Quantum Processor Chips Get Processing Boost

Rigetti Computing, a leading quantum computing company based in the US, has recently unveiled a groundbreaking fabrication process aimed at fine-tuning its quantum processor chips. The innovative technique, known as Alternating-Bias Assisted Annealing (ABAA), promises to revolutionize the performance of Rigetti's quantum processors by enabling more precise tuning of qubit frequencies.

This advancement is expected to significantly enhance the execution of 2-qubit gates and reduce defects within the system, ultimately leading to higher fidelity in quantum computations. Rigetti has already begun implementing the ABAA technique in the production of quantum processor chips for its cutting-edge systems, such as the Novera QPU and the highly anticipated Ankaa-3 quantum computer featuring 84 qubits, slated for release by the end of 2024. Additionally, the company has initiated shipments of a 24-qubit machine to the UK, marking a significant milestone in its global expansion.

At the core of Rigetti's quantum processors are superconducting qubits that utilize Josephson Junctions (JJs) – a key component comprising two superconducting aluminum layers separated by an aluminum oxide barrier. The unique design allows electrons to tunnel across the insulator, resulting in a distinct qubit frequency that facilitates precise control and measurement.

While challenges related to reproducibility and energy loss in Josephson junctions have posed obstacles, the inherent simplicity, scalability, and ease of fabrication of superconducting devices make them an attractive choice for quantum computing applications. By leveraging low alternating voltages at room temperature on the oxide barrier, Rigetti's ABAA technique enables targeted tuning of qubit frequencies, a critical step in optimizing large-scale QPU production.

Unlike traditional methods such as laser trimming, the ABAA technique offers a straightforward and scalable approach that involves applying voltage pulses directly to the quantum processor chip. Developed at the state-of-the-art Rigetti Fab-1 facility in Fremont, California, this technique underscores the company's commitment to innovation and continuous improvement in chip design and fabrication processes.

Dr. Subodh Kulkarni, CEO of Rigetti, expressed enthusiasm about the potential of the ABAA technique, stating, "We believe this new technique strengthens our path to scaling to even higher qubit count systems with greater control over our qubit performance." In addition to enhancing qubit performance, the ABAA technique plays a crucial role in mitigating defects and imperfections in Josephson junctions, fostering clearer communication between qubits and couplers and ultimately optimizing overall system performance.