Benefits and challenges of integrating control electronics within the cryostat

by Chris Morrison, Director of Product Marketing at Agile Analog

Quantum computing, with its potential to tackle problems way beyond the capabilities of standard computers, has ignited a global scientific and technological race. While the focus often lies on the qubits themselves, the entire hardware and software stack plays a crucial role in enabling quantum operations. Of particular interest to electronic engineers is the control and measurement that sits between the quantum qubits, as well as the software controlling them.

There are several main types of quantum computer that scientists and technology companies are currently developing.

Superconducting quantum computers use superconducting circuits to create qubits. The circuits are cooled to extremely low temperatures, which allows them to maintain their quantum properties. Superconducting quantum computers are relatively mature and can perform a wide range of calculations. However, they are very sensitive to their environment and can be difficult to scale to larger sizes.

Trapped ion quantum computers use trapped ions to create qubits. Ions are atoms that have lost or gained electrons, and they can be trapped in an electromagnetic field. Trapped ion quantum computers are also relatively mature, but they are complex to build and operate.

Photonic quantum computers use photons (particles of light) to create qubits. These are still in the early stages of development but are believed to have the capacity to scale as photons can be easily transmitted over long distances using optical fibers. Photonic quantum computers are also challenging to build and require specialized hardware.

Neutral atom quantum computers use neutral atoms (atoms that have not lost or gained electrons) to create qubits. These too are in the early phases of development and have the potential to be highly scalable. This is because neutral atoms can be easily trapped using lasers. Neutral atom quantum computers are also complex to build and need specialized hardware.

Integrating control electronics to scale quantum computers

To achieve their true potential, there is a need to dramatically increase the number of qubits, from the several hundred that is possible today to millions. These qubits need to be controlled, and currently this is performed using external control electronics housed outside of the cryostat at room temperature. By generating semiconductor IP that can operate at cryogenic temperatures, quantum computing developers can quickly design their own control ASICs that can be co-located with the qubits in the cryostat.

Whilst semiconductor process technologies are typically characterized for operation from –40°C to +125°C, in the world of quantum computing, where operational qubits demand temperatures even lower than 4K, co-locating the control electronics close to the qubits within the cryostat is crucial for quantum computer scaling.

Integrating the control electronics directly within the cryostat, the ultra-cold chamber housing the quantum computer, offers several benefits as follows:

  • Reduced cable complexity: Traditionally, control electronics are located at room temperature and communicate with the qubits via long cables that snake into the cryostat. This creates a bulky and complex setup. Integrating the electronics eliminates the need for these extensive cables, streamlining the physical layout and reducing the overall system size.
  • Shorter signal paths: With on-chip control, the distance the control signals need to travel is significantly reduced. This minimizes signal degradation and ensures the accuracy of the signals reaching the qubits. This is imperative for large quantum computers where even small amounts of noise can lead to significant errors.
  • Faster communication: The closeness of the control electronics to the qubits allows for faster communication. This translates to quicker manipulation of qubits and potentially faster execution of quantum algorithms. This is particularly important for applications where time is a key factor.
  • Reduced power consumption: Conventional control systems at room temperature require significant power to operate. Placing them within the cryogenic environment can potentially reduce their power consumption as these operate at much lower temperatures. This translates to a more efficient system overall.
  • Improved scalability: Integrating control electronics makes it easier to scale the system to a larger number of qubits. Imagine adding more processing units alongside the qubits within the cryostat, rather than trying to squeeze in more cables from the outside. This modular approach allows for a more effective way to build larger quantum computers.

Integration challenges

Integrating electronics, particularly integrated circuits (ICs), into the cryostat comes with challenges as follows:

  • Process selection: Integrated circuits typically rely on processes optimized for room temperature operation. These processes may not function correctly or reliably at cryogenic temperatures. The models that an electronics engineer uses to design these circuits are temperature dependent and characterization may not exist at these temperatures. Special foundry processes may be needed to create ICs that can operate within the cryostat.
  • Heat dissipation: Even minimal heat generation from the electronics can disrupt the delicate quantum state of the qubits. Careful design and heat management techniques are vital to ensure the electronics do not introduce unwanted thermal noise.
  • Limited space: Cryostats have limited space, so miniaturization of the control electronics becomes essential. This might require custom-designed ICs specifically suited for the cold environment.


Despite the challenges, integrating the control electronics—which includes analog-to-digital converters (ADCs) and digital-to-analog converters (DACs)—directly within the cryostat is a promising approach for building future large-scale quantum computers. The benefits, such as improved scalability, unquestionably outweigh current limitations.