  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.
