Vivek Maurya, Daria Kowsari, Kumar Saurav, Rajamani Vijayaraghavan, Daniel Lidar, Eli Levenson-Falk, University of Southern California, Los Angeles, CA
High-fidelity multi-qubit control is essential for quantum processors to achieve practical advantage over classical computers. For analog quantum simulation, it is especially useful to have general control over a multi-qubit Hamiltonian. However, most processor architectures have a limited multi-qubit gate set to work with, meaning that arbitrary operations may require many gates, reducing fidelity. Multi-mode superconducting circuits provide a possible solution, as their strong couplings and mode hybridization allow a wide variety of control techniques. We present results on the trimon 3-mode circuit, a ring of 4 Josephson junctions with 4 capacitor pads implementing 3 modes of oscillation, all similar to transmon qubits. The modes all have strong dispersive interactions, leading to native 3-qubit gates. We demonstrate how we can implement a wide variety of canonical 2-qubit and 3-qubit gates with the trimon. We use ordinary microwave drives and 2-tone Raman drives to achieve arbitrary Hamiltonian control in the 2-qubit space, and discuss simple modifications of the device to achieve arbitrary 3-qubit control. We discuss possible integration of trimons into large scale architectures and the possibility for compact error suppression encodings.