Tag: quantum mechanics

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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Research group detects a quantum entanglement wave for the first time using real-space measurements

Triplons are tricky little things. Experimentally, they’re exceedingly difficult to observe. And even then, researchers usually conduct the tests on macroscopic materials, in which measurements are expressed as an average across the whole sample.

That’s where designer quantum materials offer a unique advantage, says Academy Research Fellow Robert Drost, the first author of a paper published in Physical Review Letters. These designer quantum materials let researchers create phenomena not found in natural compounds, ultimately enabling the realization of exotic quantum excitations.

“These materials are very complex. They give you very exciting physics, but the most exotic ones are also challenging to find and study. So, we are trying a different approach here by building an artificial material using individual components,” says Professor Peter Liljeroth, head of the Atomic Scale physics research group at Aalto University.

Quantum materials are governed by the interactions between electrons at the microscopic level. These electronic correlations lead to unusual phenomena like high-temperature superconductivity or complex magnetic states, and quantum correlations give rise to new electronic states.

In the case of two electrons, there are two entangled states known as singlet and triplet states. Supplying energy to the electron system can excite it from the singlet to the triplet state. In some cases, this excitation can propagate through a material in an entanglement wave known as a triplon. These excitations are not present in conventional magnetic materials, and measuring them has remained an open challenge in quantum materials.

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Physicists Just Figured Out How Wormholes Could Enable Time Travel

Theoretical physicists have a lot in common with lawyers. Both spend a lot of time looking for loopholes and inconsistencies in the rules that might be exploited somehow.

Valeri P. Frolov and Andrei Zelnikov from the University of Alberta in Canada and Pavel Krtouš from Charles University in Prague probably couldn’t get you out of a traffic fine, but they may have uncovered enough wiggle room in the laws of physics to send you back in time to make sure you didn’t speed through that school zone in the first place.

Shortcuts through spacetime known as wormholes aren’t recognized features of the cosmos. But for the better part of a century, scientists have wondered if the weft and warp instructed by relativity prescribe ways for quantum ripples – or even entire particles – to break free of their locality.

At their most fantastic, such reconfigurations in the fabric of the Universe would allow human-sized masses to traverse light-years to cross galaxies in a heartbeat or perhaps move through time as quickly as one might move through their kitchen.

At the very least, exercises that probe the more exotic side of spacetime behavior could guide speculation over the mysterious meeting point of quantum physics and the general theory of relativity.

Wormholes are, in effect, little more than shapes. We’re used to dealing with single-dimensional lines, two-dimensional drawings, and three-dimensional objects in everyday life. Some we can intuitively fold, mold, and poke holes in.

Physics allows us to explore these changes in situations we can’t intuitively explore. On the smallest of levels, quantum effects give distances and time some wiggle room.

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Quantum Theory’s ‘Measurement Problem’ May Be a Poison Pill for Objective Reality

Imagine a physicist observing a quantum system whose behavior is akin to a coin toss: it could come up heads or tails. They perform the quantum coin toss and see heads. Could they be certain that their result was an objective, absolute and indisputable fact about the world? If the coin was simply the kind we see in our everyday experience, then the outcome of the toss would be the same for everyone: heads all around! But as with most things in quantum physics, the result of a quantum coin toss would be a much more complicated “It depends.” There are theoretically plausible scenarios in which another observer might find that the result of our physicist’s coin toss was tails.

At the heart of this bizarreness is what’s called the measurement problem. Standard quantum mechanics accounts for what happens when you measure a quantum system: essentially, the measurement causes the system’s multiple possible states to randomly “collapse” into one definite state. But this accounting doesn’t define what constitutes a measurement—hence, the measurement problem.

Attempts to avoid the measurement problem—for example, by envisaging a reality in which quantum states don’t collapse at all—have led physicists into strange terrain where measurement outcomes can be subjective. “One major aspect of the measurement problem is this idea … that observed events are not absolute,” says Nicholas Ormrod of the University of Oxford. This, in short, is why our imagined quantum coin toss could conceivably be heads from one perspective and tails from another.

But is such an apparently problematic scenario physically plausible or merely an artifact of our incomplete understanding of the quantum world? Grappling with such questions requires a better understanding of theories in which the measurement problem can arise—which is exactly what Ormrod, along with Vilasini Venkatesh of the Swiss Federal Institute of Technology in Zurich and Jonathan Barrett of Oxford, have now achieved. In a recent preprint, the trio proved a theorem that shows why certain theories—such as quantum mechanics—have a measurement problem in the first place and how one might develop alternative theories to sidestep it, thus preserving the “absoluteness” of any observed event. Such theories would, for instance, banish the possibility of a coin toss coming up heads to one observer and tails to another.

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Discovery of the ‘bubble phase of composite fermions’ confirms existence of a new family of quantum matter

 Like finding a hidden world, physicists dialing up the magnetic field on a semiconducting material have discovered the first in a new family of matter that flowers from the bizarre realm of the quantum scale. In what researchers dubbed the bubble phase of composite fermions, pairs of quasiparticles – particle-like entities arising from the interaction of particles – align in a crystalline pattern, allowing electricity to flow along the edge of the material.  

The discovery represents a previously unobserved arrangement of composite fermions, which are entities that behave like particles and are formed from the interaction between electrons and magnetism. The bubble phase of composite fermions falls into a category of matter properly called topological insulators, which denotes that electricity flows only along the outer surface or edge of the material, while the cross-section does not conduct electricity. While dozens of topological insulators have been discovered by condensed matter physicists, the combined paired and periodic structure of the bubble phase represents an entirely new family or sub-category of “highly correlated topological phases” that had been theorized but not previously observed. 

“As the first member of a new family of highly correlated topological phases, this new phase expands our understanding and offers a glimpse of the role of electronic interactions in generating higher order correlations in electronic systems,” said Gábor Csáthy, a Purdue University professor and head of the Department of Physics and Astronomy.  

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“Nothing” doesn’t exist. Instead, there is “quantum foam”

What is nothing? This is a question that has bothered philosophers as far back as the ancient Greeks, where they debated the nature of the void. They had long discussions trying to determine whether nothing is something.

While the philosophical facets of this question pose some interest, the question is also one that the scientific community has addressed. (Big Think’s Dr. Ethan Siegel has an article describing the four definitions of “nothing.”)

It’s nothing, really

What would happen if scientists took a container and removed all the air out of it, creating an ideal vacuum that was entirely devoid of matter? The removal of matter would mean that energy would remain. Much in the same way that the energy from the Sun can cross to the Earth through empty space, heat from outside the container would radiate into the container. Thus, the container wouldn’t be truly empty.

However, what if scientists also cooled the container to the lowest possible temperature (absolute zero), so it radiated no energy at all? Furthermore, suppose that scientists shielded the container so no outside energy or radiation could penetrate it. Then there would be absolutely nothing inside the container, right?

That’s where things become counterintuitive. It turns out that nothing isn’t nothing.

The nature of “nothing”

The laws of quantum mechanics are confusing, predicting that particles are also waves and that cats are simultaneously alive and dead. However, one of the most confusing of all quantum principles is called the Heisenberg Uncertainty Principle, which is commonly explained as saying that you cannot simultaneously perfectly measure the location and movement of a subatomic particle. While that is a good representation of the principle, it also says that you cannot measure the energy of anything perfectly and that the shorter the time you measure, the worse your measurement is. Taken to the extreme, if you try to make a measurement in near-zero time, your measurement will be infinitely imprecise.

These quantum principles have mind-bending consequences for anyone trying to understand the nature of nothing. For example, if you try to measure the amount of energy at a location — even if that energy is supposed to be nothing — you still cannot measure zero precisely. Sometimes, when you make the measurement, the expected zero turns out to be non-zero. And this isn’t just a measurement problem; it’s a feature of reality. For short periods of time, zero is not always zero.

When you combine this bizarre fact (that zero expected energy can be non-zero, if you examine a short enough time period) with Einstein’s famous equation E = mc2, there is an even more bizarre consequence. Einstein’s equation says that energy is matter and vice versa. Combined with quantum theory, this means that in a location that is supposedly entirely empty and devoid of energy, space can briefly fluctuate to non-zero energy — and that temporary energy can make matter (and antimatter) particles.

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Scientists Claim To Have Created A Tiny Wormhole In The Quantum Realm

For some who find the Fibonacci sequence used to entanglement qubits to be baffling, which is a crazy topic we published a video about here, you’d best grab onto something solid.

Recently, a group of scientists discovered that quantum systems may mimic wormholes, theoretical shortcuts in spacetime, in that they permit the instantaneous transfer of information between distant places.

Despite the fact that quantum particles are unaffected by gravity in the same manner that classical objects are, the study team believes their results may have ramifications for investigating quantum gravity. The study appeared this week in the journal Nature.

“The relationship between quantum entanglement, spacetime, and quantum gravity is one of the most important questions in fundamental physics and an active area of theoretical research,” California Institute of Technology physicist Maria Spiropulu, the paper’s primary author, claimed in a press release. “We are excited to take this small step toward testing these ideas on quantum hardware and will keep going.“

It’s time to take a breather. It should be made clear that the researchers did not really transmit quantum information via a spacetime rip, which in principle would unite previously disconnected parts of the universe.

Think of it as folding a sheet of paper in half and sticking a pencil in between the folds. Since the paper represents spacetime, you may use it as a gateway to connect two seemingly inaccessible locations.

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