Research indicates diamonds could be key to quantum storage

Posted by Wolfgang Gruener

Cambridge (MA) – Scientists at Harvard University discovered that Carbon-13 atoms in diamonds can be used to create a stable and controllable  quantum mechanical memory and a small quantum processor, often referred to as quantum register.   

The research, published in this week’s Science magazine, makes use of spinning properties of atomic nuclei to encode quantum bits. Apparently, experiments with a single spinning nuclei of Carbon-13 resulted in a stable quantum computing building block at room temperatures.

In quantum research, nuclear spins are known for their characteristics as tiny magnets with high stability. However, so called “spintronics” requires weak interactions of such spins, as information is lost through contact with virtually any other object. But the fact that spins are almost perfectly isolated, makes it impossible to address and manipulate individual nuclei.

According to the Harvard research, that Carbon-13 atoms, however, can be manipulated through nearby single electrons, whose own spin can be controlled with optical and microwave radiation. The scientists believe that the single electron's spin can “act as a very sensitive magnetic probe with extraordinary spatial resolution.”

The controlled interaction between the electron and nuclear spins is creating a single, isolated quantum bit (qubit) and allows the Carbon-13 nuclei to be used as what was described a “very robust quantum memory.” Typically, qubits have a short coherence time – a tiny fraction of a second unless the qubit is suspended in a high vacuum - and decay extremely fast as quantum information is lost through contact with virtually anything: The Harvard researchers claim that their Carbon-13-electron approach achieves a coherence time that “approaches seconds.”

The scientists claim that their research “revolutionizes” the approach to quantum computing and lay the ground work for a new way of computing, which is generally believed to be able to outperform conventional supercomputers in solving specific problems.

Carbon-13 is one of the two naturally-occurring stable isotopes of carbon and makes up only about 1.1% of a diamond. The other one, Carbon-12, is responsible for the remaining 98.9%.

In an unrelated research project, a University of Alberta research team this week said that they can apply “plasmonics” principles to spintronics and develop a novel way to control the quantum state of an electron’s spin. Plasmonics involves the transfer of light electromagnetic energy into a tiny volume and creating intense electric fields as a result. "We've only just begun to scratch the surface of this field, but we believe we have the physics sorted out and one day this technology will be used to develop very fast, very small electronics that have a very low power consumption," said Abdulhakem Elezzabi, computer engineering professor at the University.