Scientists at Kyoto University and Hiroshima University have achieved a breakthrough in quantum physics by successfully identifying the elusive W state of quantum entanglement, solving a 25-year-old challenge in the field[1].
The team developed a method to measure entangled W states using photonic quantum circuits, demonstrating it successfully with three photons. This achievement is significant because W states, along with GHZ states, are fundamental building blocks for quantum networks[1:1][2].
“More than 25 years after the initial proposal concerning the entangled measurement for GHZ states, we have finally obtained the entangled measurement for the W state as well,” said Shigeki Takeuchi, the study’s corresponding author[1:2].
The breakthrough enables single-shot identification of quantum states, eliminating the need for numerous measurements that grow exponentially with added photons. This advancement opens paths for:
- Quantum teleportation of information between distant locations
- New quantum communication protocols
- More efficient quantum computing methods
- Transfer of multi-photon quantum entangled states[1:3][3]
The research team used highly stable optical quantum circuits that could operate for extended periods without active control. They validated their method by successfully distinguishing different types of three-photon W states[3:1].
Unfortunately not. Quantum teleportation is an awful name: it’s called that way because it implies “destroying” a quantum state somewhere, and “recreating” it identically somewhere else, effectively transmitting information. However, the process also requires a classical information transfer at some point, and is absolutely not instantaneous . It’s only useful for cryptography because it’s mathematically impossible to listen in on this information being transferred without disturbing it.
It’s one of the most unfavorable coolness-of-name vs. coolness-of-actual-thing ratio in physics.