Russ Garcia is CEO of Menlo Micro. He has more than 30 years of experience in the electronic systems and semiconductor industries.

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Machine learning is the hottest topic in computing today, but what may become the most consequential development is being explored at temperatures close to absolute zero. This is where quantum states replace binary ones and zeros, enabling a computing paradigm that promises to answer otherwise impossible questions. For quantum computing, cold is the new hot.

The Quantum Advantage

In quantum computing, a qubit (quantum bit) represents all possible states of that bit until its value is measured, at which point it collapses to either 0 or 1. This is of limited practical advantage for one qubit, but when a set of qubits becomes entangled, their states can become correlated thanks to what Einstein described as “spooky action at a distance.” Together, the qubits then represent all possible combinations of their individual states. Quantum gates can act on these qubits to perform computations on all possible states at once. Measurement then collapses the quantum system's state from a probabilistic superposition to a definite result.

Quantum computation is expected to have advantages for tackling problems that are highly combinatorial and so have very large search or optimization spaces; strongly affected by quantum phenomena themselves, e.g., for simulations of chemical reactions or physical processes; or based on mathematical forms that have been specially developed to be addressable by quantum algorithms.

Building Better Quantum Computers

The challenge for implementing quantum computing is that it relies on being able to set, store, operate upon and read out the quantum states of a system, which may be represented by such ephemeral signals as the energy level of an ion, or the spin orientation of an electron. Any mechanical, thermal, electrical or electromagnetic interference will upset these states and destroy the calculation, and so many quantum computers are designed to operate at as close to absolute zero (–273.15ºC) as possible.

Some quantum computers use radio-frequency (RF) signals to set quantum states, and to read out results by capturing the very weak signals emitted by qubits. This demands RF circuits, connectors, cables and switching that minimize signal loss, noise and interference.

Satellite systems face similar issues, even though they can operate at much warmer temperatures, e.g., between –65 ºC and +125 ºC for low-earth-orbit constellations. These systems use RF switching to route transmit and receive paths between multiple antennas and transceivers, to manage failovers to redundant equipment and to reconfigure payloads.

RF switching in satellites is handled by high reliability mechanical, semiconductor or microelectromechanical (MEMS) switches. These devices face common challenges including thermal cycling, power handling, package integrity and demands for very high reliability. Semiconductor switches are also affected by cosmic radiation, which can degrade or destroy their switching capabilities.​

The MEMS Alternative

MEMS, built using variants of standard IC manufacturing processes, is already widely used in mobile phones, airbag sensors and vehicle inertial navigation units. The challenge for MEMS switch design has been to produce a switch that offers better performance than other approaches and overcomes outdated ideas about their drawbacks.

The concern with MEMS switches has always been that, since they are mechanical, material mismatches and fatigue processes will eventually wear them out. And this has been taken to be doubly so if the switches are working at very low temperatures, where materials become brittle.

​Best Practices For MEMS Implementation

Therefore, when evaluating multiple architectural options and determining where advanced micro‑mechanical switching technologies (MEMS) could add value, decision makers should concentrate on a few pivotal variables.

For example, it is important to identify where switching quality directly affects efficiency, signal integrity or functional capability. MEMS is most impactful when low loss, high precision or fast reconfiguration can be shown to demonstrably improve overall system output.

It is also important to assess expected operating conditions and endurance needs. MEMS can excel where long life, stable performance and minimal degradation are strategic advantages.

Consider whether reducing component count, shrinking form factors or simplifying system architecture could lead to cost, performance and scalability benefits.

Evaluate opportunities to lower power consumption and cut thermal load, particularly in high‑density, remote or energy‑constrained systems.

And finally, balance performance gains against cost, supply chain resilience and total cost of ownership.

MEMS In The Cold

Given the importance of high-quality switching at cryogenic temperatures in quantum computing and satellite design, research is underway to characterize how various types of switch are affected. The consensus seems to be that semiconductor devices are likely to experience a reduction in On resistances and an increase in switching speeds at low temperatures. However, shifts in characteristics such as threshold voltages and turn-on/turn-off times can become less consistent at low temperatures, meaning that drive electronics must be adjusted to compensate for these changes.

Research is also underway into the effect of cryogenic temperatures on MEMS switches. A collaboration between America’s National Institute of Standards and Technology and the University of Colorado at Boulder has already shown that MEMS switches can work down to 18K over 1 million switching cycles. All the MEMS switches tested were still working after this many cycles, but their (very low) contact resistances had changed slightly. It is worth noting that the switch’s manufacturer rates them to survive 3bn cycles at room temperature before failure.

Conclusion

Quantum computing may be the most significant breakthrough in computing this decade. Implementing it effectively will involve assessing all possible architectures and components, considering the probability that each will make a useful contribution and then collapsing those options to produce a final design. MEMS switches are already showing positive results in terms of reliability at low temperatures. Looked at in the cold light of day, they could become the hot choice for the next generation of quantum computers. ​

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