Suppressed Crosstalk between Two-Junction Superconducting Qubits with Mode-Selective Exchange Coupling

Fixed-frequency qubits can suffer from always-on interactions that inhibit independent control. Here, we address this issue by experimentally demonstrating a superconducting architecture using qubits that comprise of two capacitively shunted Josephson junctions connected in series. Historically known as tunable coupling qubits (TCQs), such two-junction qubits support two modes with distinct frequencies and spatial symmetries. By selectively coupling only one type of mode and using the other as our computational basis, we greatly suppress crosstalk between the data modes while permitting all-microwave two-qubit gates.

Automated summary

The study experimentally demonstrates a superconducting architecture using qubits composed of two capacitively shunted Josephson junctions connected in series to address the issue of fixed-frequency qubits suffering from always-on interactions that inhibit independent control. These new two-junction qubits, historically known as tunable coupling qubits (TCQs), support two modes with distinct frequencies and spatial symmetries, allowing for greatly suppressed crosstalk between data modes by selectively coupling only one type of mode.