The goal is ambitious: to make quantum technologies more stable and reliable. Once achieved, the impact on society will be significant – from enabling more robust quantum processors based on photonic chips, to creating noise-resistant quantum communication networks and advancing high-precision quantum sensors. These breakthroughs could influence various fields, from more secure communications to more precise scientific instrumentation.
This is where the QUANTHOS (Quantum Topological Integrated Photonics) project comes in – approved under the Exploratory Project Call of the Portuguese Foundation for Science and Technology (FCT). It brings together two of the Institute’s research areas – photonics and high-performance computing (HPC) – and according to Ariel Guerreiro, INESC TEC researcher and QUANTHOS principal investigator, it aims to “to explore whether topological photonics, already demonstrated in classical optical systems, can be extended to quantum states of light (single photons and entangled pairs).”
In essence, INESC TEC researchers are looking towards the future of integrated photonics. Today, devices that rely on quantum properties are typically assembled on optical tables, with large-scale architectures and macroscopic components. The goal of QUANTHOS is to develop and demonstrate the relevant concepts and technologies, and to miniaturise optical devices, typically involving integrated optics on photonic chips.
But let’s start with the underlying challenge. Quantum computing and communications depend on very fragile properties of light, such as quantum coherence (i.e., the ability of a quantum state to demonstrate quantum behaviour) and quantum entanglement (a form of shared quantum coherence between multiple particles). The major obstacle in quantum technologies is that these properties are easily lost due to noise or imperfections in materials and optical components – a phenomenon known as decoherence, which has hindered much progress in this field.
“The sources of these disturbances include external noise, imperfections in system fabrication, and others. Recently, it was discovered that it is possible to protect quantum systems from such noise through what is known as topological protection. This protection is achieved by manipulating certain geometric properties of the system, making it more difficult to alter quantum states. This principle has been used in a new generation of qubits – the so-called topological qubits,” explained Ariel Guerreiro.
As mentioned earlier, topological photonics has already been demonstrated in classical optical systems, showing the ability to guide light in this context. However, QUANTHOS aims to go further by testing whether this protection also works for quantum states of light – for instance, with single photons or entangled photon pairs.
“The question driving the project is: can we do the same with the quantum properties of light as it propagates through a waveguide – from an optical fibre to an integrated optics waveguide?” added the INESC TEC researcher.
To achieve this, the team will use supercomputers (such as Deucalion) for highly complex simulations, develop advanced models of quantum light transport, and create a prototype of an optimised quantum photonic waveguide.
“We want to test the limits of topological protection and develop a computational tool that can help optimise photonic systems – especially in integrated optics – and extend the application to the transmission and processing of quantum information encoded in the quantum state of light,” said Ariel Guerreiro. QUANTHOS will also create computational simulation frameworks (using cutting-edge methods such as FEM, FDTD, Green’s functions, and others), essential for designing the quantum photonic circuits of the future.
Beyond the scientific and technological advances – which, as mentioned, will have an impact on several areas of society -, the project also focuses on training new researchers, including new hiring processes and the creation of an internal school dedicated to quantum topological photonics.
This INESC TEC initiative strengthens the connection between high-performance computing (HPC) – using the Deucalion supercomputer – and quantum technologies in Portugal. It also illustrates the Institute’s ability to bring together researchers from different regions – in this case, Ariel Guerreiro, based at the INESC TEC centre at the Faculty of Sciences of the University of Porto (FCUP), whose main research focus is photonics, and André Martins Pereira, INESC TEC researcher in advanced computing, whose work is carried out at the University of Minho – and who will be responsible for the HPC-related aspects.
“The use of the Deucalion supercomputer allows us to perform highly complex simulations, ensuring the optimisation and energy efficiency of scientific processes supported by specialised human resources – tasks that would be impossible to achieve with conventional means. The integration of HPC in support of quantum science accelerates research, enabling more results in less time and generating outcomes with real impact on society,” said André Martins Pereira.
“Once we have these tools, we will carry out an exploratory study to determine whether topological protection exists in very simple systems. The long-term goal is to have a tool that enables us to justify future projects and, ideally, to join teams applying for upcoming European funding calls on quantum chips. A second strategic goal is to begin building a set of competencies in HPC-based physical simulation at INESC TEC, allowing us to make the most of the resources within our ecosystem,” mentioned Ariel Guerreiro.
QUANTHOS represents a decisive step towards positioning Portugal at the forefront of quantum science, exploring robust solutions that could transform fields like quantum computing, communications, and fundamental science.
The researchers mentioned in this news piece are associated with INESC TEC, the Faculty of Sciences of the University of Porto and the UMinho
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