This device could usher in GPS-free navigation

One of the key components of next-generation navigation systems could be a compact device that was designed and manufactured at Sandia National Laboratories. Credit: Bret Latter
Do not let the sapphire windows or titanium metal walls fool you. This tiny, curious device could one day be the start of a new era in navigation.

The vacuum chamber, which is about the size of an avocado, has held a cloud containing atoms in the right conditions to allow precise navigational measurements for more than a year. It is the first device to be small enough, energy-efficient, and reliable enough for quantum sensorssensors using quantum mechanics to move from the lab to commercial use.

He said that Sandia created the chamber to be a core technology in future navigation systems that do not rely on GPS satellites. It was published in the journal AVS Quantum Science earlier this year.

Numerous devices use GPS to find their way around the globe. This is possible due to atomic clocks which are well-known for their precise timekeeping and keep the satellite network perfectly in sync.

Schwindt stated that GPS signals can be jammed, spoofed or altered, which could disable navigation systems for both military and commercial vehicles.

Schwindt suggested that future vehicles could keep track of their position, rather than relying on satellites. They could achieve this with on-board devices that are as precise as atomic clocks but which measure acceleration and rotation using lasers that shine into tiny clouds of rubidium gas, like the one Sandia contains.

Sandia National Laboratories scientist Peter Schwindt and Bethany Little, postdoctoral scientist, examine the vacuum package in a yellow 3D-printed mount. Credit: Bret Latter

Real-world applications require compactness

Although atomic accelerometers and geoscopes are already available, they're too heavy and power-hungry for use in an aircraft's navigation system. They require a large vacuum system, which requires thousands of volts of electricity to function.

Bethany Little, a Sandia postdoctoral researcher, said that quantum sensors are an important field. She is also contributing to the research. There are many problems to solve when the sensor is moved into the real world. The sensor is compact and rugged because of two factors. All the physics is done in one cubic centimeter (0.06 cubic inches) of volume. Anything larger than that would be wasted space.

Little stated that her team has demonstrated quantum sensing without the use of a vacuum system. This reduces the size of the package without compromising reliability.

Instead of using a vacuum pump to remove molecules and ruin measurements, a pair called getters uses chemical reactions to bind intruders. Each of the getters is about the same size as a pencil eraser. They can be hidden inside the two tubes that stick out from the titanium package. They can also be used without power.

Schwindt collaborated with Sandia material scientists to create the chamber from titanium and sapphire. These materials are particularly effective at blocking gasses such as helium which can easily pass through Pyrex and stainless steel. Sandia's Laboratory Directed Research and Development Program provided funding.

Sandia developed sophisticated manufacturing techniques to construct the nuclear weapons components. The titanium chamber must function reliably for many years, just like a nuclear weapon.

The device is being monitored by the Sandia team. They aim to keep the device sealed and operational for five more years. This is a significant milestone towards proving that the technology can be used. They are exploring ways to improve manufacturing efficiency in the interim.

Continue reading

Bethany J. has more information. Little et.al., A passively pumped vacuum packaging that sustains cold atoms for over 200 days, AVS Quantum Science (2021). Bethany J. Little et.al. A passively pumped vacuum packaging that sustains cold atoms for more then 200 days (2021). DOI: 10.116/5.0053885

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