Nav: Home

A quantum mechanical 'tune up' for better measurement

June 04, 2004

By exploiting the weird quantum behavior of atoms, physicists at the Commerce Department's National Institute of Standards and Technology (NIST) have demonstrated a new technique that someday could be used to save weeks of measurements needed to operate ultraprecise atomic clocks. The technique also could be used to improve the precision of other measurement processes such as spectroscopy.

The technique, described in today's issue of Science, effectively turns atoms into better frequency sensors. Eventually, the technique could help scientists measure the ticks of an atomic clock faster and more accurately. Just as a grandfather clock uses the regular swings of a pendulum to count off each second of time, an atomic clock produces billions of ticks per second by detecting the regular oscillations of atoms. The trick to producing extremely accurate atomic clocks is to measure this frequency very precisely for a specific atom.

In the latest experiment, the scientists used very brief pulses of ultraviolet light in a NIST-developed technique to put three beryllium ions (charged atoms) into a special quantum state called entanglement. In simple terms, entanglement involves correlating the fates of two or more atoms such that their behavior--in concert--is very different from the independent actions of unentangled atoms. One effect is that, once a measurement is made on one atom, it becomes possible to predict the result of a measurement on another. When applied to atoms in an atomic clock, the effect is that n entangled atoms will tick n times faster than the unentangled atoms.

Currently, scientists at NIST and other laboratories make many thousands of measurements of the ticks of unentangled atoms and average these results to get highly accurate atomic clocks (currently keeping time to better than one second in 40 million years).

If entangled atoms could be used in a clock, the same or better results could be achieved with far fewer separate measurements. The current experiment demonstrates this new approach to precision measurement with three ions; however, the researchers are looking forward to entangling even more ions to take greater advantage of the technique.

"Even if we could implement this new technique with only 10 ions, in the clock business that's really important because the clocks must be averaged for weeks and even months," says NIST physicist Dave Wineland, leader of the research group. "The time needed to do that would be reduced by a factor of 10."

In the experiment reported in Science, scientists entangled the ions with two laser beams, using a technique originally developed for quantum computing applications. The ions are hit with another series of laser pulses and their fluorescence (emitted light, which represents the ions' quantum state) is measured for a specific period of time. The duration of the steps, number of ions, and other experimental conditions are controlled carefully to ensure all the ions are in the same state when they are measured, so that either all or none fluoresce, which simplifies the readout.
The research was supported in part by the Advanced Research and Development Activity and the National Security Agency.

As a non-regulatory agency of the U.S. Department of Commerce's Technology Administration, NIST develops and promotes measurement, standards and technology to enhance productivity, facilitate trade and improve the quality of life.

National Institute of Standards and Technology (NIST)

Related Atomic Clock Articles:

Interaction between the atomic nucleus and the electron on trial
A team of researchers under the leadership of TU Darmstadt and with the participation of scientists from the Physikalisch-Technische Bundesanstalt (PTB) has measured the transition between energy levels of heavy ions with such precision that it has become possible to reassess underlying theories.
Atomic 're-packing' behind metallic glass mystery
A new method uncovers a four-decade mystery about metallic glass that could allow researchers to fine-tune its properties to develop new materials.
Atomic map of malaria drug gives it new life
Researchers have mapped how the malaria drug mefloquine works, providing a route to make effective alternatives and combat rising drug resistance.
Atomic resolution of muscle contraction
Osaka University researchers capture atomic images of muscle molecules in action, giving possibility of new nanomachines.
Atomic force imaging used to study nematodes
In a new study, researchers report for the first time the effective imaging of the nanoscale structure of C. elegans nematodes' cuticle using atomic force microscopy operating in PeakForce Tapping mode.
Creating atomic scale nanoribbons
A recent study conducted by researchers at the Beckman Institute for Advanced Science and Technology at the University of Illinois and the Department of Chemistry at the University of Nebraska-Lincoln has demonstrated the first important step toward integrating atomically precise graphene nanoribbons (APGNRs) onto nonmetallic substrates.
Explaining how 2-D materials break at the atomic level
IBS physicists found that to shed light on the cracking of MoS2, we must go beyond the theory used so far.
JILA atomic clock mimics long-sought synthetic magnetic state
JILA physicists have caused atoms in a gas to behave as if they possess unusual magnetic properties long sought in harder-to-study solid materials.
NIST debuts dual atomic clock -- and a new stability record
Physicists at the National Institute of Standards and Technology have combined two experimental atomic clocks based on ytterbium atoms to set yet another world record for clock stability.
When it comes to atomic-scale manufacturing, less really is more
Robert Wolkow is no stranger to mastering the ultra-small and the ultra-fast.

Related Atomic Clock Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Bias And Perception
How does bias distort our thinking, our listening, our beliefs... and even our search results? How can we fight it? This hour, TED speakers explore ideas about the unconscious biases that shape us. Guests include writer and broadcaster Yassmin Abdel-Magied, climatologist J. Marshall Shepherd, journalist Andreas Ekström, and experimental psychologist Tony Salvador.
Now Playing: Science for the People

#514 Arctic Energy (Rebroadcast)
This week we're looking at how alternative energy works in the arctic. We speak to Louie Azzolini and Linda Todd from the Arctic Energy Alliance, a non-profit helping communities reduce their energy usage and transition to more affordable and sustainable forms of energy. And the lessons they're learning along the way can help those of us further south.