One should not be fooled by the sapphire windows or titanium metal walls. It is what is on the inner side of a new compact, intuitive device that could someday initiate a new era of navigation.
For more than a year, the avocado-sized vacuum chamber has consisted of a cloud of atoms at the proper conditions for accurate navigational measurements. It is the first device that has been developed such that it is tiny, energy-efficient, and reliable enough to possibly move quantum sensors.
These are sensors that make use of quantum mechanics to surpass conventional technologies—right from the laboratory into commercial use, stated Sandia National Laboratories scientist Peter Schwindt.
The chamber was developed by Sandia as a core technology for future navigation systems that do not depend on GPS satellites. It was explained in the journal AVS Quantum Science in early 2021.
Countless devices throughout the world make use of GPS for wayfinding. This seems to be possible since atomic clocks, which are familiar for extremely precise timekeeping, hold the network of satellites ideally in sync.
However, GPS signals can be spoofed or jammed, possibly disabling navigation systems on commercial and military vehicles alike, stated Schwindt.
Hence, rather than depending on satellites, Schwindt stated that future vehicles might keep track of their position. They could perform that using onboard devices as precise as atomic clocks. However, those measure acceleration and rotation by shining lasers onto small clouds of rubidium gas such as the one found at Sandia.
Compactness Crucial to Real-World Applications
Already, atomic accelerometers and gyroscopes are in use. However, they are too heavy and power-hungry to be utilized in a navigation system in an airplane. The reason is they require a huge vacuum system to work, one that requires thousands of volts of electricity.
Quantum sensors are a growing field, and there are lots of applications you can demonstrate in the lab. But when you move it into the real world there are lots of problems you have to solve. Two are making the sensor compact and rugged. The physics takes place all in a cubic centimeter (0.06 cubic inches) of volume, so anything larger than that is wasted space.”
Bethany Little, Postdoctoral Scientist, Sandia National Laboratories
According to Little, who contributed to the study, her team has demonstrated that quantum sensing can function without a high-powered vacuum system. This decreases the package to a viable size without compromising on reliability.
As an alternative to a powered vacuum pump, which whisks away molecules that tend to leak in and wreck measurements, a pair of devices known as getters utilize chemical reactions to fasten intruders. Each of the getters measures around the size of a pencil eraser so they could be tucked within two narrow tubes popping out of the titanium package. Also, they function without a power source.
To further exclude contaminants, Schwindt collaborated with Sandia materials scientists to construct the chamber out of sapphire and titanium. Most significantly, these materials are good at inhibiting the entry of gases like helium, which have the potential to squeeze via Pyrex glass and stainless steel. This study was financially supported by Sandia’s Laboratory Directed Research and Development program.
Construction involves advanced fabrication methods that Sandia has optimized to bond advanced materials for nuclear weapons components. Also, similar to a nuclear weapon, the titanium chamber should work dependably for several years.
The Sandia team has been continuously monitoring the device. They aim to keep it closed and operational for almost five years. It is a key milestone toward displaying that the technology is ready to be fielded. Meanwhile, they are finding out ways to simplify manufacturing.
Little, B. J., et al. (2021) A passively pumped vacuum package sustaining cold atoms for more than 200 days. AVS Quantum Science. doi.org/10.1116/5.0053885.