Meter-scale quantum interconnects between large quantum processors
Abstract
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 and scale to multiple connections between any two modules. 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. 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 1.09e6, carry relay-based state transfer at a mean network benchmarking fidelity of 99.00%, with a best link of 99.29 +/- 0.07%. We then realize distant CZ gates 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.
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BibTeX
@misc{sundaresan2026meterscale,
title = {{Meter-scale quantum interconnects between large quantum processors}},
author = {Neereja M. Sundaresan and Nicholas Cotaj and Yadav Prasad Kandel and Eric Lewandowski and Christian Robert Longton and Yves Martin and Jae-woong Nah and Kathryn Pooley and Martin Sandberg and Michael Scanlon and Chi Xiong and Emanuil Sashev Yanev and David Abraham and Abhinandan Antony and Vincent Arena and Nicholas Bornman and Khanh Dang and Oliver Dial and Christopher Guarino and Gabriel Haspil and Jared Hertzberg and Kentaro Heya and Swetha Kamlapurkar and Michael Karschner and George Keefe and Eric Liniger and Laura Luo and Thomas G. McConkey and David Olson and Jason Orcutt and Dmitry Ovchinnikov and Timothy Phung and Sankeerth Rajalingam and Michael Selvanayagam and William Shanks and Dongbing Shao and Abigail Shearrow and Adam Stabile and Jiri Stehlik and Joseph Suttle and Jeng-Bang Yau and Eric Zhang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29986},
eprint = {2610.29986},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29986},
}
RIS
TY - UNPB
TI - Meter-scale quantum interconnects between large quantum processors
AU - Neereja M. Sundaresan
AU - Nicholas Cotaj
AU - Yadav Prasad Kandel
AU - Eric Lewandowski
AU - Christian Robert Longton
AU - Yves Martin
AU - Jae-woong Nah
AU - Kathryn Pooley
AU - Martin Sandberg
AU - Michael Scanlon
AU - Chi Xiong
AU - Emanuil Sashev Yanev
AU - David Abraham
AU - Abhinandan Antony
AU - Vincent Arena
AU - Nicholas Bornman
AU - Khanh Dang
AU - Oliver Dial
AU - Christopher Guarino
AU - Gabriel Haspil
AU - Jared Hertzberg
AU - Kentaro Heya
AU - Swetha Kamlapurkar
AU - Michael Karschner
AU - George Keefe
AU - Eric Liniger
AU - Laura Luo
AU - Thomas G. McConkey
AU - David Olson
AU - Jason Orcutt
AU - Dmitry Ovchinnikov
AU - Timothy Phung
AU - Sankeerth Rajalingam
AU - Michael Selvanayagam
AU - William Shanks
AU - Dongbing Shao
AU - Abigail Shearrow
AU - Adam Stabile
AU - Jiri Stehlik
AU - Joseph Suttle
AU - Jeng-Bang Yau
AU - Eric Zhang
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.29986
UR - https://arxiv.org/abs/2610.29986
AB - 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 and scale to multiple connections between any two modules. 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. 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 1.09e6, carry relay-based state transfer at a mean network benchmarking fidelity of 99.00%, with a best link of 99.29 +/- 0.07%. We then realize distant CZ gates 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.
ER -