HARQ: Heterogeneous Architectures for Quantum

The planned Heterogeneous Architectures for Quantum (HARQ) program will seek to transform how quantum computing systems are designed and scaled by moving beyond today’s one-qubit-to-rule-them-all approach. 

Currently, most quantum systems rely on a single type of qubit to perform all functions. HARQ, drawing inspiration from the diverse hardware used in classical computing, will explore how to combine distinct qubit types – each providing best-in-class performance specific to processing, memory, or communication function – into interconnected, heterogeneous quantum systems. By leveraging advances in photonic integration, quantum interconnects, and quantum circuit design, HARQ seeks to overcome current scaling and performance bottlenecks in quantum systems. 

If successful, it could unlock powerful quantum applications for national security, industry, and society that remain out of reach with today’s homogeneous architectures.

HARQ will consist of two core technical areas:

1. Developing compiler tools that can efficiently assign quantum operations to the most suitable qubit types, potentially cutting resource demands by a factor of 1,000
2. Engineering high-fidelity, high-speed quantum interconnect components to enable reliable communication between different types of qubits

HARQ will also include a government-led architecture study to guide co-design across software and hardware efforts, assess scalability, and estimate potential economic impacts. 

In support of these efforts, DARPA will host a virtual Proposers Day on Aug. 8, 2025, to share program goals and foster teaming. 

Additionally, DARPA has issued a Request for Information seeking responses from organizations interested in participating in the government study, and/or supporting independent verification and validation, test and evaluation, and program oversight of performer efforts.