The word “quantum” has acquired a peculiar aura in modern culture, often with a science-fiction quality, far from its rigorous scientific origin. Yet quantum is neither mystical nor metaphorical. Born more than a century ago, quantum theory is one of the most precise scientific theories ever developed.
Quantum physics has already transformed everyday life once. It did so quietly, through lasers, transistors, LEDs, solar panels, fiber-optic internet, magnetic resonance imaging and the microchips inside our phones and computers. Now, it may be preparing to do so again.
This second transformation began when quantum physics met computation science. A quantum computer is, in essence, a computer that processes information using quantum bits, or qubits. Unlike an ordinary bit, which is either 0 or 1, a qubit can be prepared in a superposition of both possibilities. This does not make quantum computers universally faster, nor magical machines, but indispensable for solving specific problems, such as simulating molecules and optimizing complex systems.
A quantum computer, however, is not a future household appliance. It is an extraordinarily delicate device that must be protected from heat, noise, vibration and other imperfections, often under extreme laboratory conditions. The idea is therefore not that everyone will own one, but that users may remotely access a network of quantum computers from their homes, forming a quantum internet.
The same power also creates risks. Much of modern cybersecurity relies on mathematical problems that are easy to create but extremely difficult to reverse. A classic example is factorization: multiplying two very large prime numbers is simple, but recovering those primes from their product can become practically impossible. Yet, factorization was one of the earliest problems shown to be efficiently solvable by a quantum computer, placing current information security at risk. In response, a quantum hacker might be fought with the same weapon: quantum cryptography. The idea is that quantum information cannot be observed passively: measuring a quantum state inevitably disturbs it. As a result, any attempt to intercept quantum communication cannot pass unnoticed. Security would then rely not only on mathematical complexity, but on the laws of physics themselves.
Quantum sensing may have an even more immediate impact. Quantum systems are fragile, but that fragility can be turned into extraordinary sensitivity. They can detect tiny changes in time, gravity, magnetic fields or motion, with applications in medicine, navigation, geology and fundamental science. The most dramatic example comes from gravitational-wave astronomy, where scientists must measure distortions of space itself. At LIGO, laser-light travels through two four-kilometre arms, reflects from massive mirrors and returns to reveal whether the arms have changed length. When a gravitational wave passes, the length shift is roughly 0.001 of a proton’s diameter, an absurdly small displacement, yet one that can be measured.
Together, these advances devise a future shaped by an ecosystem of quantum technologies, though it will not resemble science-fiction with flying cars, human teleportation or time travel. More likely, it will improve health, security, communication and technology from the background, similarly as quantum physics has already done before.
Carles Roch i Carceller holds a BSc in Theoretical Physics from the University of Barcelona and an MSc in Quantum Physics from the University of Copenhagen. He completed his PhD at the Technical University of Denmark in 2023. During his doctoral studies, he was a visiting researcher at the Korea Advanced Institute of Science and Technology (KAIST) in Daejeon, South Korea. Carles is currently a postdoctoral researcher at Lund University in Sweden. He has recently been awarded a Marie Skłodowska-Curie Actions (MSCA) fellowship to investigate semi-device-independent quantum communication and cryptography at the Institute of Photonic Sciences (ICFO) in Barcelona, Spain.