Quantum Entanglement Can Be Cloned
New Research Shows How to Copy Quantum Connections
Scientists have figured out how to “clone” the bizarre quantum property called entanglement. They designed a theoretical machine that can make copies of this "spooky action at a distance."
The researchers asked if a special kind of quantum machine, called a quantum cloning machine (QCM), could make duplicates of entanglement. It's like asking if you can perfectly copy a delicate dance between two distant partners.
They designed a theoretical QCM to optimally copy the entanglement of a pair of quantum systems [tiny particles or energy packets]. The machine aims to create the most entanglement possible in the two new copies, while making sure that systems that weren't entangled to begin with stay separate. This was a theoretical study, using advanced math and group theory to figure out the best way to make these copies.
Key Findings on Cloning Fidelity
The study found that the best possible copy of entanglement, measured by something called "fidelity," gets very close to 50 percent for very large quantum systems. This means that for big systems, the copies hold about half the entanglement of the original.
For smaller systems, like those with a dimension (d) of 2, the fidelity reaches about 71.7 percent.
"The entanglement of the clones is always less than one half the entanglement of the input state, while it asymptotically approaches this value for large d."
— Karpov, Navez, & Cerf (2005)
This means that while you can't get a perfect copy, you can get a significant amount of the original entanglement into the new copies.
Implications and Future Work
This discovery is a big step in understanding how to manage and use entanglement, a key ingredient for future quantum computers and communication systems. If we can copy entanglement, we might be able to send quantum information more securely or build more powerful quantum technologies.
One limitation of this new cloning machine is that it works best for a specific type of entanglement called "maximally-entangled states." Future research will need to explore how to clone other kinds of entangled states.
This new blueprint brings us closer to a future where quantum entanglement, one of the universe's most mysterious connections, can be duplicated and put to work.
Reference
Karpov, E., Navez, P., & Cerf, N. J. (2005). Cloning quantum entanglement in arbitrary dimensions. arXiv preprint quant-ph/0503148.