Giovanna Morigi

Bio: Giovanna Morigi is an academic researcher from Saarland University. The author has contributed to research in topics: Photon & Optical cavity. The author has an hindex of 36, co-authored 208 publications receiving 4531 citations. Previous affiliations of Giovanna Morigi include University of Pisa & Max Planck Society.

Ground State Laser Cooling Using Electromagnetically Induced Transparency

Abstract: A laser cooling method for trapped atoms is described which achieves ground state cooling by exploiting quantum interference in a driven Lambda-shaped arrangement of atomic levels. The scheme is technically simpler than existing methods of sideband cooling, yet it can be significantly more efficient, in particular when several motional modes are involved, and it does not impose restrictions on the transition linewidth. We study the full quantum mechanical model of the cooling process for one motional degree of freedom and show that a rate equation provides a good approximation.

Laser Cooling of Trapped Ions

Abstract: Laser cooling was first proposed in 1975 by Hansch and Schawlow, and simultaneously by Wineland and Dehmelt. After some general remarks on laser cooling in traps we report on experiments featuring two special laser cooling techniques for ions which are stored in Paul traps. With both techniques we demonstrate ground state cooling of a single trapped ion. Ground state cooling of one or a string of ions might help to improve ion-based frequency standards, and is a prerequisite for an ion-based quantum processor.

Crystallization of strongly interacting photons in a nonlinear optical fibre

Abstract: Understanding strongly correlated quantum systems is a central problem in many areas of physics. The collective behaviour of interacting particles gives rise to diverse fundamental phenomena such as confinement in quantum chromodynamics, electron fractionalization in the quantum Hall regime and phase transitions in unconventional superconductors and quantum magnets. Such systems typically involve massive particles, but optical photons can also interact with one another in a nonlinear medium. In practice, however, such interactions are often very weak. Here we describe a technique that enables the creation of a strongly correlated quantum gas of photons using one-dimensional optical systems with tight field confinement and coherent photon trapping techniques. The confinement enables the generation of large, tunable optical nonlinearities via the interaction of photons with a nearby cold atomic gas. In its extreme, we show that a quantum light field can undergo fermionization in such one-dimensional media, which can be probed via standard photon correlation measurements. Interactions between photons are typically extremely weak. But when light pulses are confined to an optical waveguide and manipulated with nearby cold atoms, strongly interacting photons can be created that may even undergo crystallization, as is now shown theoretically.

Structural Defects in Ion Chains by Quenching the External Potential: The Inhomogeneous Kibble-Zurek Mechanism

Abstract: The nonequilibrium dynamics of an ion chain in a highly anisotropic trap is studied when the transverse trap frequency is quenched across the value at which the chain undergoes a continuous phase transition from a linear to a zigzag structure. Within Landau theory, an equation for the order parameter, corresponding to the transverse size of the zigzag structure, is determined when the vibrational motion is damped via laser cooling. The number of structural defects produced during a linear quench of the transverse trapping frequency is predicted and verified numerically. It is shown to obey the scaling predicted by the Kibble-Zurek mechanism, when extended to take into account the spatial inhomogeneities of the ion chain in a linear Paul trap.

Structural phase transitions in low-dimensional ion crystals

Abstract: A chain of singly charged particles, confined by a harmonic potential, exhibits a sudden transition to a zigzag configuration when the radial potential reaches a critical value, depending on the particle number. This structural change is a phase transition of second order, whose order parameter is the crystal displacement from the chain axis. We study analytically the transition using Landau theory and find full agreement with numerical predictions by Schiffer [Phys. Rev. Lett. 70, 818 (1993)] and Piacente et al. [Phys. Rev. B 69, 045324 (2004)]. Our theory allows us to determine analytically the system's behavior at the transition point.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Cavity Optomechanics

Abstract: We review the field of cavity optomechanics, which explores the interaction between electromagnetic radiation and nano- or micromechanical motion This review covers the basics of optical cavities and mechanical resonators, their mutual optomechanical interaction mediated by the radiation pressure force, the large variety of experimental systems which exhibit this interaction, optical measurements of mechanical motion, dynamical backaction amplification and cooling, nonlinear dynamics, multimode optomechanics, and proposals for future cavity quantum optomechanics experiments In addition, we describe the perspectives for fundamental quantum physics and for possible applications of optomechanical devices

Quantum dynamics of single trapped ions

Abstract: Single trapped ions represent elementary quantum systems that are well isolated from the environment. They can be brought nearly to rest by laser cooling, and both their internal electronic states and external motion can be coupled to and manipulated by light fields. This makes them ideally suited for quantum-optical and quantum-dynamical studies under well-controlled conditions. Theoretical and experimental work on these topics is reviewed in the paper, with a focus on ions trapped in radio-frequency (Paul) traps.