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Intelligent infrared sensing enabled by tunable moiré quantum geometry.

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Researchers observed tunable mid-infrared bulk photovoltaic effect (BPVE) in twisted double bilayer graphene. This quantum geometric phenomenon, driven by moiré patterns, enables compact, on-chip polarimetry and sensing.

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Area of Science:

  • Condensed matter physics
  • Quantum geometry
  • Nonlinear optics

Background:

  • Quantum geometric properties like Berry curvature influence electron behavior in solids.
  • The bulk photovoltaic effect (BPVE) is a nonlinear optical phenomenon governed by quantum geometry.
  • Infrared BPVE has not been observed in graphene or moiré systems previously.

Purpose of the Study:

  • To observe and characterize tunable mid-infrared BPVE in twisted double bilayer graphene (TDBG).
  • To investigate the role of moiré-induced symmetry breaking and quantum geometry in nonlinear light-matter interactions.
  • To demonstrate a novel sensing platform for polarimetry and wavelength detection.

Main Methods:

  • Fabrication and characterization of twisted double bilayer graphene (TDBG) devices.
  • Measurement of mid-infrared photoresponse at 5 µm and 7.7 µm.
  • Application of convolutional neural networks for simultaneous full-Stokes polarimetry and wavelength detection.

Main Results:

  • Observation of tunable mid-infrared BPVE in TDBG, tunable by external electric fields.
  • Photoresponse demonstrated strong dependence on excitation light polarization.
  • A single TDBG device with a 3x3 µm² footprint achieved simultaneous polarimetry and wavelength detection.

Conclusions:

  • Moiré-engineered quantum geometry plays a crucial role in tunable nonlinear light-matter interactions.
  • TDBG offers a promising platform for exploring quantum geometric effects in nonlinear optics.
  • The developed device provides a pathway for compact, on-chip intelligent sensing technologies.