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Generation and Coherent Control of Pulsed Quantum Frequency Combs
Published on: June 8, 2018
Correlated quantum shift vector of particle-hole excitations
Xu Yang1, Ajit Srivastava2, Justin C W Song3
1Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.
Nature Communications
|May 15, 2026
Summary
Bound excitons exhibit a unique quantum geometry with a polarization-independent shift vector. This contrasts with non-interacting excitations, offering a new diagnostic for particle-hole localization in materials.
Area of Science:
- Solid-state physics
- Quantum optics
- Materials science
Background:
- Electron interactions significantly influence material optical properties and excitation dynamics.
- Bound excitons, formed by electron-hole pairs, exhibit distinct spectral features due to their correlated nature.
Purpose of the Study:
- To investigate the quantum geometric properties of excitonic excitations.
- To demonstrate how the bound nature of excitons impacts their geometric response, specifically the quantum shift vector.
- To differentiate excitonic behavior from non-interacting particle-hole excitations.
Main Methods:
- Theoretical analysis of excitonic excitations and their quantum geometry.
- Investigation of the quantum shift vector's dependence on light polarization.
- Comparison of shift vectors for bound excitons versus delocalized particle-hole excitations.
Main Results:
- Bound excitons possess a quantum shift vector that is independent of light polarization.
- In noncentrosymmetric, non-polar materials, vertical excitonic transitions exhibit a vanishing shift vector, leading to zero shift photocurrent.
- Non-interacting delocalized particle-hole excitations display finite, polarization-dependent shift vectors.
Conclusions:
- The quantum shift vector serves as a critical diagnostic tool for distinguishing the localized nature of excitonic particle-hole pairs.
- Electron-electron interactions have non-perturbative effects on the quantum geometric response of excited states.
- This work highlights the importance of quantum geometry in understanding excited-state phenomena beyond spectral properties.
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