Tag: quantum mechanics

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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THROUGH THE LOOKING-GLASS: ODD NEW METASURFACE MATERIAL IS A “DOORWAY” TO STRANGE QUANTUM PHENOMENON

A phenomenon that often accompanies technological innovations involves how they tend to become smaller with their improvement over time. From televisions and communication devices like telephones to computers and microchip components, many of the technologies we use every day occupy a fraction of the space in our homes and offices that their predecessors did just decades ago.

In keeping with this trend, it is no surprise that a new tech developed by scientists at Sandia National Laboratories, in cooperation with the Max Planck Institute for the Science of Light, may soon replace cumbersome technologies than once required an entire room to operate, thanks to an ultrathin invention that could change the future of computation, encryption, and a host of other technologies.

At the heart of the invention and its function is a peculiar phenomenon that has perplexed physicists for decades, known as quantum entanglement.

Entanglement involves particles (photons, in this case) that are linked in such a way that any changes that affect one of them will affect the other. Strangely, the distance between entangled particles does not affect the way such changes occur, a peculiarity first described by Albert Einstein, Boris Podolsky, and Nathan Rosen in 1935, which Einstein called “spooky action at a distance.”

Although physicists have difficulty reconciling this mainstay of the quantum mechanical world with our concepts of classical mechanics, scientists have nonetheless succeeded in tapping the strange phenomenon of entanglement in developing new information technologies, improving encryption technologies, and even correcting errors in the burgeoning field of quantum computing.

Now, the creation of an all-new material by the Sandia Labs and Max Planck Institute team could further improve efforts to harness quantum entanglement in the production of innovative new technologies.

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Strange new phase of matter created in quantum computer acts like it has two time dimensions

By shining a laser pulse sequence inspired by the Fibonacci numbers at atoms inside a quantum computer, physicists have created a remarkable, never-before-seen phase of matter. The phase has the benefits of two time dimensions despite there still being only one singular flow of time, the physicists report July 20 in Nature.

This mind-bending property offers a sought-after benefit: Information stored in the phase is far more protected against errors than with alternative setups currently used in quantum computers. As a result, the information can exist without getting garbled for much longer, an important milestone for making quantum computing viable, says study lead author Philipp Dumitrescu.

The approach’s use of an “extra” time dimension “is a completely different way of thinking about phases of matter,” says Dumitrescu, who worked on the project as a research fellow at the Flatiron Institute’s Center for Computational Quantum Physics in New York City. “I’ve been working on these theory ideas for over five years, and seeing them come actually to be realized in experiments is exciting.”

Dumitrescu spearheaded the study’s theoretical component with Andrew Potter of the University of British Columbia in Vancouver, Romain Vasseur of the University of Massachusetts, Amherst, and Ajesh Kumar of the University of Texas at Austin. The experiments were carried out on a quantum computer at Quantinuum in Broomfield, Colorado, by a team led by Brian Neyenhuis.

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Entangling a live tardigrade, radiation warning on anti-5G accessories

Tardigrades are tiny organisms that can survive extreme environments including being chilled to near absolute zero. At these temperatures quantum effects such as entanglement become dominant, so perhaps it is not surprising that a team of physicists has used a chilled tardigrade to create an entangled qubit.

According to a preprint on the arXiv server, the team cooled a tardigrade to below 10 mK and then used it as the dielectric in a capacitor that itself was part of a superconducting transmon qubit. The team says that it then entangled the qubit – tardigrade and all – with another superconducting qubit. The team then warmed up the tardigrade and brought it back to life.

To me, the big question is whether the tardigrade was alive when it was entangled. My curiosity harks back to the now outdated idea that living organisms are “too warm and wet” to partake in quantum processes. Today, scientists believe that some biological processes such as magnetic navigation and perhaps even photosynthesis rely on quantum effects such as entanglement. So perhaps it is possible that the creature was alive and entangled at the same time.

In the preprint, the researchers say that the entangled tardigrade was in a latent state of life called cryptobiosis. They say they have shown that it is “possible to do a quantum and hence a chemical study of a system, without destroying its ability to function biologically”.

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World’s 1st multinode quantum network is a breakthrough for the quantum internet

Scientists have gotten one step closer to a quantum internet by creating the world’s first multinode quantum network. 

Researchers at the QuTech research center in the Netherlands created the system, which is made up of three quantum nodes entangled by the spooky laws of quantum mechanics that govern subatomic particles. It is the first time that more than two quantum bits, or “qubits,” that do the calculations in quantum computing have been linked together as “nodes,” or network endpoints. 

Researchers expect the first quantum networks to unlock a wealth of computing applications that can’t be performed by existing classical devices — such as faster computation and improved cryptography.

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