Quantum engineering

Aug 13, 2014 by Eric Smalley
Paola Cappellaro's work with nanoscale diamonds opens a route to computers that can search huge databases in a flash or crack virtually any secret code. Credit: Len Rubenstein

It can be difficult to distinguish between basic and applied research in the nascent field of quantum engineering. One person's exploration of quantum systems like atoms and electrons yields another's building block for quantum computers, and vice versa. Paola Cappellaro's lab operates at the interface of basic and applied research. "We sometimes go more in one direction and sometimes more in the other," she said.

Cappellaro works with nanoscale diamonds that contain a defect consisting of an embedded nitrogen atom next to a gap in the diamond crystal. If you had a large enough gem-quality diamond with this type of defect throughout, it would be pink. These nitrogen vacancy, or NV, centers have spins that can be readily controlled, said Cappellaro, who is an associate professor in the Department of Nuclear Science and Engineering and holds an Esther and Harold E. Edgerton Career Development Professorship.

Atoms and electrons have a spin, or orientation, that's up or down—similar to the two poles of a magnet. Unlike ordinary magnets, however, atomic and subatomic spins can be a mix of up and down at the same time. This superposition of spins is the source of the fuss about quantum computing. If you use the up and down of a particle's spin to represent the 1 and 0 of a bit, then a quantum bit, or qubit, is both a 1 and 0 at the same time. A string of qubits, therefore, can represent a phenomenally large range of numbers. This opens the possibility for computers that can crack virtually any secret code or search huge databases in the blink of an eye.

One thrust of Cappellaro's research is how information is transferred in a chain of spins. Transferring information between qubits is critical for being able to build quantum computers, Cappellaro said. "What you would like to have is not only computing units, but also some wires to connect them."

NV centers are also potentially useful beyond . They're very sensitive to magnetic fields. "You can use this spin, which is basically just a magnetic dipole, just like a compass, to sense an external ," she said.

These miniscule magnetic sensors can detect magnetic fields from extremely small, closely spaced objects. One potential use is inspecting magnetic bits in the production of data storage devices. Unlike most quantum devices, the NV center magnetometer operates in a wide range of temperatures, she said. This opens the possibility of detecting magnetic fields from superconducting devices, which operate at very low temperatures.

Another possibility is detecting magnetic fields inside living cells. For example, neural cell signaling operates via exchanges of ions, which are positively or negatively charged atoms. In theory, an NV center magnetometer could monitor neural cell functioning, Cappellaro said.

Knowing that her research could have a significant impact in practical applications like these is very satisfying, but Cappellaro is also motivated by basic science. "Very often what drives us is intellectual curiosity about how our system behaves," she said. "It's nice to be able to go toward both directions at the same time."

Explore further: Planting imperfections at specific spots within diamond lattice could advance quantum computing

add to favorites email to friend print save as pdf

Related Stories

Electrical control of nuclear spin qubits

Jun 06, 2014

Researchers of Karlsruhe Institute of Technology (KIT) and their French partners succeeded in making an important step towards quantum computers. Using a spin cascade in single-molecule magnet, the scientists ...

Diamond defect boosts quantum technology

Feb 04, 2014

New research shows that a remarkable defect in synthetic diamond produced by chemical vapor deposition allows researchers to measure, witness, and potentially manipulate electrons in a manner that could lead ...

Recommended for you

Backpack physics: Smaller hikers carry heavier loads

13 hours ago

Hikers are generally advised that the weight of the packs they carry should correspond to their own size, with smaller individuals carrying lighter loads. Although petite backpackers might appreciate the ...

Extremely high-resolution magnetic resonance imaging

13 hours ago

For the first time, researchers have succeeded to detect a single hydrogen atom using magnetic resonance imaging, which signifies a huge increase in the technology's spatial resolution. In the future, single-atom ...

'Attosecond' science breakthrough

14 hours ago

Scientists from Queen's University Belfast have been involved in a groundbreaking discovery in the area of experimental physics that has implications for understanding how radiotherapy kills cancer cells, among other things.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Aug 14, 2014
This comment has been removed by a moderator.
not rated yet Aug 16, 2014
The caption that QC will be able to "crack virtually any secret code" is misleading. Most popular cyphers ("codes") are nearly unaffected by it, and cryptographers are busy researching alternatives to the others.

The field is called "post-quantum cryptography". Most people are fascinated by what QC is good at -- the possibilities! But cryptographers are interested in what it's no good at, and it turns out to be no good at plenty of things. Codes can simply be based on those things.