Physicists at the National Institute of Standards and Technology
(NIST) have demonstrated an ion trap with a built-in optical fiber that
collects light emitted by single ions (electrically charged atoms),
allowing quantum information stored in the ions to be measured. The
advance could simplify quantum computer design and serve as a step
toward swapping information between matter and light in future quantum
networks.
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Diagram of a NIST ion trap that incorporates an optical fiber to Credit: A. VanDevender/NIST |
Described in a forthcoming issue of Physical Review Letters,*
the new device is a 1-millimeter-square ion trap with a built-in
optical fiber. The authors use ions as quantum bits (qubits) to store
information in experimental quantum computing, which may someday solve
certain problems that are intractable today. An ion can be adjustably
positioned 80 to 100 micrometers from an optical fiber, which detects
the ion's fluorescence signals indicating the qubit's information
content.
"The design is helpful because of the tight coupling between the ion
and the fiber, and also because it's small, so you can get a lot of
fibers on a chip," says first author Aaron VanDevender, a NIST
postdoctoral researcher.
NIST scientists demonstrated the new device using magnesium ions.
Light emitted by an ion passes through a hole in an electrode and is
collected in the fiber below the electrode surface (see image). By
contrast, conventional ion traps use large external lenses typically
located 5 centimeters away from the ions—about 500 times farther than
the fiber—to collect the fluorescence light. Optical fibers may handle
large numbers of ions more easily than the bulky optical systems,
because multiple fibers may eventually be attached to a single ion trap.
The fiber method currently captures less light than the lens system
but is adequate for detecting quantum information because ions are
extremely bright, producing millions of photons (individual particles of
light) per second, VanDevender says. The authors expect to boost
efficiency by shaping the fiber tip and using anti-reflection coating on
surfaces. The new trap design is intended as a prototype for eventually
pairing single ions with single photons, to make an interface enabling
matter qubits to swap information with photon qubits in a quantum
computing and communications network. Photons are used as qubits in
quantum communications, the most secure method known for ensuring the
privacy of a communications channel. In a quantum network,
the information encoded in the "spins" of individual ions could be
transferred to, for example, electric field orientations of individual
photons for transport to other processing regions of the network.
The research was supported by the Defense Advanced Research Projects
Agency, National Security Agency, Office of Naval Research, Intelligence
Advanced Research Projects Activity, and Sandia National Laboratories.
*A.P. VanDevender, Y. Colombe, J. Amini, D. Leibfried and D.J.
Wineland. Efficient fiber optic detection of trapped ion fluorescence. Physical
Review Letters. Forthcoming.
Media Contact: Laura Ost, laura.ost@nist.gov, 303-497-4880
