The chemical reaction 2KRb → K2 + Rb2 is studied under ultralow temperatures at the quantum state-to-state level, allowing unprecedented details of the reaction dynamics to be observed.
Category: quantum physics – Page 684
A Ghostly Solution: Strange Property of the Quantum Realm Enables Efficient Energy Harvesting in Tiny Device
Scientists at the University of Colorado Boulder have tapped into a poltergeist-like property of electrons to design devices that can capture excess heat from their environment — and turn it into usable electricity.
The researchers have described their new “optical rectennas” in a paper published today (May 18, 2021) in the journal Nature Communications. These devices, which are too small to see with the naked eye, are roughly 100 times more efficient than similar tools used for energy harvesting. And they achieve that feat through a mysterious process called “resonant tunneling” — in which electrons pass through solid matter without spending any energy.
“They go in like ghosts,” said lead author Amina Belkadi, who recently earned her PhD from the Department of Electrical, Computer and Energy Engineering (ECEE).
Gigajot Unveils World’s First Commercially Available Quanta Image Sensors
Photon counting and reliable photon number resolving, until now, only partially available utilizing esoteric EMCCD technology in highly controlled laboratory environments, is now possible with a compact form-factor camera, operating at room temperature — with the additional benefits of higher resolution and speed. “The ability to do photon counting at room temperature is a game changer for our research efforts in Astrophysics and Quantum Information Science,” said Dr. Don Figer, Director of Center for Detectors and the Future Photon Initiative in the College of Science, Rochester Institute of Technology.
Future sparkles for diamond-based quantum technology
Marilyn Monroe famously sang that diamonds are a girl’s best friend, but they are also very popular with quantum scientists—with two new research breakthroughs poised to accelerate the development of synthetic diamond-based quantum technology, improve scalability, and dramatically reduce manufacturing costs.
While silicon is traditionally used for computer and mobile phone hardware, diamond has unique properties that make it particularly useful as a base for emerging quantum technologies such as quantum supercomputers, secure communications and sensors.
However there are two key problems; cost, and difficulty in fabricating the single crystal diamond layer, which is smaller than one millionth of a meter.
Direct observation of deterministic macroscopic entanglement
Quantum entanglement occurs when two separate entities become strongly linked in a way that cannot be explained by classical physics; it is a powerful resource in quantum communication protocols and advanced technologies that aim to exploit the enhanced capabilities of quantum systems. To date, entanglement has generally been limited to microscopic quantum units such as pairs or multiples of single ions, atoms, photons, and so on. Kotler et al. and Mercier de Lépinay et al. demonstrate the ability to extend quantum entanglement to massive macroscopic systems (see the Perspective by Lau and Clerk). Entanglement of two mechanical oscillators on such a large length and mass scale is expected to find widespread use in both applications and fundamental physics to probe the boundary between the classical and quantum worlds.
Science, this issue p. 622, p. 625; see also p. 570
Quantum entanglement of mechanical systems emerges when distinct objects move with such a high degree of correlation that they can no longer be described separately. Although quantum mechanics presumably applies to objects of all sizes, directly observing entanglement becomes challenging as masses increase, requiring measurement and control with a vanishingly small error. Here, using pulsed electromechanics, we deterministically entangle two mechanical drumheads with masses of 70 picograms. Through nearly quantum-limited measurements of the position and momentum quadratures of both drums, we perform quantum state tomography and thereby directly observe entanglement. Such entangled macroscopic systems are poised to serve in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes of future quantum networks.
Quantum Leap for Quantum Computing: Ion Beams Create Chains of Closely Coupled Qubits
A new way to form self-aligned ‘color centers’ promises scalability to over 10000 qubits for applications in quantum sensing and quantum computing.
Achieving the immense promise of quantum computing requires new developments at every level, including the computing hardware itself. A Lawrence Berkeley National Laboratory (Berkeley Lab)-led international team of researchers has discovered a way to use ion beams to create long strings of “color center” qubits in diamond. Their work is detailed in the journal Applied Physics Letters.
The authors includes several from Berkeley Lab: Arun Persaud, who led the study, and Thomas Schenkel, head of the Accelerator Technology and Applied Physics (ATAP) Division’s Fusion Science & Ion Beam Technology Program, as well as Casey Christian (now with Berkeley Lab’s Physics Division), Edward Barnard of Berkeley Lab’s Molecular Foundry, and ATAP affiliate Russell E. Lake.
Riding bosonic qubits towards fault-tolerant quantum computation
A guide to bosonic codes and error correction in a photonic platform.
Ilan Tzitrin, J. Eli Bourassa, and Krishna Kumar Sabapathy
You and two of your friends, Judit and Gary, are on a long-awaited trip in southern India. On a leg of your journey, you find yourselves on a luxurious train ride through the Deccan Plateau, about to meander through the breathtaking Western Ghats. Before the scenery captures your attention, your friends decide to entertain themselves with a game of chess, while you continue to devour Carl Sagan’s Contact.
A half hour into an intensive game, Judit and Gary agree they could use a break to refresh, and they head to the dining car for some samosas and chai. At this very moment, the train begins a gentle ascent up a mountain, and all the chess pieces slide a little in one direction. The board ends up looking like this:
Something’s Up In Switzerland: Explaining The B Meson News From The Large Hadron Collider
Particle physics is a field of extremes. Scales always have 10really big number associated. Some results from the Large Hadron Collider Beauty (LHCb) experiment have recently been reported that are statistically significant, and they may have profound implications for the Standard Model, but it might also just be a numbers anomaly, and we won’t get to find out for a while. Let’s dive into the basics of quantum particles, in case your elementary school education is a little rusty.
New evidence for electron’s dual nature found in a quantum spin liquid
A new discovery led by Princeton University could upend our understanding of how electrons behave under extreme conditions in quantum materials. The finding provides experimental evidence that this familiar building block of matter behaves as if it is made of two particles: one particle that gives the electron its negative charge and another that supplies its magnet-like property, known as spin.
“We think this is the first hard evidence of spin-charge separation,” said Nai Phuan Ong, Princeton’s Eugene Higgins Professor of Physics and senior author on the paper published this week in the journal Nature Physics.
The experimental results fulfill a prediction made decades ago to explain one of the most mind-bending states of matter, the quantum spin liquid. In all materials, the spin of an electron can point either up or down. In the familiar magnet, all of the spins uniformly point in one direction throughout the sample when the temperature drops below a critical temperature.
New atomically precise graphene nanoribbon heterojunction sensor developed
An international research team led by the University of Cologne has succeeded for the first time in connecting several atomically precise nanoribbons made of graphene, a modification of carbon, to form complex structures. The scientists have synthesized and spectroscopically characterized nanoribbon heterojunctions. They then were able to integrate the heterojunctions into an electronic component. In this way, they have created a novel sensor that is highly sensitive to atoms and molecules. The results of their research have been published under the title Tunneling current modulation in atomically precise graphene nanoribbon heterojunctions’ in Nature Communications. The work was carried out in close cooperation between the Institute for Experimental Physics with the Department of Chemistry at the University of Cologne, as well as with research groups from Montreal, Novosibirsk, Hiroshima, and Berkeley. It was funded by the German Research Foundation (DFG) and the European Research Council (ERC).
The heterojunctions of graphene nanoribbons are just one nanometer—one millionth of a millimeter—wide. Graphene consists of only a single layer of carbon atoms and is considered the thinnest material in the world. In 2010, researchers in Manchester succeeded in making single-atom layers of graphene for the first time, for which they won the Nobel Prize. The graphene nanoribbon heterojunctions used to make the sensor are each seven and fourteen carbon atoms wide and about 50 nanometres long. What makes them special is that their edges are free of defects. This is why they are called atomically precise nanoribbons, explained Dr. Boris Senkovskiy from the Institute for Experimental Physics. The researchers connected several of these nanoribbon heterojunctions at their short ends, thus creating more complex heterostructures that act as tunneling barriers.
The heterostructures were investigated using angle-resolved photoemission, optical spectroscopy, and scanning tunneling microscopy. In the next step, the generated heterostructures were integrated into an electronic device. The electric current flowing through the nanoribbon heterostructure is governed by the quantum mechanical tunneling effect. This means that under certain conditions, electrons can overcome existing energy barriers in atoms by ‘tunneling,’ so that a current then flows even though the barrier is greater than the available energy of the electron.