Oct 18, 2022 01:34 AM
Quantum entanglement has been directly observed at the macroscopic scale
https://www.sciencealert.com/quantum-ent...opic-scale
EXCERPTS: In a 2021 study, quantum entanglement was directly observed and recorded at the macroscopic scale – a scale much bigger than the subatomic particles normally associated with entanglement.
[...] While there's nothing to say that quantum entanglement can't happen with macroscopic objects, before this it was thought that the effects weren't noticeable at larger scales – or perhaps that the macroscopic scale was governed by another set of rules. [...] The recent research suggests that's not the case. In fact, the same quantum rules apply here, too, and can actually be seen as well.
[...] Previous studies had also reported on macroscopic quantum entanglement, but the 2021 research went further: All of the necessary measurements were recorded rather than inferred, and the entanglement was generated in a deterministic, non-random way.
What makes this headline news is that it gets around Heisenberg's Uncertainty Principle – the idea that position and momentum can't be perfectly measured at the same time. The principle states that recording either measurement will interfere with the other through a process called quantum back action.
[...] One of the potential future applications of both sets of findings is in quantum networks – being able to manipulate and entangle objects on a macroscopic scale so that they can power next-generation communication networks.
"Apart from practical applications, these experiments address how far into the macroscopic realm experiments can push the observation of distinctly quantum phenomena," write physicists Hoi-Kwan Lau and Aashish Clerk, who weren't involved in the studies, in a commentary on the research published at the time.
Both the first and the second study were published in Science... (MORE - missing details)
A reboot of the Maxwell’s demon thought experiment—in real life
https://www.wired.co.uk/article/maxwells...ent-reboot
EXCERPT: . . . To be clear, Antoine Naert’s device does not violate the second law of thermodynamics, nor does Maxwell’s Demon. Physicists, pondering the demon over decades, have delivered multiple explanations for why it doesn’t. One is that in order to sort the beads, the demon has to be cooler than the rest of the gas, says Naert. Thus, the container of gas particles is not a single temperature, which contradicts the premise of the thought experiment. In the case of Naert’s device, the rapidly bouncing steel beads are at one temperature, whereas the electronic component that converts the beads’ motion into the rotation of a blade is another temperature.
So why recreate Maxwell’s Demon? Physicists have used the thought experiment to explore common concepts in wildly different contexts. For example, in the 20th century, it led physicists to discover the physical nature of information. In order for the demon to sort molecules by speed, it needs some way of knowing the particles’ speed. The demon would need to store that knowledge and erase that information. From these ideas, physicists figured out that information isn’t just some abstract concept that we humans harness to communicate. It’s the physical state of some object, like representing the voltage across a transistor as a bit of information—a key concept now fundamental to the study of computing.
In addition, the second law of thermodynamics signifies the statistical nature of the universe. Its building blocks are not stars, planets, humans, or bacteria—they’re the atoms and molecules that make us up. You can think of the atoms in the universe as a deck of cards, constantly being shuffled and reshuffled. By the end of the reshuffling, the deck will have no semblance of order. But instead of dealing with a deck of 52 cards, the universe has a deck on the order of 10^82 atoms.
Or if you want to be more manageable, consider the 10^24 molecules in a cup of coffee. If you drop a sugar cube into that coffee, those sugar molecules have so many more ways of redistributing themselves throughout the coffee than staying in cube form. Or consider someone who releases perfume in a room. That perfume will rush to fill the space. This illustrates the concept of entropy, often described as “disorder.” The most likely arrangement of atoms has the highest entropy. A deck of cards sorted according to the four suits has lower entropy, for example, than one that is not. Similarly, dissolved sugar molecules cannot re-cube, and the perfume cannot rush back into the vial, without some external intervention requiring energy.
Ultimately, the second law of thermodynamics says that energy moves around in nature to increase entropy. “If you ask what physics is, you might just say it is the study of energy,” says Leff. “What’s happening as far as I can see is that energy keeps redistributing itself.”
However, as people invent new technology, it’s not always clear how the second law applies. For example, seemingly straightforward concepts like temperature get complicated... (MORE - missing details)
https://www.sciencealert.com/quantum-ent...opic-scale
EXCERPTS: In a 2021 study, quantum entanglement was directly observed and recorded at the macroscopic scale – a scale much bigger than the subatomic particles normally associated with entanglement.
[...] While there's nothing to say that quantum entanglement can't happen with macroscopic objects, before this it was thought that the effects weren't noticeable at larger scales – or perhaps that the macroscopic scale was governed by another set of rules. [...] The recent research suggests that's not the case. In fact, the same quantum rules apply here, too, and can actually be seen as well.
[...] Previous studies had also reported on macroscopic quantum entanglement, but the 2021 research went further: All of the necessary measurements were recorded rather than inferred, and the entanglement was generated in a deterministic, non-random way.
What makes this headline news is that it gets around Heisenberg's Uncertainty Principle – the idea that position and momentum can't be perfectly measured at the same time. The principle states that recording either measurement will interfere with the other through a process called quantum back action.
[...] One of the potential future applications of both sets of findings is in quantum networks – being able to manipulate and entangle objects on a macroscopic scale so that they can power next-generation communication networks.
"Apart from practical applications, these experiments address how far into the macroscopic realm experiments can push the observation of distinctly quantum phenomena," write physicists Hoi-Kwan Lau and Aashish Clerk, who weren't involved in the studies, in a commentary on the research published at the time.
Both the first and the second study were published in Science... (MORE - missing details)
A reboot of the Maxwell’s demon thought experiment—in real life
https://www.wired.co.uk/article/maxwells...ent-reboot
EXCERPT: . . . To be clear, Antoine Naert’s device does not violate the second law of thermodynamics, nor does Maxwell’s Demon. Physicists, pondering the demon over decades, have delivered multiple explanations for why it doesn’t. One is that in order to sort the beads, the demon has to be cooler than the rest of the gas, says Naert. Thus, the container of gas particles is not a single temperature, which contradicts the premise of the thought experiment. In the case of Naert’s device, the rapidly bouncing steel beads are at one temperature, whereas the electronic component that converts the beads’ motion into the rotation of a blade is another temperature.
So why recreate Maxwell’s Demon? Physicists have used the thought experiment to explore common concepts in wildly different contexts. For example, in the 20th century, it led physicists to discover the physical nature of information. In order for the demon to sort molecules by speed, it needs some way of knowing the particles’ speed. The demon would need to store that knowledge and erase that information. From these ideas, physicists figured out that information isn’t just some abstract concept that we humans harness to communicate. It’s the physical state of some object, like representing the voltage across a transistor as a bit of information—a key concept now fundamental to the study of computing.
In addition, the second law of thermodynamics signifies the statistical nature of the universe. Its building blocks are not stars, planets, humans, or bacteria—they’re the atoms and molecules that make us up. You can think of the atoms in the universe as a deck of cards, constantly being shuffled and reshuffled. By the end of the reshuffling, the deck will have no semblance of order. But instead of dealing with a deck of 52 cards, the universe has a deck on the order of 10^82 atoms.
Or if you want to be more manageable, consider the 10^24 molecules in a cup of coffee. If you drop a sugar cube into that coffee, those sugar molecules have so many more ways of redistributing themselves throughout the coffee than staying in cube form. Or consider someone who releases perfume in a room. That perfume will rush to fill the space. This illustrates the concept of entropy, often described as “disorder.” The most likely arrangement of atoms has the highest entropy. A deck of cards sorted according to the four suits has lower entropy, for example, than one that is not. Similarly, dissolved sugar molecules cannot re-cube, and the perfume cannot rush back into the vial, without some external intervention requiring energy.
Ultimately, the second law of thermodynamics says that energy moves around in nature to increase entropy. “If you ask what physics is, you might just say it is the study of energy,” says Leff. “What’s happening as far as I can see is that energy keeps redistributing itself.”
However, as people invent new technology, it’s not always clear how the second law applies. For example, seemingly straightforward concepts like temperature get complicated... (MORE - missing details)
