# Tokyo Metropolitan University physicists confirm chiral trions in carbon nanotubes

- Published: 2026-11-08 03:40 UTC
- Section: Science › Physics
- Tags: single wall carbon nanotubes, chiral trions, circular dichroism, Tokyo Metropolitan University, charged excitons, optics
- URL: https://realtech.media/news/rt-1c476d5c4a0503b606453d2c_tokyo_metropolitan_university/

**Researchers showed that charged three-body states in enantiopure carbon nanotubes inherit the chirality and circular dichroism of parent excitons.**

![Tokyo Metropolitan University physicists confirm chiral trions in carbon nanotubes](https://realtech.media/media/2026/11/af35f376516d6bf6.jpg)
*U.S. Department of Energy from United States, Wikimedia Commons, Public domain*

Physicists from Tokyo Metropolitan University have detected and measured the configurational circular dichroism of trions in enantiopure single-wall carbon nanotubes (SWCNTs), according to an experiment published in Nature Communications [1]. The team demonstrated that the structural handedness of the nanotubes directly governs the chiroptical response of charged three-body states, which consist of two electrons and one hole or two holes and one electron.

Circular dichroism occurs when a material interacts differently with left- and right-handed circularly polarized light [1]. While this property was previously documented for neutral excitons in chiral carbon nanotubes, it remained unverified whether adding an extra free charge would disrupt the structural optical signature. Using enantiomerically separated right- and left-handed SWCNT samples, the team generated trions through electrochemical carrier injection and measured their optical absorption spectra [1].

## Chirality in three-body bound states

The spectroscopic measurements confirmed that the sign of the trion circular dichroism corresponds directly to the handedness of the underlying carbon nanotube [1]. In addition, the trion circular dichroism exhibited the same sign and roughly the same magnitude as that observed for the original neutral excitons. The Coulomb-bound three-body system therefore preserves the structural chiroptical response intact, without degradation from the additional charge carrier [1].

## Potential for optical modulation

Prior observations of circular dichroism in trions relied entirely on spin selection rules, such as those found in quantum dots or monolayer transition metal dichalcogenides [1]. The Tokyo experiment confirms the first direct observation of configurational circular dichroism arising strictly from the spatial lattice chirality of the nanotube host. Because trion populations can be tuned directly by injecting electrons or holes into SWCNTs, the authors noted this provides a pathway for electrochemically or electrically controlling interactions with polarized light [1].

## Sources

1. [Nature Communications](https://doi.org/10.1038/s41467-026-78073-z)
2. [EurekAlert](https://www.eurekalert.org/news-releases/1150454)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-1c476d5c4a0503b606453d2c_tokyo_metropolitan_university/