Quantum theory traditionally viewed events at extremely short time scales, such as electron orbits and particle collisions, as instantaneous. However, recent advancements allow for the investigation of these rapid processes.
Researchers from TU Wien and China have created computer simulations to explore ultrafast events, enabling the study of quantum entanglement development on attosecond time scales.
When two particles are quantum entangled, they cannot be described separately; their properties are shared rather than individual. Prof. Joachim Burgdörfer from TU Wien explains that mathematically, entangled particles are inseparable, even if they are distant.
While most experiments focus on preserving this entanglement for applications like quantum cryptography or computing, researchers, including Prof. Iva Březinová, aim to understand how entanglement develops and the physical effects involved on extremely short time scales.
The researchers studied atoms subjected to intense, high-frequency laser pulses, which can eject one electron and potentially elevate a second electron to a higher energy state, altering its orbital path. After this process, the two electrons become quantum entangled, meaning they must be analyzed together. As Prof. Joachim Burgdörfer notes, measuring one electron provides information about the other, highlighting the interconnected nature of their states.
The research team demonstrated that the “birth time” of an electron ejected by a laser pulse is quantum entangled with the state of the remaining electron in the atom.
According to Prof. Joachim Burgdörfer, this means the ejected electron exists in a superposition of having left the atom multiple times without a definitive moment. The state of the remaining electron affects the likelihood of the ejected electron’s birth time: if the remaining electron has higher energy, the ejected electron likely left earlier; if it has lower energy, it likely left later, averaging around 232 attoseconds.
This incredibly short duration can be both calculated and experimentally measured, and discussions are underway with other research teams to validate these ultrafast entanglements.
Journal Reference:
- Wei-Chao Jiang, Ming et al. Time Delays as Attosecond Probe of Interelectronic Coherence and Entanglement. Phys. Rev. Lett. DOI: 10.1103/PhysRevLett.133.163201
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