Sandia builds tiny quantum sensor using 5 milliwatts of power for navigation

Researchers at the Sandia National Laboratory (SNL) in the US have built a quantum sensor that uses just 5 milliwatts of power, about 2,000 times less than a standard LED bulb, and uses optical fibers that are just 420 nanometers thick, or 200 times thinner than human hair. The development of the sensor and associated technology paves the way for quantum sensing to be deployed in the field soon. The world relies heavily on satellite-based signals for navigation. From the app-based taxis to commercial aircraft, container ships at sea, and even military drones engaging in combat, all rely on satellite signals to know their position and navigate to their destinations. With such high dependence, it is easy to cripple systems by jamming or spoofing the satellite signals, and it can be done with a electromagnetic scream, which can drown out these signals. To overcome this, scientists have been working on quantum-based navigation systems which are not just unjammable but also highly accurate. There are different approaches to how such systems work, and one among them is free-space atom interferometry. In this approach, ultracold atoms are released in a vacuum chamber, and their motion is measured using lasers. However, vibrations or other disturbances can make these measurements unreliable, prompting scientists to look for a more contained approach. Tight light A guided atom interferometry approach uses nonfibers to guide atoms in a tight light, much like marbles flowing through a narrow pipe. It ensures that they are constantly observed by the lasers. Jongmin Lee, a quantum sensing scientist at SNL, has been working to build an extremely small version of this device, one that consumes very little power and can be used in the field. Lee’s ambitious plan is to place this device on a photon-integrated circuit so measurements can continue even when the device is knocked around. In a real-world scenario, this could support navigation when a vehicle is moving through rough terrain or an aircraft is going through turbulence. “This idea has not been fully realized by the community for decades, due to challenges in dissipating heat from photonic devices in vacuum and in efficiently loading atoms around them,” explained Lee in a press release. Solving heat problems Lasers are needed to create a halo effect that can guide and count the moving atoms. Still, these are also major sources of heat in the system, especially when dealing with components like nanofibers that are much thinner than a human hair. In such situations, scientists have always had to make a trade-off. Either use a fragile design that loads atoms well but breaks under high heat conditions or a sturdy design that handles heat well but not the atoms. The SNL researchers led by Lee solved this problem by using small silicon pins that anchor the waveguide on either side and serve as heat sinks. “Building on our nanofiber results, we showed cesium atoms can be trapped with just five milliwatts of optical power and that atomic coherence can be measured using sub-microwatt fiber-coupled beams, all while minimizing in-vacuum heat loads,” added Lee in the press release. After resolving a few kinks in the setup, the team hopes to integrate the guide and other components on a chip and build a inertial quantum sensor array. The research findings were published in the journal AVS Quantum Science. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Ameya is a science writer based in Hyderabad, India. A Molecular Biologist at heart, he traded the micropipette to write about science during the pandemic and does not want to go back. He likes to write about genetics, microbes, technology, and public policy.