Liberating Quantum Processors from parasitic interactions

New research results of Jülich and international researchers allow more precise entanglement to be engineered between two qubits that are at the very heart of quantum computers, such as the one currently being developed as part of the European OpenSuperQ project, to be operated in Jülich. The photo shows a detail of the cryostat that is used to cool the chip to a temperature of 10 millikelvin (-273.13℃). Copyright: Forschungszentrum Jülich / Ralf-Uwe Limbach

Creating perfect entanglement requires full control over all qubit-qubit interactions. Until now, this goal has been hindered by the presence of an always-on and fundamental parasitic interaction that disturbs entanglement. Now, researchers at Forschungszentrum Jülich and RWTH Aachen University in collaboration with IBM T.J. Watson Research Center and Syracuse University both in the USA, have developed a theory-motivated idea and successfully implemented it to eliminate these interactions between two qubits.

The researchers performed two-qubit gate operations on the two qubits and showed that for boosting the gate fidelity, zeroing the parasitic interaction is as important as enhancing qubit coherence times. Their theory predicts that their architecture is not far off from achieving 99.9% fidelity in a two-qubit gate.

Their work results in a better understanding of the physics behind the error which also allows more precise entanglement to be engineered, as well as the unentanglement of two qubits.

The paper has been published in Physical Review Letters.

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