Article
Engineering, Electrical & Electronic
Karen Dowling, Yicong Dong, David Hall, Saptarshi Mukherjee, Joseph D. Schneider, Stefan Hau-Riege, Sara E. Harrison, Laura Leos, Adam Conway, Shaloo Rakheja, Lars Voss
Summary: This work presents a new optoelectronic device that has the potential to be used as a high-frequency, high-power RF source or amplifier. By introducing optical illumination into a small gap in the signal trace of a gallium-arsenide coplanar waveguide, a confined charge cloud is generated. The phenomenon of negative differential mobility is utilized to achieve pulse compression, resulting in a temporally compressed output electrical pulse compared to the input optical pulse. Experimental results demonstrate a 66% reduction in the full-width at half-maximum of the electrical pulse, relative to the input optical pulse. This novel coupled optoelectronic device opens up possibilities for high-frequency, high-power, compact devices that could enhance satellite communication systems.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Mircea Dragoman, Daniela Dragoman
Summary: This article provides an overview of various physical phenomena that result in negative differential resistance (NDR) effects in nanoscale devices. These phenomena include quantum tunneling, ballistic electronic transport in nanostructures, and insulator-metal transitions. These effects are significant for high-frequency applications and emerging computing architectures.
SOLID-STATE ELECTRONICS
(2022)
Article
Nanoscience & Nanotechnology
Tung Huu Dang, Adrien Khalili, Claire Abadie, Charlie Greboval, Mariarosa Cavallo, Huichen Zhang, Erwan Bossavit, James K. Utterback, Erwan Dandeu, Yoann Prado, Gregory Vincent, Sandrine Ithurria, Yanko Todorov, Carlo Sirtori, Angela Vasanelli, Emmanuel Lhuillier
Summary: The integration of photonic structures in nano crystal-based photodetectors improves device performances by demonstrating bias-dependent photo response, resulting from the interplay between hopping transport and inhomogeneous electromagnetic field. This study investigates the voltage-dependent photoresponse and provides evidence of bias dependent carrier mobilities in a wide range of temperatures. The fabricated infrared sensing device using HgTe NCs exhibits a significant bias-dependent photoresponse, competitive detection performance in the extended short-wave and mid-wave infrared, and a fast response time. This work lays the foundation for further advancements in NC-based-active photonics devices.
Review
Physics, Applied
Oskar Hallatschek, Sujit S. Datta, Knut Drescher, Joern Dunkel, Jens Elgeti, Bartek Waclaw, Ned S. Wingreen
Summary: The fascinating patterns of collective motion created by autonomously driven particles have fueled active-matter research for over two decades. In this Perspective, researchers argue that the unique features emerging in systems with proliferation represent a distinct form of activity, and propose proliferation as another direction of active-matter physics. They believe that by extending the conceptual framework developed for conventional active matter to proliferating active matter, researchers can have a profound impact on quantitative biology and reveal fascinating emergent physics.
NATURE REVIEWS PHYSICS
(2023)
Review
Physics, Applied
Suraj Shankar, Anton Souslov, Mark J. Bowick, M. Cristina Marchetti, Vincenzo Vitelli
Summary: This review focuses on topological defects and topologically protected edge modes in active matter, highlighting their distinctive properties in non-equilibrium systems. The review also emphasizes the significance of topological excitations in non-equilibrium settings.
NATURE REVIEWS PHYSICS
(2022)
Review
Physics, Multidisciplinary
Igor S. Aranson
Summary: Bacteria, as one of the oldest and most abundant species on Earth, play a significant role in various ecological cycles and can cause infectious diseases. Bacterial suspensions, as examples of active matter, exhibit complex collective behavior. This study provides a critical assessment of the progress in bacterial active matter from a physics perspective, covering experimental results and theoretical approaches.
REPORTS ON PROGRESS IN PHYSICS
(2022)
Article
Economics
Yongjiang Yang, Kuniaki Sasaki, Long Cheng, Sui Tao
Summary: The study explores the determinants of older adults' walking and cycling behavior, specifically focusing on built environment factors. The results show that factors such as the availability of transit facilities, population density, and mixed land use have profound effects on the frequency and duration of active travel among older people. These findings provide evidence for policymakers to develop strategies that promote active travel among older adults in the context of Japan's hyper-ageing society.
JOURNAL OF TRANSPORT GEOGRAPHY
(2022)
Review
Environmental Sciences
Hui Zhong, Ning Hu, Qinghua Wang, Yucheng Chen, Lei Huang
Summary: Constructed wetland is a cost-effective and environmentally friendly technology for contaminated water treatment. However, substrate clogging is a major challenge in its long-term operation. This study reviews the effects of substrates on clogging and provides recommendations for substrates that can alleviate clogging, aiming to enhance the stable operation and technical level of constructed wetlands.
SCIENCE OF THE TOTAL ENVIRONMENT
(2022)
Article
Engineering, Civil
J. Godinaud, M. Klepikova, F. Larroque, N. Guiheneuf, A. Dupuy, O. Bour
Summary: Fiber-Optic Active Distributed Temperature Sensing (FO-ADTS) experiments were conducted on an ATES site in Bordeaux, France. The experiments involved heating the FO cable's steel core and monitoring the rate of temperature increase. The results showed that ADTS can estimate thermal conductivity, Darcy velocity distribution, and detect clogging in boreholes, offering potential benefits for maintaining ATES system performance without the need for extensive drilling or system shutdown.
JOURNAL OF HYDROLOGY
(2023)
Article
Neurosciences
Adam X. Gorka, Ryan T. Philips, Salvatore Torrisi, Adrienne Manbeck, Madeline Goodwin, Monique Ernst, Christian Grillon
Summary: Computational models suggest that negative prediction errors (PEs) weaken aversive associations during conditioning and extinction. This study investigates the role of periaqueductal gray matter (PAG) in processing negative PEs in the human brain using ultra-high-field functional magnetic resonance imaging. Results show that negative PEs are associated with increased PAG responses and connectivity with medial areas of Brodmann area 9 during differential conditioning.
SOCIAL COGNITIVE AND AFFECTIVE NEUROSCIENCE
(2023)
News Item
Physics, Multidisciplinary
Patrick Pietzonka
Summary: The macroscopic properties of active matter can be attributed to the non-equilibrium character and handedness of interactions between individual particles.
Article
Green & Sustainable Science & Technology
Hengyu Guo, Jie Chen, Longfei Wang, Aurelia Chi Wang, Yafeng Li, Chunhua An, Jr-Hau He, Chenguo Hu, Vincent K. S. Hsiao, Zhong Lin Wang
Summary: This study introduces a corona-type, mechanically stimulated triboelectric NAI generator that efficiently produces negative air ions for air purification. The device is simple, safe, and effective, offering a sustainable solution for improving indoor air quality.
NATURE SUSTAINABILITY
(2021)
Article
Chemistry, Physical
William Savoie, Harry Tuazon, Ishant Tiwari, M. Saad Bhamla, Daniel I. I. Goldman
Summary: This study examines the emergent properties of amorphous entangled systems and identifies the method of changing particle shape as the most effective way to improve tensile strength. The research also demonstrates the control of individual worm activity through dissolved oxygen, leading to complex emergent properties of the entangled collective.
Article
Mechanics
John F. Brady
Summary: A new continuous perspective for phoretic motion applicable to particles of any shape in 'microstructured' fluids has been developed, explaining how the local osmotic pressure of solute adjacent to the phoretic particle generates a thrust force. The study covers passive Brownian bath particles in suspension and active particles with characteristic speed and run length variations, showing that phoretic motion arises from a gradient in swim pressure of active matter.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Electrical & Electronic
Sanghyun Jo, Hyangsook Lee, Duk-Hyun Choe, Jung-Hwa Kim, Yun Seong Lee, Owoong Kwon, Seunggeol Nam, Yoonsang Park, Kihong Kim, Byeong Gyu Chae, Sangwook Kim, Seunghun Kang, Taehwan Moon, Hagyoul Bae, Jung Yeon Won, Dong-Jin Yun, Myoungho Jeong, Hyun Hwi Lee, Yeonchoo Cho, Kwang-Hee Lee, Hyun Jae Lee, Sangjun Lee, Kab-Jin Nam, Dongjin Jung, Bong Jin Kuh, Daewon Ha, Yongsung Kim, Seongjun Park, Yunseok Kim, Eunha Lee, Jinseong Heo
Summary: Ferroelectric zirconium-doped hafnia (Hf0.5Zr0.5O2) can be used to create negative differential capacitance behavior in capacitors and transistor gate stacks, providing reliable enhancements in switching performance. The effect is achieved in metal-oxide-semiconductor capacitors and field-effect transistors, leading to improved device performance with increased on current and decreased off current.
NATURE ELECTRONICS
(2023)
Article
Physics, Multidisciplinary
C. J. O. Reichhardt, A. del Campo, C. Reichhardt
Summary: This study investigates the non-equilibrium phase transitions of superconducting vortices and colloids, and demonstrates that the Kibble-Zurek mechanism is applicable to these transitions. The density of topological defects is measured, and it is found that the defect density scales according to a power law, with exponents falling in the directed percolation universality class. These results suggest that the Kibble-Zurek mechanism can be applied to a broader range of systems exhibiting absorbing phase transitions.
COMMUNICATIONS PHYSICS
(2022)
Article
Physics, Condensed Matter
C. J. O. Reichhardt, C. Reichhardt
Summary: This study investigates the motion of superconducting vortices and skyrmions near the first commensurate matching field. The results show the presence of dynamic phases, such as interstitial flow, above commensuration. A transition from fluid flow to soliton flow can generate negative differential conductivity. Below commensuration, vacancy depinning occurs. The findings have implications for understanding the velocity-force curves, differential mobility, and velocity fluctuations. When a Magnus force is present, an expansion of the fluid state and a reentrant Hall effect are observed.
EUROPEAN PHYSICAL JOURNAL B
(2022)
Article
Physics, Condensed Matter
J. C. Bellizotti Souza, N. P. Vizarim, C. J. O. Reichhardt, C. Reichhardt, P. A. Venegas
Summary: Using a particle based model, this study investigates the dynamic behavior of skyrmions in a channel with different depth divots on the upper and lower walls. The research reveals that under an applied driving force, skyrmions exhibit a finite skyrmion Hall angle, deflecting towards the upper wall for -x direction driving and the lower wall for +x direction driving. Various trapping phenomena and non-linear velocity-force responses are observed depending on the depth differences of the divots. The study also discusses the implications of these findings for continuum modeling of similar skyrmion diode systems.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Physics, Multidisciplinary
J. C. Bellizotti Souza, N. P. Vizarim, C. J. O. Reichhardt, C. Reichhardt, P. A. Venegas
Summary: Using a particle-based model, the collective dynamics of skyrmions interacting with a funnel potential under dc driving are examined. The study finds that increasing skyrmion density reduces average velocity and leads to accumulation on one side of the funnel array. In the hard direction, a critical skyrmion density is identified below which trapping occurs, and above which a clogging effect is observed with multiple depinning and repinning states. The size of the funnel opening is reduced by the pile up of skyrmions, resulting in a diode effect where the critical depinning force is higher and the velocity response is smaller for hard direction driving.
NEW JOURNAL OF PHYSICS
(2022)
Article
Physics, Condensed Matter
C. Reichhardt, C. J. O. Reichhardt
Summary: We investigated the effects of quenched disorder on driven Wigner crystals and found that at low temperatures, there is a clear depinning threshold and a peak in the noise power with 1/f noise characteristics. As the temperature increases, the depinning threshold shifts to lower drives and the noise power decreases, resulting in a more white noise character. Additionally, the washboard frequency signal, observed when the system depins elastically or forms a moving smectic state, is significantly reduced at higher temperatures and disappears above the melting temperature of a system without quenched disorder. Our results are consistent with recent studies on transport and noise in electron crystal depinning and demonstrate how noise can be used to distinguish between different phases.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Physics, Multidisciplinary
J. C. Bellizotti Souza, N. P. Vizarim, C. J. O. Reichhardt, C. Reichhardt, P. A. Venegas
Summary: This study investigates the behavior of compressed ferromagnetic skyrmions under direct current (dc) and alternating current (ac) drives using atomistic-based simulations. The compressed skyrmions can be annihilated close to the wall and form a conformal crystal with size and density gradients. Both dc and ac driving can induce transverse motion due to the combination of density and size gradients, where the Magnus force plays a role in converting forces in the compression direction. Additionally, under ac driving, the skyrmion annihilation is reduced and a skyrmion Magnus ratchet pump is observed.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
C. Reichhardt, C. J. O. Reichhardt
Summary: We study the simulation of Wigner crystals in solid state systems interacting with random quenched disorder and thermal fluctuations. The effects of quenched disorder and thermal fluctuations compete, and the thermal fluctuations can reduce the effectiveness of the quenched disorder, leading to a reentrant ordered phase. Our simulations show that both competing theories for low temperature behavior capture aspects of the actual response. The critical disorder strength remains finite as the temperature approaches zero, and decreases with decreasing temperature. The onset of the reentrant phase can be deduced based on changes in the transport response.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
Wenqi Zhu, C. Reichhardt, C. J. O. Reichhardt, Yan Feng
Summary: The transverse depinning dynamics of a two-dimensional dusty plasma solid with a periodic-square-substrate modulation and driven by a constant force in the longitudinal direction is investigated using Langevin dynamical simulations. It is found that the critical transverse depinning force shows a nonmonotonic variation with the increase of the commensuration ratio. The dynamical commensuration effect is observed in the stable one-dimensional channel particle trajectories and the highly ordered structure, while both the particle trajectories and the structure are more disordered under the incommensurate conditions. The nonmonotonic variation of the critical transverse depinning force is attributed to the stability of the lattice structure at specific commensuration ratios.
PHYSICS OF PLASMAS
(2023)
Article
Physics, Multidisciplinary
Peter Forgacs, Andras Libal, Charles Reichhardt, Nicolas Hengartner, Cynthia J. O. Reichhardt
Summary: This article investigates time-dependent pattern formation in active matter particle systems, including motility-induced phase separation (MIPS), wetting phase, and fragmented state. The study shows that pattern formation is influenced by poisoning rates and activity levels, and contact poisoning can promote nucleation in certain cases.
COMMUNICATIONS PHYSICS
(2023)
Article
Physics, Multidisciplinary
C. Reichhardt, Ido Regev, K. Dahmen, S. Okuma, C. J. O. Reichhardt
Summary: Reversible to irreversible (R-IR) transitions occur in various periodically driven collective systems. These systems organize into a reversible state after a certain number of driving cycles, where particle trajectories repeat. On the irreversible side, motion is chaotic. R-IR transitions have been extensively studied in different systems, including dilute colloids, amorphous solids, crystals, superconductors, and magnetic textures. The transition to a reversible state is often an absorbing phase transition, with a critical divergence in the organization timescale. These transitions can be applied to a broader range of nonequilibrium systems, such as commensurate-incommensurate states, systems with hysteresis or avalanches, and systems with absorbing phase transitions.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Physics, Fluids & Plasmas
A. Libal, P. Forgacs, A. Neda, C. Reichhardt, N. Hengartner, C. J. O. Reichhardt
Summary: The SI and SIR models represent epidemic evolution, distinguishable by whether susceptibles always drop to zero at long times. The new SCZR model is introduced, where spontaneous recovery is absent but zombies can recover with probability gamma through interaction with a cleric. By changing the initial fraction of clerics or their healing ability rate gamma, the SCZR model can be tuned between SI dynamics and SIR dynamics.
Article
Chemistry, Physical
A. Libal, S. Stepanov, C. Reichhardt, C. J. O. Reichhardt
Summary: In this study, we investigate the dynamics of elongated particles in a two-dimensional system with randomly placed pinning sites. By varying the density of pinning sites, external drive magnitude, and particle elongation, we observe a wide range of dynamic phases including random structures, stripe or combed phases with nematic order, and clogged states. The effects of pinning sites on particle alignment result in nonmonotonic nematic ordering in certain regimes.
Article
Physics, Multidisciplinary
D. Minogue, M. R. Eskildsen, C. Reichhardt, C. J. O. Reichhardt
Summary: Numerical simulations were conducted to investigate the transition dynamics between metastable and ground state vortex lattice phases in a system with combined sixfold and twelvefold vortex-vortex interactions. The study revealed that the metastable state can decay by changing the vortex-vortex interaction and applying a drive that mimics an oscillating magnetic field.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
C. J. O. Reichhardt, C. Reichhardt
Summary: In this study, we investigate a charge lattice coupled to a one-dimensional asymmetric potential in the presence of an applied magnetic field. An applied external ac drive can induce a ratchet effect at zero magnetic field, and the addition of a magnetic field leads to new behaviors, including transverse ratchet motion. The system also exhibits commensuration effects and nonmonotonic ratchet efficiency.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
C. Reichhardt, C. J. O. Reichhardt
Summary: We investigated the generation and disappearance of topological defects in superconducting vortices and magnetic skyrmions. The study shows that when the pinning substrate is strong enough, the system undergoes a non-equilibrium phase transition into a state with higher topological order. Different behaviors are observed for vortex and skyrmion cases when crossing the ordering transition at different rates.
PHYSICAL REVIEW RESEARCH
(2023)
