Key Points
- TU Wien scientists study how quantum entanglement develops over time on an attosecond scale.
- Advanced simulations allow the team to track ultrafast quantum processes, challenging previous ideas that entanglement happens instantaneously.
- The study involved high-frequency laser pulses to knock electrons out of atoms, leading to quantum entanglement between two electrons.
- The ejected electron’s exact “birth time” is quantum-entangled with the electron’s energy state left behind, forming a measurable link.
Quantum entanglement, one of nature’s fastest processes, is being unraveled on an unprecedented time scale by scientists at TU Wien (Vienna). Along with collaborators in China, they have developed advanced computer simulations to explore the formation of quantum entanglement in attoseconds—trillionths of a second. This breakthrough reveals the hidden dynamics behind what was once considered an “instantaneous” quantum event.
Quantum entanglement occurs when two particles are so intertwined that their individual properties become inseparable, even across vast distances. Traditionally, quantum effects like entanglement were thought to happen instantly. However, the TU Wien team, led by Professors Joachim Burgdörfer and Iva Brezinová, has shown that these processes unfold over extremely short intervals. Their findings, published in Physical Review Letters, provide fresh insight into the temporal evolution of entanglement.
The researchers examined atoms bombarded by an intense, high-frequency laser pulse. When one electron is ejected from the atom, another electron within the atom is simultaneously excited to a higher energy state. This interaction leads to the quantum entanglement of the two electrons: one remains with the atom while the other flies away. Crucially, the timing of this electron ejection—referred to as the “birth time”—is entangled with the state of the electron left behind.
Through a combination of laser pulses, the team demonstrated that the moment the free electron left the atom was connected to the energy state of the electron that stayed behind. In essence, the exact time when the ejected electron left the atom cannot be determined in isolation—it is in a superposition of both earlier and later times. This superposition is quantum-entangled with the remaining electron’s energy state, a relationship that can now be measured experimentally.
This research challenges the traditional notion of quantum effects as being instantaneous. It shows that entanglement develops during a short but measurable period, where the electron transitions from the atom wave-like. This brief phase of entanglement formation, lasting around 232 attoseconds, has now been resolved and quantified. The study opens new doors for investigating the temporal structure of quantum processes, allowing scientists to probe deeper into the fundamental mechanics of the quantum world.
