Tag Archives: atoms

Ultracold Atoms May Investigate Relativity in the Quantum Realm

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Spinning ultracold atoms could uncover the limits of Einstein’s relativity

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Small Ferris wheels made from light and extremely chilled particles could enable scientists to investigate elements of Albert Einstein’s theory of relativity on an extraordinary level.

Einstein’s special and general theories of relativity, established in the early 20th century, transformed our comprehension of time by illustrating that a moving clock can tick slower than a stationary one. If one moves rapidly or accelerates significantly, time measured will also increase. The same applies when an object moves in a circular path. While these effects have been noted in relatively large celestial entities, Vassilis Rembesis and his team at King Saud University in Saudi Arabia have developed a method to test these principles on a diminutive scale.

By examining rotation and time at the molecular level (atoms and molecules), they explored ultracold regions, just a few millionths of a degree above absolute zero. In this domain, the quantum behavior and movement of atoms and molecules can be meticulously controlled with laser beams and electromagnetic fields. In 2007, Rembesis and his colleagues formulated a technique to tune a laser beam to trap atoms in a cylindrical form, allowing them to spin. They refer to this as an “optical Ferris wheel,” and Rembesis asserts that their new findings propose that it can be used to observe relativistic time dilation in ultracold particles.

Their predictions indicate that nitrogen molecules are optimal candidates for investigating rotational time delays at the quantum level. By considering the movement of electrons within them as the ticks of an internal timer, the researchers detected frequency changes as minuscule as 1/10 quintillion.

Simultaneously, Rembesis noted that experiments utilizing optical Ferris wheels have been sparse up until now. This new proposal opens avenues for examining relativity theory in uncharted conditions where new or surprising phenomena may emerge. For instance, the quantum characteristics of ultracold particles may challenge the “clock hypothesis,” which states how a clock’s acceleration influences its ticking.

“It’s crucial to validate our interpretations of physical phenomena within nature. It’s often during unexpected occurrences that we need to reevaluate our understanding for a deeper insight into the universe. This research offers an alternative approach to examining relativistic systems, providing distinct advantages over traditional mechanical setups,” says Patrick Oberg from Heriot-Watt University, UK.

Relativistic phenomena, such as time dilation, generally necessitate exceedingly high velocities; however, optical Ferris wheels enable access to them without the need for impractically high speeds, he explains. Aidan Arnold from the University of Strathclyde, UK adds, “With the remarkable accuracy of atomic clocks, the time difference ‘experienced’ by the atoms in the Ferris wheel should be significant. Because the accelerated atoms remain in close proximity, there is ample opportunity to measure this difference,” he states.

By adjusting the focus of the laser beam, it may also become feasible to manipulate the dimensions of the Ferris wheel that confines the particles, allowing researchers to explore time-delay effects for various rotations, as noted by Rembesis. Nevertheless, technical challenges persist, including the need to ensure that atoms and molecules do not heat up and become uncontrollable during rotation.

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Source: www.newscientist.com

Memory Chips Just 10 Atoms Thick Could Boost Capacity Significantly

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Current silicon chips are highly compact, but using ultrathin 2D materials could enhance their density even further.

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A memory chip with a thickness of just 10 atoms could revolutionize the storage capacity of electronic gadgets like smartphones.

Despite decades of scaling down, modern computer chips often have very few components yet integrate tens of billions of transistors into an area comparable to a fingernail. Although the size of silicon components has significantly decreased, the thickness of the silicon wafers remains considerable, imposing limitations on increasing a chip’s complexity through stacking layers.

Researchers have been exploring the potential of thinner chips made from 2D materials like graphene. Graphene consists of a single layer of carbon atoms and represents the thinnest known material. However, until recently, only basic chip designs could be implemented with these materials, complicating their connection to traditional processors and integration into electrical devices.

Recently, Liu Chunsen and his team from Fudan University in Shanghai successfully integrated a 2D chip only 10 atoms thick with a CMOS chip currently utilized in computers. The manufacturing method for these chips yields a rough surface, making it challenging to layer a 2D sheet on top. The researchers addressed this issue by placing a glass layer between the 2D and CMOS chips, although this step is not yet part of the industrial process and requires further development for mass production.

The prototype memory module the team created achieved over 93% accuracy during testing. While this falls short of the reliability needed for consumer-grade devices, it serves as an encouraging proof of concept.

“This technology holds significant promise, but there’s still a considerable journey ahead before it can be commercialized,” says Steve Furber from the University of Manchester, UK.

Kai Shu, a researcher at King’s College London, mentions that further reducing current chip designs without utilizing 2D materials poses challenges due to signal leakage associated with traditional components made at very narrow widths. Thinner layers might mitigate this issue. Consequently, achieving greater thinness may facilitate additional reductions in width.

“Silicon is encountering hurdles,” said Xu. “2D materials might provide solutions. With their minimal thickness, gate control becomes more uniform and comprehensive, resulting in reduced leakage.”

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Source: www.newscientist.com

Self-Integrating Atoms Uncover Quantum Wave Functions

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The wave functions of atoms can expand without altering their shape

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Extremely cold atoms show a unique ability to self-integrate their quantum states, allowing for imaging with remarkable clarity. This capability aids researchers in exploring the behaviors of quantum particles within unusual materials like superconductors and superfluids.

Mapping the quantum states of atoms, particularly the shape of their wavefunction, poses significant challenges—especially when atoms are densely packed in solids and interact closely. To delve into the quantum behaviors of such materials, scientists convert quantum properties into extremely cold atoms, which they can manipulate with lasers and electromagnetic fields, arranging them into closely packed patterns that mimic atomic structures in solid materials.

Sandra Brantetter from the University of Heidelberg, along with her team, has developed methods to expand the wave functions of hyperpolar atoms by a factor of 50, enhancing their detectability.

Starting with around 30 lithium atoms cooled to just a few millionths above absolute zero, researchers trapped these atoms in a flat configuration using lasers, allowing for precise control of their quantum states. The team then manipulated the properties of the light used, effectively enlarging the atoms’ wave functions while carefully managing the trapping conditions to maintain stability, akin to fine-tuning a microscope’s lens, according to Brandstetter.

Following these adjustments, the researchers employed a reliable atomic detection technique to visualize wave functions in detail that were previously unattainable. “When imaging a system without prior magnification, the result is merely a singular blob, obscuring any structural insights,” Brandstetter explains.

Utilizing this innovative technique, the team examined various atomic configurations. For instance, they successfully imaged a pair of atoms interacting and forming molecules; the magnification permitted them to distinguish between each individual atom. The most complex setup involved 12 interacting atoms, each exhibiting different quantum spins that dictate the material’s magnetic properties.

Jonathan Mortlock notes that although similar magnification methods have been explored at Durham University, this experiment is the first to utilize such an approach for identifying the quantum characteristics of individual atoms in an array—details once deemed inaccessible.

The team aims to apply this method to study the phenomena when two quantum particles known as fermions coalesce into liquids that exhibit zero viscosity or conduct electricity with complete efficiency. Understanding these states could pave the way for the development of superior electronic devices. However, researchers must first achieve a deeper comprehension of how fermions assemble and the implications of pairing within the quantum state. Brandstetter states that new techniques now allow for the creation of ultra-cold fermionic atoms and the imaging of their enlarged wave functions.

topic:

  • Quantum Science/
  • Atomic Physics

Source: www.newscientist.com

Ultra-Cold Atoms Defy Entropy and Resist Heating Up

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Some atoms simply refuse to follow entropy

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Repeated energization of vast collections of atoms should result in the disruption of their established structures, yet quantum effects appear to resist these changes.

The expected outcome for a physical system is “thermalization,” where everything becomes hot and eventually turns into a puddle of water. Intuitively, one might think that continuously throwing rocks at a sculpture would accelerate this process. Hanns-Christoph Negerl and his team at the University of Innsbruck in Germany conducted experiments that mimic this notion using some of the coldest atoms on Earth, but they observed no heating.

“We anticipated witnessing the opposite,” Negerl shares. The researchers utilized roughly 100,000 cesium atoms, cooling them down to billionths of absolute zero through laser and electromagnetic pulses. At this chilling temperature, atomic behavior becomes entirely quantum. They arranged the atoms in numerous single-layer tubes and employed additional laser pulses to “kick” them repeatedly.

These kicks were intended to provide the atoms with extra energy, which should have resulted in heating and varying speeds. However, team member Yanliang Guo reported that they observed no such changes, regardless of the kick intensity or the adjustments made to the interactions between atoms. The atoms continued to display remarkably similar speeds, behaving as if they were “frozen” within a singular quantum state.

The concept of quantum particles generating heat isn’t new, tracing back to the 1950s. The timing of such occurrences has long been a topic of debate among physicists. Team member Manuele Landini noted that while previous experiments revealed mechanisms for heating atoms, this current investigation may have unveiled novel physics by exploring an alternate range of parameters.

The mathematical framework explaining these phenomena is complex and often contradictory. Adam Ranson from the University of Lille in France commented that calculating whether interacting atoms will heat up is quite challenging, often resulting in researchers simplifying equations to two or three atoms. There exists a theory suggesting that the quantum states of highly interactive atoms can align in a manner that prevents energy absorption, but Ranson believes this picture remains incomplete.

Experiments like those conducted recently act as quantum simulators capable of deeper insights, although Rançon emphasized that further exploration of kick strengths and interactions is still needed.

Robert Connick at Brookhaven National Laboratory in New York has been developing mathematical models relevant to such experiments that project the unusual behavior of atoms. He posits that discovering systems resistant to energy absorption could inspire new developments in quantum technologies, offering a stable quantum state for long-term reliable detection or data storage. “Thermalization poses a significant threat to maintaining quantum effects,” he explains.

Researchers are already planning follow-up experiments to align atoms in thicker tubes, manipulate different tubes, and investigate the possibility of “freezing” their speeds.

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Source: www.newscientist.com

Giant Atoms Kept “Confined” for Record Durations at Room Temperature

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Manipulating Giant Atoms for Enhanced Quantum Computing

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Recently, giant atoms have emerged as prime candidates for the development of advanced quantum simulators and computers, thanks to researchers demonstrating control over them for an extended period in room temperature environments.

Using electromagnetic pulses or laser light, scientists can modify the quantum properties of an atom—allowing for the adjustment of electron energy to encode information. Manipulating thousands of such atoms paves the way for constructing a quantum computer or simulating unusual quantum materials. However, spontaneous state changes in atoms can cause errors, with these atoms being controllable only within a limited “lifetime,” previously recorded at up to 1400 seconds. Despite advancements in trapping atoms longer, these methods typically required refrigeration systems, leading to logistical hurdles.

Zhenpu Zhang and Cindy Regal, along with their colleagues at the University of Colorado Boulder, have shattered previous room temperature records by employing Rydberg atoms. These atoms have outer electrons positioned far from the nucleus, resulting in a larger atomic diameter. The research team successfully loaded these atoms into a vacuum chamber, effectively blocking interfering air particles and employing laser-based “optical tweezers” for precise atom manipulation. This technique is standard for controlling Rydberg atoms, noted for their sensitivity to electromagnetic fields and light.

The team enhanced their setup by adding a copper layer inside the container, which they cooled to -269°C (-452°F). This cooling shields the atoms from thermal interference that could alter their states. Additionally, Zhang explains that air particles condense onto the copper walls, akin to how water droplets form on cold surfaces, further improving the vacuum within the chamber. Consequently, they managed to maintain control of approximately 3000 seconds (or 50 minutes), which is nearly double that achieved in previous experiments.

Zhang has been developing this innovative setup for five years from the ground up. Regal adds, “This represents a significant evolution in how we approach these experiments.”

Clement Sayrin of the Kastler Brossel Laboratory in France emphasized that this new methodology may facilitate manipulating even more atoms. “3000 seconds is quite impressive. Achieving such extended lifetimes for these atoms demands considerable effort,” he states. However, as the number of atoms in the chamber increases, so does the requirement for additional lasers to control them, potentially shortening the atomic lifespans and introducing further engineering challenges, according to Sayrin.

Topics:

  • Quantum Computing/
  • Quantum Physics

Source: www.newscientist.com

Metals can be thinned to a few atoms thick

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Two layers of bismuth sandwiched between two layers of disulphide

Luo Jun Du

By crushing the molten droplets at a large pressure between two sapphires, a sheet of thick atoms of two thick atoms can be produced. Researchers who developed the process say that rare materials can use applications in industrial chemistry, optics, and computers.

Last year, scientists created a golden sheet Thick single atom which was called “Galden” after graphene, a material made from a single layer of carbon atoms. Such materials are described as 2D because they are chemically as thin as possible.

However, it has never been possible to make other 2D metals. New techniques developed by Luo Jun Du The Chinese Academy of Sciences and his colleagues can create two sheets of bismuth, gallium, indium, tin, and lead, which are as thin as atomic bonds allow.

To squeeze the metals, the researchers used two very flat sapphire crystals with a thin layer of disulfide in a bilayer (MOS2). They placed powdered metal between these jaws, heated to 400°C until they formed droplets, crushing them with a huge pressure of up to 200 megapascals. The metal was compressed until it cooled to just two atoms thick, or, in the case of bismuth. When the pressure was removed, the 2D metal was stuck between the MOS2. The seat then slipped out of the sapphire.

Du says the process was devised eight years ago, but the team dug up the recent fruit when MOS discovered it2. The layers remained the thin metal sheet stable. “The single layer of freestanding metal atoms is simply unstable from a thermodynamic perspective. Therefore, we [had to] We’re developing whole new techniques,” says Du. “The process seems simple, but it works.”

In addition to creating very thin layers of atoms, researchers were able to fine-tune the throttle pressure and create three, four, or more atoms with accuracy.

2D metals can have anomalous properties that help scientists explore macroscopic quantum phenomena and superconductivity, DU says, which could lead to ultra-low power transistors, clear computer displays, and highly efficient catalysts for chemical reactions.

One problem is MOS2 Encapsulating metal sheets is not easily removed. DU says this may be problematic in some applications, but the experiments suggest that it does not affect electrical conductivity, thus not hindering the 2D metal used in electronic devices.

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Source: www.newscientist.com

Physicists showcase novel technique for pinpointing 3D location of individual atoms

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Developed by a team of physicists from the University of Bonn and the University of Bristol, this new method makes it possible to precisely determine the position of atoms in 3D in a single image and is based on an original physical principle.

The different directions of rotation of the various “dumbbells” indicate that the atoms are in different planes. Image credit: Institute of Applied Physics, University of Bonn.

“If you have ever used a microscope to study plant cells in your biology class, you can probably recall a similar situation,” said Tanguy Legrand and colleagues at the University of Bonn.

“It's easy to see that a particular chloroplast is located above and to the right of the nucleus. But are they both on the same plane?”

“However, when we adjust the focus of the microscope, we find that the images of the nuclei become clearer, while the images of the chloroplasts become blurred.”

“One of them has to be a little higher than the other, and the other a little lower than the other. However, this method doesn't give you exact details about the vertical position.”

“The principle is very similar if you want to observe individual atoms rather than cells. So-called quantum gas microscopes can be used for this purpose.”

“This allows us to directly determine the x and y coordinates of atoms.”

“However, it is much more difficult to measure its z-coordinate, and thus its distance to the objective lens. To find out in which plane an atom lies, we need to take multiple images by moving the focus to various different planes. I need to take a picture of a plane. This is a complex and time-consuming process. ”

“We have developed a method that completes this process in one step,” Dr. Legrand said.

“To achieve this, we use an effect that was already known in theory since the 1990s but had not yet been used in quantum gas microscopy.”

To experiment with atoms, you must first cool them down significantly until they barely move.

It is then possible to confine them to a standing wave of laser light, for example.

The egg then slides into the trough of the waves so that it fits inside the egg box.

After being captured, it is exposed to an additional laser beam and stimulated to emit light to reveal its location.

The resulting fluorescence appears as slightly blurred round spots in quantum gas microscopy.

“We have now developed a special method to transform the wavefront of light emitted by atoms,” said Dr. Andrea Alberti, also from the University of Bonn.

“Instead of a typical round spot, the deformed wavefront produces a dumbbell shape on the camera, which rotates itself.”

“The direction this dumbbell points is determined by the distance light travels from the atom to the camera.”

Professor Dieter Meschede from the University of Bonn said: “The dumbbell acts like a compass needle, and depending on its direction we can read the Z coordinate.”

This new method could be used to develop new quantum materials with special properties.

“For example, we can find out what quantum mechanical effects occur when atoms are arranged in a particular order,” said physicist Dr Carrie Widener from the University of Bristol.

“This allows us to simulate the properties of three-dimensional materials to some extent without having to synthesize them.”

team's work It was published in the magazine Physical review A.

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Tanguy Legrand other. 2024. His three-dimensional imaging of single atoms in optical lattices by helical point spread function engineering. Physics. Rev.A 109 (3): 033304; doi: 10.1103/PhysRevA.109.033304

Source: www.sci.news

Confining Atoms in a Small Tube Creates a Strange “Primary Gas”

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A single atom of krypton trapped in a Buckminsterfullerene cage

University of Nottingham

The krypton atoms become stuck in a “traffic jam” inside the carbon nanotube, unable to pass through each other, allowing scientists to more easily observe how the krypton atoms interact. Researchers hope that this “primary energetic body” can shed light on fundamental physical forces.

Andrey Klobistov and his colleagues at the University of Nottingham, UK, have discovered that the narrow space restricts movement and makes it easier to observe the inside of carbon nanotubes, which are just 1.5 nanometers thick (one-half millionth the width of a human hair). He spent years studying chemical reactions. They have now developed a way to do the same thing with atoms of the rare gas krypton, creating a so-called one-dimensional gas.

The researchers used a buckminsterfullerene molecule, a spherical cage made of 60 carbon atoms, with a krypton atom trapped inside. These molecules are sucked into the carbon nanotube by van der Waals forces, weak attractive forces caused by fluctuations in the electron cloud surrounding the atomic nucleus. Once filled, the tube is heated to 1200 °C and the cage is destroyed. The carbon atoms are absorbed into the nanotube, leaving behind a string of krypton atoms.

A single atom of krypton confined in a Buckminsterfullerene cage inside a nanotube, observed with an electron microscope

University of Nottingham

Klovistov said the result is like a “traffic jam” in which atoms can be observed slowly, rather than flying around at up to 400 meters per second, as they often do in three-dimensional gases. The group used a transmission electron microscope to image atoms, allowing them to accurately measure the distances between them.

“They fundamentally change their behavior,” Klovistov said. “This is a very interesting system. We can track their trajectories, how they move and how they interact. This is a great toy to play with with noble gases. “We can gain a fundamental understanding of the behavior of atoms under extreme confinement.”

Other researchers have already observed that krypton atoms form pairs held together by van der Waals forces. This phenomenon is difficult to observe in unconstrained atoms and can also occur within nanotubes. Klobistov said future experiments will be “full of surprises.”

Future research will investigate how temperature affects primary gas. If you reduce the temperature of a gas in three-dimensional space, it will condense into a liquid and then solidify, but there is no guarantee that the same rules will apply in his one dimension.

“Maybe there's no such thing as a 1D liquid, it's just a 1D solid. It's a bit of a voyage of discovery,” says Klobistov.

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Source: www.newscientist.com