No, you’re not dreaming. China has teleported an atom into space. Gone are the days of teleportation being a Jetson’s-esque dream.
In 2016, China launched a rocket carrying a satellite named Micius. The rocket put Micius in a Sun-synchronous orbit. This means that the satellite passes over the same point on Earth at the same time each day. Micius is a highly sensitive photoreceiver which can detect quantum states of single photons that are fired from the ground. It is a key player in the development of teleportation, entanglement and cryptography.
The Micius team has now successfully achieved earth-to-space teleportation and announced the creation of the first satellite-to-ground quantum network. They broke the record for the longest distance that entanglement has been measured and successfully used the quantum network to teleport an object from ground to orbit.
Teleportation is a standard operation in quantum optics labs and relies on entanglement. Entanglement occurs when two quantum objects like photons form at the same instant and point in space. They share the same existence and are described by the same wave function.
This shared existence continues when photons are separated by great distances. A measurement on either photon immediately influences the state of the other, even when they are separated by a large distance.
In the 1990s, the link to transmit quantum information from one point to another was discovered. Essentially, scientists “download” the information from one photon in one place and transmit it to an entangled photon in a different place. The second photon takes on the identity of the first and essentially becomes the first photon. This type of teleportation has been practiced in many labs on Earth.
Theoretically there should be no maximum distance over which teleportation can be done. But entanglement is fragile because photons interact with matter in the optical fibers or atmosphere, causing the entanglement to be lost completely. The teleportation distance over which entanglement happens has therefore been limited to a distance of 100 kilometers.
Micius has changed all that. The satellite orbits at 500 kilometers, and any photons that make the journey to the satellite must travel through a vacuum. The Chinese team set up a station in Ngari, Tibet at an altitude of over 4,000 meters in order to minimize the amount of atmosphere interfering with the signal. The distance from the ground to the satellite varies from 1,400 km when it’s near the horizon to 500 km when it is overhead.
The Chinese team created entangled pairs of photons on the ground at a rate of about 4,000 per second. Then they beamed one of the photons to the satellite, which passes overhead at midnight each night. The other photon was kept on the ground. The team then measured the photons on the ground and in orbit to ensure that entanglement was taking place; if so, they could then teleport the photons. In 32 days, millions of photons were teleported and the researchers found positive results in 911 cases.
This is the first time an object has been teleported from Earth into space. The work sets the stage for more goals in the future, maybe even allowing human teleportation into space.
A paper on the experiment is published here.