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][^3].
"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].
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][^8]
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[^8].
[^1]: ScienceDaily - New quantum breakthrough could transform teleportation and computing
[^3]: RSInc - New Quantum breakthrough could transform Teleportation and Computing
[^8]: SciTechDaily - Scientists Capture W State, Unlocking Quantum Teleportation
wait wait wait, you're telling me they just claimed to invent the core technology for an ansible? FTL communications?
But this still requires the emissions of entangled photos from a single source right? and keeping the entangled photons entangled requires preventing them from being absorbed/split by interacting with molecules?
Hmm... maybe this means potential elimination of long-fiberoptic data lag (which is tiny)? Or can they actually capture entangled photos in separate systems for meaningfully long times to transport?
Woah, holy crappie, we are already a lot further along on this than I thought.
"Northwestern University engineers are the first to successfully demonstrate quantum teleportation over a fiberoptic cable already carrying Internet traffic."
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.