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Cryo-CMOS Antenna for Wireless Communications within a Quantum Computer Cryostat

Viviana Centritto, Ama Bandara, Heqi Deng, Masoud Babaie, Evgenii Vinogradov, Sergi Abadal, Eduard Alarcon

TL;DR

This work addresses interconnect bottlenecks in scaling multi-core quantum processors by enabling wireless intra-package links inside a cryostat. It proposes a cryo-CMOS compatible on-chip differential dipole antenna operating at 28 GHz and validates its performance in a realistic cryostat environment, achieving strong impedance matching ($S11$ around $-20$ to $-18$ dB) and high efficiency at 4 K. It also explores time-reversal wireless signaling to mitigate interference in reverberant chip-packages, showing SINR gains over non-TR in multi-link scenarios and detailing how performance scales with the number of concurrent transmissions. The results support a practical pathway to reduce wiring complexity, lower thermal load, and improve scalability of multi-core quantum architectures through integrated cryogenic wireless links.

Abstract

Scaling quantum computers from a few qubits to large numbers remains one of the critical challenges in realizing practical quantum advantage. Multi-core quantum architectures have emerged as a promising solution, enabling scalability through distributed quantum processing units (QPUs) interconnected via classical and quantum links. However, the bottleneck of wired connections persists, as densely packed wired interconnects, both vertically across temperature stages and horizontally within the same layer, introduce spatial constraints, power dissipation, and latency, which could hinder performance as the number of QPUs increases. To overcome these limitations, this work proposes a cryo-compatible on-chip differential dipole antenna operating at 28 GHz to enable short-range wireless communication within a quantum computer cryostat. Temperature-dependent material properties are incorporated to accurately capture antenna behavior at 4 K. Moreover, by embedding the antenna in a realistic cryostat structure, we evaluate the feasibility of antenna operation within the cryogenic environment. The proposed antenna achieves a reflection coefficient of -20.8 dB in free space and -18.38 dB within the cryostat, demonstrating efficient impedance matching.

Cryo-CMOS Antenna for Wireless Communications within a Quantum Computer Cryostat

TL;DR

This work addresses interconnect bottlenecks in scaling multi-core quantum processors by enabling wireless intra-package links inside a cryostat. It proposes a cryo-CMOS compatible on-chip differential dipole antenna operating at 28 GHz and validates its performance in a realistic cryostat environment, achieving strong impedance matching ( around to dB) and high efficiency at 4 K. It also explores time-reversal wireless signaling to mitigate interference in reverberant chip-packages, showing SINR gains over non-TR in multi-link scenarios and detailing how performance scales with the number of concurrent transmissions. The results support a practical pathway to reduce wiring complexity, lower thermal load, and improve scalability of multi-core quantum architectures through integrated cryogenic wireless links.

Abstract

Scaling quantum computers from a few qubits to large numbers remains one of the critical challenges in realizing practical quantum advantage. Multi-core quantum architectures have emerged as a promising solution, enabling scalability through distributed quantum processing units (QPUs) interconnected via classical and quantum links. However, the bottleneck of wired connections persists, as densely packed wired interconnects, both vertically across temperature stages and horizontally within the same layer, introduce spatial constraints, power dissipation, and latency, which could hinder performance as the number of QPUs increases. To overcome these limitations, this work proposes a cryo-compatible on-chip differential dipole antenna operating at 28 GHz to enable short-range wireless communication within a quantum computer cryostat. Temperature-dependent material properties are incorporated to accurately capture antenna behavior at 4 K. Moreover, by embedding the antenna in a realistic cryostat structure, we evaluate the feasibility of antenna operation within the cryogenic environment. The proposed antenna achieves a reflection coefficient of -20.8 dB in free space and -18.38 dB within the cryostat, demonstrating efficient impedance matching.
Paper Structure (9 sections, 1 equation, 4 figures, 1 table)

This paper contains 9 sections, 1 equation, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Antenna Design and Integration
  3. Differential Dipole Antenna
  4. Integration of the antenna On-Chip
  5. Environment Description
  6. Performance Evaluation
  7. Free space
  8. Cryo-CMOS antenna within the Cryostat Scenario
  9. Conclusion

Figures (4)

  • Figure 1: On-chip dipole antenna design (a) Center fed dipole design and CMOS layered stack (top) and thickness of the top metal, insulator and substrate layer (bottom) (b) Differential fed dipole design (c) Assessment of the substrate (Si) thickness.
  • Figure 2: The cryostat system simulation model with integrated differential dipole on-chip antennas.
  • Figure 3: Performance of the on-chip differential dipole antenna at 28 GHz. Comparison across free space under room and cryogenic temperatures, and inside the cryostat, showing: (a) Reflection coefficient (dB) (b) Total efficiency
  • Figure 4: Performance of the differential dipole antenna in 28GHz (a) E-field distribution of the on-chip differential dipole inside the cryostat at 28 GHz (b) Spatial field distribution inside the cryostat, where the height=70cm and the diameter=30cm.