Chang-qi Cao, Liu Yu-Xi, Hui Cao
In low density regime, the fluorescence of Frenkel exitons in crystal slab can be studied without the aid of rotating wave and Mackoffian approximation. The equations for the case of double and triple lattice-layers are now solved exactly to give the eigen decay rates, frequency shifts and the statistical properties of the fields.
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We study the fluorescence light emitted from GaAs excitons in semiconductor quantum wells. The excitons are modeled as interacting bosons. By combining quantum optical methods for the excitonic emission spectrum with many particle descriptions of the transmission through the medium, we can evaluate the spectra outside the well. Comparing with experimental spectra, we get a very good agreement. The method helps explaining the main features of the observed spectra. It is demonstrated that the observed spectra show clear evidence of superfluorescent emission.
We propose the physical implementation of a Grover-like search problem by means of Frenkel exciton trapping at a shallow isotopic impurity against a background of competing mechanisms. The search culminating at the impurity molecule, designated the "winner" site, is marked by its enhanced interaction with acoustic phonons at low temperatures. The quantum search proceeds with the assistance of an Oracle-like exciton-phonon interaction which addresses only the impurity site, via the Dyson propagator within the Green's function formalism. The optimum parameters of a graph lattice with long-range …
Charge transfer states in organic semiconductors play crucial roles in processes such as singlet fission and exciton dissociation at donor/acceptor interfaces. Recently, a time-resolved spectroscopy study of dinaphtho[2,3-b:2'3'-f]thieno[3,2-b]-thiophene (DNTT) thin films provided evidence for the formation of mixed Frenkel and charge-transfer excitons after the photoexcitation. Here we investigate optical properties and excitation dynamics of the DNTT thin films by combining ab initio calculations and a stochastic Schrodinger equation. Our theory predicts that the low-energy Frenkel exciton b…
We systematically study the fluorescence of low density Frenkel excitons in a crystal slab containing $N_T$ V-type three-level atoms. Based on symmetric quasi-spin realization of SU(3) in large $N$ limit, the two-mode exciton operators are invoked to depict various collective excitations of the collection of these V-type atoms starting from their ground state. By making use of the rotating wave approximation, the light intensity of radiation for the single lattice layer is investigated in detail. As a quantum coherence effect, the quantum beat phenomenon is discussed in detail for different in…
Quantum Computing and Error Mitigation with Deep Learning for Frenkel Excitons
本文利用变分量子 deflate 方法计算弗伦克尔哈密顿量本征态，并结合深度学习与后选择技术缓解 NISQ 量子计算机噪声误差，验证了方法的有效性。
The high density Frenkel exciton which interacts with a single mode microcavity field is dealed with in the framework of the q-deformed boson. It is shown that the q-defomation of bosonic commutation relations is satisfied naturally by the exciton operators when the low density limit is deviated. An analytical expression of the physical spectrum for the exciton is given by using of the dressed states of the cavity field and the exciton. We also give the numerical study and compare the theoretical results with the experimental results
We study the resonant electronic excitation dynamics for ultracold atoms trapped in a deep optical lattice prepared in a Mott insulator state. Excitons in these artificial crystals are similar to Frenkel excitons in Noble atom or molecular crystals. They appear when the atomic excited state line width is smaller than the exciton band width generated by dipole-dipole coupling. When the atoms are placed within a cavity the electronic excitations and the quantized cavity mode get coupled. In the collective strong coupling regime excitations form two branches of cavity polaritons with Rabi splitti…
The control of exciton transport in organic materials is of fundamental importance for the development of efficient light-harvesting systems. This transport is easily deteriorated by traps in the disordered energy landscape. Here, we propose and analyze a system that supports topological Frenkel exciton edge states. Backscattering of these chiral Frenkel excitons is prohibited by symmetry, ensuring that the transport properties of such a system are robust against disorder. To implement our idea, we propose a two-dimensional periodic array of tilted porphyrins interacting with a homogenous magn…
We study the effect of defects in the Mott insulator phase of ultracold atoms in an optical lattice on the dynamics of resonant excitations. Defects, which can either be empty sites in a Mott insulator state with one atom per site or a singly occupied site for a filling factor two, change the dynamics of Frenkel excitons and cavity polaritons. While the vacancies in first case behave like hard sphere scatters for excitons, singly occupied sites in the latter case can lead to attractive or repulsive scattering potentials. We suggest cavity polaritons as observation tool of such defects, and sho…
In this paper we give fully analytical description of the dynamics of a collection of $N$-Frenkel excitons in high density regime dispersively coupled to a single mode cavity field, in the presence of both exciton and cavity-field dissipations. By using excitonic operators as q-deformed bosonic operators for the system, we solve analytically the Liouville equation for the density operator at zero temperature and investigate the influence of the number of excitons and the effect of both dissipations on dynamical behavior of the system. We use the solution of master equation to explore the dissi…
We study electronic excitations of a degenerate gas of atoms trapped in pairs in an optical lattice. Local dipole-dipole interactions produce a long lived antisymmetric and a short lived symmetric superposition of individual atomic excitations as the lowest internal on-site excitations. Due to the much larger dipole moment the symmetric states couple efficiently to neighbouring lattice sites and can be well represented by Frenkel excitons, while the antisymmetric dark states stay localized. Within a cavity only symmetric states couple to cavity photons inducing long range interactions to form …
Excitons with a radius of a few lattice constants can be affected by strong central-cell corrections, leading to significant deviations of the optical spectrum from the hydrogen-like Rydberg series, and also to an enhancement of the exciton mass. We present an approach to this situation based on a lattice model that incorporates the effects of a non-parabolic band structure, short distance corrections to the Coulomb interaction between electrons and holes, spin-orbit and exchange coupling. The lattice model allows for observation of the crossover from large radius Wannier to small radius Frenk…
Ultracold polar molecules trapped on an optical lattice is a many-body system that, under appropriate conditions, may support collective excitations reminiscent of excitons in solid state crystals. Here, we discuss the rotational excitations of molecules on an optical lattice leading to rotational Frenkel excitons. Apart from solid hydrogen, there is no other natural system that exhibits rotational excitons. The rotational excitons have unique properties that can be exploited for tuning non-linear exciton interactions and exciton-impurity scattering by applying an external electric field. We s…
We study Frenkel exciton-polariton Bose-Einstein condensation in a two-dimensional defect-free triangular photonic crystal with an organic semiconductor active medium containing bound excitons with dipole moments oriented perpendicular to the layers. We find photonic Bloch modes of the structure and consider their strong coupling regime with the excitonic component. Using the Gross- Pitaevskii equation for exciton polaritons and the Boltzmann equation for the external exciton reservoir, we demonstrate the formation of condensate at the points in reciprocal space where photon group velocity equ…
We show that an ensemble of $^2Σ$ molecules in the rotationally ground state trapped on an optical lattice exhibits collective spin excitations that can be controlled by applying superimposed electric and magnetic fields. In particular, we show that the lowest energy excitation of the molecular ensemble at certain combinations of electric and magnetic fields leads to the formation of a magnetic Frenkel exciton. The exciton bandwidth can be tuned by varying the electric or magnetic fields. We show that the exciton states can be localized by creating vacancies in the optical lattice. The localiz…
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