Quasiparticles & collective excitations as a research area investigates emergent, effective degrees of freedom in many-body systems, where interactions among underlying microscopic constituents give rise to particle-like or mode-like entities such as phonons, magnons, polarons, excitons, and plasmons. This field focuses on formulating and analyzing low-energy effective theories, dispersion relations, lifetimes, and interaction vertices of these excitations using frameworks such as many-body perturbation theory, Green’s functions, field-theoretic methods, and numerical many-body techniques. It plays a central role in understanding transport, superconductivity, topological phases, and nonequilibrium dynamics in condensed matter, ultracold atomic systems, and related quantum materials.
Spin waves are considered to be promising candidates for a new form of electronics. Instead of electrons, the focus here is on magnons. These quantized units of spin waves describe how spin precession propagates. Similar ...
Condensed Matter
Oct 16, 2025
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92
Electrons in two-dimensional (2D) systems placed under strong magnetic fields often behave in unique ways, prompting the emergence of so-called fractional quantum Hall liquids. These are exotic states of matter in which electrons ...
Light is fast, but travels in long wavelengths and interacts weakly with itself. The particles that make up matter are tiny and interact strongly with each other, but move slowly. Together, the two can combine into a hybrid ...
Optics & Photonics
Oct 10, 2025
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88
When optical materials (molecules or solid-state semiconductors) are embedded in tiny photonic boxes, known as optical microcavities, they form hybrid light-matter states known as polaritons. Most of the optical properties ...
Optics & Photonics
Oct 9, 2025
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177
An international team of researchers has developed a novel technique to efficiently excite and control highly-confined light-matter waves, known as higher-order hyperbolic phonon polaritons. Their method not only sets new ...
Optics & Photonics
Oct 7, 2025
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40
Researchers have created a chip-based device that can split phonons—tiny packets of mechanical vibration that can carry information in quantum systems. By filling a key gap, this device could help connect various quantum ...
Optics & Photonics
Oct 6, 2025
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70
Atoms in crystalline solids sometimes vibrate in unison, giving rise to emergent phenomena known as phonons. Because these collective vibrations set the pace for how heat and energy move through materials, they play a central ...
Condensed Matter
Sep 30, 2025
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62
Time-varying systems, materials with properties that change over time, have opened new possibilities for the experimental manipulation of waves. Contrarily to static systems, which exhibit the same properties over time, these ...
Ferrimagnets are a special type of magnet where different atoms' magnetic moments partially cancel each other out, creating a rich internal structure. They are widely used in technologies from magneto-optical devices to spin-based ...
In a world-first, researchers from the Femtosecond Spectroscopy Unit at the Okinawa Institute of Science and Technology (OIST) have directly observed the evolution of the elusive dark excitons in atomically thin materials, ...
Condensed Matter
Sep 25, 2025
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