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Newswise In physics, Schroedingers cat is an allegory for two of the most awe-inspiring effects of quantum mechanics: entanglement and superposition. Researchers from Dresden and Munich have now observed these behaviors on a much larger scale than that of the smallest of particles. Until now, materials that display properties like, e.g., magnetism have been known to have so-called domains islands in which the materials properties are homogeneously either of one or a different kind (imagine them being either blackorwhite, for example). Looking at lithium holmium fluoride (LiHoF4), the physicists have now discovered a completely new phase transition, at which the domains surprisingly exhibit quantum mechanical features, resulting in their properties becoming entangled (being black and white at the same time). Our quantum cat now has a new fur because weve discovered a new quantum phase transition in LiHoF4which has not previously been known to exist, comments Matthias Vojta, Chair of Theoretical Solid State Physics at TUD.

Phase transitions and entanglement

We can easily observe the spontaneously changing properties of a substance if we look at water: at 100 degrees Celsius it evaporates into a gas, at zero degrees Celsius it freezes into ice. In both cases, these new states of matter form as a consequence of a phase transition where the water molecules rearrange themselves, thus changing the characteristics of the matter. Properties like magnetism or superconductivity emerge as a result of electrons undergoing phase transitions in crystals. For phase transitions at temperatures approaching the absolute zero at -273.15 degrees Celsius, quantum mechanical effects such as entanglement come into play, and one speaks of quantum phase transitions. Even though there are more than 30 years of extensive research dedicated to phase transitions in quantum materials, we had previously assumed that the phenomenon of entanglement played a role only on a microscopic scale, where it involves only a few atoms at a time,explains Christian Pfleiderer, Professor of Topology of Correlated Systems at the TUM.

Quantum entanglement is one of the most astonishing phenomena of physics, where the entangled quantum particles exist in a shared superposition state that allows for usually mutually exclusive properties (e.g., black and white) to occur simultaneously. As a rule, the laws of quantum mechanics only apply to microscopic particles. The research teams from Munich and Dresden have now succeeded in observing effects of quantum entanglement on a much larger scale, that of thousands of atoms. For this, they have chosen to work with the well-known compound LiHoF4.

Spherical samples enable precision measurements

At very low temperatures, LiHoF4acts as a ferromagnet where all magnetic moments spontaneously point in the same direction. If you then apply a magnetic field exactly vertically to the preferred magnetic direction, the magnetic moments will change direction, which is known as fluctuations. The higher the magnetic field strength, the stronger these fluctuations become, until, eventually, the ferromagnetism disappears completely at a quantum phase transition. This leads to the entanglement of neighboring magnetic moments. If you hold up a LiHoF4sample to a very strong magnet, it suddenly ceases to be spontaneously magnetic. This has been known for 25 years, summarizes Vojta.

What is new is what happens when you change the direction of the magnetic field. We discovered that the quantum phase transition continues to occur, whereas it had previously been believed that even the smallest tilt of the magnetic field would immediately suppress it, explains Pfleiderer. Under these conditions, however, it is not individual magnetic moments but rather extensive magnetic areas, so-called ferromagnetic domains, that undergo these quantum phase transitions. The domains constitute entire islands of magnetic moments pointing in the same direction. We have used spherical samples for our precision measurements. That is what enabled us to precisely study the behavior upon small changes in the direction of the magnetic field, adds Andreas Wendl, who conducted the experiments as part of his doctoral dissertation.

From fundamental physics to applications

We have discovered an entirely new type of quantum phase transitions where entanglement takes place on the scale of many thousands of atoms instead of just in the microcosm of only a few, explains Vojta. If you imagine the magnetic domains as a black-and-white pattern, the new phase transition leads to either the white or the black areas becoming infinitesimally small, i.e., creating a quantum pattern, bevor dissolving completely. A newly developed theoretical model successfully explains the data obtained from the experiments. For our analysis, we generalized existing microscopic models and also took into account the feedback of the large ferromagnetic domains to the microscopic properties, elaborates Heike Eisenlohr, who performed the calculations as part of her PhD thesis.

The discovery of the new quantum phase transitions is important as a foundation and general frame of reference for the research of quantum phenomena in materials, as well as for new applications. Quantum entanglement is applied and used in technologies like quantum sensors and quantum computers, amongst other things, says Vojta. Pfleiderer adds: Our work is in the area of fundamental research, which, however, can have a direct impact on the development of practical applications, if you use the materials properties in a controlled way.

Publikation:Emergence of mesoscale quantum phase transitions in a ferromagnetAndreas Wendl, Heike Eisenlohr, Felix Rucker, Christopher Duvinage, Markus Kleinhans, Matthias Vojta & Christian Pfleiderer,Nature609, 6570 (2022)https://www.nature.com/articles/s41586-022-04995-5

More information:The research has been financially supported by the Excellence Strategy of the German Federal and State Governments within the Wrzburg-Dresden Cluster of Excellence Complexity and Topology in Quantum Matter (ct.qmat) and the Cluster of Excellence Munich Center for Quantum Science and Technology (MCQST). In addition, the work has been supported by the European Research Council (ERC) via the Advanced Grant ExQuiSid and by the Deutsche Forschungsgemeinschaft (DFG) within the Collaborative Research Centers (SFB) 1143 und TRR80.

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Quantum materials: entanglement of many atoms discovered for the first time - Newswise

Posted on Sep 1, 2022 in Astrobiology, Astronomy, Astrophysics, Extraterrestrial Life, James Webb Space Telescope, quantum physics, Science, Science News, Space News, Universe

Todays stories from our amazing Universe include Will NASA Beat China to a Giant Radio Telescope on the Moons Far Side to What will Humanitys Legacy to the Universe Be, and much more.

Webb Snaps Its First Image Of An Exoplanet And Its A Very Weird World The unusual world is among the first targets studied by the new space observatory, reports IFL Science. The world in question is called HIP 65426b and its truly puzzling. Previous claims said it shouldnt exist as it doesnt fit our models of exoplanets (planets outside the Solar System), so observations of it are crucial to help astronomers develop better ones.

What will humanitys legacy to the Universe be? The last 70 years have taken us farther than the previous 70,000. But can we accomplish more than creating a record saying, We were here? asks Big Think.

Unexplored Quantum Realm about 3 Billion Times Colder than Deep Space, reports Rice University Japanese and U.S. physicists have used atoms about 3 billion times colder than interstellar space to open a portal to an unexplored realm of quantum magnetism.

NASAs Next Launch Attempt for Artemis I Will Occur September 3Technical glitches and questionable weather forecasts continue to delay liftoff for NASAs landmark lunar mission, reports Scientific American.

NASA Unveils Candidate Landing Sites for Artemis AstronautsWhen humans return to the moon, theyll likely visit one of these 13 regions near the moons south pole, reports Scientific American.

NASA and China Want to Land on the Same Areas on the Moon. They may have to compete for the limited resources on the lunar surface, reports Gizmodo. NASAs Artemis 3 mission has its sights set on the Moons south pole, a particularly valuable area since it may contain water ice in its shadowed regions.

Unobstructed Window on the Cosmos Will NASA Beat China to a Giant Radio Telescope on Moons Far Side? asks The Daily Galaxy. NASA better move fast! In February of 2019, China established the first human-technology landing site on Moons far side that they named The Milky Way Base. China has named the landing site of its Change-4 lunar probe (image landing above) Statio Tianhe after the Chinese name for the Milky Way Galaxy for the first-ever soft landing on the far side of the moon.

The Milky Way An Autobiography of Our Galaxy

Immortal Mystery ObjectEvery Brown Dwarf Ever Created Still Exists, reports The Daily Galaxy. Unlike stars, brown dwarfs cool as they age morphing in their appearance.

Webb inspects the heart of the Phantom Galaxy The Phantom Galaxy is around 32 million light-years away from Earth in the constellation Pisces, and lies almost face-on to Earth. This, coupled with its well-defined spiral arms, makes it a favorite target for astronomers studying the origin and structure of galactic spirals.

NASA Webbs First Full-Color Images, Data Are Set to Sound, reports NASATheres a new, immersive way to explore some of the first full-color infrared images and data from NASAs James Webb Space Telescope through sound. Listeners can enter the complex soundscape of the Cosmic Cliffs in the Carina Nebula, explore the contrasting tones of two images that depict the Southern Ring Nebula, and identify the individual data points in a transmission spectrum of hot gas giant exoplanet WASP-96 b.

Object Bigger than Pluto Discovered, Called 10th Planet, reports Robert Roy Britt for Space.com The new object, temporarily named 2003 UB313, is about three times as far from the Sun as is Pluto.

Jupiters true colors pop in new images from NASAs Juno mission, reports Tereza Pultarova for Space.com

1.7 billion years ago, Earth had a natural nuclear reactor Planets can create nuclear power on their own, naturally, without any intelligence or technology. Earth already did: 1.7 billion years ago, reports Big Think.

New telescopes seek the cosmic dark ages Radio astronomers look to far-flung locations to detect low-frequency signals that emanate from the ancient universe, reports Physics Today.

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Unexplored Quantum Realm to Webb Reveals a Very Weird Alien Planet (The Galaxy Report) - The Daily Galaxy --Great Discoveries Channel