Physicists Stephan Ritter and Gerhard Rempe headed up a team at the Max Plank Institute of Quantum Optics (MPQ) in Germany that has successfully produced quantum computing. Quantum computing uses an atom as the smallest piece of information. In traditional computing, a bit is the smallest piece of information. A bit can hold the value of either 0 or 1. In quantum computing, an atom can hold a value of 0 and 1 at the same time.
Graphic by Andreas Neuzner, MPQ
The scientist achieved quantum computing by isolating a rubidium atom in a cavity with mirrors on either side. They shoot a fine-tuned laser at the atom. This causes the atom to emit a photon through a 120-foot fiber optic cable to another atom also in a cavity with mirrors in another lab. The photon bounces thousands of times off the mirrors until it hits the second atom. By absorbing the photon, the second atom absorbs information about the first. This is how transfer of information works in quantum computing.
The scientist also achieved something called "entanglement" between the atoms. Entanglement links the two atoms. If the first atom is in quantum state X, the photon will communicate that to the second atom and place the second atom in quantum state X.
"We can generate remote entanglement between the two nodes and keep it for about 100 micro-seconds, whereas the generation of the entanglement takes only about one microsecond. Entanglement of two systems separated by a large distance is a fascinating phenomenon in itself. However, it could also serve as a resource for the teleportation of quantum information. One day, this might not only make it possible to communicate quantum information over very large distances, but might enable an entire quantum internet."
An entire quantum internet would be a hack-proof internet. As soon as someone hacks into the network, the atoms would be in different states. The network would know immediately that something is wrong and take steps to prevent the intruder from accessing information.
Although the quantum network at MPQ consists of only two nodes, the work done holds promise in that it can be scaled up. Ritter adds:
"Everything is at the edge of what can be done. All these characteristics are good enough to do what we've done, but there are clear strategies to make them better."