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Atomic Clocks

2. How to Use Atomic Oscillators to Make Clocks

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In this mini-lecture, we explore the basic ideas behind how clocks work and why we prefer atomic clocks. As we move through this mini-lecture, we consider: (i) the basic components behind a clock: a periodic event generator and a counter to determine the time; (ii) two traditional periodic-event generators: the rotation of the Earth and a pendulum clock; (iii) the picture of an atom, specifically the picture of an oscillating electron density and the quantum interpretation involving superposition, energy states, and oscillation frequency; (iv) how to use lasers and masers to generate time in an atomic clock; (v) some of the work done in Norman Ramsey’s group at Harvard in the 1960s; (vi) a comparison of pendulum clocks and atomic clocks, noting frequencies, environmental sensitivities, and reproducibility; (vii) caesium clocks in the 1960s; and (viii) a summary of why we prefer atomic clocks for precise, reliable measurements of time.


In this course, Professor David Wineland (University of Oregon) discusses atomic clocks. In the first mini-lecutre, we compare traditional and modern methods of navigation, where we see that precision in a clock’s ‘tick rate’ is essential for modern satellites and GPS. In the second mini-lecture, we discuss how a basic, mechanical clock (such as a pendulum clock) works, compare these clocks with atomic clocks, explain how to make an atomic clock with lasers/masers, and discuss why atomic clocks are so accurate and reliable. In the third mini-lecture, we introduce the concept of holding, or trapping, a single atom (or ion) and how this can be used to detect atomic transitions between the energy levels of the atom. The fourth mini-lecture discuses further effects on atomic clocks, notably gravitational-potential redshifts, and notes future uses of atomic clocks.


Professor David Wineland is the Philip H. Knight Distinguished Research Chair and Research Professor in the Department of Physics at the University of Oregon and was jointly awarded the 2012 Nobel Prize in Physics for devising methods to study the quantum mechanical behaviour of individual ions. In 1975, he joined the National Institute of Standards and Technology (NIST) in Boulder, Colorado, where he started the ion storage group and was a professor adjoint at the University of Colorado at Boulder. Professor Wineland and his group at NIST were able to place an individual electrically trapped laser-cooled ion in a superposition of two different locations. This permitted them to experimentally study fundamental physics, such as quantum mechanical behavior. This work led Professor Wineland and his group to make advances in quantum computing and atomic clocks.

Cite this Lecture

APA style

Wineland, D. (2022, January 12). Atomic Clocks - How to Use Atomic Oscillators to Make Clocks [Video]. MASSOLIT.

MLA style

Wineland, D. "Atomic Clocks – How to Use Atomic Oscillators to Make Clocks." MASSOLIT, uploaded by MASSOLIT, 13 Jan 2022,

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