MP-2: Quantum API gateway

Summary: The Quantum API Gateway , being one of the middleware services, is responsible for routing API requests appropriately (Marosi et al. 2023) as well as identifying the most suitable quantum computer to execute a specific quantum service at runtime.

Problem: The problem is establishing a way for clients of a quantum microservices-based application to access individual quantum services and determine the most suitable host for running quantum algorithms, all while keeping the application hardware-agnostic.

Solution: The Quantum API Gateway serves as the system’s entry point, routing requests to the most appropriate quantum microservices. It also aggregates results to return to the consumer or creates a fine-grained API tailored to each specific client type. In making these decisions, the Quantum API Gateway utilizes various available information, such as the availability of quantum computers, economic costs associated with hardware usage, and estimated response times. It also considers the current characteristics of quantum computers, including qubit topology, error rates, and fidelity. This gateway is an adaptation of the API Gateway pattern from traditional microservice architecture, tailored to address the unique deployment requirements of quantum services (Garcia-Alonso et al. 2022).

Benefits:

  • Deployablity. The Quantum API Gateway optimises the deployment strategy by determining, at runtime, which available quantum computer is best suited for executing a specific quantum service. This approach enhances the efficiency of the quantum service invocation process (Garcia-Alonso et al. 2022).
  • Hardware decoupling. The use of this pattern also facilitates decoupling between services and between services and hardware, as the API Gateway conceals this complexity from service clients (Valencia et al. 2022; Moguel et al. 2022).
  • Services composability. This approach facilitates the composability of heterogeneous microservices by breaking down a single invocation into calls to various services without their awareness.

Drawbacks:

  • Performance. A quantum API Gateway can introduce an additional single point of failure and increase response time. If not scaled properly, it can become a performance bottleneck.

Known uses:

  • As a proof of concept, the quantum API gateway has been implemented for the Amazon Braket quantum computing platform (Garcia-Alonso et al. 2022).
  • Authors of several works (Valencia et al. 2022; Moguel et al. 2022; De Stefano et al. 2022) consider the quantum API gateway to be a necessary integral component of the quantum service-oriented
    architecture.
  • Marosi et al. 2023 propose a hybrid cloud-based reference architecture for the quantum-science gateway that reduces the complexity of using quantum computing resources and increases their accessibility.