Lifeboat Foundation

Self-testing is a promising method to infer the physics underlying specific quantum experiments using only collected measurements. While this method can be used to examine bipartite pure entangled states, so far it could only be applied to limited kinds of quantum states involving an arbitrary number of systems.

Researchers at Sorbonne University, ICFO-Institute of Photonic Sciences and Quantinuum recently introduced a framework for the quantum network-assisted self-testing of all pure entangled states of an arbitrary number of systems. Their paper, published in Nature Physics, could inform future research efforts aimed at certifying quantum phenomena.

“I was a postdoctoral researcher in Barcelona in 2014 in the group of Antonio Acín when the first author, Ivan Šupić and I began working on self-testing quantum states together,” Matty Hoban, one of the researchers who carried out the study, told Phys.org. “That is, certifying that you have systems in particular quantum states without trusting the devices and treating them as black boxes (called the device-independent setting). Part of this work involved exploring different kinds of scenarios of trust.”

Quantum processors are computing systems that process information and perform computations by exploiting quantum mechanical phenomena. These systems could significantly outperform conventional processors on certain tasks, both in terms of speed and computational capabilities.

While engineers have developed several promising quantum computing systems over the past decade or so, scaling these systems and ensuring that they can be deployed on a large-scale remains an ongoing challenge. One proposed strategy to increase the scalability of quantum processors entails the creation of modular systems containing multiple smaller quantum modules, which can be individually calibrated and then arranged into a bigger architecture. This, however, would require suitable and effective interconnects (i.e., devices for connecting these smaller modules).

Researchers at the Southern University of Science and Technology, the International Quantum Academy and other institutes in China have recently developed low-loss interconnects for linking the individual modules in modular superconducting quantum processors. These interconnects, introduced in Nature Electronics, are based on pure aluminum cables and on-chip impendence transformers.

Super-resolution microscopy methods are essential for uncovering the structures of cells and the dynamics of molecules. Since researchers overcame the resolution limit of around 250 nanometers (while winning the 2014 Nobel Prize in Chemistry for their efforts), which had long been considered absolute, the methods of microscopy have progressed rapidly.

Now a team led by LMU chemist Prof. Philip Tinnefeld has made a further advance through the combination of various methods, achieving the highest resolution in three-dimensional space and paving the way for a fundamentally new approach for faster imaging of dense molecular structures. The new method permits axial resolution of under 0.3 nanometers.

The researchers combined the so-called pMINFLUX method developed by Tinnefeld’s team with an approach that utilizes special properties of graphene as an energy acceptor. pMINFLUX is based on the measurement of the fluorescence intensity of molecules excited by laser pulses. The method makes it possible to distinguish their lateral distances with a resolution of just 1 nanometer.

A venerable strategy for approximating a system’s ground states has now been extended to accommodate its excited states.

Density-functional theory (DFT) owes its name and utility to its central insight: that a potential’s influence on a system of interacting electrons can be expressed in terms of the electrons’ density. Existing models restrict DFT to ground states and exclude excited states. But now Tim Gould of Griffith University, Australia, and his collaborators have found a way to overcome the restriction [1].

At the heart of DFT are exchange-correlation models, which simplify the treatment of electrons’ behavior by using certain limiting cases. This simplification allows DFT to simulate ground states of large electronic systems. A generalization of the theory, called ensemble DFT, can cope with excited states, but this theory’s more complex exchange-correlation models make large systems computationally intractable. Gould and his collaborators discovered that when the electron density is sufficiently low, these complications vanish and the models for dealing with excited states revert to being as simple as those used for regular DFT. Then, regular DFT suffices. At the other extreme—when electron density is high—complications are simplified to the point that exact solutions can be obtained.

Another part of that wariness arises because, to date, no one has independently reproduced Dias’ team’s results. This lack of verification was raised by Jorge Hirsch of the University of California, San Diego, in the last talk of the session in which Dias and his team spoke. Hirsch argued that those claiming to have created high-temperature superconducting hydrides suffered from “confirmation bias,” cherry-picking evidence to support their agenda. (Hirsch has been an outspoken critic of Dias’ work.) As the last question of the session, Dias asked Hirsch, “Could you also have confirmation bias?” “Maybe,” Hirsch replied.

After the session, a few attending researchers—all collaborators of Dias—spoke with Physics Magazine, telling us that they disagreed with Hirsch’s cherry-picking conclusion. One of them, Russell Hemley of the University of Illinois Chicago confirmed Pasan’s claim that they have replicated the 2020 carbonaceous sulfur hydride—as reported in an arXiv paper that the team recently posted [3].

Dias’ group still needs to more precisely characterize NLH’s chemical composition, Pasan said. The samples also appear to consist of two phases, an observation that they need to investigate. Ultimately, they plan to innovate upon this material to create a superconductor at ambient pressure and temperature conditions, a goal that Pasan said he thinks is feasible. But extraordinary claims require extraordinary evidence, and the community has much of the latter still to gather.

The ultimate miniature electronic device may be one that manipulates individual electrons with subnanometer and subfemtosecond precision. The past few decades have seen immense progress in the control of ultrafast electronic processes, including in the context of vacuum nanoelectronics, where electrons travel from a nanoscale emitter to a target electrode through a vacuum. Now Hirofumi Yanagisawa at the Japan Science and Technology Agency and colleagues have taken an important step toward optimal spatial control by using the orbitals of a single molecule to shape its electron emission (Fig. 1) [1]. The approach offers the prospect of building highly controllable electron emitters, but also of furthering our understanding of the role of molecular orbitals in the electronic structure of solids.

Fundamental to achieving extreme control over electron emission is defining the spot from which electrons are ejected from the emitter. One approach is to physically shape the material of the emitter into the desired spot pattern. Doing that at the subnanometer scale would entail significant material-and fabrication-related challenges, however. Instead, Yanagisawa and colleagues have demonstrated the clever idea of using the inherent electronic structure of a molecule to route the electrons for emission. In essence, the molecular orbitals are used as a spatial filter to control the emission pattern.

The team’s work grows out of two broad areas of investigation that have progressed significantly over the past few decades. One of these involves the study of femto-and attosecond electron dynamics and the creation of ultrafast electron sources, exemplified by the 2006 demonstration of tight spatial control over femtosecond electron pulses through emission from a nanoscale metallic tip [2– 8]. The second is the study of electron emission patterns originating from molecular structures and nanostructures. Examples include patterns corresponding to the tip structures of nanotubes and nanowires, which change as the tip evolves during nanotube growth [9– 11]. It is by combining the techniques of ultrafast emission and emission microscopy that Yanagisawa and colleagues have demonstrated that the emission patterns can be directly linked to specific molecular orbitals.

Prompt engineering enables researchers to generate customized training examples for lightweight “student” models.

The thyroid is a small, butterfly-shaped gland at the base of the neck. It’s responsible for the hormones that control your heart rate, blood pressure, temperature and metabolism.

When thyroid cells grow abnormally, they can cause thyroid cancer. But because symptoms are vague and may mimic other less-serious conditions, it’s possible you could have thyroid cancer for months or even years without knowing it.

Thyroid cancer surgeon Nancy Perrier, M.D., explains how thyroid cancer can go unnoticed – and what you can do to catch it early when it’s easiest to treat.

The potential for supply constraints also concerns industry analysts. For example, McKinsey analysts have warned that limited AAV vector capacity could delay the commercialization of new gene therapies, particularly those intended for larger patient populations.

Last March, a McKinsey article stated, “The majority of early viral-vector-based therapeutics were developed within the context of rare diseases. [Only small] quantities of viral vectors were required, particularly as most therapies were still in the clinical stage of development. Now, with the shift beyond ultrarare indications, viral vector manufacturing requires rapid expansion to be able to address these diseases in the commercial space.”