Tag Archives: Politecnico di Milano

A couple of proposed solutions to AI’s insatiable need for power?

I have two stories about research into making artificial intelligence (AI) less wasteful of power. One is from the International Society for Optics and Photonics (SPIE) and the other from the Politecnico di Milano (Polytechnic of Milan).

International Society for Optics and Photonics (SPIE)

A September 9, 2025 news item on ScienceDaily announced a more energy efficient AI chip,

Artificial intelligence (AI) systems are increasingly central to technology, powering everything from facial recognition to language translation. But as AI models grow more complex, they consume vast amounts of electricity — posing challenges for energy efficiency and sustainability. A new chip developed by researchers at the University of Florida could help address this issue by using light, rather than just electricity, to perform one of AI’s most power-hungry tasks. Their research is reported in Advanced Photonics.

A September 8, 2025 SPIE (International Society for Optics and Photonics) press release, which originated the news item, provides more detail about the work, Note: Links have been removed,

The chip is designed to carry out convolution operations, a core function in machine learning that enables AI systems to detect patterns in images, video, and text. These operations typically require significant computing power. By integrating optical components directly onto a silicon chip, the researchers have created a system that performs convolutions using laser light and microscopic lenses—dramatically reducing energy consumption and speeding up processing.

“Performing a key machine learning computation at near zero energy is a leap forward for future AI systems,” said study leader Volker J. Sorger, the Rhines Endowed Professor in Semiconductor Photonics at the University of Florida. “This is critical to keep scaling up AI capabilities in years to come.”

In tests, the prototype chip classified handwritten digits with about 98 percent accuracy, comparable to traditional electronic chips. The system uses two sets of miniature Fresnel lenses—flat, ultrathin versions of the lenses found in lighthouses—fabricated using standard semiconductor manufacturing techniques. These lenses are narrower than a human hair and are etched directly onto the chip.

To perform a convolution, machine learning data is first converted into laser light on the chip. The light passes through the Fresnel lenses, which carry out the mathematical transformation. The result is then converted back into a digital signal to complete the AI task.

“This is the first time anyone has put this type of optical computation on a chip and applied it to an AI neural network,” said Hangbo Yang, a research associate professor in Sorger’s group at UF and co-author of the study.

The team also demonstrated that the chip could process multiple data streams simultaneously by using lasers of different colors—a technique known as wavelength multiplexing. “We can have multiple wavelengths, or colors, of light passing through the lens at the same time,” Yang said. “That’s a key advantage of photonics.”

The research was conducted in collaboration with the Florida Semiconductor Institute, UCLA [University of California at Los Angeles], and George Washington University. Sorger noted that chip manufacturers such as NVIDIA already use optical elements in some parts of their AI systems, which could make it easier to integrate this new technology.

“In the near future, chip-based optics will become a key part of every AI chip we use daily,” Sorger said. “And optical AI computing is next.”

There’s also a September 8, 2025 University of Florida news release (also on EurekAlert), which is similar to the one issued by SPIE.

The paper has been published on two different sites; the citation for the paper remains the same and there are links to two different sites hosting the paper,

Near-energy-free photonic Fourier transformation for convolution operation acceleration by Hangbo Yang, Nicola Peserico, Shurui Li, Xiaoxuan Ma, Russell L. T. Schwartz, Mostafa Hosseini, Aydin Babakhani, Chee Wei Wong, Puneet Gupta, Volker J. Sorger SPIE Digital library or Advanced Photonics Vol. 7, Issue 5, 056007 (2025) DOI: 10.1117/1.AP.7.5.056007

Both sites offer open access to the paper.

Politecnico di Milano (Polytechnic of Milan)

Caption: The photonic microchip (below) developed for the study on physical neural networks, along with the electronic chip (above, the yellow one) of control. Credit: Politecnico di Milano, DEIB – Department of Electronics, Information and Bioengineering

A September 12, 2025 Politecnico di Milano (Polytechnic of Milan) press release (also on EurekAlert but published September 9, 2025) announces work into a more energy efficient way to train artificial intelligence, specifically physical neural networks,

Artificial intelligence is now part of our daily lives, with the subsequent pressing need for larger, more complex models. However, the demand for ever-increasing power and computing capacity is rising faster than the performance traditional computers can provide.

To overcome these limitations, research is moving towards innovative technologies such as physical neural networks, analogue circuits that directly exploit the laws of physics (properties of light beams, quantum phenomena) to process information. Their potential is at the heart of the study published by the prestigious journal Nature. It is the outcome of collaboration between several international institutes, including the Politecnico di Milano, the École Polytechnique Fédérale in Lausanne, Stanford University, the University of Cambridge, and the Max Planck Institute.

The article entitled “Training of Physical Neural Networks” discusses the steps of research on training physical neural networks, carried out with the collaboration of Francesco Morichetti, professor at DEIB – Department of Electronics, Information and Bioengineering, and head of the university’s Photonic Devices Lab.

Politecnico di Milano contributed to this study by developing photonic chips for the creation of neural networks, exploiting integrated photonic technologies. Mathematical operations, such as sums and multiplications, can now be performed through light interference mechanisms on silicon microchips barely a few square millimetres in size.

By eliminating the operations required for the digitisation of information, our photonic chips allow calculations to be carried out with a significant reduction in both energy consumption and processing time,” says Francesco Morichetti. A step forward to make artificial intelligence (which relies on extremely energy-intensive data centres) more sustainable.

The study published in Nature addresses the theme of training, precisely the phase in which the network learns to perform certain tasks. «With our research within the Department of Electronics, Information and Bioengineering, we have helped develop an “in-situ” training technique for photonic neural networks, i.e. without going through digital models. The procedure is carried out entirely using light signals. Hence, network training will not only be faster, but also more robust and efficient», adds Morichetti.

The use of photonic chips will allow the development of more sophisticated models for artificial intelligence, or devices capable of processing real-time data directly on site – such as autonomous cars or intelligent sensors integrated into portable devices – without requiring remote processing.

Here’s a link to and a citation for the paper,

Training of physical neural networks by Ali Momeni, Babak Rahmani, Benjamin Scellier, Logan G. Wright, Peter L. McMahon, Clara C. Wanjura, Yuhang Li, Anas Skalli, Natalia G. Berloff, Tatsuhiro Onodera, Ilker Oguz, Francesco Morichetti, Philipp del Hougne, Manuel Le Gallo, Abu Sebastian, Azalia Mirhoseini, Cheng Zhang, Danijela Marković, Daniel Brunner, Christophe Moser, Sylvain Gigan, Florian Marquardt, Aydogan Ozcan, Julie Grollier, Andrea J. Liu, Demetri Psaltis, Andrea Alù, Romain Fleury. Nature volume 645, pages 53–61 (2025) DOI: https://doi.org/10.1038/s41586-025-09384-2 Published: 03 September 2025 Version of record: 03 September 2025 Issue date: 04 September 2025

This paper is behind a paywall.

Cellulose nanofibers for sustainable hydrophobic paper

A November 5, 2024 news item on phys.org announces research with cellulose nanofibers (CNFx)

A recent study has aimed to create hydrophobic paper by exploiting the mechanical properties and water resistance of cellulose nanofibers, and so produce a sustainable, high-performance material suitable for packaging and biomedical devices. This involved a supramolecular approach, i.e., combining short chains of proteins (peptide sequences) that do not chemically modify the cellulose nanofibers. Sustainable hydrophobic paper may one day replace petroleum-related products.

An August 11, 2024 Politecnico di Milano (Polytechnic University of Milan) press release, also on EurekAlert but published November 5, 2024), which originated the news item, provides more information, Note: Links have been removed,

The aim was to create hydrophobic paper by exploiting the mechanical properties and water resistance of cellulose nanofibres, and so produce a sustainable, high-performance material suitable for packaging and biomedical devices. This involved a supramolecular approach, i.e. combining short chains of proteins (peptide sequences) that do not chemically modify the cellulose nanofibres. Sustainable hydrophobic paper may one day replace petroleum-related products.

The study is entitled: Nanocellulose-short peptide self-assembly for improved mechanical strength and barrier performance, and has just featured on the cover of the Journal of Materials Chemistry B. The work was carried out by researchers from the “Giulio Natta” Department of Chemistry, Materials and Chemical Engineering at the Politecnico di Milano, in collaboration with Aalto University, the VTT-Technical Research Centre in Finland and the SCITEC Institute of the CNR.

Cellulose nanofibres (CNFs) are natural fibres derived from cellulose – a renewable and biodegradable source – and are well known for their strength and versatility. In the study, the researchers from the SupraBioNanoLab (https://www.suprabionano.eu/) of the “Giulio Natta” Department of the Politecnico di Milano showed how it is possible to greatly improve the properties of cellulose nanofibres without chemically modifying them, instead adding small proteins known as peptides.

Our supramolecular approach involved adding small sequences of peptides, which bind onto the nanofibres and so improve their mechanical performance and water-resistance. Elisa Marelli, co-author of the study, explained the methodology:“The results of the study showed that even minimal quantities of peptides (less than 0.1%) can significantly increase the mechanical properties of the hybrid materials produced, giving them greater resistance to stress.”

Finally, the researchers assessed the impact of adding fluorine atoms in the peptide sequences. This made it possible to create a structured hydrophobic film on the material, providing even greater water resistance while still preserving its biocompatible and sustainable characteristics.

As Pierangelo Metrangolo, co-author of the study, pointed out: “This advance opens up new opportunities for creating biomaterials that can compete with petroleum-derived materials in terms of performance, achieving the same quality and efficiency while reducing environmental impact. These hybrid materials are very suitable for sustainable packaging, where resistance to moisture is vital, and also for use in biomedical devices, thanks to their biocompatibility.

Here’s a link to and a citation for the paper,

Nanocellulose-short peptide self-assembly for improved mechanical strength and barrier performance by Alessandro Marchetti, Elisa Marelli, Greta Bergamaschi, Panu Lahtinen, Arja Paananen, Markus Linder, Claudia Pigliacelli and Pierangelo Metrangolo.. J. Mater. Chem. B, 2024,12, 9229-9237 DOI: 10.1039/D4TB01359J First published online: 19 Aug 2024

This paper is open access.

Innovative nanovector (nanogel) could pave way for new spinal cord injury treatments

Caption: Nanogel – Scheme of selective drug treatment in the central nervous system. Credit Politecnico di Milano – Istituto Mario Negri

A February 14, 2024 news item on Nanowerk provides some context for the image in the above, Note: A link has been removed,

In a study published in Advanced Materials (“Synergistic Pharmacological Therapy to Modulate Glial Cells in Spinal Cord Injury”), researchers Pietro Veglianese, Valeria Veneruso and Emilia Petillo from Istituto di Ricerche Farmacologiche Mario Negri IRCCS in collaboration with Filippo Rossi of the Politecnico di Milano have demonstrated that an innovative nanovector (nanogel), which they developed, is able to deliver anti-inflammatory drugs in a targeted manner into glial cells actively involved in the evolution of spinal cord injury, a condition that leads to paraplegia or quadriplegia [also known as tetraplegia].

A February 20, 2024 Politecnico di Milano press release (also on EurekAlert but published February 14, 2024) which originated the news item, provides a bit more information about the difficulties with current treatments and the advantages of the new approach,

Treatments currently available to modulate the inflammatory response mediated by the component that controls the brain’s internal environment after acute spinal cord injury showed limited efficacy. This is also due to the lack of a therapeutic approach that can selectively act on microglial and astrocytic cells.

The nanovectors developed by Politecnico di Milano, called nanogels, consist of polymers that can bind to specific target molecules. In this case, the nanogels were designed to bind to glial cells, which are crucial in the inflammatory response following acute spinal cord injury. The collaboration between Istituto di Ricerche Farmacologiche Mario Negri IRCCS and Politecnico di Milano showed that nanogels, loaded with a drug with anti-inflammatory action (rolipram), were able to convert glial cells from a damaging to a protective state, actively contributing to the recovery of injured tissue. Nanogels showed to have a selective effect on glial cells, releasing the drug in a targeted manner, maximising its effect and reducing possible side effects.

“The key to the research was understanding the functional groups that can selectively target nanogels within specific cell populations”, explains Filippo Rossi, professor at the Department of Chemistry, Materials and Chemical Engineering ‘Giulio Natta’ at Politecnico di Milano – This makes it possible to optimise drug treatments by reducing unwanted effects”.

“The results of the study”, continues Pietro Veglianese, Head of the Acute Spinal Trauma and Regeneration Unit, Department of Neuroscience at Istituto Mario Negri, “show that nanogels reduced inflammation and improved recovery capacity in animal models with spinal cord injury, partially restoring motor function. These results open the way to new therapeutic possibilities for myelolysis patients. Moreover, this approach may also be beneficial for treating neurodegenerative diseases such as Alzheimer’s, in which inflammation and glial cells play a significant role”.

Here’s a link to and a citation for the paper,

Synergistic Pharmacological Therapy to Modulate Glial Cells in Spinal Cord Injury by Valeria Veneruso, Emilia Petillo, Fabio Pizzetti, Alessandro Orro, Davide Comolli, Massimiliano De Paola, Antonietta Verrillo, Arianna Baggiolini, Simona Votano, Franca Castiglione, Mattia Sponchioni, Gianluigi Forloni, Filippo Rossi, Pietro Veglianese. Advanced Materials Volume 36, Issue 3 January 18, 2024 2307747 DOOI: https://doi.org/10.1002/adma.202307747 First published: 22 November 2023

This paper is open access.

Memristors based on halide perovskite nanocrystals are more powerful and easier to manufacture

A March 8, 2023 news item on phys.org announces research from Swiss and Italian researchers into a new type of memristor,

Researchers at Empa, ETH Zurich and the Politecnico di Milano are developing a new type of computer component that is more powerful and easier to manufacture than its predecessors. Inspired by the human brain, it is designed to process large amounts of data fast and in an energy-efficient way.

In many respects, the human brain is still superior to modern computers. Although most people can’t do math as fast as a computer, we can effortlessly process complex sensory information and learn from experiences, while a computer cannot – at least not yet. And, the brain does all this by consuming less than half as much energy as a laptop.

One of the reasons for the brain’s energy efficiency is its structure. The individual brain cells – the neurons and their connections, the synapses – can both store and process information. In computers, however, the memory is separate from the processor, and data must be transported back and forth between these two components. The speed of this transfer is limited, which can slow down the whole computer when working with large amounts of data.

One possible solution to this bottleneck are novel computer architectures that are modeled on the human brain. To this end, scientists are developing so-called memristors: components that, like brain cells, combine data storage and processing. A team of researchers from Empa, ETH Zurich and the “Politecnico di Milano” has now developed a memristor that is more powerful and easier to manufacture than its predecessors. The researchers have recently published their results in the journal Science Advances.

A March 8, 2023 Swiss Federal Laboratories for Materials Science and Technology (EMPA) press release (also on EurekAlert), which originated the news item, provides details about what makes this memristor different,

Performance through mixed ionic and electronic conductivity

The novel memristors are based on halide perovskite nanocrystals, a semiconductor material known from solar cell manufacturing. “Halide perovskites conduct both ions and electrons,” explains Rohit John, former ETH Fellow and postdoctoral researcher at both ETH Zurich and Empa. “This dual conductivity enables more complex calculations that closely resemble processes in the brain.”

The researchers conducted the experimental part of the study entirely at Empa: They manufactured the thin-film memristors at the Thin Films and Photovoltaics laboratory and investigated their physical properties at the Transport at Nanoscale Interfaces laboratory. Based on the measurement results, they then simulated a complex computational task that corresponds to a learning process in the visual cortex in the brain. The task involved determining the orientation of light based on signals from the retina.

“As far as we know, this is only the second time this kind of computation has been performed on memristors,” says Maksym Kovalenko, professor at ETH Zurich and head of the Functional Inorganic Materials research group at Empa. “At the same time, our memristors are much easier to manufacture than before.” This is because, in contrast to many other semiconductors, perovskites crystallize at low temperatures. In addition, the new memristors do not require the complex preconditioning through application of specific voltages that comparable devices need for such computing tasks. This makes them faster and more energy-efficient.

Complementing rather than replacing

The technology, though, is not quite ready for deployment yet. The ease with which the new memristors can be manufactured also makes them difficult to integrate with existing computer chips: Perovskites cannot withstand temperatures of 400 to 500 degrees Celsius that are needed to process silicon – at least not yet. But according to Daniele Ielmini, professor at the “Politecnico di Milano”, that integration is key to the success for new brain-like computer technologies. “Our goal is not to replace classical computer architecture,” he explains. “Rather, we want to develop alternative architectures that can perform certain tasks faster and with greater energy efficiency. This includes, for example, the parallel processing of large amounts of data, which is generated everywhere today, from agriculture to space exploration.”

Promisingly, there are other materials with similar properties that could be used to make high-performance memristors. “We can now test our memristor design with different materials,” says Alessandro Milozzi, a doctoral student at the “Politecnico di Milano”. “It is quite possible that some of them are better suited for integration with silicon.”

Here’s a link to and a citation for the paper,

Ionic-electronic halide perovskite memdiodes enabling neuromorphic computing with a second-order complexity by Rohit Abraham John, Alessandro Milozzi, Sergey Tsarev, Rolf Brönnimann, Simon C. Boehme, Erfu Wu, Ivan Shorubalko, Maksym V. Kovalenko, and Daniele Ielmini. Science Advances 23 Dec 2022 Vol 8, Issue 51 DOI: 10.1126/sciadv.ade0072

This paper is open access.

Synthesizing a superfluorinated gold nanocluster with a core of 25 gold atoms,

A June 21, 2022 Politecnico di Milano press release (also on EurekAlert but published June 15, 2022) describes work that researchers believe could be instrumental in precision medicine and the production of ‘green’ hydrogen,

The SupraBioNano Lab (SBNLab) at the Politecnico di Milano’s Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, in partnership with the University of Bologna and the Aalto University of Helsinki (Finland) has, for the first time, synthesised a superfluorinated gold nanocluster, made up of a core of only 25 gold atoms, to which 18 branch-structured fluorinated molecules are linked.

The metal clusters are an innovative class of very complex nanomaterial, characterised by ultra-small dimensions (<2nm) and peculiar chemical-physical properties such as luminescence and catalytic activity, which encourage its application in various scientific fields of high importance in relation to modern global challenges. These include precision medicine, in which metal nanoclusters are used as innovative probes for diagnostic and therapeutic applications, and the energy transition, where they are applied as efficient catalysers for the production of green hydrogen.

The crystallisation of metal nanoclusters offers the possibility of obtaining high-purity samples, allowing their fine atomic structure to be determined; however, at present this remains a very difficult process to control. The methodologies developed in this study promoted the crystallisation of nanoclusters, allowing their atomic structure to be determined. The end result is the structural description of the most complex fluorinated nano-object ever reported.

The atomic structure has been determined by means of x-ray diffraction at the Sincrotrone Elettra in Trieste. It will soon be possible to study the structure of these advanced nanomaterials at the Politecnico di Milano, where – thanks also to the grant from the Region of Lombardy – Next-GAME (Next-Generation Advanced Materials), a laboratory dedicated to the use of state-of-the-art x-ray instruments to characterise crystals, nanoparticles and colloids, is being established.

Among the authors of the study were Prof. Pierangelo Metrangolo, Prof. Giancarlo Terraneo, Prof. Valentina Dichiarante, Prof. Francesca Baldelli Bombelli, Dr. Claudia Pigliacelli (SBNLab); professor Giulio Cerullo, from the Politecnico di Milano’s Department of Physics, also contributed to the study, looking at the nanocluster’s optical characteristics and demonstrating the fluorinated binders’ impact on the gold core’s optical activity.

Here’s a link to and a citation for the paper,

High-resolution crystal structure of a 20 kDa superfluorinated gold nanocluster by Claudia Pigliacelli, Angela Acocella, Isabel Díez, Luca Moretti, Valentina Dichiarante, Nicola Demitri, Hua Jiang, Margherita Maiuri, Robin H. A. Ras, Francesca Baldelli Bombelli, Giulio Cerullo, Francesco Zerbetto, Pierangelo Metrangolo & Giancarlo Terraneo. Nature Communications volume 13, Article number: 2607 (2022) DOI https://doi.org/10.1038/s41467-022-29966-2 Published11 May 2022 DOI https://doi.org/10.1038/s41467-022-29966-2

This paper is open access.

Quantum memristors

This March 24, 2022 news item on Nanowerk announcing work on a quantum memristor seems to have had a rough translation from German to English,

In recent years, artificial intelligence has become ubiquitous, with applications such as speech interpretation, image recognition, medical diagnosis, and many more. At the same time, quantum technology has been proven capable of computational power well beyond the reach of even the world’s largest supercomputer.

Physicists at the University of Vienna have now demonstrated a new device, called quantum memristor, which may allow to combine these two worlds, thus unlocking unprecedented capabilities. The experiment, carried out in collaboration with the National Research Council (CNR) and the Politecnico di Milano in Italy, has been realized on an integrated quantum processor operating on single photons.

Caption: Abstract representation of a neural network which is made of photons and has memory capability potentially related to artificial intelligence. Credit: © Equinox Graphics, University of Vienna

A March 24, 2022 University of Vienna (Universität Wien) press release (also on EurekAlert), which originated the news item, explains why this work has an impact on artificial intelligence,

At the heart of all artificial intelligence applications are mathematical models called neural networks. These models are inspired by the biological structure of the human brain, made of interconnected nodes. Just like our brain learns by constantly rearranging the connections between neurons, neural networks can be mathematically trained by tuning their internal structure until they become capable of human-level tasks: recognizing our face, interpreting medical images for diagnosis, even driving our cars. Having integrated devices capable of performing the computations involved in neural networks quickly and efficiently has thus become a major research focus, both academic and industrial.

One of the major game changers in the field was the discovery of the memristor, made in 2008. This device changes its resistance depending on a memory of the past current, hence the name memory-resistor, or memristor. Immediately after its discovery, scientists realized that (among many other applications) the peculiar behavior of memristors was surprisingly similar to that of neural synapses. The memristor has thus become a fundamental building block of neuromorphic architectures.

A group of experimental physicists from the University of Vienna, the National Research Council (CNR) and the Politecnico di Milano led by Prof. Philip Walther and Dr. Roberto Osellame, have now demonstrated that it is possible to engineer a device that has the same behavior as a memristor, while acting on quantum states and being able to encode and transmit quantum information. In other words, a quantum memristor. Realizing such device is challenging because the dynamics of a memristor tends to contradict the typical quantum behavior. 

By using single photons, i.e. single quantum particles of lights, and exploiting their unique ability to propagate simultaneously in a superposition of two or more paths, the physicists have overcome the challenge. In their experiment, single photons propagate along waveguides laser-written on a glass substrate and are guided on a superposition of several paths. One of these paths is used to measure the flux of photons going through the device and this quantity, through a complex electronic feedback scheme, modulates the transmission on the other output, thus achieving the desired memristive behavior. Besides demonstrating the quantum memristor, the researchers have provided simulations showing that optical networks with quantum memristor can be used to learn on both classical and quantum tasks, hinting at the fact that the quantum memristor may be the missing link between artificial intelligence and quantum computing.

“Unlocking the full potential of quantum resources within artificial intelligence is one of the greatest challenges of the current research in quantum physics and computer science”, says Michele Spagnolo, who is first author of the publication in the journal “Nature Photonics”. The group of Philip Walther of the University of Vienna has also recently demonstrated that robots can learn faster when using quantum resources and borrowing schemes from quantum computation. This new achievement represents one more step towards a future where quantum artificial intelligence become reality.

Here’s a link to and a citation for the paper,

Experimental photonic quantum memristor by Michele Spagnolo, Joshua Morris, Simone Piacentini, Michael Antesberger, Francesco Massa, Andrea Crespi, Francesco Ceccarelli, Roberto Osellame & Philip Walther. Nature Photonics volume 16, pages 318–323 (2022) DOI: https://doi.org/10.1038/s41566-022-00973-5 Published 24 March 2022 Issue Date April 2022

This paper is open access.