More stable states for quantum computers – com! professionals

Quantum computers are the computers of the future. A and O are quantum bits (qubits), which are the smallest computing unit in quantum computers. Because they contain not only two states but also states in between, qubits process more information in less time. However, maintaining this state for a longer period is difficult and depends particularly on material properties. A research team from the Karlsruhe Institute of Technology (KIT) has created qubits that are 100 times more sensitive to physical defects – a crucial step in eliminating them.

Quantum computers can process large amounts of data faster because they perform many computation steps in parallel. The information carrier of a quantum computer is the qubit. With qubits, not only do the information ‘0’ and ‘1’ exist, but there are also values ​​in between. The difficulty at the moment is making qubits small enough and that they can be swapped fast enough to perform quantum computations. Superconducting circuits are a promising option here. Superconductors are materials that have no electrical resistance at very low temperatures, and therefore they conduct electricity without loss. This is critical to efficiently preserving the quantum state of the qubits and linking them together.

Gralmonium Qubits: superconducting and sensitive
KIT researchers have succeeded in developing new, unconventional, superconducting qubits. says d. Ewan M. Bob is from KIT’s Institute for Quantum Materials and Technologies (IQMT). These Josephson junctions for superconducting qubits are typically created by separating two layers of aluminum with a thin oxide barrier. “In contrast, for our qubits, we only use a single layer of ‘granular aluminum,’ which is a superconductor made up of aluminum grains a few nanometers in size embedded in an oxide matrix,” says Pope. As a result, the material itself forms a three-dimensional network of Josephson junctions. Simon Gunzler of IQMT adds, “It is interesting that the entire properties of our qubits are dominated by a narrowing of only 20 nm. This makes it act as a magnifying glass for microscopic material defects in superconducting qubits and provides a promising perspective for their improvement.” .

The qubits the team developed are a fundamental advance of a previously tested approach using so-called fluxonium qubits. In this earlier version, the parts were made of aluminum grain and other parts were traditionally made of aluminum. In the current work, the researchers went a critical step further and produced complete qubits from granular aluminum. says Dennis Rieger of KIT Physics.