Atomic beams shoot more upright via cascading silicon peashooters

For a non-physicist, an "atomic beam collimator" may look like a phaser projecting mystic particles. This is perhaps not the worst metaphor for introducing a technology that researchers have miniaturized, which makes it more likely to land on handheld devices someday.

Today, atomic beam collimators are found mainly in physics laboratories, where they project atoms into a beam producing exotic quantum phenomena and possessing properties that may prove useful in precision technologies. By reducing collimators to the size of a small device to insert them at the fingertip, researchers at the Georgia Institute of Technology want to make technology available to engineers who develop devices such as atomic clocks or accelerometers , a component of smartphones.

"A typical device of this type is a new generation gyroscope for a GPS-independent, precision navigation system that can be used when you are out of range of the satellite in a remote area or traveling in the remote area. space, "said Chandra. Raman, an associate professor at the Georgia Tech School of Physics and co-principal investigator of the study.

The research was funded by the Office of Navy Research. The researchers published their findings in the journal Nature Communications April 23, 2019.

This is a collimator, part of the quantum potential of atomic beams, and how the miniature collimator format could help atomic beams shape new generations of technologies.

Atomic pocket shotgun

"Collimated atomic beams have been around for decades," said Raman, "but currently, the collimators must be bulky to be precise."

The atomic beam begins in a box full of atoms, often of rubidium, heated in vapor so that the atoms rotate in a chaotic manner. A tube sinks into the box and random atoms with the correct trajectory sink into the tube like pellets entering the barrel of a rifle.

Like pellets leaving a shotgun, the atoms come out of the end of the tube pulling reasonably straight, but also with a random jet of atomic fire flying at biased angles. In an atomic beam, this sputtering produces a signal noise, and the improved on-chip collimator removes most of it for a more accurate and nearly perfectly parallel beam of atoms.

The beam is much more concentrated and pure than beams from existing collimators. Researchers would also like their collimator to allow experimental physicists to more easily create complex quantum states.

Inertia machine with inertia

But more immediately, the collimator establishes a Newtonian mechanics that could be adapted to a practical use.

The improved beams are unshakable inertia streams because, unlike the laser beam consisting of massless photons, the atoms have a mass and therefore an impulse and an inertia. This makes their beams potentially ideal reference points in beam-driven gyroscopes that help track movement and location changes.

Current gyroscopes in navigation devices without GPS are accurate in the short term but not in the long term, which means that they need to be recalibrated or replaced very often, which makes them less practical, for example on the Moon or on Mars.

"Conventional chip-based instruments based on MEMS technology (microelectromechanical systems) suffer from various constraints," said Farrokh Ayazi, senior researcher and professor Ken Byers at the Georgia Tech School of Electrical and Computer Engineering. "To eliminate this drift, you need an absolutely stable mechanism.This atomic beam creates this type of reference on a chip."

Quantum entanglement beam

Atoms excited by heat in a beam can also be converted into Rydberg atoms, which provide a multitude of quantum properties.

When an atom is sufficiently excited, its electron in the outermost orbit jumps so far that the size of the atom increases. If far into orbit with as much energy, this outermost electron behaves like the only electron of a hydrogen atom, and the Rydberg atom acts as it does. contained only one proton.

"You can create certain types of multi-atom quantum entanglement using Rydberg states because atoms interact much more strongly than two atoms in the ground state," Raman said.

"Rydberg's atoms could also advance future sensor technologies as they are sensitive to current fluxes or in electronic fields smaller than an electron's size," Ayazi said. "They could also be used in the processing of quantum information."

Lithographed silicon grooves

Researchers have come up with a surprisingly practical way to manufacture the new collimator, which could encourage manufacturers to adopt it: they cut long, extremely narrow channels in a silicon wafer parallel to its flat surface. The canals were like shotgun barrels lined up side by side to project a beam of atomic beams.

Silicon is an extremely smooth material that atoms can cross and is also used in many existing microelectronic and computer technologies. This opens the possibility of combining these technologies on a chip with the new miniature collimator. Lithography, used to engrave existing chip technology, was used to accurately cut the collimator channels.

The greatest innovation of researchers has significantly reduced spray, such as the sound of the signal. They dug two holes in the channels, forming an aligned waterfall of three sets of parallel rungs.

The atoms flying at biased angles exit channels at the interstices and those flying reasonably parallel in the first network of channels continue on the next, then the process is repeated from the second to the third network of channels. This gives the atomic beams the new collimator their exceptional straightness.