Teleportation

Teleportation, or the the ability to transport a person or object instantly from one place to another, is a technology that could change the source of civilization and alter the destiny of nations. It could irrevocably alter the rules of warfare: armies could teleport troops behind enemy lines or simply teleport the enemy's leadership and capture them.

Today's transportation system-from cars to ships to airplanes and railroads, and all the many industries that service these systems would become obsolete; we could simply teleport ourselves to work and goods to market. Vacations would become effortless, as we teleport ourselves to our destination. Teleportation would change everything.

According to Newtonian theory, teleporation is clearly impossible. Newton's laws are based on the idea that matter is made of tiny, hard billiard balls. Objects do not move until they are pushed: objects do not suddenly disappear and reappear somewhere else.

But in the quantum theory, that's precisely what particles can do. Newton's laws, which hed sway for 250years, were overthrown in 1925 when Werner Heisenberg, Erwin Schrodinger, and their colleagues developed the quantum theory. When analyzing the bizarre properties of atoms, physicists discovered that electrons acted like waves and could make quantum leaps in their seemingly chaotic motions within the atom.

In 1905 Einstein had shown that waves of light can have particle-like properties; that is, they can be described as packets of energy called photons. But by the 1920s it was becoming apparent to Schrodinger that the opposite was true: that particles like electrons could exhibit wavelike behavior. this idea was first pointed out by the French physicist Louis de Broglie, who won the Nobel Prize for this conjecture.

But there was still a nagging question that haunts physics even today. If the electron is described by a wave, then what is waving? This has been answered by physicist Max Born, who said that these waves are actually waves of probability. These waves tell you only the chance of finding a particlar electron at any place and any time. In other words, the electron is a particle, but the probability of finding that particle is given the Schrodinger's wave. The larger the wave, the greater the chance of finding the particle at that point.

In reality the quantum "jumps" so common inside the atom cannot be easily generalized to large objects such as people, which contain trillions upon trillions of atoms. Even if the election in out body are dancing and jumping in their fantastic journey around the nucleus, there are so many of them that their motions average out.

One can use the laws of quantum theory to create a machine to teleport something on demand, as in science fiction stories? Surprisingly, the answer is a qualified yes.

Then comes Quantum teleportation. Everything changed in 1993, when scientists at IBM, led by Charles Bennett, showed that it was physically possible to teleport objects, as least at the atomic level. Physicists have been able to teleport photons and even entire caesium atoms. Within a few decades scientists may be able to eleport the first DNA molecule and virus.

Quantum teleportation exploits some the more bizarre properties of the EPR experiment. In these teleportation experiments physicists star with two atoms, A and C. Let's say we wish to teleport information from atom A to atom C. We begin by introducing a their atom, B, which starts out being entangled with C, so B and C are coherent. Now atom A comes in contact with atom B. A scans B, so that the information content of atom A is transferred to atom B. A and B become entangled in the process. But since B and C were orignally entangled, information within A has now been transfferred to atom C. In conclusion atom A has now been teleported into atom C, that is the information content of A is now identical to that of C.

Teleportation without entanglement? Progress in teleportation is rapidly accelerating. In 2007 yet another breakthrough was made. Physicists proposed a teleportation method that does not require entanglement.

"We're talking about a beam of 5,000 particles disappearing from one place and appearing somewhere else,," says physicist Aston Bradley of the Austrailian Research Council Center of Excellence for Quantum Atom Optics in Brisbane, Australia.

He and his colleagues take a beam of rubidium atoms, convert all its information into a beam of light, send this beam of light across a fiber-optic cable, and then reconstruct the original beam of atoms in a distant location.

here's how Bradley and company's teleporation device works. First they start with a collection of supercold rubidium atoms in a BEC state ("Bose Einstein condensate" which is a millionth to a billionth of a degree above absolute zero). these atoms in the beam also want to tumble down to the lowest energy state, so they shed their excess energy in the form of a pulse of light. This light beam is then send down a fiber-optic cable. Remarkably the light beam contains all the quantum information necessary to describe the original matter beam (e.g., the location and velocity of all its atoms). Then the light beam hits another BEC, which then converts the light beam into the original matter beam.

So teleportation exists at the atomic level, and we may eventually teleport complex and even organic molecules within a few decades. But the teleporation of a macroscopic object will have to wait for several decades to centuries beyond that, or longer, if indeed it is even possible. Therefore teleporting complex molecules, perhaps even a virus or living cell, qualifies as a Class I impossibility, one that should be possible within this century. But teleporting a human being, although it is allowed by the laws of physics, may take many centuries beyond that, assuming it is possible at all. Hence it would qualify as a Class II impossibility.