Working Model of a Two-Qubit Electronic Quantum Processor Developed

A high-performance silicon-based quantum processor has been developed in which the spins of nine phosphorus nuclei — divided into two groups, or registers — and two shared electrons act as quantum bits (qubits). The modular design of this 11-qubit processor opens the door to a scalable approach to building large, reliable quantum-computing processors. An 11-qubit processor, comprising a 4-nucleus and a 5-nucleus register, coupled by 2 electrons, is a milestone in quantum computing.

David Hanneke, Jonathan Home, John D. Jost +3 more

Rohith Acharya, Fahd A. Mohiyaddin, Anton Potočnik +5 more

Quantum computers based on superconducting qubits have emerged as a leading candidate for a scalable quantum processor architecture. The core of a quantum processor consists of quantum devices that are manipulated using classical electronic circuits, which need to be co-designed for optimal performance and operation. As the principles governing the behavior of the classical circuits and the quantum devices are different, this presents a unique challenge in terms of the simulation, design and optimization of the joint system. A methodology is presented to transform the behavior of small-scale quantum processors to equivalent circuit models that are usable with classical circuits in a generic electrical simulator, enabling the detailed analysis of the impact of many important non-idealities. The methodology has specifically been employed to derive a circuit model of a superconducting qubit interacting with the quantized electromagnetic field of a superconducting resonator. Based on this technique, a comprehensive analysis of the qubit operation is performed, including the coherent control and readout of the qubit using electrical signals. Furthermore, the effect of several non-idealities in the system such as qubit relaxation, decoherence and leakage out of the computational subspace are captured, in contrast to previous works. As the presented method enables the co-simulation of the control electronics with the quantum system, it facilitates the design and optimization of near-term superconducting quantum processors.

Thomas F. Watson, Stephan G. J. Philips, Erika Kawakami +9 more

Yao Tong, Quan Chen

Quantum computers based on spin qubits and superconducting qubits require radio-frequency (RF) electronic circuits to control and read out the state. As the scale of the quantum processors increases, the inaccuracy in the RF circuit becomes an increasingly significant source of nonidealities that impacts the qubit operations. In this article, we propose a closed-form model to characterize the effects of inaccuracies in the controlling RF circuits on the fidelity of single-qubit control operation of superconducting qubits. Different from previous works, our model allows characterization of multiple inaccuracies at the same time, significantly enhancing the guidance capabilities for practical quantum computing hardware design and optimization. In addition, the accuracy of the proposed model is also verified by a quantum-classical co-simulator.

L. DiCarlo, Jerry M. Chow, Jay Gambetta +8 more