While working on their long-term goal of achieving a true quantum computer, a team of researchers from Stanford University, the Joint Quantum Institute, MIT and Texas A&M University has recently discovered that tiny nitrogen impurities in diamonds make outstanding magnetic probes in the cellular and molecular scale, with important applications that could truly benefit medical research.

Quantum computing harnesses the properties of subatomic particles — photons and electrons in particular — to manipulate data in a highly efficient way. A subfield of quantum computing known as spintronics deals with the negatively-charged electrons and their spin, which together give these particles very precise magnetic properties.


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While looking for a magnetic material that could manipulate electrons one by one for their purposes, the team discovered that diamonds with trace concentrations of nitrogen make excellent magnetic probes. Nitrogen impurities are partly responsible for diamonds' fame, as they glow a brilliant red and become fluorescent when they are hit by green light.

Measuring slight variations in the fluorescence levels can determine the magnetic spin of a single electron in nitrogen and, unlike so many of the results obtained so far in quantum computing or small-scale magnetic sensing, it can be done at room temperatures rather than requiring cooling to close to absolute zero.

The system developed by the team is formed from a single nitrogen atom lodged within a diamond crystal and, because it doesn't require cooling, it could be safely used to probe and precisely manipulate live tissue such as living cells and individual drug molecules, an important step forward for medical research.

The researchers also managed to repeatedly bounce the quantum information back and forth between the nitrogen electron and the adjacent carbon atoms in the diamond, forming a small quantum circuit capable of performing logic operations at room temperatures. Transferring the information back and forth, the team found, has the effect of amplifying the information and making it easier to read.

As NIST theoretical physicist Jacob Tayler explained, the findings are just a relatively small step forward in quantum computing, but the medical community might find practical applications for their findings long before the first quantum computer is built.

The team's findings were published on the online issue of the journal Science.