Joint quantum measurements are essential in quantum theory but not well understood. A key question is whether measurements on separate systems can be done without physically combining them. Surprisingly, this is possible using shared entanglement, though only if we ignore the system’s state after measurement. However, current methods often demand unlimited entanglement, making them impractical.
Researchers at the University of Geneva (UNIGE) have addressed the fundamental question: Which joint measurements can be localized with a finite amount of entanglement?
Researchers at the University of Geneva have demonstrated that joint measurements can be performed on distant particles without physically bringing them together. This is possible due to quantum entanglement, which connects particles across space as if invisibly linked.
The breakthrough has significant implications for quantum communication and computing, where information only becomes accessible upon measurement. The team has also created a catalog that classifies measurements based on the number of entangled particles required.
A practical method to measure quantum entanglement
Entanglement connects particles so that measuring one instantly determines the state of the other, no matter how far apart they are.
However, different measurements require varying amounts of entangled particles. To clarify this, researchers have created a classification system that organizes measurements based on the entanglement needed for each.
These findings help improve our understanding of quantum measurements and could impact quantum communication and computing. In classical computing, calculations are spread across multiple machines, with results gathered later.
Quantum computers may follow a similar approach, but reading the data requires measurements across several machines. With joint remote measurement protocols, there’s no need to centralize data. Each quantum computer can measure its portion, and the final result can be assembled without physically transferring information.
Journal Reference:
- Jef Pauwels, Alejandro Pozas-Kersjens, Flavio Del Santo and Nicolas Gisin. Classification of Joint Quantum Measurements Based on Entanglement Cost of Localization. Physical Review X. DOI: 10.1103/PhysRevX.15.021013
