Lifeboat Foundation

Back in the old days—the really old days—the task of designing materials was laborious. Investigators, over the course of 1,000-plus years, tried to make gold by combining things like lead, mercury, and sulfur, mixed in what they hoped would be just the right proportions. Even famous scientists like Tycho Brahe, Robert Boyle, and Isaac Newton tried their hands at the fruitless endeavor we call alchemy.

Materials science has, of course, come a long way. For the past 150 years, researchers have had the benefit of the periodic table of elements upon which to draw, which tells them that different elements have different properties, and one can’t magically transform into another. Moreover, in the past decade or so, machine learning tools have considerably boosted our capacity to determine the structure and physical properties of various molecules and substances.

New research by a group led by Ju Li—the Tokyo Electric Power Company Professor of Nuclear Engineering at MIT and professor of materials science and engineering—offers the promise of a major leap in capabilities that can facilitate materials design. The results of their investigation appear in Nature Computational Science.

The operation and performance of quantum computers relies on the ability to realize and control entanglement between multiple qubits. Yet entanglement between many qubits is inherently susceptible to noise and imperfections in quantum gates.

In recent years, quantum physicists and engineers worldwide have thus been trying to develop more robust protocols to realize and control entanglement. To be most effective for real-world applications, these approaches should reliably support long-range entanglement, or in other words ensure that qubits remain entangled even when they are separated by large distances.

Researchers at IBM Quantum, University of Cologne and Harvard University set out to demonstrate one of these protocols in an experimental setting.

Enhanced Sensitivity and Wave-Structure Interaction in Nonsingular Flat-Band Lattices with Compact Localized States https://arxiv.org/html/2412.05610v1

A team of UConn College of Engineering (CoE) researchers have achieved a major milestone in the field of phononics with the first experimental demonstration of an all-flat phononic band structure (AFB). Phononics concerns the study of sound and heat control.

The breakthrough, detailed in an article just published in Physical Review Letters, introduces a new class of materials capable of uniquely controlling sound and vibrations by trapping energy with unprecedented intensity, offering exciting possibilities for potential applications in acoustics, vibration insulation, energy harvesting, and beyond.

Continue reading “All-flat phononic band structure controls sound and vibrations by trapping energy” »

Physicists have spent more than a century measuring and making sense of the strange ways that photons, electrons, and other subatomic particles interact at extremely small scales. Engineers have spent decades figuring out how to take advantage of these phenomena to create new technologies.

In one such phenomenon, called quantum entanglement, pairs of photons become interconnected in such a way that the state of one photon instantly changes to match the state of its paired photon, no matter how far apart they are.

Nearly 80 years ago, Albert Einstein referred to this phenomenon as “spooky action at a distance.” Today, entanglement is the subject of research programs across the world—and it’s becoming a favored way to implement the most fundamental form of quantum information, the qubit.

Quantum computing promises to solve complex problems exponentially faster than a classical computer, by using the principles of quantum mechanics to encode and manipulate information in quantum bits (qubits).

Qubits are the building blocks of a quantum computer. One challenge to scaling, however, is that qubits are highly sensitive to background noise and control imperfections, which introduce errors into the quantum operations and ultimately limit the complexity and duration of a quantum algorithm. To improve the situation, MIT researchers and researchers worldwide have continually focused on improving qubit performance.

In new work, using a superconducting qubit called fluxonium, MIT researchers in the Department of Physics, the Research Laboratory of Electronics (RLE), and the Department of Electrical Engineering and Computer Science (EECS) developed two new control techniques to achieve a world-record single-qubit fidelity of 99.998%. This result complements then-MIT researcher Leon Ding’s demonstration last year of a 99.92% two-qubit gate fidelity.

Since Morinaga proposed more than six decades ago that the excited \(0_2^+\) state in the ¹⁶ O nucleus was deformed¹, a large body of experimental evidence has been collected to demonstrate that atomic nuclei can possess different shapes². Apart from the lightest elements, shape coexistence has been suggested to be present in all nuclei³ and the competition of different configurations can result in several different shapes within the same nucleus⁴. Nevertheless, coexistence of three or more total energy minima near the ground state have been predicted to occur in only few regions in the chart of nuclei⁵, but direct experimental proof remained to be obtained. A notable example to date is the ¹⁸⁶ Pb₁₀₄ nucleus, where the three lowest-energy states are 0⁺ states, each assigned with a different shape – namely spherical, prolate and oblate^6,7. The ¹⁸⁶ Pb nucleus lies at the heart of the neutron-deficient Pb region, which has been a subject for numerous theoretical and experimental investigations^3,8,9,10,11. Within the mean-field picture, the total energy curve along the quadrupole deformation shows spherical, prolate and oblate minima close in energy. These minima are related to the spherical Z = 82 shell gap, and prolate and oblate deformed gaps in the proton and neutron Nilsson orbitals, respectively. From a shell model perspective, the deformed minima (noted as \(\pi (h_9/2⁴)\) for prolate and \(\pi (h_9/2²)\) for oblate in the present work) are expected to have a complex spherical multiparticle-multihole configuration both for protons and neutrons^10,11,12. Similar competition of different configurations is present in neighbouring isotopes around the N = 104 midshell¹³. In ¹⁸⁸ Pb, in addition to low-lying deformed bands associated with predominantly prolate and oblate shapes^14,15,16, three isomeric states assigned with different shapes^17,18 have been proposed.

Intruding structures built on different configurations have also been observed in nuclei in the region around ¹⁸⁶ Pb. In fact, the shape staggering of Hg isotopes observed in an isotopic shift experiment was a groundbreaking discovery in the 1970’s¹⁹ that triggered multiple investigations into shape coexistence. Laser spectroscopic measurements have examined the onset of ground-state deformation also in the even-mass Po and Pt isotopes^20,21. Since the neutron-deficient Pb isotopes are spherical in their ground states^22,23,24, the onset of deformation in the Pb isotopes can be assessed by investigating the \(2_1^+\) states. It is proposed that the heaviest Pb nucleus exhibiting collectivity associated with deformation is ¹⁹⁴ Pb²⁵, whereas in heavier Pb isotopes the underlying configurations of the lowest excited states arise from single-nucleon excitations in the seniority scheme leading to a spherical interpretation²⁶.

Science is always looking for more computing power and more efficient tools capable of answering its questions. Quantum computers are the new frontier in data processing, as they use the quantum properties of matter, such as the superposition of states and entanglement, to perform very complex operations.

A research team coordinated by the Department of Physics of the University of Trento had the opportunity to test some hypotheses on confinement in Z₂ lattice gauge theory on the quantum computers of Google’s Quantum Artificial Intelligence Lab, in California. Their work was published in Nature Physics.

Gauge theories describe the fundamental forces in the standard model of particle physics and play an important role in condensed matter physics. The constituents of gauge theories, such as charged matter and electric gauge field, are governed by local gauge constraints, which lead to key phenomena that are not yet fully understood. In this context, quantum simulators may offer solutions that cannot be reached using conventional computers.

Quantum networking continues to encode information in polarization states due to ease and precision. The variable environmental polarization transformations induced by deployed fiber need correction for deployed quantum networking. Here, we present a method for automatic polarization compensation (APC) and demonstrate its performance on a metropolitan quantum network. Designing an APC involves many design decisions as indicated by the diversity of previous solutions in the literature. Our design leverages heterodyne detection of wavelength-multiplexed dim classical references for continuous high-bandwidth polarization measurements used by newly developed multi-axis (non-)linear control algorithm(s) for complete polarization channel stabilization with no downtime. This enables continuous relatively high-bandwidth correction without significant added noise from classical reference signals. We demonstrate the performance of our APC using a variety of classical and quantum characterizations. Finally, we use C-band and L-band APC versions to demonstrate continuous high-fidelity entanglement distribution on a metropolitan quantum network with an average relative fidelity of 0.94 ± 0.03 for over 30 hrs.

Since the invention of the laser in 1960, nonlinear optics has aimed to broaden light’s spectral range and create new frequency components. Among the various techniques, supercontinuum (SC) generation stands out for its ability to produce light across a wide portion of the visible and infrared spectrum.

However, traditional SC sources rely on weak third-order optical nonlinearity, requiring long interaction lengths for broad spectral output. In contrast, second-order optical nonlinearity offers far greater efficiency and lower power requirements, though phase mismatching in bulk crystals has historically limited its spectral coverage and overall efficiency.

In a study published in Light: Science & Applications, a collaborative research team from Aalto University, Tampere University, and Peking University, led by Professor Zhipei Sun, has demonstrated a revolutionary method for generating octave-spanning coherent light at the deep-subwavelength scale (100 nm). Their innovative approach employs phase-matching-free second-order nonlinear optical frequency down-conversion in ultrathin gallium selenide (GaSe) and niobium oxide diiodide (NbOI₂) crystals.