Find more information about standardization of quantum computer hardware and software modules and interfaces
A quantum computer is built from multiple interconnected layers. Broadly, the full quantum computing stack can be divided into two major domains: the hardware stack and the software stack. As a company dedicated to advanced quantum computer hardware—and primarily interfacing with other physical components of the quantum system—we focus mainly on the quantum computer hardware.
Until recently, the quantum computing field focused on developing prototypes for proof-of-concept experiments, typically aimed at validating small, few-qubit setups. Today, however, the quantum computing hardware landscape is rapidly evolving. What was once a prototype-driven field is transforming into a mature supply-chain ecosystem, where specialized vendors deliver advanced, state-of-the-art components: a quantum computing industry.
Modularity played a key role in the growth of the classical computer market. By organizing the structure and functionalities of a computer into distinct layers, each module can be optimized and specialized. This modular approach has accelerated the advancement of the field and fosters a global market with a matured supply chain.
The development of quantum computers can take advantage of this example by following the same approach. Modularity with standardized interfaces, requirements, and functionalities will accelerate a global market for the entire quantum computer industry. But how do we get there? And what is the role of Delft Circuits in it?
It is a quantum computer built with selected objects from specialized vendors of the quantum computer supply-chain. All components are combined easily into a single system.
To achieve this modularity, the quantum computing hardware and software functionalities have to be organized into distinct layers. For this, we need a top-down vision on how to subdivide a computer in smaller specialized parts. For every layer, there needs to be consensus on the layer’s functionality, requirements, and interfaces. All this must be documented in standards.
Standardization will accelerate the progress and stimulate the development of quantum computers. Meanwhile, customers and vendors also benefit from modularity.
For customers, like research institutes and system integrators, it becomes possible to select the best products on the market and integrate it easily into their system. There is no risk of vendor lock-in; they do not need to make adjustments to other parts to integrate the module.
The vendors are able to sell their innovations sooner due to simplified upgrading and offering their products to a bigger global market. Besides, they will receive less requests for tailor-made products, because the standards are set and checked. This allows vendors to produce in higher volumes.
Qubit architectures might require different hardware architectures, therefore different layer models. So far, we distinguish between cryogenic solid-state based, room-temperature solid-state based, trapped ions, neutral atoms and photonic quantum computing systems. Because Delft Circuits specializes in cryogenic cabling for microwave signals, we will focus on the layer model for the first quantum architecture family: cryogenic solid-state systems. This family includes the most popular qubit architectures currently used such as transmons, flux qubits, semiconductor spin qubits and topological qubits.
In general, when a user initiates a session, he or she is not necessarily aware of the quantum computer hardware that will perform the calculations and all the software and hardware layers in between. The user simply starts to program to give instructions to the quantum computer. These instructions need to be adapted to fit the set-up, because not all instructions can directly be executed on the chip. For example, not all qubits are connected to each other, this influences which gates can be performed directly and which ones not. Clever mapping and routing are necessary to compile the circuit so it becomes executable on the device. A Hardware Abstraction Layer translates the instructions of the user into executable commands that fit the underlying architecture.
The executable gate instructions are passed onto the next software layer: the control software. This Instruction Set Architecture generates low-level commands that are optimized for the control electronics. Pulse level programming, for example, translates gates into specified wave pulses for a certain time on a specific qubit.
The commands are now passed on to the quantum computer hardware stack. At room temperature, the control electronics generate, receive, and process all signals needed to perform the calculation. This includes DC, RF, and microwave signals. The commands it received are modulated into baseband and modulated pulses to generate pump signals and measure the qubits.
All signals are transported electronically and/ or optically from the control electronics to the qubits via the control highway. This carefully designed system requires high attenuation for downstream signals, low-noise amplification for upstream signals, vibration isolation, thermalization, and low crosstalk without becoming bulky within high vacuum conditions. This hardware layer includes cryostats with top or side-loaders inserts.
The final layer of the system, performing the calculations, is the quantum device. This module contains the qubits and is usually placed on a PCB as a chip where it is isolated from environmental factors such as temperature and magnetic fields causing too much noise. The sent pulses interact with the qubits, thereby manipulating and measuring the response. This concludes the session initiated by the user.
Delft Circuits is actively leading European projects, such as building a layer model for Gate-based Modular Quantum Computers. Subscribe to our newsletter to receive all latest updates, including standardization contributions and developments on quantum computer hardware.