Conical Intersections in an Ultracold Gas

Wüster, Sebastian; Eisfeld, Alexander; Rost, Jan M.

doi:10.1103/physrevlett.106.153002

Cited by 47 publications

(97 citation statements)

References 26 publications

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“…In direct analogy to the discussion above, the interaction of the OH stretch vibrations among each other and with the hydrogen bonding network is expected to give rise to intermolecular vibrational CIs [38], which may help to explain the so-far little understood multidimensional infrared spectra of these systems.…”

mentioning

confidence: 81%

Vibrational Conical Intersections as a Mechanism of Ultrafast Vibrational Relaxation

Hamm

Stock

2012

Phys. Rev. Lett.

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Presenting true crossings of adiabatic potential energy surfaces, conical intersections are a paradigm of ultrafast and efficient electronic relaxation dynamics. The same mechanism is shown to apply also for vibrational conical intersections, which may occur when two high-frequency modes (such as OH stretch vibrations) are coupled to low-frequency modes (such as hydrogen bonding modes). By derivation of a model Hamiltonian and its parametrization for a concrete example, malonaldehyde, the conditions that such conical intersections occur are identified and the consequences for the vibrational dynamics and spectra are demonstrated.

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confidence: 81%

Vibrational Conical Intersections as a Mechanism of Ultrafast Vibrational Relaxation

Hamm

Stock

2012

Phys. Rev. Lett.

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“…(4) represents an adequate model (see, e.g., [58]). However, corrections due to atomic motion can easily become relevant [59][60][61][62][63][64][65], in which case the kineticenergy term…”

Section: B Rydberg Excitations In a Bose Gasmentioning

confidence: 99%

Quantum dynamics of long-range interacting systems using the positive- P and gauge- P representations

et al. 2017

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We provide the necessary framework for carrying out stochastic positive-P and gauge-P simulations of bosonic systems with long-range interactions. In these approaches, the quantum evolution is sampled by trajectories in phase space, allowing calculation of correlations without truncation of the Hilbert space or other approximations to the quantum state. The main drawback is that the simulation time is limited by noise arising from interactions. We show that the long-range character of these interactions does not further increase the limitations of these methods, in contrast to the situation for alternatives such as the density matrix renormalization group. Furthermore, stochastic gauge techniques can also successfully extend simulation times in the long-range-interaction case, by making using of parameters that affect the noise properties of trajectories, without affecting physical observables. We derive essential results that significantly aid the use of these methods: estimates of the available simulation time, optimized stochastic gauges, a general form of the characteristic stochastic variance, and adaptations for very large systems. Testing the performance of particular drift and diffusion gauges for nonlocal interactions, we find that, for small to medium systems, drift gauges are beneficial, whereas for sufficiently large systems, it is optimal to use only a diffusion gauge. The methods are illustrated with direct numerical simulations of interaction quenches in extended Bose-Hubbard lattice systems and the excitation of Rydberg states in a Bose-Einstein condensate, also without the need for the typical frozen gas approximation. We demonstrate that gauges can indeed lengthen the useful simulation time.

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“…There is a growing interest in these concepts applied to trapping and dynamics of ultracold atoms [17].…”

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confidence: 99%

Observation of Quantum Interferences via Light-Induced Conical Intersections in Diatomic Molecules

et al. 2016

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We observe energy-dependent angle-resolved diffraction patterns in protons from strong-field dissociation of the molecular hydrogen ion H + 2 . The interference is a characteristic of dissociation around a laser-induced conical intersection (LICI), which is a point of contact between two surfaces in the dressed 2-dimensional Born-Oppenheimer potential energy landscape of a diatomic molecule in a strong laser field. The interference magnitude and angular period depend strongly on the energy difference between the initial state and the LICI, consistent with coherent diffraction around a cone-shaped potential barrier whose width and thickness depend on the relative energy of the initial state and the cone apex. These findings are supported by numerical solutions of the time-dependent Schrödinger equation for similar experimental conditions.The Born-Oppenheimer approximation (BOA) represents intramolecular dynamics as the motion of nuclear wave packets on potential energy surfaces (PES) of electronic eigenvalues embedded in the space of nuclear geometries. A molecule on a single PES remains there so long as the adiabatic condition is obeyed, i.e. so long as nuclear kinetic energies are small compared to electronic state separations. This assumption must break down, however, if two or more PESs approach each other [1][2][3]. When this happens non-adiabatic couplings between the nearly-degenerate surfaces become important. The true eigenvalues can then be calculated by diagonalizing the Hamiltonian in the reduced space of the near degeneracy.According to simple geometrical arguments, molecules with at least two dimensions of internal nuclear motion (i.e. three or more atoms) must have some points where two or more PESs become degenerate, a condition known as a conical intersection (CI) [4]. These CIs play a key role in the relaxation dynamics of most polyatomic molecules including important biochemical processes such as the photostability of DNA [5], and the preliminary process of vision [6]. The dimension of the CI manifold is two less than the internal nuclear geometry. Thus for the simplest case of a tri-atomic molecule, the CI manifold has dimensionality of 3N − 8 = 1. The topological nature of CIs allows the nonadiabatic couplings to diverge and thus display related phenomena such as a geometric or Berry's phase [4,7] in wavepackets that circumnavigate the CI.Naturally occurring CIs cannot exist for a free diatomic molecule because the internuclear separation vector R is the only internal nuclear degree of freedom, and this is insufficient to fulfil the crossing condition. The nonadiabatic terms in the full Hamiltonian cause the BOA states to repel according to the so-called "no-crossing" rule. A diatomic molecule in a strong laser field, however, has a second degree of freedom defined by the laser polarization ε. When viewed in a Floquet basis of laserdressed electronic states, a molecule coupled by this field can exhibit a point of degeneracy called a light-induced conical intersection (LICI) in the 2−dimension...

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Conical Intersections in an Ultracold Gas

Cited by 47 publications

References 26 publications

Vibrational Conical Intersections as a Mechanism of Ultrafast Vibrational Relaxation

Vibrational Conical Intersections as a Mechanism of Ultrafast Vibrational Relaxation

Quantum dynamics of long-range interacting systems using the positive- P and gauge- P representations

Observation of Quantum Interferences via Light-Induced Conical Intersections in Diatomic Molecules

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