Hexbyte Glen Cove Event horizons are tunable factories of quantum entanglement

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Artist rendering of optical systems containing the analog of a pair white-black hole. Credit: 2021 PhD alumnus Anthony Brady, postdoctoral researcher at the University of Arizona

Louisiana State University physicists have leveraged quantum information theory techniques to reveal a mechanism for amplifying, or “stimulating,” the production of entanglement in the Hawking effect in a controlled manner. Furthermore, these scientists propose a protocol for testing this idea in the laboratory using artificially produced event horizons. These results have been recently published in Physical Review Letters, “Quantum aspects of stimulated Hawking radiation in an analog white-black hole pair,” where Ivan Agullo, Anthony J. Brady and Dimitrios Kranas present these ideas and apply them to optical systems containing the analog of a pair white-black hole.

Black holes are some of the most mystifying objects in our universe, largely due to the fact that their inner-workings are hidden behind a completely obscuring veil—the black hole’s event horizon.

In 1974, Stephen Hawking added more mystique to the character of black holes by showing that, once are considered, a black hole isn’t really black at all but, instead, emits radiation, as if it was a hot body, gradually losing mass in the so-called “Hawking evaporation process.” Further, Hawking’s calculations showed that the emitted radiation is quantum mechanically entangled with the bowels of the black hole itself. This entanglement is the quantum signature of the Hawking effect. This astounding result is difficult, if not impossible, to be tested on astrophysical black holes, since the faint Hawking radiation gets overshined by other sources of radiation in the cosmos.

On the other hand, in the 1980’s, a seminal article by William Unruh established that the spontaneous production of entangled Hawking particles occurs in any system that can support an effective event horizon. Such systems generally fall under the umbrella of “analog gravity systems” and opened a window for testing Hawking’s ideas in the laboratory.

Serious experimental investigations into analog gravity systems—made of Bose-Einstein condensates, non-linear optical fibers, or even flowing water—have been underway for more than a decade. Stimulated and spontaneously-generated Hawking radiation has recently been observed in several platforms, but measuring entanglement has proved elusive due to its faint and fragile character.

“We show that, by illuminating the horizon, or horizons, with appropriately chosen quantum states, one can amplify the production of entanglement in Hawking’s process in a tunable manner,” said Associate Professor Ivan Agullo. “As an example, we apply these ideas to the concrete case of a pair of analog white-black holes sharing an interior and produced within a non-linear optical material.”

“Many of the quantum information tools used in this research were from my graduate research with Professor Jonathan P. Dowling,” said 2021 Ph.D. alumnus Anthony Brady, postdoctoral researcher at the University of Arizona. “Jon was a charismatic character, and he brought his charisma and unconventionality into his science, as well as his advising. He encouraged me to work on eccentric ideas, like analog black holes, and see if I could meld techniques from various fields of physics—like quantum information and analog gravity—in order to produce something novel, or ‘cute,’ as he liked to say.”

“The Hawking process is one of the richest physical phenomena connecting seemingly unrelated fields of physics from the quantum theory to thermodynamics and relativity,” said Dimitrios Kranas, LSU graduate student. “Analog black holes came to add an extra flavor to the effect providing us, at the same time, with the exciting possibility of testing it in the laboratory. Our detailed numerical analysis allows us to probe new features of the Hawking process, helping us understand better the similarities and differences between astrophysical and analog .”

More information:
Ivan Agullo et al, Quantum Aspects of Stimulated Hawking Radiation in an Optical Analog White-Black Hole Pair, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.128.091301

Event horizons are tunable factories of quantum entanglement (2022, March 4)
retrieved 5 March 2022
from https://phys.org/news/2022-03-event-horizons-tunable

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Hexbyte Glen Cove You can help train NASA’s rovers to better explore Mars

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With AI4Mars, users outline rock and landscape features in images from NASA’s Perseverance Mars rover. The project helps train an artificial intelligence algorithm for improved rover capabilities on Mars. Credit: NASA/JPL-Caltech

Members of the public can now help teach an artificial intelligence algorithm to recognize scientific features in images taken by NASA’s Perseverance rover.

Artificial intelligence, or AI, has enormous potential to change the way NASA’s spacecraft study the universe. But because all machine learning algorithms require training from humans, a recent project asks members of the public to label features of scientific interest in imagery taken by NASA’s Perseverance Mars rover.

Called AI4Mars, the project is the continuation of one launched last year that relied on imagery from NASA’s Curiosity rover. Participants in the earlier stage of that project labeled nearly half a million images, using a tool to outline features like sand and rock that rover drivers at NASA’s Jet Propulsion Laboratory typically watch out for when planning routes on the Red Planet. The end result was an algorithm, called SPOC (Soil Property and Object Classification), that could identify these features correctly nearly 98% of the time.

SPOC is still in development, and researchers hope it can someday be sent to Mars aboard a future spacecraft that could perform even more autonomous driving than Perseverance’s AutoNav technology allows.

Images from Perseverance will further improve SPOC by expanding the kinds of identifying labels that can be applied to features on the Martian surface. AI4Mars now provides labels to identify more refined details, allowing people to choose options like float rocks (“islands” of rocks) or nodules (BB-size balls, often formed by water, of minerals that have been cemented together).

The goal is to hone an algorithm that could help a future rover pick out needles from the haystack of data sent from Mars. Equipped with 19 cameras, Perseverance sends anywhere from dozens to hundreds of images to Earth each day for scientists and engineers to comb through for specific geological features. But time is tight: After those images travel millions of miles from Mars to Earth, the team members have a matter of hours to develop the next set of instructions, based on what they see in those images, to send to Perseverance.

“It’s not possible for any one scientist to look at all the downlinked images with scrutiny in such a short amount of time, every single day,” said Vivian Sun, a JPL scientist who helps coordinate Perseverance’s daily operations and consulted on the AI4Mars project. “It would save us time if there was an algorithm that could say, ‘I think I saw rock veins or nodules over here,’ and then the science team can look at those areas with more detail.”

Especially during this developmental stage, SPOC requires lots of validation from scientists to ensure it’s labeling accurately. But even when it improves, the algorithm is not intended to replace more complex analyses by human scientists.

It’s all about the data

Key to any successful algorithm is a good dataset, said Hiro Ono, the JPL AI researcher who led the development of AI4Mars. The more individual pieces of data available, the more an algorithm learns.

The robotic arm of NASA’s Perseverance rover is visible in this image used by the AI4Mars project. Users outline and identify different rock and landscape features to help train an artificial intelligence algorithm that will help improve the capabilities of Mars rovers. Credit: NASA/JPL-Caltech

“Machine learning is very different from normal software,” Ono said. “This isn’t like making something from scratch. Think of it as starting with a new brain. More of the effort here is getting a good dataset to teach that brain and massaging the data so it will be better learned.”

AI researchers can train their Earth-bound algorithms on tens of thousands of images of, say, houses, flowers, or kittens. But no such data archive existed for the Martian surface before the AI4Mars project. The team would be content with 20,000 or so images in their repository, each with a variety of features labeled.

The Mars-data repository could serve several purposes, noted JPL’s Annie Didier, who worked on the Perseverance version of AI4Mars. “With this algorithm, the rover could automatically select science targets to drive to,” she said. It could also store a variety of images onboard the rover, then send back just images of specific features that scientists are interested in, she said.

That’s on the horizon; scientists may not have to wait that long for the algorithm to benefit them, however. Before the algorithm ever makes it to space, it could be used to scan NASA’s vast public archive of Mars data, allowing researchers to find surface features in those images more easily.

Ono noted it’s important to the AI4Mars team to make their own dataset publicly available so that the entire data science community can benefit.

“If someone outside JPL creates an algorithm that works better than ours using our dataset, that’s great, too,” he said. “It just makes it easier to make more discoveries.”

More about the mission

A key objective for Perseverance’s mission on Mars is astrobiology, including the search for signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, pave the way for human exploration of the Red Planet, and be the first mission to collect and cache Martian rock and regolith (broken rock and dust).

Subsequent NASA missions, in cooperation with ESA (European Space Agency), would send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis.

The Mars 2020 Perseverance mission is part of NASA’s Moon to Mars exploration approach, which includes Artemis missions to the Moon that will help prepare for human exploration of the Red Planet.

You can help train NASA’s rovers to better explore Mars (2021, October 26)
retrieved 26 October 2021
from https://phys.org/news/2021-10-nasa-rovers-explore-mars.html

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Hexbyte Glen Cove Astronomers spot bizarre, never-before-seen activity from one of the strongest magnets in the universe thumbnail

Hexbyte Glen Cove Astronomers spot bizarre, never-before-seen activity from one of the strongest magnets in the universe

Hexbyte Glen Cove

Artist’s impression of the active magnetar Swift J1818.0-1607. Credit: Carl Knox, OzGrav.

Astronomers from the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) and CSIRO have just observed bizarre, never-seen-before behavior from a radio-loud magnetar—a rare type of neutron star and one of the strongest magnets in the universe.

Their new findings, published today in the Monthly Notices of the Royal Astronomical Society (MNRAS), suggest magnetars have more complex magnetic fields than previously thought, which may challenge theories of how they are born and evolve over time.

Magnetars are a rare type of rotating neutron star with some of the most in the universe. Astronomers have detected only 30 of these objects in and around the Milky Way—most of them detected by X-ray telescopes following a high-energy outburst.

However, a handful of these magnetars have also been seen to emit radio pulses similar to pulsars—the less-magnetic cousins of magnetars that produce beams of radio waves from their magnetic poles. Tracking how the pulses from these radio-loud magnetars change over time offers a unique window into their evolution and geometry.

In March 2020, a new magnetar named Swift J1818.0-1607 (J1818 for short) was discovered after it emitted a bright X-ray burst. Rapid follow-up observations detected radio pulses originating from the magnetar. Curiously, the appearance of the radio pulses from J1818 were quite different from those detected from other radio-loud magnetars.

Most radio pulses from magnetars maintain a consistent brightness across a wide range of observing frequencies. However, the pulses from J1818 were much brighter at low frequencies than high frequencies—similar to what is seen in pulsars, another more common type of radio-emitting neutron star.

In order to better understand how J1818 would evolve over time, a team led by scientists from the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) observed it eight times using the CSIRO Parkes radio telescope (also known as Murriyang) between May and October 2020.

During this time, they found the magnetar underwent a brief identity crisis: In May it was still emitting the unusual pulsar-like pulses that had been detected previously; however, by June, it had started flickering between a bright and a weak state. This flickering behavior reached a peak in July, when the astronomers saw it flickering back and forth between pulsar-like and magnetar-like radio pulses.

“This bizarre behavior has never been seen before in any other radio-loud magnetar,” explains study lead author and Swinburne University/CSIRO Ph.D. student Marcus Lower. “It appears to have only been a short-lived phenomenon, as by our next observation, it had settled permanently into this new magnetar-like state.”

The scientists also looked for pulse shape and brightness changes at different radio frequencies and compared their observations to a 50-year-old theoretical model. This model predicts the expected geometry of a pulsar, based on the twisting direction of its polarized light.

“From our observations, we found that the magnetic axis of J1818 isn’t aligned with its rotation axis,” says Lower. “Instead, the radio-emitting magnetic pole appears to be in its southern hemisphere, located just below the equator. Most other magnetars have magnetic fields that are aligned with their spin axes or are a little ambiguous. This is the first time we have definitively seen a magnetar with a misaligned magnetic pole.”

Remarkably, this magnetic geometry appears to be stable over most observations. This suggests any changes in the pulse profile are simply due to variations in the height the radio pulses are emitted above the neutron star surface. However, the August 1st 2020 observation stands out as a curious exception.

“Our best geometric model for this date suggests that the radio beam briefly flipped over to a completely different magnetic pole located in the northern hemisphere of the magnetar,” says Lower.

A distinct lack of any changes in the magnetar’s profile shape indicate the same lines that trigger the ‘normal’ radio pulses must also be responsible for the pulses seen from the other magnetic .

The study suggests this is evidence that the radio pulses from J1818 originate from loops of connecting two closely spaced poles, like those seen connecting the two poles of a horseshoe magnet or sunspots on the sun. This is unlike most ordinary neutron stars, which are expected to have north and south poles on opposite sides of the star that are connected by a donut-shaped magnetic field.

This peculiar magnetic field configuration is also supported by an independent study of the X-rays pulses from J1818 that were detected by the NICER telescope on board the International Space Station. The X-rays appear to come from either a single distorted region of magnetic field lines that emerge from the magnetar surface or two smaller, but closely spaced, regions.

These discoveries have potential implications for computer simulations of how magnetars are born and evolve over long periods of time, as more complex magnetic field geometries will change how quickly their magnetic fields are expected to decay over time. Additionally, theories that suggest fast radio bursts can originate from magnetars will have to account for radio pulses potentially originating from multiple active sites within their magnetic fields.

Catching a flip between in action could also afford the first opportunity to map the magnetic field of a magnetar.

“The Parkes telescope will be watching the closely over the next year” says scientist and study co-author Simon Johnston, from the CSIRO Astronomy and Space Science.

More information:
M E Lower et al. The dynamic magnetosphere of Swift J1818.0−1607, Monthly Notices of the Royal Astronomical Society (2020). DOI: 10.1093/mnras/staa3789

Marcus E. Lower, et al. The dynamic magnetosphere of Swift J1818.0−1607 arxiv.org/abs/2011.12463 arXiv:2011.12463v2 [astro-ph.HE] T

Astronomers spot bizarre, never-before-seen activity from one of the strongest magnets in the universe (2021, February 1)
retrieved 2 February 2021

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