다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Coherent preparation by laser light of quantum states of atoms and molecules can lead to quantum interference in the amplitudes of optical transitions. In this way the optical properties of a medium can be dramatically modified, leading to electromagnetically induced transparency and related effects, which have placed gas-phase systems at the center of recent advances in the development of media with radically new optical properties. This article reviews these advances and the new possibilities they offer for nonlinear optics and quantum information science. As a basis for the theory of electromagnetically induced transparency the authors consider the atomic dynamics and the optical response of the medium to a continuous-wave laser. They then discuss pulse propagation and the adiabatic evolution of field-coupled states and show how coherently prepared media can be used to improve frequency conversion in nonlinear optical mixing experiments. The extension of these concepts to very weak optical fields in the few-photon limit is then examined. The review concludes with a discussion of future prospects and potential new applications.

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Electromagnetically induced transparency : Optics in coherent media

Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

Bose-Einstein condensation in a gas of sodium atoms

Feshbach resonances are the essential tool to control the interaction between atoms in ultracold quantum gases. They have found numerous experimental applications, opening up the way to important breakthroughs. This review broadly covers the phenomenon of Feshbach resonances in ultracold gases and their main applications. This includes the theoretical background and models for the description of Feshbach resonances, the experimental methods to find and characterize the resonances, a discussion of the main properties of resonances in various atomic species and mixed atomic species systems, and an overview of key experiments with atomic Bose-Einstein condensates, degenerate Fermi gases, and ultracold molecules.

Feshbach resonances in ultracold gases

Rydberg atoms with principal quantum number $n⪢1$ have exaggerated atomic properties including dipole-dipole interactions that scale as ${n}^{4}$ and radiative lifetimes that scale as ${n}^{3}$. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom qubits. The availability of a strong long-range interaction that can be coherently turned on and off is an enabling resource for a wide range of quantum information tasks stretching far beyond the original gate proposal. Rydberg enabled capabilities include long-range two-qubit gates, collective encoding of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing.

Quantum information with Rydberg atoms

In 2000, the three seminal papers launched a new era in Rydberg physics, predicting the blockade mechanism [1], exploring Rydberg dressed interactions [2], and foreseeing trilobite-like molecules [3]. Here, we explore how a new binding mechanism between ground state atoms, based on Rydbergdressing, can lead to ultra-long-range molecules. We show that by using far-detuned lasers to couple a small but adjustable Rydberg component to the ground state atom, localized long-range potential wells can be created that can support molecular bound levels (Fig. 1).

Ultra-long-range molecule engineering via Rydberg-dressing

Calculated potentials for collisions of one-electron Ca+ ions with co-trapped Na atoms suggest the excited (triplet sigma +) state of (NaCa)+ is metastable with respect to charge transfer. Measurements of the elastic cross sections for cooling of Ca+ and of internally hot Na molecular ions by ultracold Na are planned.

On the collisional cooling of co-trapped atomic and molecular ions by ultracold atoms: Ca+ + Na and Na2+(v*,J* ) + Na.

The lowest doublet electronic state for the lithium trimer (12A′) is calculated for use in three-body scattering calculations using the valence electron FCI method with atomic cores represented using an effective core potential. It is shown that an accurate description of core-valence correlation is necessary for accurate calculations of molecular bond lengths, frequencies and dissociation energies. Interpolation between 12A′ ab initio surface data points in a sparse grid is done using the global interpolant moving least squares method with a smooth radial data cutoff function included in the fitting weights and bivariate polynomials as a basis set. The Jahn–Teller splitting of the 12E′ surface into the 12A1 and 12B2 states is investigated using a combination of both CASSCF and FCI levels of theory. Additionally, preliminary calculations of the 12A″ surface are also presented using second order spin restricted open-shell Moller–Plesset perturbation level of theory. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009

Potential energy surface of the 12A′ Li2 + Li doublet ground state

We explore how atoms and polar molecules can be manipulated using evanescent-wave mirrors (EWM). We review the simpler case of ultracold atoms incident on EWM, and show that quantum effects such as tunneling, above barrier reflection, and Casimir retardation corrections, can be probed. We show that it is possible to enhance significantly quantum effects by engineering sharp features in the effective atom-EWM potential. We illustrate the concept with a bichromatic EWM created by using red and blue detuned lasers. Finally, we extend the treatment to ultracold diatomic polar molecules. Quantum reflection and molecular state selection are demonstrated under attainable physical conditions. By facilitating the manipulation and trapping of ultracold molecules, such molecular mirrors could have several applications, e.g., as devices to filter and select state for ultracold chemistry, or to manipulate states for quantum information processing.

Manipulating atoms and molecules with evanescent-wave mirrors

We report calculations of diffusion, excitation transfer, width, and shift cross sections. We use these cross sections to obtain the diffusion coefficient and the width and line shift due to collisions of alkali-metal atoms in the impact approximation. The results are compared to analytical expressions obtained from semiclassical treatments, and with measured widths for sodium atoms. Extension to other alkali metal atoms is also given.

Robin Côté

Papers

Ultra-long-range molecule engineering via Rydberg-dressing

On the collisional cooling of co-trapped atomic and molecular ions by ultracold atoms: Ca+ + Na and Na2+(v,J ) + Na.

Potential energy surface of the 12A′ Li2 + Li doublet ground state

Manipulating atoms and molecules with evanescent-wave mirrors

Diffusion and excitation transfer of excited alkali-metal atoms