Contents
📌 Research Reference
Yoon-Ho Kim, R. Yu, S.P. Kulik, Y.H. Shih, Marlan O. Scully
arXiv:quant-ph/9903047v1, March 13
👉 Read on arXiv
📄 Download PDF
🔍 What Is It About?
This groundbreaking experiment implements a “delayed choice quantum eraser” — a concept originally proposed by Scully and Drühl in 1982. It shows that we can erase or preserve which-path information of a quantum particle after it has been detected — and this changes the result retroactively.
The experiment combines quantum entanglement with a delayed measurement, causing interference patterns to either appear or disappear depending on future choices.
🧠 Why It Matters
The results demonstrate that a quantum particle behaves like a wave only if no one knows which path it took. But even if a particle has already been detected, and then its twin’s information is erased, the interference comes back — as if the particle “knew” in advance.
This calls into question the classical idea of fixed objective reality. It suggests that information — or meaning — affects the outcome, and future actions influence past events.
🧩 Link to “Deconstruction of Reality”
This experiment supports a central idea of the project:
Meaning is primary, and matter is secondary.
We do not simply observe a fixed, material world. Instead, the context and informational state — what can be known or not known — actively shapes what reality manifests.
This is more than physics — it’s a philosophical shift.
🧪 Key Features of the Experiment
- Uses entangled photons (signal and idler).
- The signal photon is detected at detector D₀.
- The idler photon, traveling a longer path, is either sent through a setup that preserves or erases which-path information.
- If the information is preserved → no interference.
- If it is erased → interference pattern appears, even though D₀ already registered the signal photon.
🧾 Quote from the Paper
“The which-path or both-path information of a quantum can be erased or marked by its entangled twin even after the registration of the quantum.”
🧠 Conclusion
The experiment confirms that reality is not built from particles moving along determined paths. Instead, the act of knowing, the availability of information, and future measurements shape what we observe — even after the fact.
This is not just a curiosity of quantum mechanics. It is a direct challenge to materialism. The delayed-choice quantum eraser proves that reality is deeply contextual, and that information creates the conditions for what is possible.