Physiker entdecken Verhalten in Quantensupraleitern, das eine neue Ebene der Kontrolle ermöglicht

> Quantum computers often require the use of superconductors, which are fabricated from materials that can conduct electricity with zero resistance—meaning, they can carry electric current without losing any energy. However, today’s superconductors only work at extremely low temperatures—close to absolute zero.

> This makes quantum computers incredibly energy-intensive to keep cold, and thus stable, because when qubits aren’t kept cold enough they become even more unstable, which means errors happen faster and more frequently.

> The scientific quest for “room-temperature superconductors” is often referred to as the Holy Grail of superconductivity, because the cooling process is so costly and complex.

> At the heart of the researchers’ study are Majorana fermions, subatomic particles that behave in unique ways; unlike most particles, Majorana fermions are their own antiparticles. (For every type of particle in the universe—such as electrons and protons—there exists a corresponding antiparticle with opposite properties)

> Researchers posit that Majorana fermions exist in certain materials, like topological superconductors. These differ from regular superconductors in that a topological superconductor has unique, stable quantum states on its surface or edges that are protected by the material’s underlying topology—the way its structure is shaped at the quantum level. These surface states make them resistant to disruptions, which is why they hold potential for developing more stable quantum computers.

> The researchers explored Majorana fermions in a specific context: superconductors that are periodically driven, meaning, they are exposed to external energy sources that cycle on and off in a repeated pattern. This periodic driving alters the behavior of the Majorana fermions, transforming them into Floquet Majorana fermions (FMFs).

> These FMFs influence the electric current in unique ways, leading to what scientists call the Josephson effect—a quantum phenomenon where current can flow between two superconductors without the need for an applied voltage—that is, the pressure that pushes electricity between two points. This periodic driving of the superconductor is key to maintaining the FMFs and the unusual patterns they create.

> In most systems, the current between two superconductors repeats itself at regular intervals. However, with FMFs, a special type of electrical behavior occurs in some advanced superconductors, where the current oscillates at half the normal rate, creating a unique, slower pattern, making the system more stable. The strength of the Josephson current—the amount of electrical flow—can be tuned using the chemical potential of the superconductors. This gives scientists a new level of control over quantum materials and opens up possibilities for applications in quantum information processing, where precise manipulation of quantum states is critical.

> The discovery that Floquet Majorana fermions have unique properties that can be controlled through external drives could help pave the way for building quantum computers that are not only faster, but also more resistant to errors.