New Ion Trap May Lead to Working Quantum Computer

Physicists have built a novel electromagnetic trap for ions that they said could be easily mass produced, potentially leading to ultrafast quantum computers large enough for practical use in complicated tasks such as breaking data encryption codes.

The new trap, designed by scientists at the National Institute of Standards and Technology (NIST), may help them surmount what they said is currently the most significant barrier to building a working quantum computer -- scaling up components and processes that have been successfully demonstrated individually.

False-color images of 1, 2, 3, 6, and 12 magnesium ions loaded into NIST's new planar ion trap. Red indicates areas of highest fluorescence, or the centers of the ions. As more ions are loaded in the trap, they squeeze closer together, until the 12-ion string falls into a zig-zag formation. (Images: Signe Seidelin and John Chiaverini/NIST)

Quantum computers would exploit the unusual behavior of the smallest particles of matter and light. Their theoretical ability to perform vast numbers of operations simultaneously has the potential to quickly solve certain problems, such as breaking data encryption codes or searching large databases, much faster than conventional computers, the scientists said.

Ions (electrically charged atoms) are promising candidates for use as quantum bits (qubits) in quantum computers. The NIST team, one of 18 research groups worldwide experimenting with ion qubits, previously demonstrated at a rudimentary level all the basic building blocks for a quantum computer, including key processes such as error correction, and also has proposed a large-scale architecture.

The new ion trap is the first functional one in which all electrodes are arranged in one horizontal layer, a “chip-like” geometry that is much easier to manufacture than previous ion traps with two or three layers of electrodes, they said. The trap, which has gold electrodes that confine ions about 40 µm above the electrodes, was constructed using standard microfabrication techniques.

NIST's novel planar ion trap was designed to be easily mass produced, potentially enabling quantum computers large enough for practical use. The trap uses gold electrodes to confine magnesium ions 40 micrometers above the plane of the electrodes. Laser beams are used to create ions from the metal vapor and then cool them.

The scientists said that their single-layer device can trap a dozen magnesium ions without generating too much heat from electrode voltage fluctuations -- also an important factor, because heating has limited the prospects for previous small traps. Microscale traps are desirable because the smaller the trap, the faster the future computer.

Work is continuing at NIST and at collaborating industrial and federal labs to build single-layer traps with more complex structures in which perhaps 10 to 15 ions eventually could be manipulated with lasers to carry out logic operations, the researchers said.

The work, described in the June 30 issue of Physical Review Letters, was supported in part by the National Security Agency/Disruptive Technology Office (formerly Advanced Research and Development Activity). For more information, visit: www.nist.gov