Lifeboat Foundation

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.

Computer scientists at the University of California San Diego have developed a method for generating highly realistic computer-generated images of fluid dynamics in elements such as smoke.

This research, conducted by the UC San Diego Center for Visual Computing, was presented at the SIGGRAPH Asia 2024 conference, where it received a Best Paper Honorable Mention for its contributions to computer graphics and physics-based simulation. The paper is published in ACM Transactions on Graphics.

Continue reading “Advanced method produces highly realistic simulations of fluid dynamics” »

USTC researchers created a groundbreaking on-chip photonic simulator, leveraging thin-film lithium niobate chips to simplify quantum simulations of complex structures, achieving high-dimensional synthetic dimensions with reduced frequency demands.

A research team led by Prof. Chuanfeng Li from the University of Science and Technology of China (USTC) has made a significant breakthrough in quantum photonics. The team successfully developed an on-chip photonic simulator capable of modeling arbitrary-range coupled frequency lattices with gauge potential. This achievement was detailed in a recent publication in Physical Review Letters.

<em>Physical Review Letters (PRL)</em> is a prestigious peer-reviewed scientific journal published by the American Physical Society. Launched in 1958, it is renowned for its swift publication of short reports on significant fundamental research in all fields of physics. PRL serves as a venue for researchers to quickly share groundbreaking and innovative findings that can potentially shift or enhance understanding in areas such as particle physics, quantum mechanics, relativity, and condensed matter physics. The journal is highly regarded in the scientific community for its rigorous peer review process and its focus on high-impact papers that often provide foundational insights within the field of physics.

face_with_colon_three year 2022 This photonic chip can transmit all the internet data every second.

A microcomb source based on a silicon nitride ring resonator is shown to support petabit-per-second data transmission over a multicore optical fibre.