ATOMIC CLOCK ONLINE SERIES

The excitation is detected by continuous monitoring of the hyperfine splitting of an atomic shell transition (laser 2). Nuclear clock schematic A cavity-stabilised frequency comb (generated by laser 1) is adjusted to the nuclear excitation of 229Th. After a certain number of oscillations, given by the frequency of the nuclear transition, one second has elapsed.

ATOMIC CLOCK ONLINE SERIES

This device (the invention of which was recognised by the 2005 Nobel Prize in Physics) is a laser source whose spectrum consists of a series of discrete, equally spaced frequency lines. For the frequency-counting device, a narrow-band laser resonantly excites the nuclear-clock transition, while the corresponding oscillations of the laser light are counted using a frequency comb. In a nuclear clock (see “Nuclear clock schematic” figure), the oscillator is provided by the frequency of a transition between two nuclear states (in contrast to a transition between two states in the electronic shell in the case of an atomic clock). ClockworkĪ clock typically consists of an oscillator and a frequency-counting device. In addition to enabling a more accurate timepiece, this offers the potential for nuclear clocks to be used as quantum sensors to test fundamental physics. Due to the small nuclear moments (corresponding to the vastly different dimensions of atoms and nuclei), and thus the very weak coupling to perturbing electromagnetic fields, a “nuclear clock” is less vulnerable to external perturbations.

To further reduce these uncertainties, in 2003 Ekkehard Peik and Christian Tamm of Physikalisch-Technische Bundesanstalt in Germany proposed the use of a nuclear instead of atomic transition for time measurements. While still under development, optical clocks based on aluminium ions are already reaching accuracies of about one second in 33 billion years, corresponding to a relative systematic frequency uncertainty below 1 × 10 –18. A newer breed of optical clocks developed since the 2000s exploit frequencies that are about 10 5 times higher. Such transitions, which correspond to radiation in the microwave regime, enable state-of-the art atomic clocks to keep time at the level of one second in more than 300 million years.

531 1800381įor the past 60 years, the second has been defined in terms of atomic transitions between two hyperfine states of caesium-133. On time An artist’s rendition of a nuclear optical clock, which promises a relative accuracy of about 1 × 10 –19. Peter Thirolf, Benedict Seiferle and Lars von der Wense describe how recent progress in understanding thorium’s nuclear structure, and new upcoming results, could enable an ultra-accurate nuclear clock with applications in fundamental physics.

Atomic clock online