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Electronics’ Speed Limit

Mention the term “speed limit” and most people think of a moving car, but did you know electronics also have a speed limit? Thanks to advances in technology, 21st-century electronic devices such as computers and mobile phones are faster than ever before.

Yet despite technology moving forward in leaps and bounds, the speed of electronics isn’t infinite. Scientists have spent years determining the absolute fastest speed possible in semiconductor electronics. They estimate it is one petahertz or one million gigahertz.

© Titima Ongkantong / Shutterstock

Tech fans needn’t worry their devices won’t progress any further, as scientists are nowhere near designing components that can reach this incredible speed. In fact, it’s so fast, we might NEVER realise it. Read on to find out how the electronics’ speed limit works and why it’s such a complex field of study.

How are electrical currents generated?

Complex quantum mechanical processes are responsible for generating electrical currents. In recent years, computer chips have been working with shorter time intervals and signals to produce faster electrical currents. However, at some point, they will reach their physical limits.

It’s not possible to increase the speed of electrical currents indefinitely, even with the use of modern technology, such as precise laser pulses. This is because the quantum mechanical processes generating the electric currents in semiconductor materials take a certain amount of time. This limits the speed of signal generation and signal transmission.

While it often feels like electronics can carry on getting faster forever, the laws of physics will intervene at some point.

How have electronics gotten faster?

Today’s high-speed printed circuit boards satisfy state-of-the-art demands of the electronics industry. PCBs are getting smaller to power our mobile phones, tablets, computers, laptops, gaming consoles, TVs and other devices.

Computers in particular are becoming smaller and faster. In the year 2000, when only 44% of UK households had a home computer, it would have been heavy and bulky, taking up a lot of space on the desk. The monitor alone could be more than 30 cm deep!

Computers could also be slow, taking a long time to load pages, especially those containing a lot of graphics. External hard drives were common because the computers had limited memory.

Surveys show almost 90% of UK households have a home computer today. The electronics revolution, including the rapid development of PCBs, means today’s computers are faster, smaller and more convenient than ever before.

They can fit into a handbag and have speed capabilities users could only dream of in years gone by. To put this into context, in the days when the only way to access the Internet was via a dial-up connection on an old desktop computer, it could take 15 minutes to download a 6 MB image! This compares with just TWO SECONDS today.

How have scientists calculated the maximum speed?

Despite the marvels of modern technology, the speed of electronics is still limited by the restrictions of an electron physically moving through matter. Research published in March 2022 has revealed there’s a physical limit on what is possible.

A joint study by scientists at Vienna University of Technology, Graz University of Technology and the Max Planck Institute of Quantum Optics has calculated the theoretical physical limit on electronics’ speed. The team completed experiments using lasers and semiconductor materials to estimate the fastest speed of optoelectronic systems before quantum mechanics took over.

Optoelectronic systems are devices that use light to control electricity. Nothing moves faster than light and this is true for electronics as well. Optoelectronic devices are the fastest in existence.

An ultra-short laser pulse hits the semiconductor, putting the electrons in the material into a high energy state. They can move around freely in this state. A longer, second laser pulse then sends the electrons shooting off in a certain direction to produce an electrical current.

Using this technique, combined with complex computer simulations, the team was able to estimate the speed limit. However, the report points out it won’t be an issue in practice for a long time – if ever. Producing computer chips with a clock frequency even close to this limit is not a realistic prospect any time soon.


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