Long-range connectivity in a superconducting quantum processor using a ring resonator

Abstract

Qubit coherence and gate fidelity are typically considered the two most important metrics for characterizing a quantum processor. An equally important metric is inter-qubit connectivity as it minimizes gate count and allows implementing algorithms efficiently with reduced error. However, inter-qubit connectivity in superconducting processors tends to be limited to nearest neighbour due to practical constraints in the physical realization. Here, we introduce a novel superconducting architecture that uses a ring resonator as a multi-path coupling element with the qubits uniformly distributed throughout its circumference. Our planar design provides significant enhancement in connectivity over state of the art superconducting processors without any additional fabrication complexity. We theoretically analyse the qubit connectivity and experimentally verify it in a device capable of supporting up to twelve qubits where each qubit can be connected to nine other qubits. Our concept is scalable, adaptable to other platforms and has the potential to significantly accelerate progress in quantum computing, annealing, simulations and error correction.

A modular quantum computer based on a quantum state router.

“…For this form of direct state exchange we require strong, switchable couplings from module to the communication channel to enable rapid operations, low losses in the channel, and a dense, reconfigurable network of couplings among many modules 21,22 . Realizations to date have focused on pairs of quantum modules, with transmission-line based 'quantum bus' communication channels and controllable module-bus couplings based on the nonlinearity of Josephson junctions [23][24][25][26][27][28][29][30] or driven exchange via a driven, nonlinear coupling mode [31][32][33][34] .…”