Teleportation is one of those bizarre concepts that rightfully belongs to the world of quantum physics. And it’s quite different from what we’re pretty sure you’re imagining it to be — you’re thinking about ‘Star Trek’ and the famous movie line ‘Beam me up, Scottie’, aren’t you?
Quantum teleportation is far from that. It relies on quantum entanglement — what Einstein referred to as ‘spooky action at a distance’ — a special kind of link that persists whether the ‘entangled’ particles, such as photons created at the same instant, are just a few meters away or are light-years apart. And measuring the state of one immediately influences the state of the other.
It is this special connection that makes teleportation possible, by allowing quantum data to be downloaded from one entangled photon to the other entangled photon, thus resulting in the second photon taking on the identity of the first photon.
Quantum entanglement is hard enough to prove. Quantum teleportation is even harder to do. But that’s exactly what a team of researchers in China were able to achieve by successfully teleporting a photon from Earth to a satellite orbiting at a distance of over 500 kilometers away.
The satellite is known as Micius, named after an ancient Chinese philosopher. It was launched last year and has been in Sun-synchronous orbit since then, which means it passes over the same spot on Earth at exactly the same time each day. This predictability is what enables scientists to plan carefully timed research and test different quantum concepts like cryptography, entanglement and teleportation.
Micius is a highly sensitive photon receiver that can detect quantum states of single photons fired from the ground. And just recently, the Micius team announced two important feats. First, they had created the first satellite-to-ground quantum network, and through it, they were able to break the record for the farthest distance over which quantum entanglement has been measured. The record previously stood at around 100 km. Their new record is at 500 km.
Second, they were able to use their newly created quantum network to teleport a photon — the first object ever to be teleported — from the ground to orbit. To do this, the team created ground entangled pairs of photons. Afterwards, they beamed one of the photons to Micius, while keeping the other photon on terra firma. They then measured the photons both in orbit and on the ground to confirm their ‘entanglement’ and that they could be teleported. In a period of 32 days, out of millions of photons, they reported positive results in 911 cases.
Proving that teleportation can be done is one thing. Applying the technology, though, is another. And while theoretically, there shouldn’t be a maximum transportation distance, there’s still the matter of entanglement being extremely fragile, and any interference — such as objects in the atmosphere or within optic fibers where photons will pass through — can instantly cause disentanglement.
Despite such limitations, China’s feat is still considered a big deal and could pave the way for more ambitious projects in the future. As the team told MIT Technology Review: “This work establishes the first ground-to-satellite up-link for faithful and ultra-long-distance quantum teleportation, an essential step toward global-scale quantum internet.”