Periodic Reporting for period 1 - QuMeta (Space-time quantum metasurfaces with two-dimensional layered materials)
Reporting period: 2023-06-01 to 2025-05-31
The project is positioned at the frontier of quantum photonics and metasurface engineering, addressing urgent global challenges in information and communication technologies. With the exponential growth of data traffic and the rise of 6G networks, artificial intelligence, and quantum information systems, there is an increasing demand for ultrafast, energy-efficient, and reconfigurable photonic devices. Existing platforms, however, face intrinsic limitations: electronic systems suffer from bandwidth and power bottlenecks, while current optical devices are typically narrowband and static, unable to adapt to dynamically evolving requirements.
To overcome these constraints, the project set out to establish a new paradigm of space–time quantum metasurfaces based on graphene and other two-dimensional (2D) materials. These metasurfaces—engineered arrays of nanostructured and electrically gated elements—enable active, multidimensional control of light fields (amplitude, phase, frequency, and polarization), unlocking powerful capabilities to manipulate both classical and quantum states of light. In particular, they promise dynamic control of quantum entanglement, a key functionality for next-generation secure communication, advanced sensing, and quantum computing technologies.
The specific objectives were defined as follows:
• Objective 1 – Theoretical design: Develop algorithms and models for metasurfaces, enabling on-demand control of electromagnetic waves across multiple harmonics and modes.
• Objective 2 – Fabrication: Realize graphene-based space–time metasurfaces through advanced nanofabrication, exploiting gate tunability to achieve atomically thin, reconfigurable platforms.
• Objective 3 – Applications: Demonstrate proof-of-concept in quantum imaging and light manipulation, highlighting the distinctive functionalities of space–time metasurfaces beyond conventional optics.
The pathway to impact was deliberately aligned with broader political and strategic priorities. The European Union’s digital and green transitions depend on cutting-edge photonic technologies to ensure secure communications, sustainable data processing, and energy-efficient infrastructures. By providing CMOS-compatible, ultrathin, and multifunctional devices, this project contributes directly to Europe’s ambition to lead globally in 6G, quantum communication, and advanced photonic sensing systems.
The scale and significance of impact are considerable:
• Scientific impact: A fundamentally new platform for nonlinear and non-Hermitian photonics, granting experimental access to phenomena such as exceptional points and singularity-enhanced sensing.
• Technological impact: Concepts demonstrated here can evolve into compact, integrable devices for THz communication, quantum imaging, and on-chip photonic computing.
• Societal impact: The technologies developed can strengthen future infrastructures for secure digital communication, healthcare monitoring, and intelligent sensing, thereby improving resilience and wellbeing in Europe and worldwide.
In summary, the project has laid the foundation for a disruptive class of active quantum metasurfaces, bridging physics, materials science, and engineering. The outcomes are expected to shape the trajectory of quantum photonics and 6G technologies, positioning Europe at the forefront of scientific and technological innovation.
To overcome these constraints, the project set out to establish a new paradigm of space–time quantum metasurfaces based on graphene and other two-dimensional (2D) materials. These metasurfaces—engineered arrays of nanostructured and electrically gated elements—enable active, multidimensional control of light fields (amplitude, phase, frequency, and polarization), unlocking powerful capabilities to manipulate both classical and quantum states of light. In particular, they promise dynamic control of quantum entanglement, a key functionality for next-generation secure communication, advanced sensing, and quantum computing technologies.
The specific objectives were defined as follows:
• Objective 1 – Theoretical design: Develop algorithms and models for metasurfaces, enabling on-demand control of electromagnetic waves across multiple harmonics and modes.
• Objective 2 – Fabrication: Realize graphene-based space–time metasurfaces through advanced nanofabrication, exploiting gate tunability to achieve atomically thin, reconfigurable platforms.
• Objective 3 – Applications: Demonstrate proof-of-concept in quantum imaging and light manipulation, highlighting the distinctive functionalities of space–time metasurfaces beyond conventional optics.
The pathway to impact was deliberately aligned with broader political and strategic priorities. The European Union’s digital and green transitions depend on cutting-edge photonic technologies to ensure secure communications, sustainable data processing, and energy-efficient infrastructures. By providing CMOS-compatible, ultrathin, and multifunctional devices, this project contributes directly to Europe’s ambition to lead globally in 6G, quantum communication, and advanced photonic sensing systems.
The scale and significance of impact are considerable:
• Scientific impact: A fundamentally new platform for nonlinear and non-Hermitian photonics, granting experimental access to phenomena such as exceptional points and singularity-enhanced sensing.
• Technological impact: Concepts demonstrated here can evolve into compact, integrable devices for THz communication, quantum imaging, and on-chip photonic computing.
• Societal impact: The technologies developed can strengthen future infrastructures for secure digital communication, healthcare monitoring, and intelligent sensing, thereby improving resilience and wellbeing in Europe and worldwide.
In summary, the project has laid the foundation for a disruptive class of active quantum metasurfaces, bridging physics, materials science, and engineering. The outcomes are expected to shape the trajectory of quantum photonics and 6G technologies, positioning Europe at the forefront of scientific and technological innovation.
The project progressed through three main research thrusts, each addressing a critical scientific and technological challenge. The focus was placed on the design, fabrication, and demonstration of tunable metasurfaces using graphene, carbon nanotubes, MXenes, and Moiré architectures. The key outcomes are summarized below.
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(i) Graphene metasurfaces for spatial control and optical encryption
Activities performed:
Graphene was targeted as a tunable platform for spatial electromagnetic wave manipulation. Two complementary research directions were pursued:
Graphene-based transparent metasurfaces for EM stealth – A multi-layer graphene metasurface was designed and fabricated to achieve cross-band stealth simultaneously in the microwave and terahertz regimes. Unlike conventional absorbers limited to narrow bands, the design integrated resonant absorption in the microwave band with diffuse scattering in the terahertz band, while maintaining optical transparency suitable for applications such as aircraft windshields and solar panels.
Metasurface-enabled optical encryption – Metasurfaces were explored as physical platforms for information security. An incoherent one-time pad (OTP) encryption system was developed, combining metasurface-generated ciphertext with dynamic visual keys realized via a spatial light modulator. This paradigm merges the theoretically unbreakable security of OTP with the physical encoding capabilities of metasurfaces, creating a robust, parallel, and light-speed encryption scheme highly resistant to brute-force or correlation attacks.
Main achievements:
Cross-band graphene metasurface stealth demonstrated >15 dB absorption reduction in microwave frequencies and ~20 dB radar cross-section reduction in THz bands, validated by simulations and experiments.
The world’s first metasurface-based incoherent OTP encryption was realized, introducing a secure physical layer for optical communication systems.
Graphene metasurfaces were pioneered not only for EM control but also for secure information processing, expanding their impact beyond classical photonics.
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(ii) Carbon nanotubes and MXenes for hyperband wave control
Activities performed:
To extend functionalities beyond graphene, emerging carbon-based nanomaterials and MXenes were systematically investigated as building blocks for metasurfaces.
All-carbon nanotube (CNT) metasurfaces – A wafer-scale, lithography-free fabrication process was developed to integrate all-CNT photodetector arrays. Using laser-assisted patterning and dry deposition, CNTs were directly assembled into flexible substrates without wet processing. These CNT arrays exhibited high responsivity (44 A/W) and broadband photoresponse spanning from visible to infrared, demonstrating their capability as tunable and wearable optoelectronic elements.
MXene-based metasurfaces – The instability of MXenes (e.g. oxidation and aggregation) was addressed by employing lignin as a bioderived surfactant/intercalant. This innovation enabled sub-nanometer precision in interlayer spacing tuning and significantly improved colloidal stability and oxidation resistance. The resulting MXene–lignin complexes allowed the fabrication of films with tunable conductivity, infrared emissivity, and EMI shielding effectiveness, opening pathways for multifunctional EM applications.
Hyperband synergistic metadevice – By combining CNT-based meta-atoms, MXene composites, and hierarchical architectures, a multi-scale metadevice was designed to operate across the entire non-ionizing electromagnetic spectrum, from microwave through THz to optical bands. This hyperband device demonstrated three integrated functions in one compact platform: microwave absorption, THz beam steering, and optical transparency.
Main achievements:
Scalable, wafer-level integration of CNT devices into metasurfaces with demonstrated broadband photodetection and mechanical flexibility.
Stable and tunable MXene–lignin composites providing new degrees of freedom for controlling EM properties across multiple bands.
First demonstration of a hyperband synergistic metadevice, bridging microwave, THz, and optical functionalities in one integrated device.
Establishment of a multi-material platform enabling cross-band, multi-functional EM control that surpasses the inherent narrowband limits of conventional metasurfaces.
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(iii) Moiré metasurfaces for nonlinear and ultrafast electromagnetic control
Activities performed:
The original proposal emphasized time-modulated metasurfaces for dynamic wavefront shaping. Practical limitations arose due to insufficient modulation speeds of available electronic gating systems. To overcome this bottleneck, a new strategy was adopted: exploiting nonlinear ultrafast optical processes and Moiré engineering to emulate spatiotemporal modulation.
Nonlinear physics of Moiré superlattices – In collaboration with international partners, the field of nonlinear Moiré physics was advanced, identifying key phenomena such as twist-angle-tunable harmonic generation, nonlinear Hall effects, low-power optical solitons, and photogalvanic effects. These studies positioned Moiré structures as highly tunable quantum platforms for nonlinear optics.
Graphene Moiré metasurfaces for THz control – Graphene strip metasurfaces with controlled twist angles (5°–20°) and integrated electrical gating were fabricated to create Moiré superlattices. Measurements using a THz 4F system with a Keysight E5071 analyzer and WR1.5 antennas revealed independent control over amplitude, phase, and polarization of reflected THz waves.
Observation of exceptional points (EPs) – By tuning the Moiré angle and Fermi level, the emergence of non-Hermitian degeneracies (EPs) in Moiré metasurfaces was experimentally demonstrated, validated by scattering matrix analysis and beam control experiments. This represents one of the first demonstrations of EPs in a graphene-based Moiré platform.
Main achievements:
Establishment of Moiré metasurfaces as a practical route to achieve ultrafast and nonlinear functionalities, bypassing the limitations of direct time modulation.
Demonstration of dynamic and independent control of THz amplitude, frequency, and polarization, confirming the versatility of graphene Moiré architectures.
Provision of the first experimental evidence of exceptional points in Moiré metasurfaces, linking non-Hermitian photonics with 2D material platforms.
Creation of a strong conceptual and experimental foundation for future space–time quantum metasurfaces, as initially envisioned in the proposal.
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(iv) Work Challenges
The project initially pursued time-modulated metasurfaces through ionic-liquid gating of graphene. While this method significantly expanded the accessible Fermi level tuning range compared to conventional solid-state gating, its chemical nature meant that modulation relied on ion migration, which is inherently slow. As a result, despite achieving large tunability, the modulation speed was far below the optical and terahertz frequencies required for genuine time modulation, preventing direct realization of proposal-level space–time metasurfaces.
To address this limitation, Moiré engineering and ultrafast nonlinear processes were adopted as alternative strategies. Twisted graphene Moiré metasurfaces enabled independent tuning of terahertz amplitude, phase, and polarization, while nonlinear effects such as high-harmonic generation provided ultrafast dynamic responses. These advances culminated in the first experimental observation of exceptional points in graphene Moiré metasurfaces, establishing a strong foundation for non-Hermitian photonics. Although quantum-level tests, such as entangled photon manipulation, could not yet be realized due to the slow modulation speed and demanding experimental infrastructure, the project laid the essential groundwork for future quantum demonstrations.
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Overall summary:
The project advanced from graphene-based metasurface spatial control and encryption, to hyperband multi-material metadevices using CNTs and MXenes, and finally to nonlinear Moiré metasurfaces for ultrafast THz manipulation and exceptional point physics. These achievements opened unanticipated directions in secure communication, wearable optoelectronics, and non-Hermitian photonics, significantly broadening the project’s scientific and technological impact.
-----------------------------------------------
(i) Graphene metasurfaces for spatial control and optical encryption
Activities performed:
Graphene was targeted as a tunable platform for spatial electromagnetic wave manipulation. Two complementary research directions were pursued:
Graphene-based transparent metasurfaces for EM stealth – A multi-layer graphene metasurface was designed and fabricated to achieve cross-band stealth simultaneously in the microwave and terahertz regimes. Unlike conventional absorbers limited to narrow bands, the design integrated resonant absorption in the microwave band with diffuse scattering in the terahertz band, while maintaining optical transparency suitable for applications such as aircraft windshields and solar panels.
Metasurface-enabled optical encryption – Metasurfaces were explored as physical platforms for information security. An incoherent one-time pad (OTP) encryption system was developed, combining metasurface-generated ciphertext with dynamic visual keys realized via a spatial light modulator. This paradigm merges the theoretically unbreakable security of OTP with the physical encoding capabilities of metasurfaces, creating a robust, parallel, and light-speed encryption scheme highly resistant to brute-force or correlation attacks.
Main achievements:
Cross-band graphene metasurface stealth demonstrated >15 dB absorption reduction in microwave frequencies and ~20 dB radar cross-section reduction in THz bands, validated by simulations and experiments.
The world’s first metasurface-based incoherent OTP encryption was realized, introducing a secure physical layer for optical communication systems.
Graphene metasurfaces were pioneered not only for EM control but also for secure information processing, expanding their impact beyond classical photonics.
-----------------------------------------------------------------------
(ii) Carbon nanotubes and MXenes for hyperband wave control
Activities performed:
To extend functionalities beyond graphene, emerging carbon-based nanomaterials and MXenes were systematically investigated as building blocks for metasurfaces.
All-carbon nanotube (CNT) metasurfaces – A wafer-scale, lithography-free fabrication process was developed to integrate all-CNT photodetector arrays. Using laser-assisted patterning and dry deposition, CNTs were directly assembled into flexible substrates without wet processing. These CNT arrays exhibited high responsivity (44 A/W) and broadband photoresponse spanning from visible to infrared, demonstrating their capability as tunable and wearable optoelectronic elements.
MXene-based metasurfaces – The instability of MXenes (e.g. oxidation and aggregation) was addressed by employing lignin as a bioderived surfactant/intercalant. This innovation enabled sub-nanometer precision in interlayer spacing tuning and significantly improved colloidal stability and oxidation resistance. The resulting MXene–lignin complexes allowed the fabrication of films with tunable conductivity, infrared emissivity, and EMI shielding effectiveness, opening pathways for multifunctional EM applications.
Hyperband synergistic metadevice – By combining CNT-based meta-atoms, MXene composites, and hierarchical architectures, a multi-scale metadevice was designed to operate across the entire non-ionizing electromagnetic spectrum, from microwave through THz to optical bands. This hyperband device demonstrated three integrated functions in one compact platform: microwave absorption, THz beam steering, and optical transparency.
Main achievements:
Scalable, wafer-level integration of CNT devices into metasurfaces with demonstrated broadband photodetection and mechanical flexibility.
Stable and tunable MXene–lignin composites providing new degrees of freedom for controlling EM properties across multiple bands.
First demonstration of a hyperband synergistic metadevice, bridging microwave, THz, and optical functionalities in one integrated device.
Establishment of a multi-material platform enabling cross-band, multi-functional EM control that surpasses the inherent narrowband limits of conventional metasurfaces.
-----------------------------------------------------------------------------------------------------------------
(iii) Moiré metasurfaces for nonlinear and ultrafast electromagnetic control
Activities performed:
The original proposal emphasized time-modulated metasurfaces for dynamic wavefront shaping. Practical limitations arose due to insufficient modulation speeds of available electronic gating systems. To overcome this bottleneck, a new strategy was adopted: exploiting nonlinear ultrafast optical processes and Moiré engineering to emulate spatiotemporal modulation.
Nonlinear physics of Moiré superlattices – In collaboration with international partners, the field of nonlinear Moiré physics was advanced, identifying key phenomena such as twist-angle-tunable harmonic generation, nonlinear Hall effects, low-power optical solitons, and photogalvanic effects. These studies positioned Moiré structures as highly tunable quantum platforms for nonlinear optics.
Graphene Moiré metasurfaces for THz control – Graphene strip metasurfaces with controlled twist angles (5°–20°) and integrated electrical gating were fabricated to create Moiré superlattices. Measurements using a THz 4F system with a Keysight E5071 analyzer and WR1.5 antennas revealed independent control over amplitude, phase, and polarization of reflected THz waves.
Observation of exceptional points (EPs) – By tuning the Moiré angle and Fermi level, the emergence of non-Hermitian degeneracies (EPs) in Moiré metasurfaces was experimentally demonstrated, validated by scattering matrix analysis and beam control experiments. This represents one of the first demonstrations of EPs in a graphene-based Moiré platform.
Main achievements:
Establishment of Moiré metasurfaces as a practical route to achieve ultrafast and nonlinear functionalities, bypassing the limitations of direct time modulation.
Demonstration of dynamic and independent control of THz amplitude, frequency, and polarization, confirming the versatility of graphene Moiré architectures.
Provision of the first experimental evidence of exceptional points in Moiré metasurfaces, linking non-Hermitian photonics with 2D material platforms.
Creation of a strong conceptual and experimental foundation for future space–time quantum metasurfaces, as initially envisioned in the proposal.
---------------------------------------------------------------------
(iv) Work Challenges
The project initially pursued time-modulated metasurfaces through ionic-liquid gating of graphene. While this method significantly expanded the accessible Fermi level tuning range compared to conventional solid-state gating, its chemical nature meant that modulation relied on ion migration, which is inherently slow. As a result, despite achieving large tunability, the modulation speed was far below the optical and terahertz frequencies required for genuine time modulation, preventing direct realization of proposal-level space–time metasurfaces.
To address this limitation, Moiré engineering and ultrafast nonlinear processes were adopted as alternative strategies. Twisted graphene Moiré metasurfaces enabled independent tuning of terahertz amplitude, phase, and polarization, while nonlinear effects such as high-harmonic generation provided ultrafast dynamic responses. These advances culminated in the first experimental observation of exceptional points in graphene Moiré metasurfaces, establishing a strong foundation for non-Hermitian photonics. Although quantum-level tests, such as entangled photon manipulation, could not yet be realized due to the slow modulation speed and demanding experimental infrastructure, the project laid the essential groundwork for future quantum demonstrations.
------------------------------------------------------------------------
Overall summary:
The project advanced from graphene-based metasurface spatial control and encryption, to hyperband multi-material metadevices using CNTs and MXenes, and finally to nonlinear Moiré metasurfaces for ultrafast THz manipulation and exceptional point physics. These achievements opened unanticipated directions in secure communication, wearable optoelectronics, and non-Hermitian photonics, significantly broadening the project’s scientific and technological impact.
Several results have been delivered that go well beyond the current state of the art in metasurface research. Scientifically, graphene-based Moiré metasurfaces were established as a new platform for nonlinear and non-Hermitian photonics, with the first experimental observation of exceptional points in a 2D-material metasurface being achieved. This breakthrough demonstrates a powerful approach to singularity-enhanced light manipulation, with implications for supersensitive detection, nonreciprocal wave control, and quantum photonic functionalities.
Technologically, hyperband synergistic metadevices based on carbon nanotubes and MXenes were developed, providing a versatile and scalable route to control electromagnetic waves across the full spectrum—from microwave through terahertz to optical bands. These outcomes open opportunities for 6G communications, secure imaging, and multifunctional optoelectronics.
To ensure further uptake and success, several key needs remain:
1. Further research is required to integrate classical, nonlinear, and quantum functionalities into a single programmable platform, bridging current laboratory prototypes with deployable systems.
2. Demonstration and scaling of fabrication processes, particularly wafer-scale integration of graphene and CNT/MXene composites, are necessary to validate industrial relevance.
3. Commercialisation pathways should be supported, including intellectual property management, partnerships with the photonics and ICT industries, and access to finance for prototype development.
4. International collaboration and standardisation, especially in the context of emerging 6G regulatory frameworks and quantum communication standards, are essential to ensure European leadership in future markets.
Overall, the project outcomes not only advance fundamental science but also establish a clear roadmap toward practical, reconfigurable, and scalable quantum metasurface devices, with the potential to transform photonics, telecommunications, and quantum technologies.
Technologically, hyperband synergistic metadevices based on carbon nanotubes and MXenes were developed, providing a versatile and scalable route to control electromagnetic waves across the full spectrum—from microwave through terahertz to optical bands. These outcomes open opportunities for 6G communications, secure imaging, and multifunctional optoelectronics.
To ensure further uptake and success, several key needs remain:
1. Further research is required to integrate classical, nonlinear, and quantum functionalities into a single programmable platform, bridging current laboratory prototypes with deployable systems.
2. Demonstration and scaling of fabrication processes, particularly wafer-scale integration of graphene and CNT/MXene composites, are necessary to validate industrial relevance.
3. Commercialisation pathways should be supported, including intellectual property management, partnerships with the photonics and ICT industries, and access to finance for prototype development.
4. International collaboration and standardisation, especially in the context of emerging 6G regulatory frameworks and quantum communication standards, are essential to ensure European leadership in future markets.
Overall, the project outcomes not only advance fundamental science but also establish a clear roadmap toward practical, reconfigurable, and scalable quantum metasurface devices, with the potential to transform photonics, telecommunications, and quantum technologies.