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1. Models of G–spectra as presheaves of spectra

   https://doi.org/10.2140/agt.2024.24.1225  

   Guillou, Bertrand J; May, J Peter (January 2024, Algebraic & Geometric Topology)

   Greenlees, John (Ed.)

   Let G be a finite group. We give Quillen equivalent models for the category of G–spectra as categories of spectrally enriched functors from explicitly described domain categories to nonequivariant spectra. Our preferred model is based on equivariant infinite loop space theory applied to elementary categorical data. It recasts equivariant stable homotopy theory in terms of point–set-level categories of G–spans and nonequivariant spectra. We also give a more topologically grounded model based on equivariant Atiyah duality. 

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2. The Power Spectra of Polarized, Dusty Filaments

   https://doi.org/10.3847/1538-4357/ab9df9  

   Huffenberger, Kevin M.; Rotti, Aditya; Collins, David C. (August 2020, The Astrophysical Journal)

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3. The Buckling Spectra of Nanoparticle Surfactant Assemblies

   https://doi.org/10.1021/acs.nanolett.1c01454  

   Forth, Joe; Mariano, Andres; Chai, Yu; Toor, Anju; Hasnain, Jaffar; Jiang, Yufeng; Feng, Wenqian; Liu, Xubo; Geissler, Phillip L.; Menon, Narayanan; et al (September 2021, Nano Letters)
4. Polariton spectra under the collective coupling regime. II. 2D non-linear spectra

   https://doi.org/10.1063/5.0249705  

   Mondal, M Elious; Vamivakas, A Nickolas; Cundiff, Steven T; Krauss, Todd D; Huo, Pengfei (February 2025, The Journal of Chemical Physics)

   In our previous work [Mondal et al., J. Chem. Phys. 162, 014114 (2025)], we developed several efficient computational approaches to simulate exciton–polariton dynamics described by the Holstein–Tavis–Cummings (HTC) Hamiltonian under the collective coupling regime. Here, we incorporated these strategies into the previously developed Lindblad-partially linearized density matrix (L-PLDM) approach for simulating 2D electronic spectroscopy (2DES) of exciton–polariton under the collective coupling regime. In particular, we apply the efficient quantum dynamics propagation scheme developed in Paper I to both the forward and the backward propagations in the PLDM and develop an efficient importance sampling scheme and graphics processing unit vectorization scheme that allow us to reduce the computational costs from O(K2)O(T3) to O(K)O(T0) for the 2DES simulation, where K is the number of states and T is the number of time steps of propagation. We further simulated the 2DES for an HTC Hamiltonian under the collective coupling regime and analyzed the signal from both rephasing and non-rephasing contributions of the ground state bleaching, excited state emission, and stimulated emission pathways. 

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5. Polariton spectra under the collective coupling regime. I. Efficient simulation of linear spectra and quantum dynamics

   https://doi.org/10.1063/5.0243535  

   Mondal, M Elious; Vamivakas, A Nickolas; Cundiff, Steven T; Krauss, Todd D; Huo, Pengfei (January 2025, The Journal of Chemical Physics)

   We outline two general theoretical techniques to simulate polariton quantum dynamics and optical spectra under the collective coupling regimes described by a Holstein–Tavis–Cummings (HTC) model Hamiltonian. The first one takes advantage of sparsity of the HTC Hamiltonian, which allows one to reduce the cost of acting polariton Hamiltonian onto a state vector to the linear order of the number of states, instead of the quadratic order. The second one is applying the well-known Chebyshev series expansion approach for quantum dynamics propagation and to simulate the polariton dynamics in the HTC system; this approach allows us to use a much larger time step for propagation and only requires a few recursive operations of the polariton Hamiltonian acting on state vectors. These two theoretical approaches are general and can be applied to any trajectory-based non-adiabatic quantum dynamics methods. We apply these two techniques with our previously developed Lindblad-partially linearized density matrix approach to simulate the linear absorption spectra of the HTC model system, with both inhomogeneous site energy disorders and dipolar orientational disorders. Our numerical results agree well with the previous analytic and numerical work. 

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