Physicists discover quantum superconductor behavior that provides new level of control

New research reveals important behavior in the flow of electric current through quantum superconductors, which could advance the development of future technologies such as quantum computing.

In a paper accepted for publication in Physical Review Letters, the research focuses on frocket Majorana fermions and their role in a phenomenon called the Josephson effect, which allows for more precise control of quantum-powered computer systems.

The study was co-authored by Babak Seraje, a professor of physics at Indiana University Bloomington’s College of Arts and Sciences, and theoretical physicists Rekha Kumari and Arijit Kundu from the Indian Institute of Technology, Kanpur. Available on the arXiv preprint server.

Potential to revolutionize quantum computing

Professor Babak and his colleagues addressed a central problem in today’s quantum computers: instability. This instability is primarily due to something called quantum decoherence, in which quantum bits, known as qubits, lose their delicate quantum state due to interference from the environment, such as temperature fluctuations or electromagnetic noise.

Quantum computers often require the use of superconductors, made of materials that can conduct electricity with zero resistance. This means that current can flow through it without losing energy. However, today’s superconductors only work at extremely low temperatures, near absolute zero.

This causes quantum computers to consume an incredible amount of energy to maintain and stabilize their low temperatures. If qubits aren’t kept cool enough, they become even more unstable, meaning errors occur faster and more often.

The scientific search for “room-temperature superconductors” is often referred to as the holy grail of superconductivity because the cooling process is extremely expensive and complex. If scientists can develop a material that exhibits superconductivity at room temperature (about 20-25 °C or 68-77 °F), it could revolutionize technology as we know it, allowing for lossless power transmission and exponentially faster speeds. could lead to more energy-efficient electronics. Powerful magnets for applications such as MRI machines and advanced energy storage systems.

Floquet Majorana What makes fermions special for quantum computing?

The focus of the researchers’ work is the Majorana fermion, an elementary particle that behaves in a unique way. Unlike most particles, Majorana fermions are themselves antiparticles. (Every kind of particle in the universe, such as an electron or a proton, has a corresponding antiparticle with opposite properties. This symmetry between particles and antiparticles is a fundamental part of the structure of the universe )

Researchers hypothesize that Majorana fermions exist in certain materials, such as topological superconductors. They differ from ordinary superconductors in that topological superconductors have unique stable quantum states at their surfaces or edges, protected by the material’s underlying topology (the way its structure is formed at the quantum level). It is different from a conductor.

These surface states offer the potential to develop more stable quantum computers by making them more resistant to destruction. These special edge states can also contain exotic particles such as Majorana fermions that are not present in normal superconductors.

Researchers investigated Majorana fermions in specific situations. It’s a periodically driven superconductor, meaning it’s exposed to an external energy source that turns on and off in a repeating pattern. This periodic drive changes the behavior of the Majorana fermion, transforming it into a flocked Majorana fermion (FMF).

Flocke-Majorana fermions can exist in different states that change based on their interactions with cycling energy sources. These FMFs affect electrical current in a unique way, resulting in what scientists call the Josephson effect, a quantum phenomenon in which electrical current flows between two superconductors without an applied voltage, i.e. between two points. causes pressure that forces electricity into. This regular driving of the superconductor is key to maintaining the FMF and the unusual patterns it creates.

In most systems, the electrical current between two superconductors is repeated at regular intervals. However, in FMF, a special type of electrical behavior occurs in some advanced superconductors that causes the current to oscillate at half its normal speed, creating a distinctive slower pattern and making the system more stable. .

This stability is critical because it could help improve the performance and reliability of quantum computers, which rely on accurate and stable quantum states to process information. In other words, this slower oscillation could make quantum devices more efficient and less vulnerable to disruption. This is a major challenge in quantum computing today.

Adjust current with new technology

One of the key discoveries from Babak et al.’s work is that the strength of the Josephson current, or the amount of electricity flowing, can be tuned using the superconductor’s chemical potential.

Simply put, the chemical potential acts as a dial to tune the properties of the material, and the researchers discovered that they can change it by synchronizing it with the frequency of the external energy source driving the system.

This gives scientists a new level of control over quantum materials and opens up potential applications in quantum information processing, where precise manipulation of quantum states is key. The implications for quantum computing are enormous because quantum computing techniques rely on manipulating quantum states in stable and predictable ways.

The discovery that Frocket Majorana fermions have unique properties that can be controlled through an external drive could help pave the way to building quantum computers that are not only faster but also more resilient to errors.

And Majorana fermions are of particular interest to researchers because they are expected to support fault-tolerant quantum computing, where information can be stored and manipulated without being lost to noise or other disturbances.

Although the study is theoretical, the research team confirmed the results through computer simulations, and these findings provide researchers around the world with a roadmap to explore new controllable properties in quantum systems. I will.