Random access quantum information processors

TL;DR

This paper demonstrates a scalable superconducting quantum processor with random access capabilities, enabling universal operations on nine qubits using a single transmon and coupled resonators, advancing quantum computation and simulation.

Contribution

The authors implement a novel random access quantum processor with universal control over nine modes, using a single transmon and coupled resonators, showcasing scalable quantum memory manipulation.

Findings

Universal single- and two-qubit gates on arbitrary modes

Preparation of multimode entangled Bell and GHZ states

Efficient control using flux modulation and cryogenic resources

Abstract

Qubit connectivity is an important property of a quantum processor, with an ideal processor having random access -- the ability of arbitrary qubit pairs to interact directly. Here, we implement a random access superconducting quantum information processor, demonstrating universal operations on a nine-bit quantum memory, with a single transmon serving as the central processor. The quantum memory uses the eigenmodes of a linear array of coupled superconducting resonators. The memory bits are superpositions of vacuum and single-photon states, controlled by a single superconducting transmon coupled to the edge of the array. We selectively stimulate single-photon vacuum Rabi oscillations between the transmon and individual eigenmodes through parametric flux modulation of the transmon frequency, producing sidebands resonant with the modes. Utilizing these oscillations for state transfer, we perform a universal set of single- and two-qubit gates between arbitrary pairs of modes, using only the charge and flux bias of the transmon. Further, we prepare multimode entangled Bell and GHZ states of arbitrary modes. The fast and flexible control, achieved with efficient use of cryogenic resources and control electronics, in a scalable architecture compatible with state-of-the-art quantum memories is promising for quantum computation and simulation.