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Category: quantum physics – Page 295

For the first time, researchers have been able to track the behavior of triplons, a quasi-particle created between entangled electrons. They are very tricky to study and they do not form in conventional magnetic material. Now, researchers have been able to detect them for the first time using real-space measurements.

Quasi particles are not real particles. They form in specific interactions, but for as long as that interaction lasts they behave like a particle. The interaction in this case is the entanglement of two electrons. This pair can be entangled in a singlet state or a triplet state, and the triplon comes from the latter interaction.

To get the triplon in the first place, the team used small organic molecules called cobalt-phthalocyanine. What makes the molecule interesting is that it possesses a frontier electron. Now, don’t go picture some gunslinger particle – a frontier electron is simply an electron on the highest-energy occupied orbital.

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Researchers at Los Alamos National Laboratory have successfully developed a new way to produce a specific type of photon that could prove critical for quantum data exchange, notably encryption. The specific kind of photons, called “circularly polarized light,” have thus far proved challenging to create and control, but this new technique makes the process easier and, importantly, cheaper. This was achieved, the team explains, by stacking two different, atomically thin materials to “twist” (polarize) photons in a predictable fashion.

Encoded, “twisted,” photons

“Our research shows that it is possible for a monolayer semiconductor to emit circularly polarized light without the help of an external magnetic field,” explained Han Htoon, a scientist at Los Alamos National Laboratory. “This effect has only been achieved before with high magnetic fields created by bulky superconducting magnets, by coupling quantum emitters to very complex nanoscale photonics structures, or by injecting spin-polarized carriers into quantum emitters. Our proximity-effect approach has the advantage of low-cost fabrication and reliability,” he added.

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The association between this mass concentration and the idea that atoms are empty stems from a flawed view that mass is the property of matter that fills a space. However, this concept does not hold up to close inspection, not even in our human-scale world. When we pile objects on top of each other, what keeps them separated is not their masses but the electric repulsion between the outmost electrons at their touching molecules. (The electrons cannot collapse under pressure due to the Heisenberg uncertainty and Pauli exclusion principles.) Therefore, the electron’s electric charge ultimately fills the space.

Anyone taking Chemistry 101 is likely to be faced with diagrams of electrons orbiting in shells.

In atoms and molecules, electrons are everywhere! Look how the yellow cloud permeates the entire molecular volume in Figure 1. Thus, when we see that atoms and molecules are packed with electrons, the only reasonable conclusion is that they are filled with matter, not the opposite.

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Diamond has long been the preferred material for quantum sensing, but its size limits its applications. Recent research highlights hBN’s potential as a replacement, especially after TMOS researchers developed methods to stabilize its atomic defects and study its charge states, opening doors for its integration into devices where diamond can’t fit.

Diamond has long held the crown in the realm of quantum sensing, thanks to its coherent nitrogen-vacancy centers, adjustable spin, magnetic field sensitivity, and capability to operate at room temperature. With such a suitable material so easy to fabricate and scale, there’s been little interest in exploring diamond alternatives.

However, this titan of the quantum domain has a vulnerability. It’s simply too large. Much like how an NFL linebacker isn’t the top pick for a jockey in the Kentucky Derby, diamond falls short when delving into quantum sensors and data processing. When diamonds get too small, the super-stable defect it’s renowned for begins to crumble. There is a limit at which a diamond becomes useless.

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In their 1982 paper, Fredkin and Toffoli had begun developing their work on reversible computation in a rather different direction. It started with a seemingly frivolous analogy: a billiard table. They showed how mathematical computations could be represented by fully reversible billiard-ball interactions, assuming a frictionless table and balls interacting without friction.

This physical manifestation of the reversible concept grew from Toffoli’s idea that computational concepts could be a better way to encapsulate physics than the differential equations conventionally used to describe motion and change. Fredkin took things even further, concluding that the whole Universe could actually be seen as a kind of computer. In his view, it was a ‘cellular automaton’: a collection of computational bits, or cells, that can flip states according to a defined set of rules determined by the states of the cells around them. Over time, these simple rules can give rise to all the complexities of the cosmos — even life.

He wasn’t the first to play with such ideas. Konrad Zuse — a German civil engineer who, before the Second World War, had developed one of the first programmable computers — suggested in his 1969 book Calculating Space that the Universe could be viewed as a classical digital cellular automaton. Fredkin and his associates developed the concept with intense focus, spending years searching for examples of how simple computational rules could generate all the phenomena associated with subatomic particles and forces3.

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• Encryption and segmentation: These operate on the assumption some fraction of the network is already compromised. Restricting the reach and utility of any captured data and accessible networks will mitigate the damage even on breached systems.

• SBOM documentation: Regulatory compliance can be driven by industry organizations and the government, but it will take time to establish standards. SBOM documentation is an essential foundation for best practices.

If “democracy dies in darkness,” and that includes lies of omission in reporting, then cybersecurity suffers the same fate with backdoors. The corollary is “don’t roll your own crypto” even if well-intentioned. The arguments for weakening encryption to make law enforcement easier falls demonstrably flat, with TETRA just the latest example. Secrets rarely stay that way forever, and sensitive data is more remotely accessible than at any time in history. Privacy and global security affect us all, and the existence of these single points of failure in our cybersecurity efforts are unsustainable and will have unforeseeable consequences. We need to innovate and evolve the internet away from this model to have durable security assurances.

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The Fine Structure Constant is one the strangest numbers in all of physics. It’s the job of physicists to worry about numbers, but there’s one number that physicists have stressed about more than any other. That number is 0.00729735256 — approximately 1/137. This is the fine structure constant, and it appears everywhere in our equations of quantum physics, and we’re still trying to figure out why.

Continue reading “Why Is 1/137 One of the Greatest Unsolved Problems In Physics?” | >