Building the Quantum Future: Leveraging Modular Standards for Control System Design
In quantum computing systems, control electronics are critical in facilitating the operation and manipulation of qubits. Their precision ensures the integrity and accuracy of quantum computing processing and results. For effective operation, engineers need complete latency in the low milliseconds for their chassis, including switches and central processing unit (CPU) ports. There’s also a need for precise clocks, low electronic noise emissions, strong synchronization across multiple boards, and the capacity to scale along with qubit count.
When it comes to building these quantum computing control systems, it’s human nature to start with what you know. However, many engineers end up reinventing the wheel, often without credence for existing platforms that could serve as a strong design foundation. This article discusses the merits of considering open-standard systems for quantum computing control units.
Quantum computing specialists in university settings tend to have deep theoretical knowledge and less experience with industrial implementation. Proof-of-concepts are usually built with existing equipment in the lab and hand-wired. While this may be suitable for prototyping, it’s not ideal for commercial scaling. Specialists who approach quantum computing with experience from another physics-focused role may understand nuanced control and measurement technologies but may not be versed in the broader spectrum of technologies available. In either case, many engineers end up reinventing the wheel in their quantum computing control system design, often without credence for existing platforms that could serve as a strong design foundation.
Modular Platforms for Quantum Computing Control: Building on Pre-Established Standards
Advanced Telecom Computing Architecture (AdvancedTCA) and Micro Telecommunications Computing Architecture (MicroTCA) are modular, open standards that have been adapted for large-scale scientific research and development. Originally, AdvancedTCA and MicroTCA were designed for transferring large amounts of data in telecommunications applications. Today, the functionality of MicroTCA has expanded for stronger board synchronization and clock precision for beam control in particle accelerators. It was the physics community that instigated the implementation of rear transition modules and the separation of digital and analog circuitry. Application-ready precision test and measurement (T&M) systems featuring PXIe are similarly favorable for these types of applications in electronic and simulation labs in university settings.
While particle acceleration is a different application area, designing with systems like MicroTCA or AdvancedTCA offers a path for scalable quantum computing control design; there are already standard transfer protocols like PCI Express, Ethernet, or Serial RapidIO (SRIO) with low latency and high data transfer rates in place. The technology framework is pre-defined with common standards for power, cooling, and electromagnetic compatibility (EMC) noise. Further, they comply with certificates like CE and UL, put forth standard board form factors, and provide defined interoperability. With a well-developed base, engineers can adjust or remove features that aren’t required for quantum computing control units.
PXIe already offers add-ons for clocks and triggers that were originally designed for synchronizing measurements in parallel. MicroTCA has even more sophisticated clock implementations due to existing requirements for particle beam synchronization. Selecting and building on a modular, open-standard platform gives you access to a pre-established, holistic approach. Each of these platforms is focused on protocols, data speeds, communication between slots, power per slot, slot count, form factor, etc. The key is determining the differences between these platforms and the modifications needed to fit your unique application requirements. An experienced electronics packaging partner will be able to support you in that assessment.
| PXI Express | MicroTCA | AdvancedTCA | |
| Data transfer | - PCI Express Gen3, x4 or x8 - PCI bus, 32-bit - CLK and Trigger lines for T&M applications | - Base interface, 10 GbE, - Fabric interface, x4, 100 GbE or 4x PCIe Gen 4 - CLK and Trigger lines for big science applications (MTCA.4) | - Base interface, 10 GbE, - Fabric interface, x4, 100 GbE or 4x PCIe Gen 3 - CLK and Trigger lines for Telecommunications |
| Topology | 1 root complex | 1 root complex or Dual-Star | 1 root complex, Dual-Star, Dual-Dual-Star, Full-mesh |
| Board area (height / depth) | 160 cm² (3 U / 160 mm) // 373 cm² (6 U / 160 mm) | 132 cm² (75 mm / 180 mm) // 268 cm² (150 mm / 180 mm) | 902 cm² (8 U / 280 mm) |
| Board width | 4 HP (20.32 mm) | 3 HP (15.24 mm), 4 HP (20.32 mm), 6 HP (30.48 mm) | 6 HP (30.48 mm) |
| Max. number of boards | 21 | 12 | 16 |
| Max, power / board | 80 W | 80 W | 450 W |
Table 1: Comparison between PXIe, MicroTCA, and AdvancedTCA for a 19-inch system
It’s common for quantum computing control system requirements to exceed those of modular open-standard systems when it comes to clock synchronization and the number of devices on one node. Achieving requirements starts with actions like:
- Removing built-in redundancy features of MicroTCA and AdvancedTCA and implementing additional signals instead
- Adding more precise clock sources (PXIe)
- Extending the number of boards within one system
- Increasing board size (height and depth)
- Increasing board width to accommodate larger heat sinks
We’ve already seen specifications change to support requirements specific to particle accelerators, and we expect to see the same happen for quantum computing control systems in the future. For now, open-standard systems should be part of the consideration set for quantum computing control systems because they serve as a strong and viable design foundation. The more you step away from the standard, the more engineering work there is that doesn’t relate to the core function of the quantum computer.