Those most devoted to quantum physics and its computing potential have been winning the bets for some time. Adán Cabello, of the University of Seville, had already promised to have dinner in Rome for predicting his last Nobel Prize a decade ago. On the contrary, a Spanish researcher based in Austria, Miguel Navasques, lost 50 euros in a hamburger four years ago because he did not expect to control 50 qubits (a key element in quantum computing) before 2050. Time has proven to be the most optimistic, but this continues. Science faces key challenges: Increasing the capacity of computers and reducing errors. Alejandro González Tudela, of Murcia, a scientific researcher at the Institute of Fundamental Physics at CSIC, decided at the age of 37 to open a new door for trying to solve it: to combine the unprecedented capabilities of metamaterials (structures designed with unusual properties) with the properties of the quantum light. His work earned him a Leonardo Scholarship from the BBVA Foundation, with up to €40,000 per project. The total aid since the creation of the program, in 2014, amounted to 20 million.
In traditional computing, the basic unit of information is the bit, which can contain two values: 0 and 1. These combinations actually give an unusual amplitude. But in quantum computing, the key element is the qubit (Quantum bit), a quantum system that can be in two states (0 and 1) or in any superposition who are they. The result is that using qubits allows for trillions of bit combinations and thus infinite computational possibilities. According to Alberto Casas, CSIC researcher and author Quantum Revolution (Ediciones B, 2022), “A quantum computer with 273 qubits would have more memory than atoms in the observable universe.”
The problem is that this quantum property of superposition is elusive and is currently only stable for a short time. Any tiny circumstance of the environment (temperature, electromagnetic noise or vibration) degrades it and makes efficient quantum computing impossible, and large-scale practical computations in a robust way. This effect is known as decoherence.
A recent investigation was published in Nature Physics Scientists from the UK and from the universities of Arizona (USA) and Zhejiang (China) used a programmable superconducting processor with 30 qubits and showed that “they can be modified to interact with each other while maintaining coherence for an unprecedented time”. Error correction is also used, but this technique requires addressing one of the challenges of quantum computing: significantly increasing the number of qubits.
The path Gonzalez Tudela is studying is going in a new direction: using metamaterials, structures designed with unusual properties, to create quantum devices with more qubits without increasing error levels. “In these metamaterials, their properties are modified below the wavelength to achieve exotic responses such as invisible matter or focusing light beyond limits,” the researcher explains.
The “starting hypothesis,” according to the CSIC researcher, “is based on the fact that light has a very good coherence. [preserva fácilmente sus propiedades cuánticas]So the goal is to exploit these very powerful responses that must light up the material to improve fidelity.”
Pros and cons
The idea is to take advantage of this ability of light to preserve its quantum properties, since it interacts very little with the environment. However, the same researcher admits that this property is, at the same time, a drawback: “it is difficult to manipulate.”
This is where his search for metamaterials comes in, which has advanced in the past two years after designing a network of atoms separated by very short distances that allows to exploit the quantum behavior of light.
“By placing the atoms at very small distances, they act collectively and can have very strong interactions with light,” explains Gonzalez Tudela. In this way, the researcher intends to advance the control of light with metamaterials and thus overcome the drawbacks of difficult particle manipulation with more coherent quantum behavior.
The ultimate goal is that hardware (a physical or physical component in computers and computer systems) solves the scalability problem, building a quantum computer with more qubits and fewer errors.
Gonzalez Tudela comments: “It is interesting to explore alternative models. I am not saying that my proposal would be the one that solves the problem, that it assumes a major change or the ultimate platform. Currently the best applications are for ions trapped in superconducting circuits, but there are also Photon-based quantum technology. Perhaps the big leap forward is coming from one thing off the radar or from a combination.”
But this researcher highlights the need to open up new paths such as the one that won the Leonardo scholarship. In the view of Alberto Casas himself, he wrote: “The future of quantum computing is unknown, but it is undoubtedly worth exploring.”
This potential value of quantum computing does not solve factor problems such as those raised so far, for testing the system rather than as a practical application. Not even to answer logistical questions like what is the best way to connect cities? The greatest hopes for this technology, explains Gonzalez Tudela, as well as encryption, which would allow for secure communication, are “certain physical or chemical problems.” “These are questions for many bodies, with many elements interacting with each other that are difficult to solve in classical computers,” he comments.
In this sense, the researcher is referring to the “exponential advantage” that quantum computing will bring to the pharmaceutical industry, in the search for customized treatments. He adds: “It may be that other, now unknown problems have been found that could have a quantitative advantage or that the applications have been developed and are not being considered now.”
In this sense, scientists from Trinity College Dublin have published a paper on Physics Communication Journal And then they think they’ve discovered that brains, consciousness, and short-term memory processes exhibit quantum behaviors. “Quantum brain processes could explain why we can still outperform supercomputers when it comes to unexpected circumstances, decision making, or learning something new,” says Christian Kerskens, co-author of the article and member of the University of Ireland’s Institute of Neuroscience. According to the researchers, “If the findings are confirmed, perhaps using advanced interdisciplinary approaches, it will improve public understanding of how the brain works and help find innovative technologies and build more advanced quantum computers.”
Spain is still in the quantum race not only in basic research but also in technological developments. Barcelona’s Supercomputing Center – Centro Nacional de Supercomputación (BSC-CNS) has been selected to be part of the EU Supercomputing Consortium, the European Joint Undertaking for High Performance Computing, to host and operate the first EuroHPC quantum computers. The new infrastructure will be installed and integrated into the MareNostrum 5 supercomputer, the most powerful computer in Spain and one of the most advanced in Europe. The investment for this part of the QuantumSpain program will amount to €12.5 million, co-financed by 50% of the European Union and the Secretary of State for Digitalization and Artificial Intelligence (SEDIA). “This new infrastructure, which will integrate quantum computing with MareNostrum 5, will allow us to advance in multiple academic applications,” BSC-CNS Director Matteo Valero says in a statement from the foundation. The Barcelona facilities will form a network with supercomputers from Germany, the Czech Republic, France, Italy and Poland to meet the growing demand for quantum computing resources and potential new services by European industry and research in areas such as health, climate change, logistics or energy use.
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