Periodic Reporting for period 3 - SURQUID (Super-Resolving Quantum Imaging and Detection)
Okres sprawozdawczy: 2022-10-01 do 2025-03-31
The SURQUID project addressed limitations of current remote sensing technologies by pursuing a multi-scale quantum sensing approach for light detection and ranging (Lidar) with enhanced resolution and sensitivity. Conventional Lidar systems are constrained by shot noise and classical resolution limits, restricting the information that can be extracted from remote targets. SURQUID aimed to overcome these constraints by exploiting non-classical states of light, fast optical modulation, and efficient single-photon detection with picosecond timing and photon-number resolution, establishing a pathway toward quantum-enhanced super-resolution and super-sensitivity.
The project objectives focused on three pillars: (i) realization of quantum light sources for Lidar, (ii) development of a high-performance receiver unit for single-photon counting quantum Lidar, and (iii) demonstration of representative Lidar use cases showcasing improved spatial resolution, material discrimination, and functional sensing. A compact and portable quantum light source prototype was realized, enabling the generation of entangled and non-classical states, including N00N states, spectrally pure pulsed two-mode squeezed vacuum, and non-Gaussian states suitable for remote sensing.
In parallel, SURQUID advanced nanophotonic-integrated SNSPD-based receiver units on silicon platforms combined with high-timing resolution electronics. These receivers achieved ultra-high timing accuracy, enabling millimeter and sub-millimeter ranging resolution, photon-number-resolving capabilities, high-speed electro-optic modulation, and sub-picosecond time tagging. Implemented in compact cryogenic packages, the receiver systems were field-compatible and deployed across diverse Lidar demonstrations, including high-resolution 3D imaging, material classification, time-of-flight and FMCW Lidar, Doppler-based audio reconstruction, defense-relevant target identification, and long-distance ranging using photon bunching in thermal light.
In conclusion, SURQUID demonstrated that integrated quantum state generation, modulation, and single-photon detection enable robust and versatile quantum-enhanced Lidar systems operating beyond classical performance limits, providing a strong foundation for future real-world quantum sensing platforms.
The project objectives focused on three pillars: (i) realization of quantum light sources for Lidar, (ii) development of a high-performance receiver unit for single-photon counting quantum Lidar, and (iii) demonstration of representative Lidar use cases showcasing improved spatial resolution, material discrimination, and functional sensing. A compact and portable quantum light source prototype was realized, enabling the generation of entangled and non-classical states, including N00N states, spectrally pure pulsed two-mode squeezed vacuum, and non-Gaussian states suitable for remote sensing.
In parallel, SURQUID advanced nanophotonic-integrated SNSPD-based receiver units on silicon platforms combined with high-timing resolution electronics. These receivers achieved ultra-high timing accuracy, enabling millimeter and sub-millimeter ranging resolution, photon-number-resolving capabilities, high-speed electro-optic modulation, and sub-picosecond time tagging. Implemented in compact cryogenic packages, the receiver systems were field-compatible and deployed across diverse Lidar demonstrations, including high-resolution 3D imaging, material classification, time-of-flight and FMCW Lidar, Doppler-based audio reconstruction, defense-relevant target identification, and long-distance ranging using photon bunching in thermal light.
In conclusion, SURQUID demonstrated that integrated quantum state generation, modulation, and single-photon detection enable robust and versatile quantum-enhanced Lidar systems operating beyond classical performance limits, providing a strong foundation for future real-world quantum sensing platforms.
The SURQUID project developed and validated key prototype technologies for quantum-enhanced remote sensing, including quantum light sources, superconducting nanowire–based receiver units, high-resolution time-to-digital converters, and integrated photonic modulators. Together, these components form a comprehensive technological basis for advanced single-photon and quantum Lidar systems.
On the source side, a compact and portable quantum light source prototype was realized, enabling the generation of spectrally pure pulsed two-mode squeezed vacuum states through cascaded nonlinear processes and joint spectral amplitude engineering. Photon-number-resolving detection schemes were demonstrated using temporal and spatial multiplexing, as well as intrinsic photon-number sensitivity of SNSPDs. These advances enabled photon subtraction for distributions of up to five photons, supporting the generation of non-Gaussian quantum states. The entangled photon source further enabled the generation and tomography of N00N states using Hong–Ou–Mandel common-path interferometry. Theoretical and experimental studies showed that photon subtraction from realistic squeezed states can yield quantum states that enhance Lidar performance beyond classical coherent-state limits.
A compact cryogenic single-photon counting Lidar receiver was realized by integrating SNSPDs with photonic integrated circuits. Through systematic optimization of thin-film materials, nanowire patterning, and photonic interfaces, timing accuracies of 7 ps for single telecom photons were achieved, improving to sub-3 ps jitter in multiphoton regimes relevant to time-of-flight Lidar. Integrated demonstrations achieved 1.65 mm single-shot ranging resolution and sub-millimeter resolution of approximately 750 μm in multi-shot operation. Photonic integration enabled low-loss optical interfaces (<1 dB insertion loss) and on-chip detection efficiencies up to 95%. Photon-number-resolving capabilities were extended through spatial multiplexing schemes supporting quasi-photon-number resolution up to 16 photons, complemented by intrinsic photon-number resolution via tailored nanowire geometries and inductances.
To fully exploit detector performance, a high-resolution Time-to-Digital Converter (TDC) ASIC was designed, fabricated, and integrated into an FPGA-based time-tagging system, demonstrating sub-picosecond timing resolution. High-speed electro-optic modulation was also demonstrated using transfer-printed lithium niobate devices integrated with silicon photonics, achieving modulation speeds up to 45 Gbit/s and electro-optic bandwidths of up to 33 GHz.
These capabilities enabled a wide range of Lidar and remote sensing demonstrations, including sub-millimeter 3D ToF Lidar, multiscale ToF and FMCW Lidar, material identification, Doppler-based audio reconstruction, defense-relevant target identification, and ranging with thermal light. Project results were disseminated through high-impact publications, conferences, outreach activities, and three patent applications.
On the source side, a compact and portable quantum light source prototype was realized, enabling the generation of spectrally pure pulsed two-mode squeezed vacuum states through cascaded nonlinear processes and joint spectral amplitude engineering. Photon-number-resolving detection schemes were demonstrated using temporal and spatial multiplexing, as well as intrinsic photon-number sensitivity of SNSPDs. These advances enabled photon subtraction for distributions of up to five photons, supporting the generation of non-Gaussian quantum states. The entangled photon source further enabled the generation and tomography of N00N states using Hong–Ou–Mandel common-path interferometry. Theoretical and experimental studies showed that photon subtraction from realistic squeezed states can yield quantum states that enhance Lidar performance beyond classical coherent-state limits.
A compact cryogenic single-photon counting Lidar receiver was realized by integrating SNSPDs with photonic integrated circuits. Through systematic optimization of thin-film materials, nanowire patterning, and photonic interfaces, timing accuracies of 7 ps for single telecom photons were achieved, improving to sub-3 ps jitter in multiphoton regimes relevant to time-of-flight Lidar. Integrated demonstrations achieved 1.65 mm single-shot ranging resolution and sub-millimeter resolution of approximately 750 μm in multi-shot operation. Photonic integration enabled low-loss optical interfaces (<1 dB insertion loss) and on-chip detection efficiencies up to 95%. Photon-number-resolving capabilities were extended through spatial multiplexing schemes supporting quasi-photon-number resolution up to 16 photons, complemented by intrinsic photon-number resolution via tailored nanowire geometries and inductances.
To fully exploit detector performance, a high-resolution Time-to-Digital Converter (TDC) ASIC was designed, fabricated, and integrated into an FPGA-based time-tagging system, demonstrating sub-picosecond timing resolution. High-speed electro-optic modulation was also demonstrated using transfer-printed lithium niobate devices integrated with silicon photonics, achieving modulation speeds up to 45 Gbit/s and electro-optic bandwidths of up to 33 GHz.
These capabilities enabled a wide range of Lidar and remote sensing demonstrations, including sub-millimeter 3D ToF Lidar, multiscale ToF and FMCW Lidar, material identification, Doppler-based audio reconstruction, defense-relevant target identification, and ranging with thermal light. Project results were disseminated through high-impact publications, conferences, outreach activities, and three patent applications.
SURQUID delivered significant progress beyond the state of the art by showing how quantum and single-photon technologies can extend the performance of Lidar and remote sensing systems beyond classical limits. The combination of ultra-low timing jitter SNSPDs, photon-number-resolving detection, integrated photonics, and sub-picosecond electronic readout enabled sensing capabilities unattainable with conventional semiconductor detectors.
The project advanced ranging accuracy to the sub-millimeter level and introduced multi-parameter sensing approaches that jointly exploit distance, reflectivity, and temporal signal spread. This enriched information content supports improved object recognition, material classification, and digital twin generation. Multiscale Lidar demonstrations under photon-starved conditions showed stable performance across wide dynamic ranges, addressing a key limitation of existing Lidar systems.
SURQUID also introduced unconventional sensing paradigms, including audio reconstruction via Doppler FMCW Lidar and ranging with thermal light exploiting photon bunching. These approaches enable continuous, self-referenced, and potentially stealth sensing, with relevance for security, defense, and safety-critical applications. The integration of quantum Fisher Information analysis provides a rigorous framework for evaluating and optimizing sensing performance.
From a socio-economic perspective, the project lays the groundwork for next-generation Lidar technologies with impact across automotive sensing, industrial inspection, environmental monitoring, infrastructure surveillance, and emerging biomedical and agricultural applications. Enhanced material discrimination, eye-safe operation, and compatibility with scalable photonic integration strengthen Europe’s competitiveness in quantum technologies and advanced sensor markets, while addressing broader societal needs in safety, sustainability, and technological sovereignty.
The project advanced ranging accuracy to the sub-millimeter level and introduced multi-parameter sensing approaches that jointly exploit distance, reflectivity, and temporal signal spread. This enriched information content supports improved object recognition, material classification, and digital twin generation. Multiscale Lidar demonstrations under photon-starved conditions showed stable performance across wide dynamic ranges, addressing a key limitation of existing Lidar systems.
SURQUID also introduced unconventional sensing paradigms, including audio reconstruction via Doppler FMCW Lidar and ranging with thermal light exploiting photon bunching. These approaches enable continuous, self-referenced, and potentially stealth sensing, with relevance for security, defense, and safety-critical applications. The integration of quantum Fisher Information analysis provides a rigorous framework for evaluating and optimizing sensing performance.
From a socio-economic perspective, the project lays the groundwork for next-generation Lidar technologies with impact across automotive sensing, industrial inspection, environmental monitoring, infrastructure surveillance, and emerging biomedical and agricultural applications. Enhanced material discrimination, eye-safe operation, and compatibility with scalable photonic integration strengthen Europe’s competitiveness in quantum technologies and advanced sensor markets, while addressing broader societal needs in safety, sustainability, and technological sovereignty.