Beam Us Up One Day, Scotty?
When news broke last month of Chinese researchers successfully teleporting a photon — a particle of light — from an instrument on the Tibetan plateau to an orbiting satellite 1,400 km away in space, it sent a frisson of excitement through the scientific community. But it wasn’t quite ‘Beam me up, Scotty’ time yet.
When physicists talk about teleportation, they mean the creation of a single particle that can be in two or more states at the same time, and transferring characteristics that define the particle’s nature and behaviour to its twin without using any physical link. The particles share their ‘quantum states’ — such as energy, motion and magnetic field — regardless of the distance separating them.
Scientists have known for decades that teleportation is possible using a process called ‘quantum entanglement’ — at least for subatomic particles. This involves what Albert Einstein famously described as “spooky action at a distance” between two linked particles that are created at the same time and place so that essentially they have the same existence. The entanglement so entwines the fate of each inextricably that if one changes its state, the other takes on its old properties and becomes a replica of the first’s original state.
This ‘entangled’ state continues even if you separate the particles: if one particle changes, its doppelgänger in the other location also changes. This goes against the known laws of physics where we are used to everyday objects behaving in familiar ways.
Till now, this ability to transfer key properties from a quantum particle to another has been confined to experiments at limited distances. So how did the Chinese teleport a photon many times this distance into space? Well, photons can travel easily through the vacuum of space, provided they are able to negotiate Earth’s fickle atmospheric conditions on their way out first.
The Chinese apparently created thousands of quantum-entangled pairs of photons per second and allowed one from each pair to ride a shaft of light that was beamed towards an orbiting satellite. A supersensitive receiver on board the satellite detected the quantum states of the single photons coming its way so that the entangled photons could be transmitted to ground stations.
The phantom character of quantum particles that lets them be teleported — the simultaneous existence of two of a kind — can be used for developing quantum computers. Here, information is processed in the form of qubits used in computers today. With quantum computing, you can have central processing elements smaller than a sugar crystal that can carry out unimaginably complex computations and they are faster, too. And this also means practically ‘un-hackable’ cryptography as data encryption using qubits is practically unbreakable.
So, will human teleportation be a reality someday? Teleporting photons or atoms is one thing, and teleporting people quite another. To vaporise a human made up of zillions (one with 27 zeros) of atoms and accurately reassemble them elsewhere seems well-nigh impossible. Even the data processing required to teleport, say, a teacup, without the tea, would take many times the age of the universe.
True, in principle, the laws of physics allow you to recreate anything anywhere, provided you satisfy two key conditions: that you have the requisite processing power, and are willing to destroy the original (teleportation destroys the object before reconstructing it). Quantum travellers would, therefore, be virtually killed if they tried to travel in this way, as it’s only their ‘copy’ that emerges at the other end.
Perhaps, in some far future, humans may build a device similar to the ‘beam transporter’ in Star Trek. Inside the transporter, computers codify your atomic structure and transmit it on laser beams across the universe. At the destination, this ‘quantum communication’ is received by computers that use vats of chemicals to reconstruct you in your original image. And lo! You are ready to check your arrival and beam-out data from whichever universe you may be in.
Scale up quantum entanglement