Tag: quantum mechanics

BIZARRE TACHYONS THAT MAY BE ABLE TO SEND DATA BACK IN TIME COULD BE RECONCILED WITH SPECIAL RELATIVITY

Tachyons, a mysterious variety of hypothetical particles capable of exceeding light speed, could play a more significant role in our understanding of the universe and its causal structure than scientists previously realized.

Not only have tachyons been revealed to be potentially compatible with Einstein’s special theory of relativity, but now, according to an international collaboration of physicists from the University of Warsaw and the University of Oxford, these curious particles could also help shed light on remaining questions regarding our understanding of the quantum world.

EXCEEDING THE UNIVERSAL SPEED LIMIT

Tachyons, which derive their name from the Greek word tachýs, meaning fast or quick, are theorized to exist under conditions where their minimum speed would be the speed of light. This effectively means that they should only be capable of traveling at velocities that exceed this universally recognized speed limit.

Ordinary particles, by comparison, move at subluminal or slower than light speeds. As Einstein’s theory of relativity dictates, the universal laws of physics prevent anything from being capable of accelerating to the speed of light from a slower speed. The same isn’t necessarily true for tachyons, though, since they are theorized to be born at speeds that already exceed light. Hence, the opposite would seem to be the case for these unusual particles, which hypothetically should be incapable of slowing down to light speed or slower speeds.

The idea of such superluminal particles has its origins in theoretical studies conducted back in the 1960s by physicist Gerald Feinberg. Although no experimental evidence has ever confirmed their existence, a theoretical framework for how these proposed particles might come to be has been developed over the decades, occasionally resulting in some rather strange paradoxes.

Among these is a curiosity that arises from their superluminal travel speeds, which indicates that tachyons may effectively be capable of sending information backward in time, giving rise to bizarre conditions under which cause and effect could theoretically become reversed.

However, new research is revealing that despite the implications of their existence, these bizarre hypothetical particles may be compatible with the special theory of relativity and could also help offer physicists significant new insights into quantum theory.

The new findings could potentially also upend long-held notions about the unlikelihood of superluminal particles, suggesting that tachyons might even play a crucial role in the formation of matter.

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Researchers demonstrate how to build ‘time-traveling’ quantum sensors

The idea of time travel has dazzled sci-fi enthusiasts for years. Science tells us that traveling to the future is technically feasible, at least if you’re willing to go near the speed of light, but going back in time is a no-go. But what if scientists could leverage the advantages of quantum physics to uncover data about complex systems that happened in the past?

New research indicates that this premise may not be that far-fetched. In a paper published June 27, 2024, in Physical Review Letters, Kater Murch, the Charles M. Hohenberg Professor of Physics and Director of the Center for Quantum Leaps at Washington University in St. Louis, and colleagues Nicole Yunger Halpern at NIST and David Arvidsson-Shukur at the University of Cambridge demonstrate a new type of quantum sensor that leverages quantum entanglement to make time-traveling detectors.

Murch describes this concept as analogous to being able to send a telescope back in time to capture a shooting star that you saw out of the corner of your eye. In the everyday world, this idea is a non-starter. But in the mysterious and enigmatic land of quantum physics, there may be a way to circumvent the rules. This is thanks to a property of entangled quantum sensors that Murch refers to as “hindsight.”

The process begins with entanglement of two quantum particles in a quantum singlet state—in other words, two qubits with opposite spin—so that no matter what direction you consider, the spins point in opposing directions. From there, one of the qubits—the “probe,” as Murch calls it—is subjected to a magnetic field that causes it to rotate.

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CERN EXPERIMENT REVEALS “SPOOKY ACTION AT A DISTANCE” PERSISTS BETWEEN TOP QUARKS

Quantum entanglement in top quarks has been demonstrated, according to physicists at CERN who say the discovery offers new insights into the behavior of fundamental particles and their interactions at distances that cannot be attained by light-speed communication.

The research, led by University of Rochester professor Regina Demina, extends the phenomenon known as “spooky action at a distance” to the heaviest particles recognized by physicists and offers important new insights into high-energy quantum mechanics.

Initially discovered almost three decades ago, top quarks are the most massive elementary particles that have been observed. The mass of these unique particles originates from their coupling to the Higgs boson, the famous particle predicted in theory regarding the unification of the weak and electromagnetic interactions. According to the Standard Model of particle physics, this coupling is the largest that occurs at the scale of the weak interactions and those above it.

In the past, quantum entanglement has been observed in stable particles, including electrons and photons. In their new research, Demina and her team demonstrate entanglement between unstable top quarks and their antimatter counterparts, revealing spin correlations that occur over distances that extend beyond the transfer of information at light speed.

The findings present new challenges to existing models and expand our understanding of particle behavior at extreme energies. 

The experiment was conducted at the European Center for Nuclear Research (CERN) as part of the Compact Muon Solenoid (CMS) Collaboration. CERN is home to the famous Large Hadron Collider (LHC), a device that propels high-energy particles at speeds nearing those of light across a 17-mile underground track.

Given the amount of energy required for the production of top quarks, such processes can only be achieved at facilities like CERN. The results of Demina’s recent study could help to shed some light on how long entanglement persists, as well as whether it can be extended to “daughter” particles or decay products. The research also may help determine whether entanglement between particles can be broken.

Presently, it is believed that the universe was in an entangled state following its initial fast expansion stage. The revelation of entanglement in top quarks may help scientists like Demina better understand what factors may have contributed to the quantum connection in our world becoming diminished over time, ultimately leading to the state in which our reality exists today.

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Scientists Are Searching the South Pole to See if Quantum Gravity Actually Exists

Within physics, there are two enormous foundational systems—quantum mechanics and general relativity—that have been like Macs and PCs for decades. Over time, scientists on both sides have worked toward the other side, because anyone who wants to explain the entire universe has to make the two foundations work together. And, like any decent computer lab, a unifying theory has to be truly cross-platform.

In new research, researchers from the University of Copenhagen’s Niels Bohr Institute (NBI)—alongside 58 other member universities— revealed the secrets of 300,000 neutrinos they studied at the South Pole. Their paper (published in Nature Physics) is one step down a road that they hope will lead to quantum gravity. This hypothesized force, if it’s ever demonstrated in real life measurements, could be the physics dongle that adapts general relativity to quantum mechanics at last.

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QUANTUM MECHANICS HACK COULD LEAD TO “UNBREAKABLE” METALS BY LEVERAGING WEIRD DISTORTION OF ATOMS

Scientists say they have created a new method of testing materials that allows predictions to be made about their ductility, which could lead to the production of virtually “unbreakable” metals for use with components in a variety of applications.

Drawing from quantum mechanics principles, the new method allows for significant improvements by enhancing predictions about metals’ ability to be drawn out into thinner shapes while maintaining their strength.

According to researchers involved with the discovery, the new method has proven very effective for metals used in high-temperature applications and could help industries like aerospace and other fields perform tests of various materials more rapidly.

The discovery was reported by scientists at Ames National Laboratory in cooperation with Texas A&M University.

The team’s new quantum-mechanics-based approach has already proven effective on refractory multi-principal-element alloys, a group of materials that often lack the ductility required for their use in the demanding conditions of fusion technology, aerospace applications, and other applications where metals must be capable of withstanding extreme temperatures.

Problems associated with metal ductility have remained a challenge to such industries for many decades since it remains difficult to predict a metal’s thresholds for deformation without compromising its toughness. This has led many industries to resort to trial and error, which also presents issues due to the material costs associated with repeated testing and the amount of time it requires.

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Scientists Discover Bizarre Material Where Electrons Stand Still

New research validates method for guided discovery of 3D flat-band materials.

Scientists at Rice University have uncovered a first-of-its-kind material: a 3D crystalline metal in which quantum correlations and the geometry of the crystal structure combine to frustrate the movement of electrons and lock them in place.

The find is detailed in a study published in Nature Physics. The paper also describes the theoretical design principle and experimental methodology that guided the research team to the material. One part copper, two parts vanadium, and four parts sulfur, the alloy features a 3D pyrochlore lattice consisting of corner-sharing tetrahedra.

Quantum Entanglement and Electron Localization

“We look for materials where there are potentially new states of matter or new exotic features that haven’t been discovered,” said study co-corresponding author Ming Yi, a Rice experimental physicist.

Quantum materials are a likely place to look, especially if they host strong electron interactions that give rise to quantum entanglement. Entanglement leads to strange electronic behaviors, including frustrating the movement of electrons to the point where they become locked in place.

“This quantum interference effect is analogous to waves rippling across the surface of a pond and meeting head-on,” Yi said. “The collision creates a standing wave that does not move. In the case of geometrically frustrated lattice materials, it’s the electronic wave functions that destructively interfere.”

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BREAKTHROUGH IN QUANTUM MEASUREMENT OF GRAVITY ACHIEVED USING LEVITATING MAGNETS

Physicists are one step closer to the measurement of gravity at the quantum level, according to a team whose recent studies move us closer to understanding some of the most mysterious forces at work in our universe.

Gravity is the fundamental interaction that produces attraction between all the objects possessing mass in our universe. Although the weakest of the four fundamental interactions recognized by physicists, it is the one that most of us are familiar with, as we experience the effects of gravity virtually every moment of our lives.

However, due to its weakness, gravity has no significant influence when it comes to subatomic particles, and experts have long questioned how it works in the quantum realm—a conundrum that even baffled Albert Einstein, whose theory of general relativity argued that there are no experiments that could demonstrate a quantum version of gravity.

That is until now, as an international team of physicists says they have succeeded in developing a novel technique that allowed them to detect a weak gravitational pull on a microscopic particle, an achievement which they say may advance our progress toward unraveling a long-sought theory of quantum gravity.

In their experiment, the physicists were able to detect gravity on tiny particles near the boundaries of the quantum realm by employing superconducting devices called traps. During their experiment, they measured a weak pull from a microscopic particle by levitating it under extreme freezing conditions approaching absolute zero.

University of Southampton physicist Tim Fuchs said the achievement could help move us toward understanding our universe by revealing a missing puzzle piece in our current picture of reality.

 “For a century, scientists have tried and failed to understand how gravity and quantum mechanics work together,” Fuchs said in a statement.

“Now we have successfully measured gravitational signals at [the] smallest mass ever recorded, it means we are one step closer to finally realizing how it works in tandem,” he added.

Fuchs said that his team’s next objective is to attempt to reduce the scale of the source using the new technique so that it can be applied to the quantum world on both sides. This could help scientists to unravel some of the most pressing mysteries about our universe, including its origins, and whether there is indeed a grand theory that unites all the known forces.

Presently, quantum phenomena are still mysterious to physicists like Fuchs, since the behavior of particles at the microscopic scale is vastly different from how matter behaves at the normal scale we experience in our daily lives.

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ENTANGLEMENT ON-DEMAND ACHIEVED IN BREAKTHROUGH STUDY POINTING TO “NEW FRONTIER” IN QUANTUM SCIENCE

Physicists at Princeton University report the successful on-demand entanglement of individual molecules, a significant milestone that they say leverages quantum mechanics to achieve these unusual states, according to new research.

Quantum entanglement remains one of the great enigmas in contemporary physics. Essentially, the phenomenon entails particles that are bound together in such a manner that any alteration in the quantum state of one particle instantaneously influences its entangled counterpart.

Remarkably, this connection persists even over vast distances, an effect initially labeled as “spooky action at a distance” following its introduction in a seminal 1935 paper by Albert Einstein, Boris Podolsky, and Nathan Rosen.

While remaining mysterious, recent years have seen substantial progress in unraveling the mysteries of entanglement, with the additional promise for its practical application in diverse fields such as quantum computing, cryptography, and communication technology.

Now, the Princeton team’s recent success can be counted among these developments, in the application of quantum entanglement toward producing beneficial future technologies. The team’s work was recently described in a paper that appeared in the journal Science. 

Lawrence Cheuk, assistant professor of physics at Princeton and the paper’s senior author, says the achievement helps to pave the way toward the construction of quantum computers and related technologies, which will inevitably overtake their classical counterparts in speed and efficiency in the coming years.

Significantly, the new research also achieves “quantum advantage,” whereby quantum bits, or qubits, can simultaneously exist in multiple states, unlike classical binary computer bits which are limited to assuming values of either 0 or 1.

“This is a breakthrough in the world of molecules because of the fundamental importance of quantum entanglement,” Cheuk said in a statement.

“But it is also a breakthrough for practical applications because entangled molecules can be the building blocks for many future applications,” Cheuk added.

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BREAKTHROUGH REVEALS FLAWS IN DIAMONDS COULD LEAD TO NANOSCALE MAGNETIC AND THERMAL SENSORS

Cambridge researchers report a new breakthrough that could lead to the development of highly sensitive quantum sensors, which they say was achieved by exploiting tiny flaws in diamond fragments.

The discovery could pave the way toward innovative new applications that could help offer a deeper glimpse at neuron activity within living cells through magnetic imagery and other technologies.

Specifically, nanoscopic detectors capable of measuring temperature and magnetic fields could be inserted into living cells, allowing scientists an unprecedented glimpse at chemical reactions that occur on the cellular level. Beyond biology, the achievement also could have applications for helping scientists better understand the way certain unique materials gain their magnetic properties.

Flaws in diamonds that occur at the atomic scale can lead to unique and often beautiful color variations in certain rare kinds of diamonds. However, apart from their generation of precious stones, scientists view these impurities as a significant avenue for research in quantum physics.

An example of the kinds of flaws that interest scientists is what is known as the Nitrogen-vacancy Center, or NVC, where a gap exists in the crystal lattice of a diamond alongside nitrogen atoms. When this occurs, electrons become tightly contained, and scientists have learned that their spin states can be precisely manipulated.

In the past, scientists have succeeded in achieving electron coherence in the NVCs of larger diamonds. This phenomenon refers to the degree of interference between electrons emitted from a source such as an electron gun, which plays a key role in ultrafast chemistry and physics research.

Coherence times of up to one second—a significant amount for research in this field and the longest amount ever observed in any known solid material—have been achieved in the NVCs of larger diamond samples, whereas finding any amount of coherence in tiny diamonds measuring just a few nanometers has previously remained unattainable.

Achieving coherence in smaller diamonds, however, presents several advantages. One is the precision they would allow for applications at the nanoscale, as well as their ability to be inserted into living cells.

Now, researchers at Cambridge University say that the elusiveness of coherence in smaller diamonds has been identified as a concentration of nitrogen impurities instead of interactions with spins on the surfaces of the diamond.

The discovery, according to researchers at Cambridge’s Cavendish Laboratory, was made by observing the spin dynamics in nanodiamond NVCs. Independent control of the nitrogen impurities allowed the researchers to raise coherence times to 0.07 milliseconds longer than any previous attempt. The figure may sound minuscule, but it is orders of magnitude greater than past studies had ever achieved, paving the way toward nanodiamonds becoming a key material in the development of new quantum sensing technologies.

Researcher Helena Knowles, who participated in the study, said the results could ultimately lead to the development of the world’s smallest magnetic field detector, as well as the tiniest temperature detector ever made.

“Nanodiamond NVCs can sense the change of such features within a few tens of nanometres,” Knowles said in a statement. “[N]o other sensor has ever had this spatial resolution under ambient conditions.”

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BREAKTHROUGH IN QUANTUM STORAGE OF ENTANGLED PHOTONS MAY USHER AGE OF SOLID STATE-BASED QUANTUM NETWORKS

Chinese researchers report the successful quantum storage of entangled photons at telecom wavelengths within a crystal, in a breakthrough achievement that reportedly lasted 387 times longer than past similar experiments.

The research team, based at Nanjing University, says their findings could potentially “pave the way for realizing quantum networks based on solid-state devices.”

Experts have differing opinions on how soon we may see a global quantum internet. However, no one disputes that once it is achieved, it will revolutionize how information is processed and secured. In the move toward that reality, researchers are currently focusing on ensuring that processes that include quantum storage and distribution of entangled photons will be compatible with existing telecommunications networks.

In the case of entangled photons, entanglement describes the quantum phenomenon where particles remain connected, which effectively allows actions performed on one to affect its entangled counterpart even from across great physical distances.

However, making sure that quantum networks work reliably using fiber-based systems, like those the Internet currently uses, presents a number of challenges, namely signal loss due to the limitations of optical fiber systems that are presently in use.

One way of overcoming these problems involves the use of devices called quantum repeaters, which can help extend the range of these systems by storing the quantum state of photons into matter. Successful quantum repeaters must accomplish three primary tasks: 1) they must match the standard telecom wavelength, which is around 1.55 μm; 2) they must be capable of storing data for long periods; and 3) they have to be able to handle multiple data streams simultaneously.

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