Exciton-Polariton Quantum Simulators

Alexey Vitalievich Kavokin, D. Novokreschenov, Stella Kavokina

We study the dynamics of two‐bosonic condensates of exciton–polaritons confined in coupled elliptical traps. Within the mean field approximation the system is described by a generalized two‐body Schrödinger equation that accounts for the pumping of polaritons to the coupled condensates from two independent exciton reservoirs. The system is conveniently described by a truncated 4 x 4 density matrix. Applying a pair of control optical pulses, we demonstrate how coherent interactions between the condensates transform the system from an initial separable pure state with zero entanglement (negativity = 0) to an entangled state characterized by negativity close to 0.5. This study underscores the high potentiality of exciton–polariton systems for analog and quantum simulations and paves the way for the realization of ultrafast, many‐body quantum computation platforms.

Dimitris G. Angelakis

Rajanya Sarkar, Pritha Ghosh, Arshath Manjalingal +2 more

Exciton-polaritons, hybrid light-matter quasiparticles formed when a material interacts with a confined electric field, have experimentally been shown to exhibit mesoscale coherent quantum propagation that remains robust at room temperature. However, an accurate and direct quantum dynamical simulation of this phenomenon that does not resort to semi-classical approximations is prohibitively expensive computationally, limiting the microscopic understanding of the rich dynamical interplay among phonons, photons, and electrons under collective light-matter coupling. To address this fundamental challenge, we develop a non-Markovian master equation approach which enables the fully quantum mechanical simulation of non-equilibrium exciton-polariton dynamics and captures phonon-induced decoherence and dissipation beyond the conventional Markovian limit. To carry out this task, a procedure is developed in which the wave vector space is coarse-grained and each diagonal element of the density matrix is evolved in parallel. To demonstrate the utility of this approach, we simulate exciton-polariton transport in TIPS-pentacene. We find that our approach reasonably captures the experimentally observed renormalization of the polariton group velocity, which originates from the phonon-induced non-Markovian Lamb shift. We further show that this renormalization cannot be reproduced within conventional Markovian theories.

Y. Yamamotoa, Joseph M. Jacobson, Stanley Pau +2 more

Alán Aspuru‐Guzik, Philip John Walther

Ian Haines, Arshath Manjalingal, Logan Blackham +2 more

Exciton-polaritons are light-matter hybrid quasi-particles that have emerged as a flexible platform for developing quantum technologies and engineering material properties. However, the fundamental mechanistic principles that govern their dynamics and relaxation remain elusive. In this work, we provide the microscopic mechanistic understanding of the exciton-polariton relaxation process that follows from an excitation in the upper polariton. Using both mixed quantum-classical simulations and analytical analysis, we reveal that phonon-induced upper-to-lower polariton relaxation proceeds via two steps: the first step is a vertical inter-band transition from the upper to the lower polariton, which is followed by a second step that is a phonon-induced Fröhlich scattering within the lower polariton. We find that in materials of finite thickness (which include filled cavities), phonon-induced polaritonic intraband Fröhlich scattering is significantly suppressed. We show that the microscopic origin of this suppression is phonon-fluctuations synchronization (or self-averaging) due to the polaritonic spatial delocalization in the quantization direction. Finally, we show that the same phonon fluctuation-synchronization effect plays a central role across polaritonic relaxation pathways, and we derive simple analytical expressions that relate a material's finite thickness to the corresponding relaxation rate constants.