Germans created a quantum logic gate between two qubits in two different laboratories

German researchers at the Max Planck Institute for Quantum optics have a logical Gate operation performed with two qubits located in two different laboratories. Your achievement is a very important step towards distributed quantum processing. It could allow the building of modular computer systems made up of devices that are in different places but function like one big computer. The addition of another qubits now quantum computers is not an easy task. Qubits must be able to perform logical operations and at the same time from external influences (noise) that their Quantum state can destroy, be isolated.
A very important source of noise in Quantum systems is the interference between the qubits themselves. For example, if we have a system of 4 qubits and we want to perform calculations involving only 2 of them, there is still a risk of interaction between qubitswho do not participate in the calculations.

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The more qubits are in the system, the greater the noise problem. One way to deal with this problem is to distribute the qubits among different devices, but this requires the integration of the logical operations performed by those devices. If we only perform calculations on such a module and send the results to another module for processing, we still do not increase the available computing power, says Severin Daiss from the Institute for Quantum optics.

That is why the concept of Teleportation and Quantum gate of great interest from scientists. That is the idea after which the starting data of a Quantum logic gate depend on the input data of a gate at a different location.Daiss and his colleagues, who work under the direction of Professor Gerhard Rempe, have demonstrated a significantly simplified technique that uses the interaction of a photon with modules in two different laboratories to create a quantum logic gate between created two qubits. Your achievement is a very important step towards the distributed Quantum processing. It could allow the building of modular computer systems made up of devices that stand in different places but function like one big computer. Adding another qubit to a quantum computer is not an easy task. qubits must be based on logical oprs. In each of these laboratories, the researchers created an optical cavity called a Rubidium atom contained. The devices were connected by a 60 meter long optical fiber. To establish a logical gate, the scientists sent a photon that acted as a "flying cubit" between the two cavities. It moved between them, what one Entanglement its polarization with the energy state of the rubidium atoms. This is how a CNOT gatewhose state can be read out by measuring the state of the photon.

Ronald Hanson from the Technical University of Delft believes that the work of the Germans is an important step forward. They made a photon ricochet off one side, travel to the other side, and take a measurement. It's very simple conceptually and they have shown that it works. The details of the experiment are in Science described.