Lifeboat Foundation

In quantum computers, information is often carried by single photons and picked up by structures named superconducting nanostrip single-photon detectors (SNSPDs). In principle, traditional type-I superconductors would be easier to integrate into existing quantum computing architectures than the type-II materials more widely used today. So far, however, this possibility hasn’t been widely explored.

New research published in Superconductivity shows how Lixing You and colleagues at the Chinese Academy of Sciences, Shanghai, China have for the first time successfully fabricated an SNSPD using thin films of the type-I superconductor, aluminum, and used the structure to detect single photons of visible light with extremely high efficiency.

Compared with the type-II superconductors more commonly used in SNSPDs so far, aluminum is more compatible with the latest quantum computing architectures.

Simulations of neutron stars provide new bounds on their properties, such as their internal pressure and their maximum mass.

Studying neutron stars is tricky. The nearest one is about 400 light-years away, so sending a probe would likely take half a million years with current space-faring technology. Telescopes don’t reveal much detail from our vantage point, since neutron stars are only the size of a small city and thus appear as mere points in the sky. And no laboratory on Earth can reproduce the inside of neutron stars, because their density is too great, being several times that of atomic nuclei. That high density also poses a problem for theory, as the equations for neutron-star matter cannot be solved with standard computational techniques. But these difficulties have not stopped efforts to understand these mysterious objects. Using a combination of theory-based methods and computer simulations, Ryan Abbott from MIT and colleagues have obtained new, rigorous constraints for the properties of the interior of neutron stars [1].

The majority of studies on laser-driven proton–boron nuclear reaction is based on the measurement of α-particles with solid-state nuclear tracks detector (Cr39). However, Cr39’s interpretation is difficult due to the presence of several other accelerated particles which can bias the analysis. Furthermore, in some laser irradiation geometries, cross-checking measurements are almost impossible. In this case, numerical simulations can play a very important role in supporting the experimental analysis. In our work, we exploited different laser irradiation schemes (pitcher–catcher and direct irradiation) during the same experimental campaign, and we performed numerical analysis, allowing to obtain conclusive results on laser-driven proton–boron reactions. A direct comparison of the two laser irradiation schemes, using the same laser parameters is presented.

Breaking the limits of light control: non-hermitian silicon photonic switching.

Imagine a new way of controlling [#light](https://www.facebook.com/hashtag/light?__eep__=6&__cft__[0]=AZXWUWLMvFSlCWqwebCELVs4-fbCMnldCKnIVGZrgtNUTRTTYSpzFXQZE36EXaisrk4LktWLvfOHDWvPYLl3repY1GFTT1cBs7NW6b5tSZsCm6hrhxySUves0ATBtZTjr9RkS4buJBybFVuHrOjdR8CZM25CUC_y1s-Pyhej3ftz6g&__tn__=*NK-R) that defies conventional expectations, enabling faster and more efficient communication networks. This is the promise of non-Hermitian photonics, a cutting-edge field that manipulates light using the full range of complex optical properties, including gain and loss. By carefully balancing these properties, researchers have unlocked surprising behaviors, such as the ability for light to flow in counterintuitive ways.

In this study, scientists have created a revolutionary non-Hermitian switching network on a tiny, two-layer photonic chip. The chip is a hybrid design, combining a bottom silicon layer with a top layer made of indium gallium arsenide phosphide (InGaAsP), a material that amplifies light. This combination allows light to be controlled with remarkable precision.

Continue reading “‪#‎light‬ — Explore” »

January 18, 2025: A Venus-Saturn conjunction occurs after sunset in the southwestern sky. The two planets are part of a nightly planet parade that marches westward from Earth’s rotation.

By Jeffrey L. Hunt.

Chicago, Illinois: Sunrise, 7:14 a.m. CDT; Sunset, 4:49 p.m. CST. Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Quantum computing holds the promise of outperforming classical computing on some optimization and data processing tasks. The creation of highly performing large-scale quantum computers, however, relies on the ability to support controlled interactions between qubits, which are the units of information in quantum computing, at a range of distances.

So far, maintaining the coherence of interactions between distant semiconductor qubits, while also controlling these interactions, has proved challenging. By overcoming this hurdle, quantum physicists and engineers could develop more advanced quantum computers that can tackle more complex problems.

Researchers at Delft University of Technology (TU Delft) have devised a promising approach to realize coherent quantum interactions between distant semiconductor qubits. Their paper, published in Nature Physics, demonstrates the use of this approach to attain coherent interaction between two electron spin qubits that are 250 μm apart.

While most of us are familiar with magnets from childhood games of marveling at the power of their repulsion or attraction, fewer realize the magnetic fields that surround us—and the ones inside us. Magnetic fields are not just external curiosities; they play essential roles in our bodies and beyond, influencing biological processes and technological systems alike. A recent arXiv publication from the University of Chicago’s Pritzker School of Molecular Engineering and Argonne National Laboratory highlights how magnetic fields in the body may be analyzed using quantum-enabled fluorescent proteins, with hopes of applying to cell formation or early disease detection.

Detecting subtle changes in magnetic fields may equate to beyond subtle impacts in certain fields. For instance, quantum sensors could be applied to the detection of electromagnetic anomalies in data centers, potentially revealing evidence of malicious tampering. Similarly, they might be used to study changes in the brain’s electromagnetic signals, offering insights into neurological diseases such as the onset of dementia. However, these applications demand sensors that are not only sensitive but also capable of operating reliably in real-world conditions.

Spin qubits, known for their notable sensitivity to magnetic fields, are introduced in the study as a compelling solution. Traditionally, spin qubits have been formed from nitrogen-vacancy centers in diamonds. While these systems have demonstrated remarkable precision, the diamonds’ bulky size in relation to molecules and complex surface chemistry limit their usability in biological environments. This creates a need for a more adaptable and biologically compatible sensor.

The relationship between brain and computer is a perennial theme in theoretical neuroscience, but it has received relatively little attention in the philosophy of neuroscience. This paper argues that much of the popularity of the brain-computer comparison (e.g. circuit models of neurons and brain areas since McCulloch and Pitts, Bull Math Biophys 5: 115–33, 1943) can be explained by their utility as ways of simplifying the brain. More specifically, by justifying a sharp distinction between aspects of neural anatomy and physiology that serve information-processing, and those that are ‘mere metabolic support,’ the computational framework provides a means of abstracting away from the complexities of cellular neurobiology, as those details come to be classified as irrelevant to the (computational) functions of the system.

Researchers have discovered that certain disordered superconductors exhibit abrupt phase transitions, a finding that challenges established theories and could have implications for quantum computing.

A study published in Nature by researchers investigating indium oxide films — a highly disordered superconductor — shows that their transition from a superconducting to an insulating state is not gradual, as traditionally assumed, but sudden. This abrupt shift, known as a first-order quantum phase transition, contrasts with the commonly observed continuous, second-order transitions in superconductors.

Key measurements revealed a sharp drop in superfluid stiffness — which is a property that reflects the superconducting state’s ability to resist phase distortions — at a critical level of disorder. Interestingly, the critical temperature of these films, where superconductivity breaks down, no longer depended on the strength of electron pairing but rather on the superfluid stiffness. This behavior aligns with a pseudogap regime, where electron pairs exist but lack the coherence needed for superconductivity.