Entangling atoms from different elements does it all, quantum-wise
Dec. 16, 2015 (ArsTechnica) -- Quantum systems are inherently fragile as any interactions with the outside world can change their state. That makes creating things like quantum memories rather challenging, since it can be hard to know if it actually preserves the information you put into it. To get around this, researchers have been looking into ways of creating error-correcting quantum memory.
Now, researchers have come up with a rather simple scheme for providing quantum error controls: entangle atoms from two different elements so that manipulating won't affect the second. Not only is this highly effective, the researchers show that they can construct quantum logic gates with the setup. And while they were at it, they demonstrate the quantum nature of entanglement with a precision that's 40 standard deviations away from classic physical behavior.
People have managed to entangle different types of particles previously. For example, you can entangle an atom and a photon, which allows the photon to transfer information elsewhere -- something that's undoubtedly necessary for a quantum computer.
In the two new papers, the researchers involved lay out the case for entangling different types of atoms. If you use the same types of atoms for memory and backup copies of the bits, then there's always a chance that a photon meant for the memory will scatter off it and hit one of the backups instead. If you use atoms from different elements, then they'll be sensitive to different wavelengths of light. Manipulating one will leave the other unaffected.
As one of the labs involved (from the University of Oxford) put it, "it allows protection of memory qubits while other qubits undergo logic operations or are used as photonic interfaces to other processing units."