How The Convergence Of RF And Quantum Technologies Is Shaping The Future Of Computing

By John Oncea, Editor

Quantum computing is driving significant advancements in radio frequency (RF) technology, particularly in the areas of signal processing, component design, and measurement techniques.

While RF and quantum technologies haven’t necessarily gone hand in hand over the years, they have gone side by side with both fields advancing significantly over the past century. The roots of RF technology can be traced back to the late 19th century with the work of scientists like Heinrich Hertz and Guglielmo Marconi while, around the same time, the foundations of quantum technology were forming.

Both RF and quantum are shaping communication, navigation, and countless other applications and, when integrated, promise even more innovative uses.

150 Years Of Development In 565 Words

RF technology has revolutionized communication, navigation, and many other aspects of modern life since James Clerk Maxwell published Treatise on Electricity and Magnetism in 1873. Heinrich Hertz proved Maxwell’s theory through experimentation a decade or so later, laying the foundation for understanding radio waves.

The turn of the century saw rapid advancements including Guglielmo Marconi’s invention of the radio in 1901 and all of Nikola Tesla’s contributions to the field. In 1935 Sir Robert Alexander Watson-Watt discovered 1935 which was then used by the Germans, Japanese, Americans, and British to detect approaching planes during World War II, writes RFID Journal. During WW II, German pilots also rolled their planes to change the reflected radio signal, identifying themselves as friendly and developing the first crude passive RFID system in the process.

After WWII, RF technology expanded into civilian applications. FM radio, TV, and portable radios became widely available for home use and in the 1950s and 1960s, scientists explored using RF energy to identify objects remotely ultimately leading to the commercialization of anti-theft systems using radio waves.

In the 1970s, electronic article surveillance tags were developed, still used in packaging today and Los Alamos National Laboratory developed a system for tracking nuclear materials using RFID. The 70s also saw an explosion of academic progress on RFID, with extensive studies at universities and government laboratories, adds Peak Technologies.

More recently, RF technology has become ubiquitous. The 1990s saw the development of ultra-high frequency (UHF) RFID systems by IBM researchers, offering longer read range and faster data transfer. RF CMOS technology emerged, allowing for densely packed mixed-signal RFICs for microwave applications and SiGe BiCMOS technology has been increasingly adopted for RFICs in high-volume applications like automotive radars.

The Internet of Things (IoT) is now driving demand for efficient and reliable RF communication and future developments are expected in areas like smart homes, self-driving vehicles, and interconnected cities.

Quantum technology can be traced back to 1900 when Max Planck introduced the concept in his work on black-body radiation, notes Quantum Zeitgeist. The development of quantum mechanics as we know it today began in the mid-1920s with the work of Werner Heisenberg and Erwin Schrödinger.

Slower to develop than RF, the concept of quantum computing began to take shape in the 1980s when Paul Benioff proposed a quantum mechanical model of computation. In 1985, David Deutsch described the first universal quantum computer, and around the same time, Richard Feynman was discussing the idea of simulating quantum systems using a quantum computer.

The late 1990s and early 2000s saw the first practical implementations of quantum technology including Oxford University researcher's demonstration of the first experimental realization of a quantum algorithm using nuclear magnetic resonance (NMR) spectroscopy in 1998.

The same year, the first working 2-qubit NMR quantum computer was used to solve Deutsch’s problem and by 2000, a 5-qubit NMR computer was demonstrated at the Technical University of Munich, Germany.

How Quantum Changed RF

Quantum computing is changing RF in several ways. The reduction in the size of quantum computing devices requires RF systems to accommodate higher frequencies in tighter spaces. Flexible cables are becoming the preferred option for connecting to various ports without wasting cable length.

 Temperature requirements are a factor, too. Quantum computers must be kept at extremely low temperatures to be stable, typically around 0 Kelvin (-273 degrees C). RF connectors must be made from materials that can withstand these conditions, such as niobium, niobium-titanium, certain stainless steels, and copper alloys.

Quantum computers transmit RF signals within a magnetic field, so connectors must be non-magnetic to avoid interference. Connectors can be coated with non-magnetic materials like gold or palladium to reduce magnetic effects.

Traditional RF control systems use analog circuits that can be bulky and complex, increasing the risk of failure. New, modular systems that use smaller mixing modules can deliver high-resolution, low-noise RF signals.

Finally, researchers are developing cryogenic measurement capabilities to characterize devices at temperatures as low as tens of mK. These capabilities will help support the creation of new and improved quantum computing devices.

Other components needed for quantum computing include cryogenic equipment, such as dilution refrigerators and pulse tubes, integrated photonics, such as quantum photonic processors, and quantum registers, which are a set of qubits that can be read after quantum calculations.

Quantum And RF In Symbiosis

As both RF and quantum technologies continue to advance, we’re seeing increasing convergence and potential for synergy:

• Quantum sensing technologies are being developed that could enhance the capabilities of RF systems.
• Quantum communication protocols are being explored for secure RF communications.
• The development of quantum radar systems could revolutionize traditional RF-based radar technology.

As these fields continue to evolve, we expect to see even more exciting developments at the intersection of RF and quantum technologies. We also can expect to see how the two technologies are helping shape each other.

For instance, a key challenge in quantum computing applications is managing signal interferences in multi-tone microwave signals used to manipulate qubits. According to the American Institute of Physics, researchers have developed a crest factor reduction algorithm to suppress voltage peaks caused by these interferences. This advancement allows for:

• Frequency-multiplexed qubit control
• Simultaneous two-qubit gate operation
• Enhanced efficiency and scalability of quantum computing systems

The algorithm successfully reduces the amplitude of a 30-frequency-multiplexed signal to less than one-tenth that of a single-tone microwave signal, showing promise for large-scale quantum computers based on frequency multiplexing.

A second instance of the two technologies benefitting each other, according to Tech Xplore, is related to RF component evaluation techniques. As quantum computers scale up, the need for specialized RF components that can operate reliably in extremely low-temperature environments increases. Researchers have developed new evaluation techniques for RF components used in quantum computers that can measure reflection and transmission characteristics (S-parameters) at temperatures from 4 K to 300 K (-269°C to 27°C), enabling the evaluation of RF components at arbitrary temperatures within this range. This is essential for developing high-performance RF components for cryogenic environments and this evaluation method is crucial for building a quantum computer supply chain and is expected to expand the market for low-temperature RF components.

Then there are non-magnetic RF connectors. According to Military Systems & Technology, quantum computers transmit RF signals within magnetic fields, necessitating the use of non-magnetic connectors in critical areas of the signal path. These specialized RF connectors must meet several requirements:

• Low loss and low noise to maintain signal integrity
• Stability in extreme environments, particularly at cryogenic temperatures
• High-frequency range capabilities
• Immunity to magnetic interference

The development of these connectors is essential for maximizing the potential of quantum computers and remains a key area of focus as quantum technology evolves.

Recent advancements in RF technology for quantum computing are focused on improving signal quality, component performance in extreme conditions, and evaluation techniques. These developments are crucial for scaling up quantum computers and realizing their full potential in various applications, from cryptography to drug discovery.