Quantum enhANched phoTonic Integrated sensors For metrologY

Informations projet

QUANTIFY

N° de convention de subvention: 101135931

DOI

10.3030/101135931

Date de signature de la CE 28 Novembre 2023

Date de début 1 Janvier 2024

Date de fin 30 Juin 2027

Financé au titre de

• Digital, Industry and Space

Coût total

€ 3 599 843,75

Contribution de l’UE

€ 3 599 843,75

Coordonné par

ISTITUTO NAZIONALE DI RICERCA METROLOGICA
Italy

Periodic Reporting for period 1 - QUANTIFY (Quantum enhANched phoTonic Integrated sensors For metrologY)

Période du rapport: 2024-01-01 au 2025-06-30

Résumé du contexte et des objectifs généraux du projet

QUANTIFY targets the transition of photonic quantum-enhanced sensors from lab prototypes to practical, integrated devices. Aligned with the Quantum Flagship’s Strategic Research Agenda, the project aims to demonstrate performance beyond classical limits for real-world use. It focuses on four pillars: chip-scale optical clocks (TPOC), optically pumped magnetometers (OPM), optomechanical temperature (OMT) sensors, and miniaturized optical quantum memories (QMs).

On photonic integrated platforms, the Consortium builds key building blocks and combines them via state-of-the-art hybrid integration to co-locate optical and optomechanical functions on a single chip. A core innovation is an integrated squeezed-light source that boosts the sensitivity of clocks and OPMs and is relevant to photonic quantum computing. The project also advances an absolute quantum-enhanced thermometer operating from cryogenic to room temperature via nanoscale optomechanics coupling photonic and phononic modes. Beyond miniaturization, lithographic precision and dispersion engineering tailor quantum states to improve reproducibility. QUANTIFY also develops compact optical QMs and systematically explores their use to enhance sensing—an emergent direction beyond simple storage/retrieval. Two national metrology institutes benchmark performance and co-develop new traceable procedures.

Scientific impact: Next-generation quantum sensors must harness superposition, entanglement, and quantum correlations to surpass the standard quantum limit, and require new calibration methods to verify gains. QUANTIFY tackles both by studying entangled/quantum-correlated optical probing in microcavities to improve clocks, magnetometers, and thermometers, and by establishing metrological protocols with NMIs for rigorous, comparable assessment.

Economic impact: The multi-billion-euro sensor market is growing, creating strong demand for higher-performance sensing. Room-temperature OPMs enable non-invasive Li-ion battery diagnostics for energy and automotive sectors and promise cost reductions in healthcare via MEG. Ultra-stable optical clocks provide resilient timing for autonomous vehicles and for network/data-center synchronization, including local ePRTC timing when GNSS is degraded.

Social impact: Improved brain diagnostics via OPM-MEG could benefit large patient populations. Battery inspection supports EU Green Deal and circular-economy goals. Miniature clocks contribute to safer mobility (Vision Zero). QUANTIFY’s primary optomechanical thermometer mitigates embedded-sensor drift, helping disseminate the redefined kelvin and improving reliability in transport, space, engine monitoring, and power-plant safety.

In sum, QUANTIFY unites integrated photonics, quantum resources (squeezing, entanglement), and rigorous metrology to deliver reproducible, scalable quantum sensors with industrial and societal impact.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

In the first 18 months, the Consortium focused on two fronts: (i) building essential blocks—photonic-integrated tunable lasers, Rb MEMS vapor cells, and GaP optomechanical crystals—for quantum-enhanced sensors; and (ii) updating protocols and test setups to characterise the new devices.

For the narrow-linewidth laser and integrated squeezed-light source, work progressed along three tracks:
• Gain chip: material selection, layer doping, quantum-well design for target wavelengths, independent characterisation, and ridge-waveguide fabrication.
• SiN circuitry and coupling: design/fabrication of the TriPleX™ cavity with electrical tuning and coupling of the gain chip to SiN.
• Packaging: spot-size converters, precision alignment, and gluing to meet stringent sensor requirements.

To realise a miniaturised squeezed-light source at 780 nm, the team designed and fabricated PPLNOI waveguides, resonators, and modulators, plus mode-field converters for efficient coupling to the SiN motherboard. Simulations prompted a revision of the frequency conversion scheme, and the poling process was optimised (pulse-duration tuning).

MEMS Rb vapor cells for TPOCs and OPMs were built from two glass wafers and a silicon wafer. Silicon cavities were made by DRIE. Four cell types meet TPOC needs; each includes an Rb dispenser, getter pills to remove residual gases after bonding, and an optical cavity. OPM cells incorporate a heater that does not perturb the magnetic field.

For optomechanical crystals, the Consortium designed and fabricated GaP structures that co-confine photons and phonons. A key result is a hybrid photonic integration platform using micro-transfer printing of GaP and lithium-niobate-on-insulator (LNOI) devices onto SiN circuits.

While awaiting shipment of some building blocks, partners aligned on target parameters, validated protocols on macroscopic testbeds, and prepared the characterisation setups. With Noisy Lab, the team developed and characterised a 780-nm balanced homodyne detector with high quantum efficiency and low electronic dark noise to measure squeezing from the integrated source.

These activities establish the devices, platforms, and metrology to move optical clocks, OPMs, and optomechanical thermometers toward reproducible, chip-scale implementation.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

During the first reporting period, QUANTIFY extended micro-transfer printing (µTP) to novel quantum-enabling sources. Rather than integrating only III–V gain chips on SiN, the team targets PP-LNOI waveguides and GaP photonic-crystal cavities, combining them by µTP—merging wafer-scale donor processing and pre-testing with massively parallel bonding. Leveraging µTP of LNOI onto TriPleX™, QUANTIFY co-integrates the pump laser and nonlinear modules on one chip, paving the way for a chip-scale, electrically pumped squeezed-light source around 780 nm (the Rb line). Because optical loss rises at shorter wavelengths, achieving useful squeezing here is challenging; the project addresses this with optimised designs and coupling.

For timekeeping, the same platform brings top TPOC laser performance to chip-scale, reducing SWaP toward CSAC/CSOC dimensions and enabling squeezed probes to improve both short- and long-term stability. For OPMs, QUANTIFY goes beyond the state of the art by (i) generating polarisation-squeezed light on-chip for non-destructive spin readout, (ii) developing MEMS cells with AR coatings, tailored volumes and gas mixtures compatible with squeezing and Earth-field operation, and (iii) adapting enhancement protocols to the Earth-field regime—together enabling OPMs with markedly lower SWaP.

The project also advances an on-chip quantum primary thermometer based on nanoscale optomechanics, using multi-physics engineering to deplete phonons, avoid mechanical instabilities and minimise self-heating. Finally, QUANTIFY is building a miniaturised quantum memory with warm Rb MEMS cells and PIC lasers, benchmarking against classical sources and assessing integration of QMs to enhance sensor performance. Metrologically, a major task is adapting characterisation, calibration and inter-comparison procedures to quantum-enhanced, miniaturised devices—work that is largely unprecedented.