Competition between Light-Induced and Intrinsic Nonadiabatic Phenomena in Diatomics

Csehi, András; Halász, Gábor J.; Cederbaum, Lorenz S.; Vibók, Ágnes

doi:10.1021/acs.jpclett.7b00413

Cited by 48 publications

(58 citation statements)

References 48 publications

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“…We show in this work that the molecular cavity photodynamics of LiF may drastically change upon the quantum field present in the cavity. In addition, contrary to previous statements [14,15] we believe that our results indicate that the fully quantum nature of the radiation is expressed in features that cannot be reproduced whatsoever using a classical light. THEORY We assume an optical cavity with a single mode confined radiation with frequency ω c .…”

Section: Introductioncontrasting

confidence: 99%

“…x Although the cavity photodynamics of NaI has been recently treated in Ref. [10,11,14,15], we would like to provide a more comprehensive account of the inner workings of the underlying mechanisms that give shape to the time-dependent populations and the dissociation yields in the similar molecule LiF. We want to address the problem assuming that the cavity can be filled with different types of quantum states of radiation, namely, Fock states, coherent states and squeezed coherent states, which are known to have very different properties.…”

Section: Resultsmentioning

confidence: 99%

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Entangled Photonic-Nuclear Molecular Dynamics of LiF in Quantum Optical Cavities

2018

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The quantum photodynamics of a simple diatomic molecule with a permanent dipole immersed within an optical cavity containing a quantized radiation field is studied in detail. The chosen molecule under study, lithium fluoride (LiF), is characterized by the presence of an avoided crossing between the two lowest 1 Σ potential energy curves (covalent-ionic diabatic crossing). Without field, after prompt excitation from the ground state 1 1 Σ, the excited nuclear wave packet moves back and forth in the upper 2 1 Σ state, but in the proximity of the avoided crossing, the nonadiabatic coupling transfers part of the nuclear wave packet to the lower 1 1 Σ state, which eventually leads to dissociation. The quantized field of a cavity also induces an additional light crossing in the modified dressed potential energy curves with similar transfer properties. To understand the entangled photonic-nuclear dynamics we solve the time dependent Schrödinger equation by using the multiconfigurational time dependent Hartree method (MCTDH). The single mode quantized field of the cavity is represented in the coordinate space instead of in the Fock space, which allows us to deal with the field as an additional vibrational mode within the MCTDH procedure on equal footing. We prepare the cavity with different quantum states of light, namely, Fock states, coherent states and squeezed coherent states. Our results reveal pure quantum light effects on the molecular photodynamics and the dissociation yields of LiF, which are quite different from the light-undressed case and that cannot be described in general by a semiclassical approach using classical electromagnetic fields.

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Section: Introductioncontrasting

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Entangled Photonic-Nuclear Molecular Dynamics of LiF in Quantum Optical Cavities

2018

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“…This scenario resembles a one-dimensional (1D), semi-classical treatment of the light-induced avoided crossing occurring in the nonadiabatic gas-phase molecular dynamics. Recent studies of the time-dependent state population in the NaI molecule have successfully demonstrated that the 1D results obtained by the semi-classical approach [50] are fully consistent with the results obtained for NaI and quantized light field [24].…”

supporting

confidence: 68%

Ultrafast dynamics in the vicinity of quantum light-induced conical intersections

et al. 2019

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Nonadiabatic effects appear due to avoided crossings or conical intersections (CIs) that are either intrinsic properties in field-free space or induced by a classical laser field in a molecule. It was demonstrated that avoided crossings in diatomics can also be created in an optical cavity. Here, the quantized radiation field mixes the nuclear and electronic degrees of freedom creating hybrid fieldmatter states called polaritons. In the present theoretical study we go further and create CIs in diatomics by means of a radiation field in the framework of cavity quantum electrodynamics. By treating all degrees of freedom, that is the rotational, vibrational, electronic and photonic degrees of freedom on an equal footing we can control the nonadiabatic quantum light-induced dynamics by means of CIs. First, the pronounced difference between the the quantum light-induced avoided crossing and the CI with respect to the nonadiabatic dynamics of the molecule is demonstrated. Second, we discuss the similarities and differences between the classical and the quantum field description of the light for the studied scenario.The dynamics initiated in a molecule by absorbing a photon is often described in the Born-Oppenheimer (BO) or adiabatic approximation [1], where the electronic and nuclear degrees of freedom are treated separately. However, in some nuclear configurations called conical intersections (CIs) the mixing between the electronic and nuclear motions are very significant [2][3][4][5][6]. Owing to the strong nonadiabatic couplings (NACs) in the close vicinity of these CIs the BO approximation breaks down. It is well-known that these CIs have a significant impact on several important photo-dynamical processes, such as vision, photosynthesis, molecular electronics, and the photochemistry of DNA [7][8][9][10][11]. During the dynamics the CIs can serve as efficient decay channels for the ultrafast transfer of the populations. In the following we call these CIs, which originate from the field free electronic structure, natural CIs.Nonadiabatic effects can also appear when molecules are exposed to resonant laser light. The electric field can couple to two or more electronic states of the molecule via the non-vanishing transition dipole moment(s) [12][13][14][15]. This results either in a light-induced avoided crossing (LIAC) or a light-induced conical intersection (LICI) depending on how many nuclear degrees of freedom are involved in the field induced process [16]. In case of poly atomic molecules a sufficient number of vibrational degrees of freedom are always present to span a twodimensional branching space (BS), which is indispensable to the formation of LICI. In the case of diatomics one always has to find a proper second degree of freedom (DOF) which can act as a dynamical variable to form a BS. As the molecule rotates [17][18][19], the rotational angle between the molecular axis and the light polarization axis can serve as the missing DOF for establishing the BS [20].Nonadiabatic effects can arise in an optical or mi...

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“…This has been already demonstrated for NaI in previous work [30]. Pure Fock states have the most resemblance with classical light in terms of interaction and dynamics, which has been demonstrated in [33]. In case of a twolevel system their population dynamics are identical (a demonstration is given in Fig.…”

Section: Resultssupporting

confidence: 64%

Quantum control with quantum light of molecular nonadiabaticity

et al. 2019

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Coherent control experiments in molecules are often done with shaped laser fields. The electric field is described classically and control over the time evolution of the system is achieved by shaping the laser pulses in the time or frequency domain. Moving on from a classical to a quantum description of the light field allows to engineer the quantum state of light to steer chemical processes. The quantum field description of the photon mode allows to manipulate the light-matter interaction directly in phase-space. In this paper we will demonstrate the basic principle of coherent control with quantum light on the avoided crossing in lithium fluoride. Using a quantum description of light together with the nonadiabatic couplings and vibronic degrees of freedoms opens up new perspective on quantum control. We show the deviations from control with purely classical light field and how back-action of the light field becomes important in a few photon regime.

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Competition between Light-Induced and Intrinsic Nonadiabatic Phenomena in Diatomics

Cited by 48 publications

References 48 publications

Entangled Photonic-Nuclear Molecular Dynamics of LiF in Quantum Optical Cavities

Entangled Photonic-Nuclear Molecular Dynamics of LiF in Quantum Optical Cavities

Ultrafast dynamics in the vicinity of quantum light-induced conical intersections

Quantum control with quantum light of molecular nonadiabaticity

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