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Quantum decoherence in finite size exciton-phonon systems
1Institut UTINAM, Université de Franche-Comté, CNRS UMR 6213, 25030 Besançon Cedex, France. vincent.pouthier@univ-fcomte.fr
The Journal of Chemical Physics
|March 25, 2011
Summary
Confinement softens quantum decoherence for confined excitons coupled with phonons. A specific exciton state acts as an ideal qubit, insensitive to its environment.
Area of Science:
- Condensed Matter Physics
- Quantum Optics
- Materials Science
Background:
- Exciton-phonon coupling is crucial for understanding optical and electronic properties of materials.
- Quantum decoherence limits the performance of quantum systems, especially at finite temperatures.
- Confinement effects can modify the behavior of quasiparticles like excitons.
Purpose of the Study:
- To investigate the properties of confined excitons coupled with phonons in thermal equilibrium.
- To analyze the time evolution of excitonic coherences under confinement and finite temperature.
- To identify conditions for robust quantum information processing using excitonic states.
Main Methods:
- Operatorial formulation of perturbation theory.
- Development of an effective Hamiltonian incorporating exciton-phonon entanglement.
- Analysis of the time evolution of excitonic coherences.
Main Results:
- Confinement softens temperature-enhanced quantum decoherence.
- Excitonic coherences exhibit state-dependent decay rates, slowing near the band center.
- For odd lattice sizes, a specific exciton state exhibits extremely long-lived coherence.
Conclusions:
- Confinement offers a route to mitigate decoherence in exciton-phonon systems.
- A unique superposition state involving the vacuum and a central exciton state functions as an environmentally-decoupled qubit.
- This finding has implications for developing robust quantum technologies.
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