Fine-Tuned Cryogenic Clock Improves Computing Capabilities

Researchers from the University of Adelaide in South Australia have enhanced the cryogenic sapphire clock to achieve near attosecond capability. Also known as a microwave oscillator, the clock features a five cm cylinder-shaped crystal cooled to -269°C.

The oscillator is 10-1000 times more stable than competing technology, according to the research team, and allows users to take ultrahigh precision measurements to improve the performance of electronic systems.

Increased time precision is an integral part of radar technology and quantum computing, both of which have previously relied on the stability of quartz oscillators as well as atomic clocks such as the hydrogen maser.

Atomic clocks are the gold standard in timekeeping for long-term stability over months and years. However, electronic systems need short-term stability over a second to control today’s devices. The new sapphire clock has a short-term stability of around 1×10ˆ-17, which is equivalent to only losing or gaining one second every three billion years, 1,000 times better than commercial atomic clocks over a second.

The original sapphire clock was developed in Western Australia by Professor Andre Luiten in 1989, before the research team moved to South Australia to continue developing the device at the University of Adelaide. The team is currently in the process of modifying the device to meet the needs of various industries including defense, quantum computing and radio astronomy, according to lead researcher Martin O’Connor.

The new version measures 100cm x 40cm x 40cm, but O’Connor says the machine could be reduced to 60 percent of its size without losing much of its capability. “Our technology is so far ahead of the game, it is now the time to transfer it into a commercial product,” says O’Connor. “We can now tailor the oscillator to the application of our customers by reducing its size, weight and power consumption, but it is still beyond current electronic systems.”

The clock uses the natural resonance frequency of a synthetic sapphire crystal to maintain a steady oscillator signal. Microwave radiation is constantly propagating around the crystal with a natural resonance, a concept first discovered by Lord Rayleigh in 1878 when he could hear someone whispering far away on the other side of the church dome at St Paul’s Cathedral.

The clock then uses small probes to pick up the faint resonance and amplifies it back to produce a pure frequency with near attosecond performance. “An atomic clock uses an electronic transition between two energy levels of an atom as a frequency standard,” says O’Connor. “The atomic clock is what is commonly used in GPS satellites and in other quantum computing and astronomy applications but our clock is set to disrupt these current applications.”

The Defense Science and Technology Group (DST Group) in Adelaide is already interested in the lab-based version of the clock, and O’Connor says the research group is also looking for more clients and is planning to release commercial versions of the sapphire clock in 2017.