The Quantum Insider (TQI) is the leading online resource dedicated exclusively to Quantum Computing.
Category: quantum physics – Page 271
A new approach to developing semiconductor materials at tiny scales could help boost applications that rely on converting light to energy. A Los Alamos-led research team incorporated magnetic dopants into specially engineered colloidal quantum dots—nanoscale-size semiconductor crystals—and was able to achieve effects that may power solar cell technology, photo detectors and applications that depend on light to drive chemical reactions.
“In quantum dots comprising a lead-selenide core and a cadmium-selenide shell, manganese ions act as tiny magnets whose magnetic spins strongly interact with both the core and the shell of the quantum dot,” said Victor Klimov, leader of the Los Alamos nanotechnology team and the project’s principal investigator. “In the course of these interactions, energy can be transferred to and from the manganese ion by flipping its spin—a process commonly termed spin exchange.”
In spin-exchange carrier multiplication, a single absorbed photon generates not one but two electron-hole pairs, also known as excitons, which occur as a result of spin-flip relaxation of an excited manganese ion.
The term molybdenum disulfide may sound familiar to some car drivers and mechanics. No wonder: the substance, discovered by U.S. chemist Alfred Sonntag in the 1940s, is still used today as a high-performance lubricant in engines and turbines, but also for bolts and screws.
This is due to the special chemical structure of this solid, whose individual material layers are easily displaceable relative to one another. However, molybdenum disulfide (chemically MoS2) not only lubricates well, but it is also possible to exfoliate a single atomic layer of this material or to grow it synthetically on a wafer scale.
The controlled isolation of a MoS2 monolayer was achieved only a few years ago, but is already considered a materials science breakthrough with enormous technological potential. The Empa team now wants to work with precisely this class of materials.
Alfred North Whitehead’s Process Philosophy, the Mystery of Consciousness and the Mind-Body Problem (2016)
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Compilation by Michael Schramm.
Background Music by Michael Schramm.
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Speakers & Quotations:
Charles Birch, Susan Blackmore, David J. Chalmers, Daniel C. Dennett, Freeman Dyson, David Ray Griffin, Charles Hartshorne, Nicholas Humphrey, Christof Koch, Colin McGinn, Thomas Nagel, Karl R. Popper, John R. Searle, Rupert Sheldrake, Galen Strawson, Alfred North Whitehead.
Tags:
panpsychism, consciousness, mind-body problem, process philosophy, process metaphysics, materialism, (property) dualism, quantum physics, indeterminism, free will.
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I have uploaded the resource document again and added a new link. Thanks for the interest!
Resources (new link):
https://theology-ethics.uni-hohenheim.de/fileadmin/einrichtu…ources.pdf.
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Some of our most important everyday items, such as computers, medical equipment, stereos, generators, and more, work because of magnets. We know what happens when computers become more powerful, but what might be possible if magnets became more versatile? What if one could change a physical property that defined their usability? What innovation might that catalyze?
It’s a question that MIT Plasma Science and Fusion Center (PSFC) research scientists Hang Chi, Yunbo Ou, Jagadeesh Moodera, and their co-authors explore in a new, open-access Nature Communications paper, “Strain-tunable Berry curvature in quasi-two-dimensional chromium telluride.”
Understanding the magnitude of the authors’ discovery requires a brief trip back in time: In 1,879, a 23-year-old graduate student named Edwin Hall discovered that when he put a magnet at right angles to a strip of metal that had a current running through it, one side of the strip would have a greater charge than the other. The magnetic field was deflecting the current’s electrons toward the edge of the metal, a phenomenon that would be named the Hall effect in his honor.
Scaling has long been recognized as a major hurdle for quantum processors, along with a need for advances in quantum error correction and the control of quantum gates.
However, while rapid progress has been made in the latter two, far less progress has been made in the development of a CMOS-based scalable system, where the devices and qubits are sufficiently identical that the number of external control signals increases slowly with the number of qubits.
Therefore the development, and taping-out, of a CMOS-based scaling architecture has taken on new significance, as scaling has become the most critical remaining task for building a commercially viable quantum computer.
We compare the performance of the Quantum Approximate Optimization Algorithm (QAOA) with state-of-the-art classical solvers Gurobi and MQLib to solve the MaxCut problem on 3-regular graphs. We identify the minimum noiseless sampling frequency and depth p required for a quantum device to outperform classical algorithms. There is potential for quantum advantage on hundreds of qubits and moderate depth with a sampling frequency of 10 kHz. We observe, however, that classical heuristic solvers are capable of producing high-quality approximate solutions in linear time complexity. In order to match this quality for large graph sizes N, a quantum device must support depth p > 11. Additionally, multi-shot QAOA is not efficient on large graphs, indicating that QAOA p ≤ 11 does not scale with N. These results limit achieving quantum advantage for QAOA MaxCut on 3-regular graphs.
At the annual APS Division of Atomic, Molecular and Optical Physics meeting, physicists made the case for a new way of modeling a universe.
With 147 fused benzene rings and 920 conjugated atoms, the nanoribbon shows optoelectronic properties that could compete with quantum dots.
When you turn on a lamp to brighten a room, you are experiencing light energy transmitted as photons, which are small, discrete quantum packets of energy. These photons must obey the sometimes strange laws of quantum mechanics, which, for instance, dictate that photons are indivisible, but at the same time, allow a photon to be in two places at once.
Similar to the photons that make up beams of light, indivisible quantum particles called phonons make up a beam of sound. These particles emerge from the collective motion of quadrillions of atoms, much as a “stadium wave” in a sports arena is due to the motion of thousands of individual fans. When you listen to a song, you’re hearing a stream of these very small quantum particles.