Abstract
The dynamics of quantum information in strongly interacting systems, known as quantum information scrambling, has recently become a common thread in our understanding of black holes, transport in exotic non-Fermi liquids, and many-body analogs of quantum chaos. To date, verified experimental implementations of scrambling have focused on systems composed of two-level qubits. Higher-dimensional quantum systems, however, may exhibit different scrambling modalities and are predicted to saturate conjectured speed limits on the rate of quantum information scrambling. We take the first steps toward accessing such phenomena, by realizing a quantum processor based on superconducting qutrits (three-level quantum systems). We demonstrate the implementation of universal two-qutrit scrambling operations and embed them in a five-qutrit quantum teleportation protocol. Measured teleportation fidelities confirm the presence of scrambling even in the presence of experimental imperfections and decoherence. Our teleportation protocol, which connects to recent proposals for studying traversable wormholes in the laboratory, demonstrates how quantum technology that encodes information in higher-dimensional systems can exploit a larger and more connected state space to achieve the resource efficient encoding of complex quantum circuits.
- Received 3 April 2020
- Revised 21 December 2020
- Accepted 22 January 2021
DOI:https://doi.org/10.1103/PhysRevX.11.021010
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Many technological approaches are currently being studied for the realization of future quantum processors. One of the most prominent is based on nonlinear superconducting circuits; such a system was used in a demonstration of quantum supremacy early last year. Most systems currently studied are based on qubits, or quantum two-level systems. These are akin to the two-state electronic circuits found in ordinary classical computers. However, theoretical work suggests that quantum processors based on three-level systems, or “qutrits,” might require fewer resources to build than one based on qubits. This work takes the first steps toward experimental quantum systems based on three-level logic.
As a proof of principle, we develop a superconducting five-qutrit processor that runs a quantum teleportation algorithm. To execute this algorithm successfully, we engineer two new ways of entangling superconducting qutrits, that is, placing them in a nonclassical state required for quantum computing. The algorithm that we use is related to current studies of quantum information propagation (known as scrambling) in black holes.
While it is still too early for these studies to teach us something new about this propagation, similar algorithms run on future quantum processors might shed light on such fundamental questions.
