A quantum clock is a type of clock that confines aluminum and beryllium ions together in an electromagnetic trap and cools them by lasers to near absolute zero temperatures. Developed by National Institute of Standards and Technology physicists, the clock is 37 times more precise than the existing international standard.
Both the aluminum-based quantum clock and the mercury-based atomic clock keep track of time from the ion vibration at an optical frequency by using a UV laser, that is 100,000 times higher than the microwave frequencies used in NIST-F1 and other similar time standards around the world. Quantum clocks like this are able to divide time into smaller units and can be far more precise than microwave standards.
In terms of standard deviation, the quantum clock loses one second every 3.4 billion years, while the current international standard NIST-F1 caesium fountain atomic clock loses a second every 100 million years.
The NIST team are not able to measure clock ticks per second because the definition of a second is based on the NIST-F1 which cannot measure a more precise machine. However the aluminum ion clock's measured frequency to the current standard is 1121015393207857.4(7)Hz. NIST have attributed the clock's accuracy to the fact that it is insensitive to background magnetic and electric fields, and unaffected by temperature.
In February 2010, NIST physicists built a second, enhanced, version of the quantum logic clock using a single aluminum atom. Considered the world's most precise clock, it offers more than twice the precision of the original, neither gaining nor losing one second in 3.7 billion years.
Gravitational time dilation
In 2010 an experiment placed two aluminium-ion quantum clocks close to each other, but with the second elevated 12 inches compared to the first, making the gravitational time dilation effect visible. It has been calculated that a human being living "12 inches" below ground level would have a life expectancy, for a 79-year life span, of 90 billionths of a second longer.
- Ghose, Tia (5 February 2010). "Ultra-Precise Quantum-Logic Clock Puts Old Atomic Clock to Shame". Wired. Retrieved 2010-02-07.
- "Frequency Ratio of Al+ and Hg+ Single-ion Optical Clocks; Metrology at the 17th Decimal Place" (pdf). sciencemag.org. 28 March 2008. Retrieved 2013-07-31.
- "Quantum Clock Proves to be as Accurate as World's Most Accurate Clock". azonano.com. 7 March 2008. Retrieved 2012-11-06.
- "NIST's Second 'Quantum Logic Clock' Based on Aluminum Ion is Now World's Most Precise Clock" (Press release). National Institute of Standards and Technology. 4 February 2010. Retrieved 2012-11-04.
- "How to add 90billionths of a second to your life . . . live in the basement: Scientists prove time really does pass quicker at a higher altitude" (Press release). Daily Mail. 24 September 2010. Retrieved 2012-11-04.