Computers, cell phones, and any other device being used to read this article rely on a three-century-old approach to computation that represents data with a binary system. However, it’s possible that some computations will shift to a different system entirely thanks to developments in the field of quantum computing.

Classical computing uses logic gates with a 1 or 0 value. Quantum bits, or qubits, can represent a 1, 0, or any state achieved by a mixture of these two through their quantum superposition. Single qubits can be linked to create a single computer that can perform parallel calculations that are out of the reach of today’s hardware.

Studies conducted at the Max-Planck-Institut in Germany may help enable these sorts of parallel computations. In their studies, published in Nature, researchers have used the two spin orientations of an atom, along with two polarization states of a photon, to represent a 0 or 1.

The atom is held trapped between two mirrors that form a cavity. By using laser pulses, single photons are prepared with the desired polarization state. The photon is then delivered to the cavity and interacts with the atom, leading to quantum entanglement. This allows the atom-photon system to act like a logic gate, one that the scientists call a quantum gate.

To test the quantum gate, the scientists varied their input using one and two laser pulses at a time, delivering photons of varying polarizations to the cavity. As they expected, atom-photon entanglement occurred between the laser pulse and the atom in the cavity. If the incoming photon vibrates at the same frequency as the atom in the cavity, it leaves through the same mirror and undergoes a phase shift. If the photon does not vibrate at the same frequency as the atom, it causes a shift in the atom's vibrational frequency, and the photon will bounce back with no shift.

Using this conditional phase shift along with quantum super-positioning, the scientists were able to implement a quantum logic gate. This gate, consisting of an atom and a photon, is crucial for creating quantum networks to store and retrieve information.

The scientists expect these results to enable the development of larger units, where dozens of quantum gates are coupled to allow for parallel calculations.

Nature, 2014. DOI: 10.1038/nature13177 (About DOIs).