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Optical Signatures of Dynamical Excitonic Condensates
Alexander Osterkorn1, Yuta Murakami2, Tatsuya Kaneko3
1Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia.
Physical Review Letters
|September 22, 2025
Summary
This study reveals how optical spectroscopy can distinguish between phase-trapped and phase-delocalized dynamical excitonic condensates. The findings show distinct absorption lines and harmonic responses, aiding experimental identification.
Area of Science:
- Condensed matter physics
- Quantum optics
- Materials science
Background:
- Dynamical excitonic condensates are exotic quantum states.
- Understanding their dynamics is crucial for novel electronic and optical applications.
- Experimental identification of different condensation regimes remains challenging.
Purpose of the Study:
- To theoretically investigate dynamical excitonic condensates in bilayers and photodoped semiconductors.
- To establish optical spectroscopy as a tool for identifying distinct dynamical regimes.
- To analyze the influence of chemical potential difference and bias voltage on condensate dynamics.
Main Methods:
- Theoretical study of excitonic condensates.
- Analysis of optical spectroscopy signatures.
- Investigation of phase-trapped and phase-delocalized dynamics.
- Comparison with a minimal model for phase dynamics.
Main Results:
- Optical spectroscopy can differentiate between phase-trapped and phase-delocalized regimes.
- Weak bias shows an in-gap absorption line nearly independent of voltage.
- Larger biases exhibit a linear increase in spectral feature frequency with bias.
- A strong response is observed near the transition to freely oscillating states.
- Pronounced second-harmonic response is present in both regimes.
Conclusions:
- Optical spectroscopy provides experimental signatures for dynamical excitonic condensate regimes.
- The study clarifies the relationship between bias voltage and spectral features.
- Findings offer a pathway for experimental realization and control of excitonic condensates.
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