8/13/2023 0 Comments Atomic clocks with accuracy![]() In the clocks I make, the principle is the same. The traditional way is to shine microwaves onto atoms, such as caesium or rubidium, to make their electrons flip from one quantum state – known as spin – to another at regular intervals. Jun Ye: People have made atomic clocks for many decades. Joshua Howgego: How do you make an atomic clock? He says versions like his could help us snare more gravitational waves, check the fundamental constants of nature and perhaps push general relativity past breaking point. Based at the JILA research institute in Boulder, Colorado, Ye has been working for 20 years on honing the design of that paragon of timepieces, the atomic clock. IF YOU EVER find yourself needing to check the time, you could do a lot worse than ask Jun Ye. Notably, most radio clocks – often falsely advertised and referred to as “atomic clocks” – receive radio time signals that do originate from atomic clocks but that doesn’t make said clocks or watches atomic timekeepers.Jun Ye’s strontium atomic clock is the most precise in the world This is why your phone and car syncs accurate time with GPS transmitters – and why GPS watches can be so incredibly accurate. The relative times are mathematically transformed into three absolute spatial coordinates and one absolute time coordinate. A GPS receiver works by measuring the relative time delay of signals from a minimum of four, but usually more GPS satellites, each of which has at least two on-board caesium and as many as two rubidium atomic clocks. However, without knowing the very exact time at any given moment, our cars and phones could never show us the way. ![]() Like so many other technological advancements, most of us take this for granted – I sure do, just occasionally taking a moment to think about how thoroughly amazing this technology is. Probably the most important application is that in Global Navigation Satellite Systems (or GPS, as it is commonly called). Today, about 400 atomic clocks around the world, interlinked via satellite, help keep global time accurate. How The Atomic Clock Helps Improve Our Daily Lives If you really want to nerd out over this, I suggest reading up on optical and quantum clocks, and especially rare-earth element ytterbium ion-clocks – just so much fascinating stuff, but we really are getting into extremely nerdy and scientific topics here that are better discovered to the depths you feel comfortable with on your own. Scott Diddams, head of a team of scientists at NIST said: “That means, if you started this clock at the beginning of the universe with the Big Bang, it would likely not have gained or lost a second for the entire age of the universe.” While optical clocks are not quite as reliable as they need to be, NIST scientists say that using a redundant system that can continue to run even if one of the dozens of lasers inside the machine break down allowed one of these clocks to remain accurate to about. This, just like a frequency bump in a mechanical watch from 4Hz to 5Hz, means greater stability and better performance over time. These use atoms or ions that oscillate about 100,000 times higher than the microwave frequencies of atomic clocks. The solution comes in the form of so-called optical clocks. You see, most atomic clocks are still not that precise, as they can accumulate an error of about one nanosecond over a month – for all sorts of scientific use scenarios, that is just not good enough. Image Source: JILA & NIST Labs at the University of Colorado …Now Accurate To +/-1 Second Per Billion YearsĪdvancements in technology cannot be stopped, though, so don’t for a second (pun intended) think that scientists and engineers stopped pushing the boundaries of chronometric performance. The JILA Strontium optical clock is world’s most precise and stable, not losing one second over the course of 5 billion years. After exactly 9,192,631,770 oscillations, a second has passed. ![]() The goal is to perfectly fine-tune the microwave frequency to the oscillation of the atoms, and then measure it. The percentage of atoms that change their state while passing through the resonator depends on the frequency of the microwave radiation, so the atomic clock’s job is to sync that frequency with the inherent oscillation frequency of the atoms. At the end, a detector counts all atoms that have changed to state B. Behind the resonator, atoms that are still in state A are removed by a second magnetic field. The state-A atoms pass through a resonator where microwave radiation triggers some of the atoms to change to state B. A magnetic field removes all atoms in state B from the beam, so only atoms in state A remain. Each atom has one of two possible energy states, referred to as hyper-fine levels – for clarity, let’s call them state A and state B. Source: įirst, the atoms are heated in an oven and bundled into a tube.
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