professors in the country.

Part of his appeal is that he takes very complex mathematical topics and unwraps them strand by strand. But best of all, he does so with great humour and there would be thunderous applause regularly coming from his lectures. Youd be forgiven for thinking you were at a comedy festival. And I would know that I would have to go in [to teach] next.

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Brave new world: On the edge of a second quantum revolution - University of Cape Town News