Periodic Reporting for period 4 - CAPABLE (Composite integrated photonic platform by femtosecond laser micromachining)
Reporting period: 2022-04-01 to 2022-12-31
The quantum technology revolution promises a transformational impact on the society and economics worldwide. It will enable breakthrough advancements in such diverse fields as secure communications, computing, metrology, and imaging. Quantum photonics, which recently received an incredible boost by the use of integrated optical circuits, is an excellent technological platform to enable such revolution, as it already plays a relevant role in many of the above applications. However, some major technical roadblocks need to be overcome. Currently, the various components required for a complete quantum photonic system are produced on very different materials by dedicated fabrication technologies, and it is very difficult to envisage a single platform integrating all the required functionalities.
This project proposes a new hybrid approach for integrated quantum photonic systems based on femtosecond laser microfabrication (FLM), enabling the innovative miniaturization of various components on different materials, but with a single tool and with very favorable integration capabilities. This will enable the realization of a complete integrated platform that encompasses all the fundamental processes (generation of quantum states of light, their manipulation, storage and detection). Achievement of this goal will only be possible by taking full advantage of the unique features of FLM, from the possibility to machine very different materials, to the 3D capabilities in waveguide writing and selective material removal. The successful demonstration and functional validation of this hybrid, integrated photonic platform will represent a significant leap for photonic microsystems in quantum computing, communication, and sensing.
This project proposes a new hybrid approach for integrated quantum photonic systems based on femtosecond laser microfabrication (FLM), enabling the innovative miniaturization of various components on different materials, but with a single tool and with very favorable integration capabilities. This will enable the realization of a complete integrated platform that encompasses all the fundamental processes (generation of quantum states of light, their manipulation, storage and detection). Achievement of this goal will only be possible by taking full advantage of the unique features of FLM, from the possibility to machine very different materials, to the 3D capabilities in waveguide writing and selective material removal. The successful demonstration and functional validation of this hybrid, integrated photonic platform will represent a significant leap for photonic microsystems in quantum computing, communication, and sensing.
The CAPABLE project has achieved many important breakthroughs. In the following, I will describe the main ones.
A first important result is the demonstration of very efficient laser-written waveguides in Pr3+:Y2SiO5 crystals, which is one of the most promising material for solid-state quantum memories. Exploiting these waveguides, we have demonstrated a single-photon integrated quantum memory with orders of magnitude longer storage times than any previous waveguide implementation and 100x reduced amount of power needed for the control signals. These results enabled the storage of a total number of ~130 modes in a single waveguide and, more recently, the demonstration of entanglement-storage in fiber-coupled integrated quantum memories, towards the vision of a quantum internet.
On the quantum protocol side, we have addressed a relevant problem: how can one validate a quantum machine when its computational power will exceed that of a classical computer? We have considered the Boson Sampling algorithm, which is known to be extremely hard to compute classically, and we have experimentally demonstrated a new technique based on machine learning that is capable of identifying specific patterns in the output distributions of photons from a Boson Sampling machine. Such patterns do not allow a classical prediction of the quantum computation result, but can prove that the machine is indeed behaving in the purely quantum regime.
Another important topic of research developed in the CAPABLE project is quantum sensing. We have developed completely reconfigurable integrated photonic circuits that can be used as testbeds to implement and verify new quantum sensing protocols. In particular, we used them to assess the quantum advantage of simultaneous multi-phase estimation with respect to individual phase estimation.
Finally, we have introduced and experimentally demonstrated a new component, the quantum memristor. This device changes its transmission properties depending on the history of quantum photonic states that traversed it. This is a very critical task where one has to fine tune the minimum amount of knowledge on the quantum states of light needed to modify the device, without causing the wavefunction collapse. The quantum memristor could become a fundamental building block in future devices for quantum artificial intelligence, paving the way to a new class of quantum photonic neuromorphic circuits.
The CAPABLE project produced 42 articles in peer-reviewed journals, many of which are highly prestigious and have a very high impact factor. The results have also been disseminated in many scientific conferences, with multiple invited talks, as well as in non-technical presentations for the general public.
The results achieved in this ERC project have also been exploited scientifically in subsequent successful applications to EU calls. In addition, the PI has been awarded 2 ERC Proof-of-concept projects, DISPLAYGHT and PHOTONFAB, to investigate commercial applications. In the DISPLAYGHT project, the PI and a startup company, named VitreaLab, exploited femtosecond laser writing of waveguides for a new generation of displays with much higher efficiency and potential use as 3D holographic displays. On the other hand, the PHOTONFAB project aims at commercializing the complex and reconfigurable photonic circuits developed in CAPABLE as quantum photonic processors for future quantum computers. Ti this aim, the PI and co-workers have founded a new startup, Faro Quantum Technologies, that is currently closing its seed round of investments and has already started selling some products.
A first important result is the demonstration of very efficient laser-written waveguides in Pr3+:Y2SiO5 crystals, which is one of the most promising material for solid-state quantum memories. Exploiting these waveguides, we have demonstrated a single-photon integrated quantum memory with orders of magnitude longer storage times than any previous waveguide implementation and 100x reduced amount of power needed for the control signals. These results enabled the storage of a total number of ~130 modes in a single waveguide and, more recently, the demonstration of entanglement-storage in fiber-coupled integrated quantum memories, towards the vision of a quantum internet.
On the quantum protocol side, we have addressed a relevant problem: how can one validate a quantum machine when its computational power will exceed that of a classical computer? We have considered the Boson Sampling algorithm, which is known to be extremely hard to compute classically, and we have experimentally demonstrated a new technique based on machine learning that is capable of identifying specific patterns in the output distributions of photons from a Boson Sampling machine. Such patterns do not allow a classical prediction of the quantum computation result, but can prove that the machine is indeed behaving in the purely quantum regime.
Another important topic of research developed in the CAPABLE project is quantum sensing. We have developed completely reconfigurable integrated photonic circuits that can be used as testbeds to implement and verify new quantum sensing protocols. In particular, we used them to assess the quantum advantage of simultaneous multi-phase estimation with respect to individual phase estimation.
Finally, we have introduced and experimentally demonstrated a new component, the quantum memristor. This device changes its transmission properties depending on the history of quantum photonic states that traversed it. This is a very critical task where one has to fine tune the minimum amount of knowledge on the quantum states of light needed to modify the device, without causing the wavefunction collapse. The quantum memristor could become a fundamental building block in future devices for quantum artificial intelligence, paving the way to a new class of quantum photonic neuromorphic circuits.
The CAPABLE project produced 42 articles in peer-reviewed journals, many of which are highly prestigious and have a very high impact factor. The results have also been disseminated in many scientific conferences, with multiple invited talks, as well as in non-technical presentations for the general public.
The results achieved in this ERC project have also been exploited scientifically in subsequent successful applications to EU calls. In addition, the PI has been awarded 2 ERC Proof-of-concept projects, DISPLAYGHT and PHOTONFAB, to investigate commercial applications. In the DISPLAYGHT project, the PI and a startup company, named VitreaLab, exploited femtosecond laser writing of waveguides for a new generation of displays with much higher efficiency and potential use as 3D holographic displays. On the other hand, the PHOTONFAB project aims at commercializing the complex and reconfigurable photonic circuits developed in CAPABLE as quantum photonic processors for future quantum computers. Ti this aim, the PI and co-workers have founded a new startup, Faro Quantum Technologies, that is currently closing its seed round of investments and has already started selling some products.
The CAPABLE project will give a boost to quantum technologies. It will create the first integrated platform produce all the quantum operations that are relevant in a quantum system, i.e. single photon generation, manipulation, storage and detection (the latter being developed in a parallel ongoing project).
Specific technological breakthroughs will be achieved, which are worth per se, e.g. the capability to produce rapidly reconfigurable and cryo-friendly waveguide phase shifters, the possibility to fabricate micromechanical resonators with waveguides embedded, the first demonstration of single-photon storage in a waveguide memory and the demonstration of complex 3D circuits for Boson Sampling experiments. Moreover, all these achievements are enabled by the same femtosecond laser microfabrication technology, thus also providing a clear vision of how they can all be combined in a single hybrid system. To further support this claim, the last two objectives of the project will show some examples of hybrid quantum systems that will have a dramatic impact on quantum information. Efficient integration of quantum memories in fiber networks will boost current quantum cryptography applications by extending their range through quantum repeaters, and will enable distributed quantum computing schemes. The implementation of Boson Sampling at an unprecedented complexity level will approach the level where the quantum advantage with respect to classical devices will be clearly visible. This will represent a landmark in quantum information providing a reliable and robust platform for the design and fabrication of noisy intermediate-scale quantum (NISQ) devices for the implementation of the first, useful quantum protocols.
In addition to the scientific impact, this project will provide top-level training on highly multidisciplinary topics to several students and early-stage researchers, thus helping in the creation of a new class of scientists with a holistic vision on material processing, microfabrication, device design, photonic characterization, and quantum information.
Specific technological breakthroughs will be achieved, which are worth per se, e.g. the capability to produce rapidly reconfigurable and cryo-friendly waveguide phase shifters, the possibility to fabricate micromechanical resonators with waveguides embedded, the first demonstration of single-photon storage in a waveguide memory and the demonstration of complex 3D circuits for Boson Sampling experiments. Moreover, all these achievements are enabled by the same femtosecond laser microfabrication technology, thus also providing a clear vision of how they can all be combined in a single hybrid system. To further support this claim, the last two objectives of the project will show some examples of hybrid quantum systems that will have a dramatic impact on quantum information. Efficient integration of quantum memories in fiber networks will boost current quantum cryptography applications by extending their range through quantum repeaters, and will enable distributed quantum computing schemes. The implementation of Boson Sampling at an unprecedented complexity level will approach the level where the quantum advantage with respect to classical devices will be clearly visible. This will represent a landmark in quantum information providing a reliable and robust platform for the design and fabrication of noisy intermediate-scale quantum (NISQ) devices for the implementation of the first, useful quantum protocols.
In addition to the scientific impact, this project will provide top-level training on highly multidisciplinary topics to several students and early-stage researchers, thus helping in the creation of a new class of scientists with a holistic vision on material processing, microfabrication, device design, photonic characterization, and quantum information.