New material bridges anti-gravity tech and super-sensitive instruments.

Flying cars and personal jetpacks notwithstanding, a new carbon-based material is bringing us closer to stable levitation technologies with no need for mechanical or electrical assists.

Today's levitation uses electrically manipulated magnetic fields, superconductors or diamagnetic (magnetically repelled) materials to float above magnets. The primary use for this is in developing super-sensitive levitation-based instruments with applications in many different fields, from earthbound seismology to detecting quantum forces and gravitational waves.

Professor Jason Twamley and his team of researchers and international collaborators at the Quantum Machines Unit at the Okinawa Institute of Science and Technology (OIST) have designed a floating platform using graphite and magnets that can remain stably suspended within a vacuum without any physical contact or mechanical support. This technology is a step toward the development of ultra-sensitive instruments for precise measurements.

When an external magnetic field is applied to a diamagnetic material, these materials generate a repulsive magnetic field, pushing the material away. With the right balance of forces, the object will float.

OIST

A graphite composite plate hovers above magnets.

The most common example is today's magnetic levitation (maglev) trains in China, Japan, and South Korea. Maglev trains are supported by a combination of diamagnetic materials and powerful superconducting magnets, defying gravity. Maglevs are more efficient than traditional trains and can reach speeds of up to 603 kilometers (375 miles) per hour. But that isn't the only application for such a force.

Floating sensors

A levitation-based system could also improve high-performance accelerometers and gyroscopes employed in inertial measurement, navigation systems used by drones in mines, as well as stabilization of low Earth orbit micro-satellites in use by the mining industry for highly accurate geophysical mineral scanning.

The two factors that come up against truly frictionless, independently floating platforms are eddy damping and controlling kinetic energy.

Eddy damping occurs when a freely oscillating system loses energy over time because of friction from external forces. Subtle magnetic drag even occurs when an electrical conductor like graphite experiences energy loss due to the flow of electrical currents in a magnetic field.

To address these challenges, the researchers transformed graphite into an electrical insulator whose structure naturally avoids energy loss while levitating in a frictionless vacuum, then applied an additional magnetic force from an overhead coil of wire to dampen the platform's vertical wobbling.

Graphite is a highly diamagnetic crystalline form of carbon. By chemically coating a powder of graphite microbeads with silica and insulating the coated powder in wax, the OIST researchers formed a thin, square eight-millimeter plate that effectively hovered above a grid of commercially available permanent magnets in an alternating checkerboard array, oscillating for an extended period without additional energy input.

"Heat causes motion, but by continuously monitoring and providing real-time feedback in the form of corrective actions to the system, we can decrease this movement. The feedback adjusts the system's damping rate, which is how quickly it loses energy, so by actively controlling the damping, we reduce the system's kinetic energy, effectively cooling it down," Twamley explained.

"If cooled sufficiently, our levitating platform could outperform even the most sensitive atomic gravimeters developed to date. These are cutting-edge instruments that use the behavior of atoms to precisely measure gravity. Achieving this level of precision requires rigorous engineering to isolate the platform from external disturbances such as vibrations, magnetic fields, and electrical noise. Our ongoing work focuses on refining these systems to unlock the full potential of this technology."

This is promising for both high-precision laboratory measurements and deployment in real-world settings. Levitated systems are natural testbeds for probing many outstanding questions in physics. This form of diamagnetic levitation is also passive, removing the noise associated with an active power source. Lowered power and hardware requirements are promising for developing commercial sensors, both large and small.

This research has focused on using levitating materials to build mechanical oscillators. By combining levitation, insulation, and adjusting forces using real-time feedback, Twamley's team is driving the materials science and sensor technology forward.