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Ingress Cryogenic Receivers Toward Scalable Quantum Information Processing: Theory and System Analysis

Malek Succar, Mohamed I. Ibrahim

TL;DR

This paper addresses the scalability bottleneck of coaxial cryogenic control lines for large-scale quantum processors by proposing a multiplexed all-passive cryogenic high-frequency direct-detection (cryo-HFDD) platform that uses photonic and sub-THz links to carry qubit control signals. It develops a detailed heat-load and SNR framework across room-temperature, 4 K, and millikelvin stages, comparing photonic links to cryoCMOS and coaxial approaches. Key findings show that 30 mK photonic receivers are impractical due to heat-load constraints, while 4 K photonic receivers with WDM can aggressively scale to thousands of qubits within existing cooling budgets, given reasonable photodiode responsivity and effective impedance matching. The work introduces a WDM-based density metric and analyzes nonlinearity in EOMs, demonstrating that with improvements in modulators, photodiodes, and fridge cooling power, cryo-HFDD could enable scalable quantum information processing with significant gains over conventional wiring. Overall, the proposed approach offers a viable pathway to large-scale quantum control by reducing passive heat load and enabling high-density, low-cost photonic links.

Abstract

Current control techniques for cryogenically cooled qubits are realized with coaxial cables, posing multiple challenges in terms of cost, thermal load, size, and long-term scalability. Emerging approaches to tackle this issue include cryogenic CMOS electronics at 4 K, and photonic links for direct qubit control. In this paper, we propose a multiplexed all-passive cryogenic high frequency direct detection control platform (cryo-HFDD). The proposed classical interface for direct qubit control utilizes optical or sub-THz bands. We present the possible tradeoffs of this platform, and compare it with current state-of-the-art cryogenic CMOS and conventional coaxial approaches. We assess the feasibility of adopting these efficient links for a wide range of microwave qubit power levels. Specifically, we estimate the heat load to achieve the required signal-to-noise ratio SNR considering different noise sources, component losses, as well as link density. We show that multiplexed photonic receivers at 4 K can aggressively scale the control of thousands of qubits. This opens the door for low cost scalable quantum computing systems.

Ingress Cryogenic Receivers Toward Scalable Quantum Information Processing: Theory and System Analysis

TL;DR

This paper addresses the scalability bottleneck of coaxial cryogenic control lines for large-scale quantum processors by proposing a multiplexed all-passive cryogenic high-frequency direct-detection (cryo-HFDD) platform that uses photonic and sub-THz links to carry qubit control signals. It develops a detailed heat-load and SNR framework across room-temperature, 4 K, and millikelvin stages, comparing photonic links to cryoCMOS and coaxial approaches. Key findings show that 30 mK photonic receivers are impractical due to heat-load constraints, while 4 K photonic receivers with WDM can aggressively scale to thousands of qubits within existing cooling budgets, given reasonable photodiode responsivity and effective impedance matching. The work introduces a WDM-based density metric and analyzes nonlinearity in EOMs, demonstrating that with improvements in modulators, photodiodes, and fridge cooling power, cryo-HFDD could enable scalable quantum information processing with significant gains over conventional wiring. Overall, the proposed approach offers a viable pathway to large-scale quantum control by reducing passive heat load and enabling high-density, low-cost photonic links.

Abstract

Current control techniques for cryogenically cooled qubits are realized with coaxial cables, posing multiple challenges in terms of cost, thermal load, size, and long-term scalability. Emerging approaches to tackle this issue include cryogenic CMOS electronics at 4 K, and photonic links for direct qubit control. In this paper, we propose a multiplexed all-passive cryogenic high frequency direct detection control platform (cryo-HFDD). The proposed classical interface for direct qubit control utilizes optical or sub-THz bands. We present the possible tradeoffs of this platform, and compare it with current state-of-the-art cryogenic CMOS and conventional coaxial approaches. We assess the feasibility of adopting these efficient links for a wide range of microwave qubit power levels. Specifically, we estimate the heat load to achieve the required signal-to-noise ratio SNR considering different noise sources, component losses, as well as link density. We show that multiplexed photonic receivers at 4 K can aggressively scale the control of thousands of qubits. This opens the door for low cost scalable quantum computing systems.

Paper Structure

This paper contains 12 sections, 11 equations, 13 figures, 1 table.

Table of Contents

  1. Introduction
  2. Link Passive Heat Load and $SNR$ Specification
  3. Photonic Links for Qubit Control
  4. Room Temperature Electro-Optic Transmission
  5. Cryogenic Photonic Detection
  6. 30 mK RX
  7. 4 K RX
  8. Dense Channel Multiplexing & Scalability
  9. EOM nonlinearity impact on $SNR$ $\&$ heat load
  10. Sub-THz Links for Qubit Control
  11. Future scalability projections
  12. Conclusion

Figures (13)

  • Figure 1: Cryogenic High Frequency Direct Detection (cryo-HFDD) qubit control platform.
  • Figure 2: Photonic control architecture for a single qubit at (a) 30 mK, (b) 4 K.
  • Figure 3: Cryogenic multi-qubit receiver at 30 mK with impedance matching.
  • Figure 4: Minimum optical power $P_{opt}$ (blue) and load impedance $Z_L$ (black) to meet $SNR$ for different peak qubit power at 30 mK and 4 K.
  • Figure 5: Cryogenic multi-qubit receiver at 4 K with impedance matching.
  • ...and 8 more figures