Teleportation: Behind the Science of Quantum Computing
Researchers were able to reliably teleport information between quantum bits.
Published August 14, 2013
It might seem like something straight from the Star Trek universe, but two new research experiments—one involving a photon and the other involving a super-conducting circuit—have successfully demonstrated the teleportation of quantum bits.
If that sounds like gobbledygook, don’t worry. We got in touch with one of the researchers, physicist Andreas Wallraff, of the Quantum Device Lab at the Swiss Federal Institute of Technology Zurich, to explain how his team and a team based at the University of Tokyo were able to reliably teleport quantum states from one place to another.
People have done this before but it hasn’t necessarily been reliable. The newcomplementary research, which comes out in Nature today, is reliable—and therefore may have widespread applications in computing and cryptography.
Before we talk about the nitty-gritty part of teleportation, we need to define a few key words. Let’s start with a regular, classical bit of information, which has two possible states: 1 or 0. This binary system is used by basically all computing and computing-based devices. Information can be stored as a 1 or a 0, but not as both simultaneously. (Related: "The Physics Behind Schrodinger’s Cat.")
But a quantum bit of information—called a qubit—can have two values at the same time.
"With the qubit, you can store more information because you have information in all of its possible states," Wallraff says. "Whereas in the classical memory system, only one can be stored." (More physics: "The Physics Behind Waterslides.")
Quantum teleportation relies on something called an entangled state. An entangled state, in the words of Wallraff, is a “state of two quantum bits that share correlations.” In other words, it’s a state that can’t be separated.
If you have a classical 1 and a 0, for example, you can separate them into a 1 and a 0. But if you have qubits, the bits can be assigned both a 1 and a 0 at the same time—meaning they can’t be separated into their individual components and must be described relative to each other. (If you’d like to know more about this, I recommend delving into "Quantum Entanglement" on the Caltech website.)