Superconductors matter because they conduct electricity with zero energy loss, a property that makes them essential to medical imaging, particle physics, quantum computing, high-speed transportation, and potentially the future of clean energy. Most electrical conductors, even excellent ones like copper, waste energy as heat. Superconductors eliminate that waste entirely, enabling technologies that would be physically impossible with conventional materials.
What Makes Superconductors Different
When certain materials are cooled below a specific threshold called the critical temperature, their electrical resistance drops to absolute zero. A current flowing through a superconducting wire will circulate indefinitely without any external power source. The vast majority of known superconductors reach this state at temperatures between 1 and 10 degrees above absolute zero, which means they need extreme cooling, typically with liquid helium.
The underlying mechanism wasn’t understood until 1957, when three physicists at the University of Illinois figured out something counterintuitive: electrons, which normally repel each other because they share a negative charge, can form pairs at low enough temperatures. These paired electrons are held together by vibrations in the atomic lattice of the material, and collectively the pairs glide through without bumping into anything. No collisions means no resistance, which means no wasted energy.
Superconductors also expel magnetic fields as they transition into the superconducting state. This is why a magnet will hover above a superconductor in those dramatic demonstration videos. That magnetic property turns out to be just as useful as the zero resistance, because it allows engineers to build extraordinarily powerful and stable magnets.
Medical Imaging Relies on Them
Every MRI machine in a modern hospital uses a superconducting magnet at its core. The magnet needs to produce an extremely uniform magnetic field across the imaging area, because even tiny variations distort the image. Superconducting magnets can sustain the required field strength continuously without consuming power, something no conventional electromagnet could do practically at the same scale. The result is imaging detailed enough to distinguish soft tissues, detect tumors, and guide surgical planning, all without radiation.
The tradeoff is size. Achieving the necessary field uniformity requires a physically large magnet with a substantial amount of superconducting wire. Researchers are working on smaller magnet designs and advanced image-processing techniques to compensate for the reduced uniformity, which could eventually make MRI machines more compact and accessible in places that can’t accommodate a full-sized unit.
Particle Physics Wouldn’t Work Without Them
The Large Hadron Collider at CERN, the machine that confirmed the existence of the Higgs boson, depends on 1,232 superconducting dipole magnets to steer beams of protons around its 27-kilometer ring. Each magnet produces a field of about 8.3 Tesla at a current of nearly 12,000 amps, cooled to 1.9 Kelvin (colder than outer space). Manufacturing the superconducting coils inside those magnets accounts for roughly 60% of the production effort for each one.
No conventional magnet could produce fields that strong without melting from its own resistive heating. Superconductors made the LHC possible, and they’ll be even more critical for next-generation colliders that aim for higher energies.
Quantum Computers Are Built From Them
The quantum computers built by companies like Google and IBM use superconducting circuits as their basic computing units. These qubits, as they’re called, are tiny loops of superconducting material interrupted by an ultra-thin insulating barrier known as a Josephson junction. When cooled to temperatures measured in thousandths of a degree above absolute zero, these circuits behave as quantum objects: they can exist in overlapping states simultaneously, which is the property that gives quantum computers their potential speed advantage for certain problems.
The Josephson junction is the key ingredient. A small electrical current can tunnel through the insulating barrier without any voltage applied, and the junction acts as a nonlinear switch that lets engineers control individual quantum states. Without the lossless, quantum-coherent behavior of superconducting materials, these circuits would generate too much noise to maintain the fragile quantum states needed for computation.
Trains That Float on Magnets
Japan’s SCMaglev system uses superconducting magnets mounted on train cars to achieve contactless levitation and propulsion. As the train accelerates along its guideway, its superconducting magnets induce currents in coils embedded in the track walls. Those induced currents generate their own magnetic fields that push the train upward and keep it centered. Once the train hits about 150 km/h (93 mph), the lift force is strong enough to raise it 100 mm off the track, eliminating friction entirely.
A separate set of coils in the guideway provides forward thrust, functioning as a linear motor. The result: a prototype L0 Series train set the world speed record for crewed rail vehicles at 603 km/h (375 mph) in 2015. That kind of speed, sustained without physical contact between vehicle and track, is only possible because superconducting magnets produce intense, stable fields without continuous power input.
Reducing Energy Loss in Power Grids
Conventional power lines lose a meaningful percentage of the electricity they carry as heat. Globally, grid losses contribute around 1 gigatonne of CO₂ emissions per year, according to the International Energy Agency. In some regions, losses reach 18% of generated electricity. Bringing worldwide losses down to an efficient baseline of roughly 5% could cut emissions by over 400 million tonnes of CO₂ annually.
Superconducting power cables are one path toward that goal. Because they carry current without resistance, they could transmit large amounts of power through compact cables with virtually no loss. The challenge is that the cables need to be continuously cooled, which adds cost and complexity. Several pilot projects have demonstrated superconducting cables in real urban grids, but widespread deployment depends on making the cooling infrastructure economical at scale.
Enabling Nuclear Fusion
Fusion reactors aim to replicate the process that powers the sun: forcing hydrogen nuclei together at extreme temperatures to release energy. The plasma inside a fusion reactor reaches hundreds of millions of degrees, far too hot for any physical container. Instead, engineers use superconducting magnets to create powerful magnetic fields that confine the plasma in a donut-shaped chamber called a tokamak.
Next-generation fusion projects are turning to newer high-temperature superconducting materials that can produce stronger fields than the ones used in ITER, the large international fusion experiment currently under construction in France. Stronger magnets allow smaller, potentially more practical reactor designs. The superconducting magnets in future reactors will need to handle enormous currents and mechanical stresses, making them among the most demanding engineering challenges in the entire fusion effort.
Grid-Scale Energy Storage
Superconducting Magnetic Energy Storage (SMES) systems store energy directly in the magnetic field of a superconducting coil rather than in chemical batteries. They can release that energy almost instantaneously, making them useful for stabilizing power grids during sudden spikes in demand or brief outages. Systems in the 1 to 10 megawatt range maintain round-trip efficiencies of 85% to 90% across a wide range of charge and discharge cycles.
SMES systems work best for applications that need fast, reliable bursts of power rather than long-duration storage. For longer cycles, like smoothing out daily fluctuations in solar or wind generation, high-field superconducting coils can actually improve efficiency by reducing certain heat losses that accumulate during rapid cycling. The technology remains expensive compared to lithium-ion batteries for most applications, but its near-instant response time fills a niche that batteries handle poorly.