Scientists build 'ultra-precise' clock in hopes of 'redefining the second'

A TEAM of scientists have invented a clock that can change time as we know it.

The clever Chinese researchers built an optical clock that loses or gains a second every seven billion years.

This brings people closer to redefining the second as a basic unit of time.

This incredible feat makes China only the second country in the world to keep time so accurately.

The team, led by physicist Pan Jianwei, wrote earlier this month in the peer-reviewed journal Metrologia.

They said the gadget paves the way for the creation of a global optical clock network.

They added that it also offers new opportunities to test fundamental physics theories, detect gravitational waves and search for dark matter.

The current record holder for the most accurate strontium-based optical clock is at the University of Colorado at Boulder.

It was developed by a group led by Chinese-American physicist Jun Ye.

It remains slightly more accurate than its Chinese competitor and its operation is more stable.

Other players in the race include the University of Tokyo and the Institute for Physical and Chemical Research in Japan, and the National Metrological Institute of Germany.

Optical clocks offer great potential for applications in critical infrastructure in the future.

They could significantly improve the precision of global navigation satellite systems and help build highly secure communications networks based on quantum key distribution.

They would also improve synchronization and efficiency current networks, and even play a crucial role in national defense and security, according to South China Morning Mail.

Today, the definition of a second is based on a type of atomic clock called the microwave fountain clock.

It works by releasing cesium atoms upward, which then fall under gravity in a fountain-like motion while being excited with microwave pulses.

Their electrons then absorb and emit light particles to jump between different energy levels.

By counting such cycles as “ticks” that mark fractions of a second, scientists can achieve highly accurate timekeeping with stabilities of a few quadrillionths.

But the accuracy of a microwave clock is limited by the microwave frequency standard.

In recent years, researchers have built optical clocks that use laser light to drive electronic transitions, achieving performance two orders of magnitude better than their microwave counterparts.

But if microwave clocks are to be replaced by optical clocks for the future definition of time, at least three laboratories in the world will need an optical clock with a stability of less than 5 quintillionths and an uncertainty of less than 2 quintillionths.

They are the two most important variables for the performance and reliability of an optical clock.

Instability measures how much the clock's frequency changes over time, while uncertainty represents the degree of confidence in the frequency measured by the clock.