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Nov 23, 2023

Larry Summers Jumps to Center of AI Stage With OpenAI Board Seat

Posted by in categories: employment, robotics/AI

Late on Tuesday night, OpenAI announced the return of Sam Altman, its ousted chief executive officer, along with a revamped board that included one name not often associated with Silicon Valley: Larry Summers.

The economist and former Treasury Secretary joined Bret Taylor, a former co-CEO of Salesforce Inc., and existing board member Adam D’Angelo in forming what the company called an “initial board.” OpenAI’s prior directors fired Altman suddenly on Friday, setting off a dramatic saga that cast doubt on the future of the most closely-watched startup and technology.

OpenAI said it was still working to “figure out the details” of its new management in a post online. But with Summers it has a board member with deep ties to Wall Street and Washington — and an adamant belief that artificial intelligence is coming for white-collar jobs.

Nov 23, 2023

Electrons Lead Their Lattice by the Nose

Posted by in categories: materials, particle physics

Experiments with an unconventional superconductor show that a change in the properties of the material’s electrons can, unexpectedly, cause the material to become dramatically less stiff.

Electrons flowing through a crystal lattice don’t usually get to call the shots: their behavior is generally set by the lattice structure. But certain materials exhibit an electron–lattice coupling that allows the conduction electrons to influence the lattice behavior. This electron version of “wagging the dog” is predicted to be quite weak, making it a surprise that experiments with an unconventional superconductor now uncover a large electron-driven softening of the material’s lattice [1]. The finding could provide new insights into the mechanisms underlying unconventional superconductivity.

The lattice in a crystalline material is a periodic framework of atoms held together by electrostatic bonds. That framework dictates the properties of electrons moving through the material. For example, if the lattice is altered by applying mechanical strain or by adding dopant atoms, the electron momenta will correspondingly change, which can affect the material’s electronic band structure.

Nov 23, 2023

“Spin” Leaves Its Mark on Some Meteorite Craters

Posted by in category: futurism

Numerical simulations reveal that an impact crater’s shape can depend on the impactor’s spin and its degree of cohesion.

Nov 23, 2023

Midcircuit Operations in Atomic Arrays

Posted by in categories: computing, particle physics, quantum physics

Three research groups have exploited the nuclear spins of ytterbium-171 to manipulate qubits before they are read out—an approach that could lead to efficient error-correction schemes for trapped-atom computing platforms.

Quantum computing on neutral-atom platforms has reached remarkable milestones in the past two decades. However, researchers have yet to overcome a key barrier to the realization of a neutral-atom-based quantum computer: the efficient correction of errors. In principle that barrier can be lowered with so-called midcircuit operations. These operations involve probing the quantum state of “ancilla” qubits without disturbing nearby “data” qubits used for computation. The ancilla qubit measurements can indicate whether the data qubits have undergone faulty operations, allowing for the data qubits to be corrected midcircuit—that is, during the execution of the computation rather than after its completion. Now three independent research groups have achieved midcircuit operation, or made progress toward this goal, with a novel choice of atom: ytterbium-171 (171 Yb) [13].

A neutral-atom qubit platform consists of a two-dimensional (2D) array of atoms trapped by optical tweezers—tightly focused laser beams whose wavelengths are tuned far away from the atomic transitions. The size of the traps, limited by diffraction, is typically about 1 µm. Thanks to the large electric-dipole force from the focused laser and to a high vacuum, the atoms can stay trapped for as long as tens of seconds.

Nov 23, 2023

Nuclear Ground State Has Molecule-Like Structure

Posted by in category: particle physics

The protons and neutrons in a nucleus can form clusters analogous to atoms in a molecule, even in the nuclear ground state.

Nov 23, 2023

Uncertainty beyond the Uncertainty Principle

Posted by in categories: particle physics, quantum physics

Heisenberg’s uncertainty principle limits the precision with which two observables that do not commute with each other can be simultaneously measured. The Wigner-Araki-Yanase (WAY) theorem goes further. If observables A and B do not commute, and if observable A is conserved, observable B cannot be measured with arbitrary precision even if A is not measured at all. In its original 1960 formulation, the WAY theorem applied only to observables, such as spin, whose possible values are discrete and bounded. Now Yui Kuramochi of Kyushu University and Hiroyasu Tajima of the University of Electro-Communications—both in Japan—have proven that the WAY theorem also encompasses observables, such as position, that are continuous and unbounded [1]. Besides resolving the decades-long problem of how to deal with such observables, the extension will likely find practical applications in quantum optics.

The difficulty of extending the WAY theorem arose from how an unbounded observable L is represented: as an infinite-dimensional matrix with unbounded eigenvalues. To tame the problem, Kuramochi and Tajima avoided considering L directly. Instead, they looked at an exponential function of L, which forms a one-parameter unitary group. Although the exponential function is also unbounded, its spectrum of eigenvalues is contained within the complex plane’s unit circle. Thanks to that boundedness, Kuramochi and Tajima could go on to use off-the-shelf techniques from quantum information to complete their proof.

Because momentum is conserved, the extended WAY theorem implies that a particle’s position cannot be measured with arbitrary precision even if its momentum is not measured simultaneously. Similar pairs of observables crop up in quantum optics. Kuramochi and Tajima anticipate that their theorem could be useful in setting limits on the extent to which quantum versions of transmission protocols can outperform the classical ones.

Nov 23, 2023

Seeking a Quantum Hall Effect for Light

Posted by in categories: information science, quantum physics

Light confined to an accelerating optical cavity could display a photonic counterpart of the electronic quantum Hall effect.

Place a conductor in a magnetic field and the electrical current driven by an applied voltage will not flow in a straight line but in a direction perpendicular to the electric field—a behavior known as the Hall effect [1]. Reduce the temperature to the point where the electrons manifest quantum-mechanical behavior, and the plot thickens. The conductivity (defined as the ratio between the sideways current and the voltage) exhibits discrete jumps as the magnetic field is varied—the quantum Hall effect [2]. Since electrons at low temperature and photons obey a similar wave equation [3], should we also expect a quantum Hall effect for light? This question has been bubbling under the surface for the past decade, leading to the observation of some aspects of an optical quantum Hall effect [4, 5]. But the analogy between photons and electrons remains incomplete.

Nov 23, 2023

Combining extreme-ultraviolet light sources to resolve a quantum mechanical dissociation mechanism in oxygen molecules

Posted by in categories: biological, chemistry, quantum physics, solar power, sustainability

For the first time, researchers have succeeded in selectively exciting a molecule using a combination of two extreme-ultraviolet light sources and causing the molecule to dissociate while tracking it over time. This is another step towards specific quantum mechanical control of chemical reactions, which could enable new, previously unknown reaction channels.

The interaction of light with matter, especially with molecules, plays an important role in many areas of nature, for example in such as photosynthesis. Technologies such as use this process as well.

On the Earth’s surface, mainly light in the visible, ultraviolet or infrared regime plays a role here. Extreme-ultraviolet (XUV) light—radiation with significantly more energy than —is absorbed by the atmosphere and therefore does not reach the Earth’s surface. However, this XUV radiation can be produced and used in the laboratory to enable a selective excitation of electrons in molecules.

Nov 23, 2023

Progress in wastewater treatment via organic supramolecular photocatalysts under sunlight

Posted by in categories: biotech/medical, chemistry, economics, health

Refractory organic pollutants, including phenols, perfluorinated compounds, and antibiotics, are abundant in various industrial wastewater streams such as chemical, pharmaceutical, coking, and dyeing sectors, as well as municipal and domestic sources. These pollutants pose significant threats to ecological well-being and human health.

The imperative to achieve complete removal of organic contaminants from water and facilitate water recycling is paramount for enhancing and ensuring sustainable economic and social progress. Addressing the efficient removal of recalcitrant organic pollutants in water is not only a focal point in environmental chemical pollution control research but also a pivotal technical challenge constraining industrial wastewater reuse.

Advanced oxidation processes (AOPs), especially heterogeneous AOPs, yield strongly including ·OH, ·O2-, and ·SO4- to oxidize organic pollutants under ambient conditions, are appealing wastewater treatment technologies for decentralized systems. AOPs often need excessive energy input (UV light or electricity) to activate soluble oxidants (H2O2, O3, persulfates), thus more cost-effective AOPs are urgently required.

Nov 23, 2023

Dynamic z-scanning for ultrafast auto-focusing in laser processing

Posted by in categories: engineering, mapping, transportation

In laser-based manufacturing, accommodating non-flat, or changing surfaces has traditionally been labor-intensive, involving complex focus mapping procedures and or ex-situ characterization. This often results in repositioning errors and extended processing times.

To address these issues, ultra-high-speed auto-focusing in laser processing has been developed. Whereas most auto-focusing techniques still require the mechanical motion of a motorized stage. This mechanical movement in the propagation axis can be significantly slower than the lateral speed, slowing down the process of detection and re-alignment. Furthermore, it requires feedback, control, and sensing methods in order to determine the optical focal position.

In a new paper published in Light: Science & Applications, a team of researchers, led by Professor Craig B. Arnold from the Department of Mechanical and Aerospace Engineering at Princeton University, U.S., developed a fast method to simultaneously track the specific location of a surface and adjust the focus of an optical system. They employed axial varifocal optics, specifically a TAG lens, which operates at 0.1−1 MHz, bypassing delays from the mechanical motion in the beam propagation direction.