I will begin with a broad introduction to the challenges associated with making matter from photons, focusing specifically on 1 how to trap photons and imbue them with mass and charge; 2 how to induce photons to collide with one another; and 3 how to drive photons to order, by cooling or otherwise.
learamede.tk I will then provide as examples two state-of-the-art photonic quantum matter platforms: microwave photons coupled to superconducting resonators and transmon qubits, and optical photons trapped in multimode optical cavities and made to interact through Rydberg-dressing. In each case I will describe a synthetic material created in that platform: a Mott insulator of microwave photons, stabilized by coupling to an engineered, non-Markovian reservoir, and a Laughlin molecule of optical photons prepared by scattering photons through the optical cavity.
Indeed, building materials photon-by-photon will provide us with a unique opportunity to learn what all of the above words mean, and why they are important for quantum-materials science. Finally, I will conclude with my view of the broad prospects of photonic matter in particular, and of synthetic matter more generally. The stable generation of high temperature Hydrogen plasmas ion and electron temperature in the range keV is the basis for the use of nuclear fusion to generate heat and thereby electric power.
The most promising path is to use strong, toroidal, twisted magnetic fields to confine the electrically charged plasma particles in order to avoid heat losses to the cold, solid wall elements. Two magnetic confinement concepts have been proven to be most suitable: a the tokamak and b the stellarator. The stellarator creates the magnetic field by external coils only, the tokamak by combining the externally created field with the magnetic field generated by a strong current in the plasma.
It is a unique feature of Wendelstein 7-X to be able to operate high-power Hydrogen plasmas under steady-state conditions, more specifically for s note that the world standard is now in the 10 s ballpark. This talk provides a review of the principles of nuclear fusion and discusses the key physics subjects of optimized stellarators. The sometimes adventurous undertaking to construct such a first-of-a-kind device is summarized as well as the most important findings during the first operation phase of Wendelstein 7-X. We finish with an outlook towards the fusion power station and address the most important remaining issues to be addressed in the framework of the world-wide fusion research endeavor.
The hard-disk model has exerted outstanding influence on computational physics and statistical mechanics. Decades ago, hard disks were the first system to be studied by reversible Markov-chain Monte Carlo methods satisfying the detailed-balance condition and by molecular dynamics. It was in hard disks, through numerical simulations, that a two-dimensional melting transition was first seen to occur even though homogeneous short-range interacting particle systems cannot develop crystalline order.
Analysis of the system was made difficult by the absence of powerful simulation methods. In recent years, we have developed a class of irreversible event-chain Monte Carlo algorithms that violate detailed balance. They realize thermodynamic equilibrium as a steady state with non-vanishing probability flows. A new factorized Metropolis filter turns them into a paradigm for general Monte Carlo calculations. I will in particular show how the event-chain Monte Carlo algorithm has allowed us to demonstrate that hard disks melt with a first-order transition from the liquid to the hexatic and a continuous transition from the hexatic to the solid.
Event-chain computations have also lead to our new understanding of two-dimensional melting for soft disks, that has been intensely studied in experiment. Finally, I will discuss two-dimensional melting on a substrate as it is realized in skyrmion systems , and for active particles, and will present a very recent application of the event-chain algorithm to Coulomb-type long-range-interacting systems.
Ultra cold atoms are remarkable systems with a truly unprecedented level of experimental control and one application of this control is creating topological band structures.
The most natural approach centers on creating suitable real-space lattice potentials that the atoms experience. We imaged the localized edge and bulk states of atomic Bose-Einstein condensates in this strip, with single lattice-site resolution along the narrow direction. In this 5-site wide strip we are able to delineate between bulk behavior quantified by Chern numbers and edge behavior which is not.
This is due to the ever-smaller sizes of the electronic components that will enter the realm of quantum physics. Computations, whether they happen in our heads or with any computational device, always rely on real physical devices and processes. Data input, data representation in a memory, data manipulation using algorithms and finally, data output require physical realizations with devices and practical procedures.
Building a quantum computer then requires the implementation of quantum bits qubits as storage sites for quantum information, quantum registers and quantum gates for data handling and processing as well as the development of quantum algorithms. In this talk, the basic functional principle of a quantum computer will be reviewed. It will be shown how strings of trapped ions can be used to build a quantum information processor and how basic computations can be performed using quantum techniques.
In particular, the quantum way of doing computations will be illustrated with analog and digital quantum simulations, which range from the simulation of quantum many-body spin systems over open quantum systems to the quantum simulation of a lattice gauge theory.
The church of Rome began to have a "top down" structure that started with the pope, then cardinals, then bishops, then priests, then the people. The commentary of the DVD series is not in the book, but there are many more quotes available than in the video series. BET Tues. An assassin toys with a White House Secret Service agent haunted for 30 years by his failure in Dallas. Philippa Bergmann is an artist working in Madison, Wisconsin.
The statistical mechanics of equilibrium systems is characterized by two fundamental ideas: that closed systems approach a late time thermal state and that of phase structure wherein such late time states exhibit singular changes as various parameters characterizing the system are changed. Recent progress has established generalizations of these ideas which apply to periodically driven, or Floquet, closed quantum systems.
I will describe this progress, which centrally uses other recent advances in our understanding of many body localization. Bose-Einstein condensation has been observed with cold atomic gases, exciton-polaritons, and more recently with photons in a dye-solution filled optical microcavity. I will here describe measurements of my Bonn group observing the transition between usual lasing dynamics and photon Bose-Einstein condensation.
The photon Bose-Einstein condensate is generated in a wavelength-sized optical cavity, where the small mirror spacing imprints a low-frequency cutoff and photons confined in the resonator thermalize to room temperature by absorption re-emission processes on the dye molecules. This allows for a particle-number conserving thermalization, with photons showing a thermodynamic phase transition to a macroscopically occupied ground state, the Bose-Einstein condensate. When the thermalization by absorption and re-emission is faster than the photon loss rate in the cavity, the photons accumulate at lower energy states above the cavity cutoff, and the system finally thermalizes to a Bose-Einstein condensate of photons.
On the other hand, for a small reabsorption with respect to the photon loss, the state remains laser-like.
I will also report recent measurements of the heat capacity of the photon gas, which were performed under the conditions of the thermalization being much faster than both photon loss and pumping. In my talk, I will begin with a general introduction and give an account of current work and future plans of the Bonn photon gas experiment. A variety of one-dimensional electronic systems can be engineered to host topological superconductivity and Majorana zero modes.
One is based on chains of magnetic atoms the work on which grew out of early efforts on the study of localized Bogoliubov quasi-particles near individual magnetic atoms on a superconductors. A second system is based on introducing superconductivity on the hinge states of a high order topological insulator. Using combination of magnetism and superconductivity, we are exploring how Majorana zero mode can emerge in this system. Actin filaments are the essential components of the cytoskeleton that provide the elasticity of a cell.
In a cell they interact with many proteins and in particular molecular motors. This talk will present 3 biological situations where actin filaments interact with molecular motors in relation with important cellular functions : the control of actin polymerization, intracellular transport and cell migration.
Actin filaments are treadmilling : they grow at one end and depolymerize at the other end. The first example of interaction between actin and molecular motors deals with the induced depolymerization of actin filaments by myosin1b molecular motors studied in motility assays.
The depolymerization requires a catch bond motor with a detachment rate decreasing strongly when the motor is under force Molecular motors navigate the cytoskeleton to position vesicles and organelles at specific locations in the cell. In order to understand this transport process, the group of Pascal Martin at Institut Curie has used an antiparallel network of overlapping filaments. Beads coated with myosin motors accumulate at the midline of the pattern.
The accumulation is well described by a three-state model of bead transport, in which active beads locally sense the net polarity of the filament network by frequently detaching from and reattaching to the filaments. The migration of immune cells is guided by several chemical signals, but also by physical cues such as the hydraulic resistance of the vessels in which they travel. This barotaxis effect has been studied in vitro by the groups of M. Piel and A. Lenon using microfluidic channels.
We show that barotaxis results from a force imbalance at the scale of the cell, amplified at the scale of a network of vessels. Electro-mechanical excitation waves in the heart may exhibit different spatio-temporal dynamics ranging from repeated plane waves to scroll waves or spatio-temporal chaos, resulting in life threatening arrhythmias.
This kind of chaotic dynamics in excitable cardiac media is often characterised by significant complexity fluctuations including laminar phases and can be non-persistent exhibiting supertransients, with lifetimes of the chaotic phases increasing exponentially with the system size. Terminating or at least shortening chaotic transients can be life saving in the medical context of cardiac arrhythmias.
Therefore, we study the impact of perturbations on the duration of transients and features of the terminal phase of chaotic transients.
Practically, such perturbations can be applied via so-called virtual electrodes where electrical heterogeneities of the cardiac muscle act as local excitation sites when subjected to a global electric field. In the talk we shall present novel results on the nonlinear dynamics of the heart including features of the terminal phase of transient chaos, parameter and state estimation, as well as experimental studies and modalities. For the macroscopic world, classical thermodynamics formulates the laws governing the transformation of various forms of energy into each other.
Stochastic thermodynamics extends these concepts to micro- and nano-systems embedded or coupled to a heat bath where fluctuations play a dominant role. Examples are colloidal particles in time-dependent laser traps, single biomolecules manipulated by optical tweezers or AFM tips, and transport through quantum dots. For these systems, exact non-equilibrium relations like the Jarzynski relation, fluctuation theorems and, most recently, a thermodynamic uncertainty relation have been discovered. First, I will introduce the main principles and show a few representative experimental applications.
In the second part, I will discuss the universal trade-off between the thermodynamic cost and the precision of any biomolecular, or, more generally, of any stationary non-equilibrium process. By applying this thermodynamic uncertainty relation to molecular motors, I will introduce the emerging field of "thermodynamic inference" where relations from stochastic thermodynamics are used to infer otherwise yet inaccessible properties of bio physical and bio chemical systems.
We introduce the broad field of active matter, a novel class of non-equilibrium materials composed of many interacting units that individually consume energy and collectively generate motion or mechanical stresses. Unlike swarms of fish and flocks of birds, cells or ants can support static loads because cells are bound by transient links.
Recently we have focused on cellular aggregate — nanoparticles hybrid systems.
This system is of great interest as it has been previously shown that particles can modify the mechanical properties of cells in terms of adhesion area, proliferation and motility. We study both small particles up to few microns , which are digested by cells by endocytosis and phagocytosis, and larger particles, which do not enter in the cells, leading to a completely different physics. We model the cell-cell adhesion induced by the nanostickers using a three states dynamical model where the NPs are free, adsorbed on the membrane or internalized by endocytosis.
We find that carboxylated polystyrene NPs are more efficient than the silica NPs of the same size, which were reported to induce fast wound healing and to glue soft tissue by Leibler et al. Nanostickers by increasing the cohesion of tissues and tumors may have important applications for cellular therapy and cancer treatment.
Microparticles size 1micron : gluttonous cells. We study the spreading of cell aggregates deposited on adhesive substrates decorated with microparticles.