Scientists from the University of MISIS and the Russian Quantum Center have developed a new approach to performing three-qubit operations on superconducting qubits—fluxoniums. This project has already been supported by Rosatom as part of the Roadmap for Quantum Computing.
As explained in the press service of NUST MISIS, the realization of a multi-qubit entangled state is one of the most important tasks for quantum computing. Entanglement allows extracting useful information from the computation of a function at several points, which is enabled by superposition.
Most modern quantum processors use two-qubit quantum operations, but errors occur during their implementation. Three-qubit operations can perform a larger range of algorithms in fewer steps, and they have fewer errors.
They are performed on a new type of superconducting qubits—fluxoniums. In terms of computational state isolation, coherence time, and other significant indicators, fluxoniums significantly outperform the most common qubits—transmons. The connecting element is a transmon qubit, but more resistant to technological errors.
The main advantage of this approach is the execution of the operation using a microwave pulse applied to the connecting element. The very presence of the connecting element significantly reduces the unwanted interaction of qubits, and activation by a microwave pulse allows for effective three-qubit interaction without taking the qubits out of the points most protected from external noise.
Quantum processors with a three-qubit operation can potentially be used to create a "noisy" quantum processor and algorithms for effective multi-qubit operations. Quantum effects are useful for studying molecules, creating drugs, and effectively solving logistics and database search problems.
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