FAST Entanglement...

While quantum entanglement usually spreads through the atoms in an optical lattice via short-range interactions with the atoms' immediate neighbors (left), new theoretical research shows that taking advantage of long-range dipolar interactions among the atoms could enable it to spread more quickly (right), a potential advantage for quantum computing and sensing applications.
Credit: Gorshkov and Hanacek/NIST

Topics: Laser, Materials Science, Optical Physics, Quantum Mechanics

“It is these long-range dipolar interactions in 3-D that enable you to create entanglement much faster than in systems with short-range interactions,” said Gorshkov, a theoretical physicist at NIST and at both the Joint Center for Quantum Information and Computer Science and the Joint Quantum Institute, which are collaborations between NIST and the University of Maryland. “Obviously, if you can throw stuff directly at people who are far away, you can spread the objects faster.”

Applying the technique would center around adjusting the timing of laser light pulses, turning the lasers on and off in particular patterns and rhythms to quick-change the suspended atoms into a coherent entangled system.

The approach also could find application in sensors, which might exploit entanglement to achieve far greater sensitivity than classical systems can. While entanglement-enhanced quantum sensing is a young field, it might allow for high-resolution scanning of tiny objects, such as distinguishing slight temperature differences among parts of an individual living cell or performing magnetic imaging of its interior.

Gorshkov said the method builds on two studies from the 1990s in which different NIST researchers considered the possibility of using a large number of tiny objects—such as a group of atom—as sensors. Atoms could measure the properties of a nearby magnetic field, for example, because the field would change their electrons’ energy levels. These earlier efforts showed that the uncertainty in these measurements would be advantageously lower if the atoms were all entangled, rather than merely a bunch of independent objects that happened to be near one another.

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Paper: Z. Eldredge, Z.-X. Gong, J. T. Young, A.H. Moosavian, M. Foss-Feig and A.V. Gorshkov. Fast State Transfer and Entanglement Renormalization Using Long-Range Interactions. Physical Review Letters. Published 25 October 2017. DOI: 10.1103/PhysRevLett.119.170503