Meter-scale quantum interconnects between large quantum processors

[erek]

"Modular quantum architecture requires long-distance quantum interconnects to stitch together individual processor modules. Such interconnects, long-distance couplers or L-couplers, must support coherent quantum operation over meter-scale distances [1, 2, 3] and scale to multiple connections between any two modules [4]. Here we demonstrate four L-couplers operating between two 120-qubit IBM Nighthawk R1 superconducting qubit processors. Each L-coupler joins two Nighthawk lattice qubits through two frequency-tunable L-qubits, two RF-SQUID based “i2m” couplers, and 80 cm of superconducting aluminum coax [5]. Each cable installs perpendicular to the processor surface, to enable denser connections, and is joined to the chip by an indium-to-indium room temperature pressure bond made after both modules were mounted. L-coupler modes near 5 GHz, with internal quality factors of 0.86 to 1.09×106, carry relay-based state transfer [1] at a mean network benchmarking [6] fidelity of 99.00%, with a best link of 99.29±0.07%. We then realize distant CZ gates [7] between lattice qubits in separate modules at a mean fidelity of 94.75%, with a best link of 96.42±0.28%, and use them to generate entangled states across the two processors, including a demonstration of simultaneous Bell pair generation using two adjacent L-couplers. These four high-fidelity L-couplers establish a practical path to scalable quantum interconnects for modular quantum computing."

Souce: https://arxiv.org/html/2610.29986v1