The quantum time it is not at all a continuous and regular line, as we imagine it by looking at a watch. In the infinitely small world of atoms and electrons, time behaves in an irregular, fragmented, almost “elastic” way. And today, thanks to new research, we finally know what the real duration of a quantum event depends on.
A study conducted by a group of physicists fromEcole Polytechnique Fédérale de Lausanne has identified a revolutionary method to measure the time that elapses during a quantum transition, without using external clocks and without interfering with the observed phenomenon. A discovery that changes the way we look at time.
Quantum time is not instantaneous
In the quantum world, some processes occur at speeds that are difficult even to imagine. When an electron absorbs light and transitions to a higher energy state, the event can last as little as a few tens ofattoseconds, or billionths of a billionth of a second. To give you an idea, in such a short time not even light would be able to cross the width of a virus.
For years it was thought that these steps were practically instantaneous. In reality, this is not the case. Scientists have demonstrated that each quantum transition has a very precise duration and that the quantum time employed depends on hidden factors, linked to the matter itself.
Measuring such extreme time intervals has always been a huge problem. In fact, any external instrument risks altering the very delicate quantum balance. And this is precisely where the turning point comes.
Measuring quantum time without clocks
Researchers have developed a technique capable of “reading” time directly from within the quantum process. When an electron absorbs a photon and exits a material, it carries with it information encoded in its spin, a property that describes its quantum state.
By analyzing how the spin changes during the transition, it is possible to reconstruct how long it takes the electron to go from one state to another. No stopwatch, no external references: only signals internal to the system.
The secret lies in quantum interference. An electron, when excited by light, does not follow a single path, but multiple simultaneous paths that interfere with each other. This interference leaves a kind of imprint in the spin of the emitted electron. By studying how this signature varies as the energy changes, scientists are able to calculate the duration of the event.
To do this they used an advanced technique, spin and angle resolved photoemission spectroscopy, which allows them to analyze the energy, direction and spin of the electrons expelled from a material hit by synchrotron light.
Because quantum time changes from material to material
The most surprising part of the study concerns the link between quantum time and atomic structure. The researchers compared very different materials. Copper, with a compact three-dimensional structure. Layered compounds such as diselenide and titanium ditelluride, formed by overlapping and weakly bonded sheets. And finally copper telluride, with an even simpler, almost chain-like structure.
The result is clear: the simpler and less symmetric the atomic structure, the more the quantum transition slows down. In three-dimensional copper the process takes about 26attoseconds. In layered materials it rises between 140 and 175attoseconds. In the case of copper telluride, it even exceeds 200attoseconds.
This means that the quantum time it is not a universal constant. It is influenced by the geometry of matter, the arrangement of atoms, the way electrons can move and interact.
Understanding how long a quantum event really lasts is not just a theoretical curiosity. This research helps clarify whether and when we can consider quantum processes to be “instantaneous” and opens new perspectives for the design of advanced materials.
Knowing quantum time could be key to developing technologies based on the precise control of electrons, from quantum devices of the future to new materials for energy and electronics. Once again, physics reminds us that reality is much more complex and fascinating than it seems at first glance.
