Topic: Physics

Physicists developed a method to measure time scales in quantum mechanics without using external clocks. They found that atomic structure affects how quickly quantum events unfold.

Quantum mechanics is the study of tiny things like atoms and particles. For a long time, scientists have struggled to understand how time works at these tiny scales. Professor Hugo Dil from EPFL says, 'The central problem is the general role of time in quantum mechanics, and especially the timescale associated with a quantum transition.'

At the smallest scales, physical processes happen very quickly. For example, an electron shifting to a new energy state after absorbing light can happen in just a few tens of attoseconds (10-18 seconds). That's so brief that even light wouldn't travel across the width of a small virus during that time.

Measuring these tiny slices of time has been extremely challenging. Any external timing device risks interfering with the fragile quantum process being studied and changing its behavior. Professor Dil says, 'Although the 2023 Nobel prize in physics shows we can access such short times, the use of such an external time scale risks to induce artifacts.'

A team led by Fei Guo developed a new method that avoids external clocks altogether. When electrons absorb a photon and are emitted from a material, they carry information encoded in their spin. By carefully analyzing these changes, the researchers were able to determine how long the transition lasts.

The team used a technique called 'spin- and angle-resolved photoemission spectroscopy' (SARPES). In this method, intense synchrotron light strikes a material, boosting its electrons to higher energy and forcing them to escape the material's structure. Scientists then measure the energy, direction, and spin of the emitted electrons.

The team tested materials with very different atomic arrangements. Some were fully three-dimensional, while others had weakly connected layers or chain-like structures. The results revealed a consistent pattern: the simpler and more reduced the atomic structure of a material, the longer the quantum transition lasted.

These findings show that the atomic scale shape of a material strongly affects how quickly a quantum event unfolds, with lower symmetry structures leading to longer transition times.

Why It Matters

Understanding quantum time is crucial for developing new technologies like super-fast computers and advanced medical treatments. This discovery can help us create more accurate models of quantum processes, which could lead to breakthroughs in fields like materials science and energy production.

Key Facts

• Physicists developed a method to measure time scales in quantum mechanics without using external clocks
• The new method uses spin- and angle-resolved photoemission spectroscopy (SARPES) to analyze the changes in electron spin
• The team tested materials with different atomic arrangements, including fully three-dimensional and layered structures
• The simpler and more reduced the atomic structure of a material, the longer the quantum transition lasted
• This discovery can help us create more accurate models of quantum processes

Key Terms

Attosecond

One billionth of a second

Implications

Understanding quantum time is crucial for developing new technologies like super-fast computers and advanced medical treatments. This discovery can help us create more accurate models of quantum processes, which could lead to breakthroughs in fields like materials science and energy production.