Quantum teleportation has recently garnered attention due to reports of Chinese scientists successfully achieving this phenomenon between a ground station and a satellite in the summer of 2017. For many, this sparked visions reminiscent of Star Trek, where matter is transported instantaneously across vast distances. However, the reality is far more complex.

The term "teleportation" can be misleading. In the realm of science fiction, it suggests the disassembly of atoms at one location and their immediate reconstruction at another. This notion gained traction as a storytelling device in Star Trek, where the crew needed a quick way to transport from their spacecraft to various planets without extensive special effects. Yet, in the scientific community, teleportation refers to a phenomenon involving the instantaneous change of state in two entangled particles, regardless of the distance that separates them.

This concept hinges on quantum entanglement, where two particles become part of a single system. Thus, any change to one particle is mirrored by the other, regardless of the space between them. Albert Einstein famously critiqued this idea, dubbing it "spooky action at a distance." Despite its intriguing nature, quantum entanglement does not allow for communication beyond the speed of light, which is approximately 300,000 kilometers per second.

To clarify, physicists use "teleportation" differently than sci-fi enthusiasts. Think of it as two telephones linked by a long cable. When one person speaks, their voice travels through the wire without the device disappearing and reappearing. Similarly, in quantum teleportation, particles linked by entanglement can influence each other instantly without one particle vanishing and reassembling elsewhere.

So, can quantum entanglement facilitate instantaneous communication, akin to subspace channels in science fiction? The answer is no, and the reasons are more intricate than mere terminology confusion.

To understand this, we begin with the entanglement process, which in the Chinese experiment involved photons—particles of light that possess both wave and particle characteristics. Photons are massless, enabling them to travel at light speed, but they do carry momentum and propagate as intertwined electric and magnetic waves. By using a specialized prism, researchers can create a pair of entangled photons, where the state of one immediately influences the other.

In the Chinese experiment, a photon was split to form an entangled pair, with one photon sent to a satellite and the other remaining on Earth. The scientists then entangled the lab photon with another and measured the quantum states of this new combination. It's crucial to note that they measured whether the states were identical or different, but they did not determine the specific state itself. The photon on the satellite would correspond with half of the state of the lab photon, but without communication from the ground, it would be impossible to ascertain the complete information.

The essence of quantum entanglement is that one must understand the entire system to fully describe it. Simply measuring one part does not yield complete information about the entangled pair. For instance, if Bob mixes two paint colors to create brown and sends Mary a sample, she cannot determine the original colors without further information from Bob.

This is a challenging concept to grasp. The photon sent to the satellite certainly carries some information, but transmission does not equate to information transfer. Consider a walkie-talkie: if radio waves are distorted by environmental factors, the receiver may detect the presence of a signal but fail to understand the message.

The entangled photon received by the satellite indicates its presence, but it cannot convey the intended information. Until the researchers on Earth communicate the necessary details through traditional methods, the entangled photon remains devoid of meaningful data.

We encounter a chicken-and-egg scenario here. Regardless of how many entangled photons reach the satellite, each one presents the same issue: the signal can be detected, but the information remains inaccessible until conventional communication occurs at light speed.

Thus, quantum entanglement cannot facilitate faster-than-light communication. Furthermore, popular science often depicts quantum phenomena as deterministic, which is misleading. The famous double-slit experiment illustrates this well. When photons or electrons pass through two slits, they behave as both particles and waves. However, when a single particle is observed, it only appears at one point, and the interference pattern emerges only after many particles have been fired.

Quantum mechanics is inherently probabilistic; while the distribution of many particles can indicate a median value, the exact position of any single particle remains uncertain.

So why did the Chinese scientists pursue this experiment? Quantum entanglement offers a potential for secure communication. If a message is sent via entangled photons, and the recipient receives corresponding information through conventional means, they can verify whether their photons match the sender's. If they do, it confirms the message wasn't intercepted. If not, it indicates that an interception occurred, as any measurement alters the quantum state.

However, measurement is a one-time event. If the recipient measures the photons before receiving any information from the sender, the entanglement is destroyed. The sender cannot communicate the message until they relay information through traditional methods, which are limited to light speed.

Ultimately, what the Chinese demonstrated was not the fantastical teleportation of science fiction but rather that under specific conditions, entanglement can secure information transmission. Any interception alters the photons, indicating a breach in security—but only if the recipient has the conventional means to interpret the information.

This application of entanglement may prove beneficial, but we are not on the cusp of stepping onto transporter pads or utilizing subspace communications. It's wise to leave those Star Trek costumes packed away for now.

REFERENCES: - https://www.technologyreview.com/2017/07/10/150547/first-object-teleported-from-earth-to-orbit/ - https://www.space.com/37506-quantum-teleportation-record-shattered.html