Optical lattice atomic clock could 'redefine the second'

 
Optical lattice clock The optical lattice clock shines lasers on atoms to measure time

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Scientists say they have found a more accurate way to measure time.

We currently use atomic clocks to count the seconds, but tests on an alternative atomic timekeeper have revealed that it is more precise.

The devices, called optical lattice clocks, lost just one second every 300 million years - making them three times as accurate as current atomic clocks.

Writing in Nature Communications, the team said they offered a better system for defining the second.

Laser show

We once used the Earth's rotation to measure time, where one spin equates to a day.

But because our planet wobbles on its axis as it rotates, some days can be shorter or longer than others.

The atomic clock has proved to be a far more accurate method of keeping the world on time and since the 1960s has been used to define a second in the International System of Units (SI units).

But now scientists say the optical lattice clock could improve the precision.

Just as a grandfather clock uses the swing of a pendulum to measure intervals of time, an atomic clock uses the very regular "vibrations" of atoms.

Our current systems, called caesium fountains, expose clouds of caesium atoms to microwaves to get them to oscillate. But the new ones use light to excite strontium atoms.

Dr Jerome Lodewyck, from the Paris Observatory, said: "In our clocks we use laser beams. Laser beams oscillate much faster than microwave radiation, and in a sense we divide time in much shorter intervals so we can measure time more precisely."

Clocks The researchers believe the new clock could be used as a standard for the world's time

The optical clocks are three times as accurate as caesium fountains, which are accurate to one second every 100 million years.

As well as comparing the optical lattice clocks with our current atomic timekeepers, the researchers compared two optical clocks with each other. They found that they kept time in agreement, and were also very stable.

"For instance, if you have your wristwatch, and one day you are one second late, and one day one second early, then your clock is not stable. But it could still have good accuracy if over a million days the time is correct," Dr Lodewyck explained.

It is important to measure both accuracy and stability, he added.

Many technologies such as telecommunications, satellite navigation and the stock markets rely on ever-better time measurements. The researchers said the new clocks could one day help to redefine the second.

Another clock is also undergoing development - an ion clock. This clock loses just one second every few billion years, but because it relies on a single ion, it is not yet deemed to be stable enough for widespread use.

 

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  • rate this
    +2

    Comment number 423.

    171.happyman
    "I don't understand the purpose of all this complicated stuff. Why can't everybody just use what nature has given us, and wake up when the sun rises and sleep when the sun sets"

    They explained exactly why it's important.
    "Many technologies such as satellite navigation rely on ever-better time measurements"

    Satellite navigation wouldn't work without precision time measurements

  • rate this
    +1

    Comment number 422.

    @ 395. johnboy99

    You are right this particular atomic clock was developed in Paris. However, the original Caesium based atomic clocks using microwaves (as opposed to lasers here) was invented at the National Physical Laboratory in the UK. We have been at the forefront since.

  • rate this
    0

    Comment number 421.

    "Another clock is also undergoing development - an ion clock. This clock loses just one second every few billion years . . ." So, with the development of this 'ion clock', our descendants will know the 'exact second' the world ends. I'm sure that will be useful . . .

  • rate this
    -2

    Comment number 420.

    So the story is that a person has to live 300 million years to enjoy that extra second of time. Okay I'll wait but I want it in writing.

  • rate this
    +1

    Comment number 419.

    416.DeeplyConcerned

    In order for us to have driverless cars, this development is absolutely crucial, otherwise the gaps between vehicles will have to be massive

    +++

    The vehicles would communicate one with another, this would permit localised systems similar to VOR/DME together with differential GPS to eliminate errors.

  • rate this
    +1

    Comment number 418.

    415.Derek Tomlin
    11 Minutes ago
    How do they know that it is accurate to a second in 300 million years? And what clock are they comparing it too?

    +++

    The accuracy of a watch can be quickly checked by measuring the frequency of its 32768Hz crystal. Similarly the rate at which the Optical Lattice clock "ticks" can be compared with other accurate clocks.

  • rate this
    +2

    Comment number 417.

    It would be nice to be given a bit more detail of how the new clock works.
    Why is it called an optical lattice clock?

  • rate this
    +1

    Comment number 416.

    To all those not getting the point of this... accurate time measurement is crucial to things such as your SatNav - the more precise the timing accuracy, the more accurate your SatNav is.

    In order for us to have driverless cars, this development is absolutely crucial, otherwise the gaps between vehicles will have to be massive

  • rate this
    -1

    Comment number 415.

    How do they know that it is accurate to a second in 300 million years? And what clock are they comparing it too?

  • rate this
    +2

    Comment number 414.

    I'll try to explain why this is useful to the morons.

    A good way of measuring distance is with light (lasers) or radio waves (gps). The problem is they move very fast.

    To know the distance something has traveled we need to know it's speed, AND HOW LONG IT WAS TRAVELING FOR.

    Speed of light = 300,000 Km/s (approx)

    If the timer is off by 0.0001 seconds the distance would be of by 30 Km.

    Get it?

  • rate this
    +2

    Comment number 413.

    410.The J Hoovers Witnesses
    9 Minutes ago
    I see the scientifically pious are out in number.

    Fine. You can have your own meaning of the word "second", just as doctors have theirs for "process" (a bit of the body that sticks out).

    Normal people will continue with the like meaning of "second".

    +++

    Is that the 1st, 2nd, 3rd etc. meaning?

  • rate this
    -2

    Comment number 412.

    No doubt such a degree of accuracy is facinating to scientists but seriously, why would the average person care?

    Come to think of it, how would a scientist measure the accuracy to within one second over 300 million years to verify the theory? Now that might be interesting.

  • rate this
    -3

    Comment number 411.

    And what exactly is the benefit to anyone (except jobs and funding for scientists)? We seem to have managed life with the second just as it is - how will a new definition help?
    Time some people stopped tinkering and got proper jobs.

  • rate this
    -2

    Comment number 410.

    I see the scientifically pious are out in number.

    Fine. You can have your own meaning of the word "second", just as doctors have theirs for "process" (a bit of the body that sticks out).

    Normal people will continue with the like meaning of "second".

  • rate this
    -1

    Comment number 409.

    Do not worry if you lose a second, maybe in the next 300 million years
    you may gain one. How do you prove this fact? Maybe in 200 years it will lose quarter of an hour but we will all be gone by then.

  • rate this
    +2

    Comment number 408.

    404.JakeJay
    9 Minutes ago
    A nice theoretical plaything for the scientists. we've gone onto space and back who knows how many times - with no time problem (correct me if I'm wrong).

    +++

    There's nowt wrong wi' science.

  • rate this
    +1

    Comment number 407.

    might be useful for Doctor Who maybe improve where he lands

  • rate this
    0

    Comment number 406.

    Can't we design a metric clock? Every other measurement seems able to go metric. One old hour could be made equal to say Hmmm ...what?

  • rate this
    0

    Comment number 405.

    Without "all of this complicated stuff", most modern navigational aids wouldn't work. It's what helps aircraft from hitting each other, ocean-going vessels steer an accurate course, and finding your way to grandma's house after she moves out into the country. GPS doesn't stand for "Global Positioning Sunbeams".

  • rate this
    0

    Comment number 404.

    A nice theoretical plaything for the scientists. we've gone onto space and back who knows how many times - with no time problem (correct me if I'm wrong).

 

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