What if one qubit could store information reliably while interacting rapidly with the rest of a quantum processor? MIT researchers have proposed an architecture.
Researchers at MIT have designed a superconducting qubit architecture that separates data storage from interaction with other components, potentially enabling faster operations and more reliable quantum error correction.
The design, called the “arm qubit”, uses two connected modes. A data mode is designed for long coherence, allowing quantum information to remain stable for longer, while an arm mode handles interactions with other qubits and electronics. This separation aims to address the trade-off between qubit stability and fast operation.
A key part of the architecture is a quarton coupler, which provides strong nonlinear coupling between the two modes. Conventional coupling can introduce unwanted interactions that become harder to manage as more qubits are connected. The quarton coupler helps reduce this unwanted mixing while maintaining strong interaction between the two modes.
By dedicating the arm mode to coupling, the architecture can interact strongly with other components while limiting disruption to the data mode. This could allow quantum operations and readout to be completed faster, reducing the time available for decoherence and associated errors.
In simulations, the arm qubit showed a combination of state-of-the-art coherence time, faster operations, and faster readout compared with other superconducting qubit architectures. The design is also intended to be robust to manufacturing variations, which could become important as quantum processors scale.
The architecture could support quantum error correction by enabling more operations within a qubit’s coherence window. Faster and more reliable operations are important for the repeated measurements and corrections required to build fault-tolerant quantum computers.
“This work leaves me with a lot of suspense because our simulations are very promising. Next, we’ll need to see if we can make it, and determine whether we missed anything in the modeling or design. If we can fabricate this qubit, it could be a building block for future error-correcting quantum computers,” says Kevin O’Brien, associate professor in electrical engineering and computer science at MIT.
