Programmable Excitonic Materials

• Programmable excitonic materials are condensed-matter systems where excitons are externally tuned via electric fields, doping, strain, and nanostructuring for optical and quantum control.
• They utilize diverse platforms such as 2D heterostructures, metasurfaces, and moiré superlattices to achieve reconfigurable optical modulation, exciton routing, and topological transport.
• Advances in experimental and theoretical methods, including multi-oscillator and Floquet models, enable precise control of exciton dynamics for applications in photonics and quantum simulation.

Programmable excitonic materials are condensed-matter systems in which the properties and dynamics of excitons—bound electron–hole pairs—can be externally tuned or dynamically reconfigured, allowing user-defined control of optical response, many-body interactions, topological phases, and quantum information functionality. Advances in device engineering, photonic integration, and external field control have rapidly expanded the scope of excitonic programmability, spanning 0D–3D geometries, organic and inorganic systems, and regimes from weakly to strongly correlated excitons. This enables functions such as reconfigurable optical modulation, quantum state manipulation, topological transport, programmable nonlinear photonics, and quantum simulation.

1. Physical Mechanisms for Exciton Programmability

Exciton programmability arises from a suite of physical control knobs that modulate exciton energy, spatial distribution, lifetime, interaction strength, or quantum phase:

• External Electric Field: Stark-effect tuning of the emission energy via direct dipole coupling, and field-induced carrier separation that enables control over the exciton dipole length, in-plane Bohr radius, and binding energy. Lateral and vertical fields can generate programmable potential landscapes for excitons (Peterson et al., 2024, Sun et al., 31 Jan 2026, Baghdasaryan et al., 2021).
• Carrier Density and Doping: Electrical gating modulates free-carrier concentration, enabling continuous tuning between neutral and charged excitonic states, and directly impacting nonradiative decay rates, transition dipoles, and oscillator strengths (Hoekstra et al., 17 Feb 2025, Peterson et al., 2024).
• Strain Engineering: Both in-plane and out-of-plane strain modify electronic band alignment, lattice registry, and exciton confinement, enabling tuning of site energies in moiré superlattices or quantum wells (Yu et al., 2017, Jankowski et al., 2024).
• Optical Floquet Engineering: Periodic driving with off-resonant fields coherently dresses excitonic states, providing control over superposition and enabling ultrafast quantum logic operations on many-body wavefunctions (Baykusheva et al., 27 Jan 2026).
• Nano-photonic and Plasmonic Structuring: Lithographically defining resonators, gratings, and metasurfaces imparts spatial, spectral, and coupling selectivity to excitonic-photonic hybrid modes, affording precise control of Rabi splitting, polariton lifetime, and directionality (Zhang et al., 2019, Hoekstra et al., 17 Feb 2025).
• Material Design: Heterostructure layer sequence, composition, organic/inorganic hybridization, and quantum well parameters serve as “static” programming knobs for bandgap, binding energy, and interaction nonlinearity (Baghdasaryan et al., 2021, Bernardi et al., 2012, Jankowski et al., 2024).

2. Device Architectures and Experimental Platforms

Programmable excitonic materials are realized in a wide diversity of platforms, as summarized below:

Platform Type	Control Knob(s)	Notable Phenomena/Applications
2D TMDC Heterostructures	Gate-defined E-field, twist angle	Dynamical Stark shifts, emission/lifetime tuning, routing networks (Peterson et al., 2024, Liu et al., 2019)
Patterned Gratings (e.g. WS₂/Au)	Litho-defined {t,p,w}, gating	Programmable polariton dispersions, switchable “invisible” modes (Zhang et al., 2019)
Hybrid 2D Metasurfaces (WS₂/dielectric grating)	Electrostatic gating	On-demand transition strong/weak coupling, optical modulation (Hoekstra et al., 17 Feb 2025)
Moiré Superlattices (TMD bilayers)	Vertical field, strain	Tunable emitter arrays ↔ 2D lattices, programmable SOC/topology (Yu et al., 2017)
Chiroptical heterostructures (CNT/PCM)	Phase change, design software	Electrically reprogrammable, reciprocal/nonreciprocal CD (Fan et al., 2024)
Tetralayer Heterostructures	Dual gate, layer design	Continuous tuning of dipole/a_B/E_b, control of quantum phases (Sun et al., 31 Jan 2026)
Organic Polymers/Nanoribbons	Chain/side-group design, strain, substrate	Excitonic topology and geometry switching (Jankowski et al., 2024)
Excitonic Mott Insulators (Nb₃Cl₈)	Local gates, interferometric mesh	Programmable high-order multiphoton generation (Skachkov et al., 1 Dec 2025)
C–BN Monolayer Solar Cells	Stripe width (“domain engineering”)	Tunable optical bandgap and band alignment (Bernardi et al., 2012)

Each platform leverages unique, sometimes complementary, degrees of freedom. Device architectures include dual- or multi-gate field effect transistors, patterned metal/dielectric nanostructures, integrated on-chip waveguides with reconfigurable splitters, and phase-change stacks with logic-controlled heating.

3. Theoretical Frameworks for Programmable Excitonics

Programmability is enabled and analyzed via a range of theoretical and computational frameworks:

• Multi-Oscillator Hamiltonians: Exciton–photon–plasmon coupling in patterned multilayer semiconductors is captured by coupled oscillator Hamiltonians with control parameters t, p, w, and external perturbations (Zhang et al., 2019).

$$H_{\rm 3osc} = \begin{pmatrix} E_G(k_x) & g_{G-U} & 0 \ g_{G-U} & E_{UEP} & g_{U-L} \ 0 & g_{U-L} & E_{LEP} \end{pmatrix}$$

• Jaynes–Cummings Models: Describe hybridization in strong-coupling systems, e.g., metasurfaces, with voltage-controlled decay rates and Rabi splitting (Hoekstra et al., 17 Feb 2025).
• Tight-Binding and Superlattice Theory: Governs exciton wave-packet dynamics, transport, and mini-band engineering in quantum dot chains and superlattices, with external field or lattice segmentation as control parameters (Zang et al., 2016, Yu et al., 2017).
• Floquet Hamiltonians: Offer a control-centric description of driven correlated excitons, allowing programmable rotations on excitonic Bloch spheres (Baykusheva et al., 27 Jan 2026).
• Quantum Geometric/TOPological Invariants: Quantify programmable excitonic topology and spatial spread via Zak phase, quantum metric tensor, and their dependence on chain geometry, strain, and environment (Jankowski et al., 2024).
• Nonlinear Susceptibility Tensor Models: Enable design of programmable multi-photon nonlinear optical sources, with gate-controlled susceptibilities and phase-matching (Skachkov et al., 1 Dec 2025).

Computationally, device- and property-specific design uses DFT, GW-BSE, ab initio modeling, real-time TDDFT, and gradient-based architectural optimization (Fan et al., 2024, Bernardi et al., 2012).

4. Functionalities and Applications

Programmable excitonic materials enable a spectrum of optoelectronic, photonic, and quantum information functionalities, including:

• Low-power optical modulators: Gate-tunable reflectance/absorption via strong–weak coupling modulation, e.g., 9.9 dB reflectance modulation with sub-μm footprints (Hoekstra et al., 17 Feb 2025).
• Excitonic routers and logic elements: All-electrical exciton steering in 2D and 1D architectures for on-chip signal processing; real-space programming of source/drain paths and multi-port networks with sub-5 ns latency and >10⁵ reconfigurations/s (Liu et al., 2019).
• Dynamic quantum-state control: Floquet-engineered ultrafast (sub-100 fs) gate operations for superpositions of correlated exciton states (Baykusheva et al., 27 Jan 2026).
• Chiroptical reconfiguration: Electrically switchable, broadband circular dichroism in scalable, layered CNT–PCM stacks, exceeding 7° modulation, with reciprocal and front–back nonreciprocal programmability (Fan et al., 2024).
• Topological transport: In situ tuning between localized quantum emitters and 2D topological lattices with Dirac/Weyl points, gapped/spin-polarized edge states, and programmable spin–orbit splitting (Yu et al., 2017, Jankowski et al., 2024).
• Tunable nonlinearity and quantum light sources: Monolayer Nb₃Cl₈ supporting electrically programmable χ^{(4)}, χ^{(5)}, and higher, with cluster/GHZ state generation at rates 10⁶–10⁸× conventional media (Skachkov et al., 1 Dec 2025).
• Photovoltaic response engineering: C–BN monolayers with bandgaps, binding energy, and donor–acceptor offsets programmable over broad ranges by lateral domain size, yielding efficiency tuning from 10–20% (Bernardi et al., 2012).

5. Key Performance Metrics and Design Guidelines

Design and performance parameters are platform-specific and include:

• Energy and Tuning Range: Stark-induced energy shifts up to 200 meV (MoSe₂/WSe₂), with typical dynamic ranges of several meV for sub-20 ns switching (Peterson et al., 2024, Sun et al., 31 Jan 2026).
• Speed and Modulation Bandwidth: Sub-20 ns electrical switching (RC-limited), optical modulation bandwidths >MHz (presently limited by contact resistance), and ms-scale phase-switching in phase-change chiroptical stacks (Hoekstra et al., 17 Feb 2025, Fan et al., 2024).
• Lifetime and Coherence: Exciton lifetimes up to hundreds of ns in interlayer systems, with coherent optical operations on picosecond to femtosecond timescales (Baykusheva et al., 27 Jan 2026, Peterson et al., 2024).
• Nonlinearity (χ^{(n)}) and Quantum Yield: χ^{(4)} in Nb₃Cl₈ up to 2.2×10⁻²⁴ (m/V)³ (five orders of magnitude above MoS₂), enabling n-photon entanglement at unprecedented rates (Skachkov et al., 1 Dec 2025).
• Scalability and Device Footprint: Vertical stacking, wafer-scale assembly, and large-area processing compatible with photolithography, supporting future integrated excitonic circuits (Fan et al., 2024, Hoekstra et al., 17 Feb 2025).

Best-practice design involves maximizing optical field overlap, optimizing gating geometry for bandwidth, leveraging high-index metasurfaces for strong coupling, and ensuring stable, reproducible tuning via environmental encapsulation or phase-change protocols.

6. Outlook: Open Directions and Quantum Simulation

Programmable excitonic materials serve as a general platform for exploring bosonic many-body physics, topological photonics, ultrafast quantum information, and new optoelectronic functionalities:

• Exciton-based quantum simulators access a continuum of phase diagrams, including Mott transitions, dipolar crystals, and correlated BEC regimes, by combining control of density, dipole moment, and spatial geometry (Sun et al., 31 Jan 2026, Baghdasaryan et al., 2021).
• Reconfigurable topological photonics leverages programmable lattice potentials, gauge fields, and Berry curvature to realize optically accessible Chern phases and robust exciton edge modes (Yu et al., 2017, Jankowski et al., 2024).
• Neuromorphic and logic circuits exploit programmable polariton or excitonic couplings for thresholding nonlinearities and signal routing (Zhang et al., 2019).
• Integrated quantum light sources benefit from programmable nonlinearities and reconfigurable interferometric networks, enabling on-demand multi-photon entanglement (Skachkov et al., 1 Dec 2025).

Programmability in excitonic materials continues to expand with advances in heterostructure assembly, phase-change integration, multi-gate electronics, and inverse device design, charting a trajectory toward complex, on-chip exciton-based photonic and quantum information technologies.