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.

/pdf/electromagnetically-induced-transparency-optics-in-coherent-2dhges92td.pdf

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

Over the past decade, ultracold polar molecules have found application in hybrid quantum computation and quantum simulation, directions established in three early papers published in Nature Physics.

Ten years of Nature Physics : Jack of all trades

Calculations of magnetic Feshbach resonances and Zeeman relaxation cross sections are reported. These calculations address two separate experiments on ultracold and cold bosonic chromium gases.

Magnetic Feshbach resonances and Zeeman relaxation in bosonic chromium gas

We analyse the formation of ultracold 7Li133Cs molecules in the rovibrational ground state through photoassociation into the B1Pi state, which has recently been reported [J. Deiglmayr et al., Phys. Rev. Lett. 101, 133004 (2008)]. Absolute rate constants for photoassociation at large detunings from the atomic asymptote are determined and are found to be surprisingly large. The photoassociation process is modeled using a full coupled-channel calculation for the continuum state, taking all relevant hyperfine states into account. The enhancement of the photoassociation rate is found to be caused by an `echo' of the triplet component in the singlet component of the scattering wave function at the inner turning point of the lowest triplet a3Sigma+ potential. This perturbation can be ascribed to the existence of a broad Feshbach resonance at low scattering energies. Our results elucidate the important role of couplings in the scattering wave function for the formation of deeply bound ground state molecules via photoassociation.

Influence of a Feshbach resonance on the photoassociation of LiCs

Potential energy surface calculations are reported for the lowest 2 A surface arising from the Li2 (X 1 g ) Li* ( 2 P) interaction. The 2 A surface with Cs symmetry, which correlates to the 2 B1 surface in C2v symmetry and to the 2 Pi surface in Cv, has been calculated using second order restricted open-shell Moller-Plesset theory. Our calculated surface has a minimum in C2v symmetry that resembles the ground state surface but does not exhibit the Jahn-Teller splitting found for the ground state potential energy surface. Dipole transition moments are calculated in C2v geometry near the 2 A minima using the internally contracted multireference singles and doubles configuration interaction theory. We have also analyzed the long range behavior of this 2 A surface by fitting the ab initio calculations at long range with a functional series of the form Cn/R n . © 2009 Wiley Periodicals, Inc. Int J Quantum Chem 109: 3626 -3631, 2009

Electronic structure of the Li2 [X 1Σ g+] Li [2p] excited 2A″ surface

We propose to use a new platform - ultracold polar molecules - for quantum computing with switchable interactions. The on/off switch is accomplished by selective excitation of one of the "0" or "1" qubits - long-lived molecular states - to an "excited" molecular state with a considerably different dipole moment. We describe various schemes based on this switching of dipolar interactions where the selective excitation between ground and excited states is accomplished via optical, micro-wave, or electric fields. We also generalize the schemes to take advantage of the dipole blockade mechanism when dipolar interactions are very strong. These schemes can be realized in several recently proposed architectures.

/pdf/dipolar-switching-for-robust-quantum-computation-with-polar-u06o3t2a31.pdf

Robin Côté

Papers

Ten years of Nature Physics : Jack of all trades

Magnetic Feshbach resonances and Zeeman relaxation in bosonic chromium gas

Influence of a Feshbach resonance on the photoassociation of LiCs

Electronic structure of the Li2 [X 1Σ g+] Li [2p] excited 2A″ surface

Dipolar switching for robust quantum computation with polar molecules