| 1. |
- Amundsen, Morten, 1988-, et al.
(author)
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Colloquium : Spin-orbit effects in superconducting hybrid structures
- 2024
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In: Reviews of Modern Physics. - 0034-6861 .- 1539-0756. ; 96:2
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Research review (peer-reviewed)abstract
- Spin-orbit coupling (SOC) relates to the interaction between an electron’s motion and its spin and is ubiquitous in solid-state systems. Although the effect of SOC in normal-state phenomena has been extensively studied, its role in superconducting hybrid structures and devices elicits many unexplored questions. In conjunction with broken symmetries and material inhomogeneities within superconducting hybrid structures, SOC may have contributions beyond its effects in homogeneous materials. Notably, even with well-established magnetic or nonmagnetic materials and conventional ?-wave spin-singlet superconductors, SOC leads to emergent phenomena including equal-spin-triplet pairing and topological superconductivity (hosting Majorana states), a modified current-phase relationship in Josephson junctions, and nonreciprocal transport, including superconducting diode effects. SOC is also responsible for transforming quasiparticles in superconducting structures, which enhances the spin Hall effect and changes the spin dynamics. Taken together, SOC in superconducting hybrid structures and the potential for electric tuning of the SOC strength create interesting possibilities to advance superconducting spintronic devices for energy-efficient computing and enable topological fault-tolerant quantum computing. By providing a description of experimental techniques and theoretical methods to study SOC, this Colloquium describes the current understanding of resulting phenomena in superconducting structures and offers a framework to select and design a growing class of materials systems where SOC plays an important role.
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| 2. |
- Ando, Shin'ichiro, et al.
(author)
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Colloquium : Multimessenger astronomy with gravitational waves and high-energy neutrinos
- 2013
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In: Reviews of Modern Physics. - 0034-6861 .- 1539-0756. ; 85:4, s. 1401-1420
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Journal article (peer-reviewed)abstract
- Many of the astrophysical sources and violent phenomena observed in our Universe are potential emitters of gravitational waves and high-energy cosmic radiation, including photons, hadrons, and presumably also neutrinos. Both gravitational waves (GW) and high-energy neutrinos (HEN) are cosmic messengers that may escape much denser media than photons. They travel unaffected over cosmological distances, carrying information from the inner regions of the astrophysical engines from which they are emitted (and from which photons and charged cosmic rays cannot reach us). For the same reasons, such messengers could also reveal new, hidden sources that have not been observed by conventional photon-based astronomy. Coincident observation of GWs and HENs may thus play a critical role in multimessenger astronomy. This is particularly true at the present time owing to the advent of a new generation of dedicated detectors: the neutrino telescopes IceCube at the South Pole and ANTARES in the Mediterranean Sea, as well as the GW interferometers Virgo in Italy and LIGO in the United States. Starting from 2007, several periods of concomitant data taking involving these detectors have been conducted. More joint data sets are expected with the next generation of advanced detectors that are to be operational by 2015, with other detectors, such as KAGRA in Japan, joining in the future. Combining information from these independent detectors can provide original ways of constraining the physical processes driving the sources and also help confirm the astrophysical origin of a GW or HEN signal in case of coincident observation. Given the complexity of the instruments, a successful joint analysis of this combined GW and HEN observational data set will be possible only if the expertise and knowledge of the data is shared between the two communities. This Colloquium aims at providing an overview of both theoretical and experimental state of the art and perspectives for GW and HEN multimessenger astronomy.
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| 3. |
- Anselmino, Mauro, et al.
(author)
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Diquarks
- 1993
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In: Reviews of Modern Physics. - 0034-6861 .- 1539-0756. ; 65:4, s. 1199-1233
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Journal article (peer-reviewed)abstract
- It is becoming increasingly clear that the concept of a diquark (a two-quark system) is important for understanding hadron structure and high-energy particle reactions. According to our present knowledge of quantum chromodynamics (QCD), diquark correlations arise in part from spin-dependent interactions between two quarks, from quark radial or orbital excitations, and from quark mass differences. Diquark substructures affect the static properties of baryons and the mechanisms of baryon decay. Diquarks also play a role in hadron production in hadron-initiated reactions, deep-inelastic lepton scattering by hadrons, and in e+e- reactions. Diquarks are important in the formation and properties of baryonium and mesonlike semistable states. Many spin effects observed in high-energy exclusive reactions pose severe problems for the pure quark picture of baryons and might be explained by the introduction of diquarks as hadronic constituents. There is considerable controversy, not about the existence of diquarks in hadrons, but about their properties and their effects. In this work a broad selection of the main ideas about diquarks is reviewed.
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| 4. |
- Bechinger, Clemens, et al.
(author)
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Active particles in complex and crowded environments
- 2016
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In: Reviews of Modern Physics. - 0034-6861. ; 88
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Research review (peer-reviewed)abstract
- Differently from passive Brownian particles, active particles, also known as self-propelled Brownian particles or microswimmers and nanoswimmers, are capable of taking up energy from their environment and converting it into directed motion. Because of this constant flow of energy, their behavior can be explained and understood only within the framework of nonequilibrium physics. In the biological realm, many cells perform directed motion, for example, as a way to browse for nutrients or to avoid toxins. Inspired by these motile microorganisms, researchers have been developing artificial particles that feature similar swimming behaviors based on different mechanisms. These man-made micromachines and nanomachines hold a great potential as autonomous agents for health care, sustainability, and security applications. With a focus on the basic physical features of the interactions of self-propelled Brownian particles with a crowded and complex environment, this comprehensive review will provide a guided tour through its basic principles, the development of artificial self-propelling microparticles and nanoparticles, and their application to the study of nonequilibrium phenomena, as well as the open challenges that the field is currently facing.
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| 5. |
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| 6. |
- Bergström, Lars, et al.
(author)
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The deuteron in high-energy physics
- 1980
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In: Reviews of Modern Physics. - 0034-6861 .- 1539-0756. ; 52:4, s. 675-697
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Journal article (peer-reviewed)abstract
- The deuterium nucleus plays an important role in several branches of high-energy physics. We review its present status as a neutron source, a relativistic bound state, a collective six-quark state and a double scatterer.
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| 7. |
- Budroni, Costantino, et al.
(author)
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Kochen-Specker contextuality
- 2022
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In: Reviews of Modern Physics. - : AMER PHYSICAL SOC. - 0034-6861 .- 1539-0756. ; 94:4
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Research review (peer-reviewed)abstract
- A central result in the foundations of quantum mechanics is the Kochen-Specker theorem. In short, it states that quantum mechanics is in conflict with classical models in which the result of a measurement does not depend on which other compatible measurements are jointly performed. Here compatible measurements are those that can be implemented simultaneously or, more generally, those that are jointly measurable. This conflict is generically called quantum contextuality. In this review, an introduction to this subject and its current status is presented. Several proofs of the Kochen-Specker theorem and different notions of contextuality are reviewed. How to experimentally test some of these notions is explained, and connections between contextuality and nonlocality or graph theory are discussed. Finally, some applications of contextuality in quantum information processing are reviewed.
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| 8. |
- Curceanu, Catalina, et al.
(author)
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The modern era of light kaonic atom experiments
- 2019
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In: Reviews of Modern Physics. - 0034-6861. ; 91:2
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Journal article (peer-reviewed)abstract
- This review covers the modern era of experimental kaonic atom studies, encompassing 20 years of activity, defined by breakthroughs in technological developments which allowed performing a series of long-awaited precision measurements. Kaonic atoms are atomic systems where an electron is replaced by a negatively charged kaon, containing the strange quark, which interacts in the lowest orbits with the nucleus also by the strong interaction. As a result, their study offers the unique opportunity to perform experiments equivalent to scattering at vanishing relative energy. This allows one to study the strong interaction between the antikaon and the nucleon or the nucleus "at threshold," namely, at zero relative energy, without the need of ad hoc extrapolation to zero energy, as in scattering experiments. The fast progress achieved in performing precision light kaonic atom experiments, which also solved long-pending inconsistencies with theoretical calculations generated by old measurements, relies on the development of novel cryogenic targets, x-ray detectors, and the availability of pure and intense charged kaon beams, which propelled an unprecedented progress in the field. Future experiments, based on new undergoing technological developments, will further boost the kaonic atom studies, thus fostering a deeper understanding of the low-energy strong interaction extended to the second family of quarks.
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| 9. |
- Dombi, Péter, et al.
(author)
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Strong-field nano-optics
- 2020
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In: Reviews of Modern Physics. - 0034-6861. ; 92:2
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Journal article (peer-reviewed)abstract
- The present status and development of strong-field nano-optics, an emerging field of nonlinear optics, is discussed. A nonperturbative regime of light-matter interactions is reached when the amplitude of the external electromagnetic fields that are driving a material approach or exceed the field strengths that bind the electrons inside the medium. In this strong-field regime, light-matter interactions depend on the amplitude and phase of the field, rather than its intensity, as in more conventional perturbative nonlinear optics. Traditionally such strong-field interactions have been intensely investigated in atomic and molecular systems, and this has resulted in the generation of high-harmonic radiation and laid the foundations for contemporary attosecond science. Over the past decade, however, a new field of research has emerged, the study of strong-field interactions in solid-state nanostructures. By using nanostructures, specifically those made out of metals, external electromagnetic fields can be localized on length scales of just a few nanometers, resulting in signficantly enhanced field amplitudes that can exceed those of the external field by orders of magnitude in the vicinity of the nanostructures. This leads not only to dramatic enhancements of perturbative nonlinear optical effects but also to significantly increased photoelectron yields. It resulted in a wealth of new phenomena in laser-solid interactions that have been discovered in recent years. These include the observation of above-threshold photoemission from single nanostructures, effects of the carrier-envelope phase on the photoelectron emission yield from metallic nanostructures, and strong-field acceleration of electrons in optical near fields on subcycle timescales. The current state of the art of this field is reviewed, and several scientific applications that have already emerged from the fundamental discoveries are discussed. These include, among others, the coherent control of localized electromagnetic fields at the surface of solid-state nanostructures and of free-electron wave packets by such optical near fields, resulting in the creation of attosecond electron bunches, the coherent control of photocurrents on nanometer length and femtosecond timescales by the electric field of a laser pulse, and the development of new types of ultrafast electron microscopes with unprecedented spatial, temporal, and energy resolution. The review concludes by highlighting possible future developments, discussing emerging topics in photoemission and potential strong-field nanophotonic devices, and giving perspectives for coherent ultrafast microscopy techniques. More generally, it is shown that the synergy between ultrafast science, plasmonics, and strong-field physics holds promise for pioneering scientific discoveries in the upcoming years.
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| 10. |
- Freese, Katherine, et al.
(author)
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Colloquium : Annual modulation of dark matter
- 2013
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In: Reviews of Modern Physics. - : American Physical Society. - 0034-6861 .- 1539-0756. ; 85:4, s. 1561-1581
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Journal article (peer-reviewed)abstract
- Direct detection experiments, which are designed to detect the scattering of dark matter off nuclei in detectors, are a critical component in the search for the Universe's missing matter. This Colloquium begins with a review of the physics of direct detection of dark matter, discussing the roles of both the particle physics and astrophysics in the expected signals. The count rate in these experiments should experience an annual modulation due to the relative motion of the Earth around the Sun. This modulation, not present for most known background sources, is critical for solidifying the origin of a potential signal as dark matter. The focus is on the physics of annual modulation, discussing the practical formulas needed to interpret a modulating signal. The dependence of the modulation spectrum on the particle and astrophysics models for the dark matter is illustrated. For standard assumptions, the count rate has a cosine dependence with time, with a maximum in June and a minimum in December. Well-motivated generalizations of these models, however, can affect both the phase and amplitude of the modulation. Shown is how a measurement of an annually modulating signal could teach us about the presence of substructure in the galactic halo or about the interactions between dark and baryonic matter. Although primarily a theoretical review, the current experimental situation for annual modulation and future experimental directions is briefly discussed.
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