Teleportation becomes a science fact, no longer fiction
Teleportation is no longer science fiction, says a team of Chinese scientists, after teleporting a photon particle from the Earth’s surface to an orbiting satellite 870 miles (1,400 km) away. This does not mean, however, that we are now able to beam people up and down like Star Trek’s captains James Kirk, Jean-Luc Picard, or Kathryn Janeway – that is still very much in the realm of science fiction, physicists say.
Teleportation, also known as teletransportation, is the theoretical transfer of energy or matter from one point to another instantly – without traveling through the physical space between them.
According to CollinsDictionary.com, teleportation is:
“The theoretical transportation of matter through space by converting it into energy and then reconverting it at the terminal point.”
For the past twenty-five years, teleportation has been a hot topic in **quantum mechanics, specifically state, energy and particles teleportation.
** Quantum mechanics, also known as quantum physics, is the fundamental theory of nature at small scales and low energy levels of atoms and subatomic particles (i.e. physics at atomic and subatomic levels).
In this image, the two photons are completely identical, so much so that one could say they are one photon at two different places at the same time. According to Wikipedia: “Spontaneous parametric down-conversion process can split photons into type II photon pairs with mutually perpendicular polarization.” (Image: adapted from wikipedia)
Nothing really travels with teleportation
In fact, the scientists explained that with the teleportation they are talking about, nothing is really transported. The mass or energy does not travel, there is an identical twin somewhere else – really, there is no traveling.
Imagine a fax machine – it sends the data about the marks on a sheet of paper rather than transporting the paper itself.
Teleportation is similar. At the other end of the fax message, the receiving fax machine gets the data and applies it to a sheet of paper that is already there – the two sheets of paper, the one in the sending fax machine and the other one in the receiving machine, stay where they are. What is transmitted is the information about what is written or drawn on the paper – it is re-written or re-drawn on the other paper.
In the Star Trek series, there are characters who refuse to use the transporter because they don’t like the idea of dematerializing and then rematerializing somewhere else.
Teleportation and quantum entanglement
What this team of scientists has done relies on a phenomenon called quantum entanglement – when two particles are created simultaneously in different places, so that effectively they have the same existence.
This entanglement – both particles being identical and changing in the same way simultaneously – continues even when the photons are far apart.
In an interview with BBC News, Sandu Popescu, Professor of Physics at Bristol University in England, who has been working on quantum entanglement since the end of the last century, said:
“Even then people were thinking about Star Trek. But we are talking about sending the state of a single particle, not the billions of billions of billions of particles that form a person.”
“If you are thinking about a remote planet, first you would have to exchange billions of entangled pairs of particles and then you have to send other information as well. This is highly non-trivial. One should not get excited by that.”
Using quantum entanglement in their latest experiment, the scientists ‘transmitted’ the information about a particle over a distance. The data about that particle was transmitted to another ‘linked’ particle instantly.
If you find the notion baffling, don’t worry, even Albert Einstein did. He described the idea as ‘spooky action at a distance’.
The scientists do not believe we will ever be able to teleport humans from one place to another. The technology being developed, they say, may lead to technologies such as ultra-secure communications, where the data is teleported from point A to point B (from one place to another).
In Star Trek’s teleportation, a human – like Captain Kirk in the image above – would gradually dematerialize in the transporter until he vanished completely, and slowly rematerialize somewhere else. Scientists say that we are nowhere near being able to teleport people in this way – it might never be possible.
Teleportation over longer distances
Long-distance teleportation has been recognized as a basic element in protocols such as large-scale quantum networks and distributed quantum computation.
However, all previous teleportation studies were successful only over relatively short distances – up to 100 kilometer’s – due to photon loss in optical fibers or terrestrial free-space channels.
With satellites, however, teleportation at much greater distances is possible. Photon loss is much less because the photons’ propagation path is in empty space.
In this latest experiment, the researchers achieved the first quantum teleportation “of independent single-photon qubits from a ground observatory to a low Earth orbit satellite – through an up-link channel – with a distance up to 1400 km.”
In an Abstract published in arXiv.org, a repository of electronic pre-prints, known as e-prints, titled “Ground-to-satellite quantum teleportation”, the scientists wrote:
“To optimize the link efficiency and overcome the atmospheric turbulence in the up-link, a series of techniques are developed, including a compact ultra-bright source of multi-photon entanglement, narrow beam divergence, high-bandwidth and high-accuracy acquiring, pointing, and tracking (APT).”
“We demonstrate successful quantum teleportation for six input states in mutually unbiased bases with an average fidelity of 0.80+/-0.01, well above the classical limit. 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.”
In another Abstract, published in the journal Science, dated 16th June 2017, titled “Satellite-based entanglement distribution over 1,200 kilometers,” the scientists wrote:
“A successful quantum communication network will rely on the ability to distribute entangled photons over large distances between receiver stations. So far, free-space demonstrations have been limited to line-of-sight links across cities or between mountaintops.”
“Scattering and coherence decay have limited the link separations to around 100 km. Yin et al. used the Micius satellite, which was launched last year and is equipped with a specialized quantum optical payload. They successfully demonstrated the satellite-based entanglement distribution to receiver stations separated by more than 1200 km. The results illustrate the possibility of a future global quantum communication network.”
Video – What is teleportation?
In this World Science Festival video, Seth Lloyd, a professor of mechanical engineering and physics at the Massachusetts Institute of Technology, who refers to himself as a quantum mechanic, explains what teleportation is.