CAREER: Second Generation Qubits -- the future of superconducting quantum computing

Quantum computing and technology are poised to transform society and business. However, the quantum computers that exist today have yet to live up to this promise, in large part because their key component –the quantum bit or qubit – is too prone to errors. Early digital computers also suffered from unreliable components, but over time new technologies such as the transistor have made today’s computers cheaper, smaller, and more reliable. Broadly, the goal of this CAREER project is to spur on similar developments in quantum technologies by designing qubits that are significantly more reliable than those used today. These low-error “Second Generation” qubits could accelerate the development of the large-scale, robust quantum computers needed to solve problems of societal interest. Additionally, this CAREER project seeks to increase public engagement with quantum technology and to broaden access to quantum education for scientists and engineers across disciplines. These aims will be met through establishing a Boulder-Denver area quantum community meetup and by developing a publicly-available introductory quantum course that will be shared with other educators. This CAREER proposal will develop theoretical foundations for novel types of ultra-low error qubits. These Second Generation qubits could transform the landscape of quantum technology, as low error qubits are critical ingredients for realizing the promise of quantum computation. While remarkable progress has already been made on reducing qubit errors across hardware modalities, these first-generation qubits are designed to perform just below the required error rate for implementing fault-tolerant quantum error correction. A guiding principle in the development of second generation qubits is: the qubit should be constructed so that the physical laws provide immunity from certain errors. This CAREER proposal will pursue the development of second generation qubits using this principle in superconducting circuits. The major objectives of the project are to (1) develop two-qubit gates for a second generation qubit called the 0–π qubit, (2) design a new class of ultra protected second generation qubits – cos(N𝜑) qubits, and (3) develop error protected gates for second generation qubits. The designs proposed will be validated by simulation with noise models. To determine whether the proposed qubits and gate have superior performance, their performance will be evaluated by comparing them to the most successful superconducting qubit: the transmon. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.