Atomic clocks are among the inventions that have greatly impacted society and other technologies. This paper discusses the atomic clock by focusing on the underlying physics of how this class of clock operates, the historical context of how the clock was discovered, and the social and cultural impact of this novel technology.
Underlying Physics of How Atomic Clocks Work 2
Atomic clocks employ atoms as their pendulum. These atoms are precisely the electronic shift from a given state to another. These clocks are founded on the principle that all atoms associated with a given element such as Rubidium and Caesium possess the same configuration of electrons (Quantum Flagship, n.d.). Therefore, the same pendulum is used by different atomic clocks employing the same element, unlike different mechanical clocks that individually employ a slightly dissimilar pendulum owing to inaccuracies in the process of manufacturing (Quantum Flagship, n.d; Vanier & Tomescu, 2015). Most atomic clocks are founded on alkali atom which possesses a solitary valence electron (Shah & Kitchin, 2010). The spectrum of energy in these atoms is relatively simple. As a result, a long-lived ground state causes slow relaxation, thin transition line widths, as well as correspondingly high precision (Shah & Kitchin, 2010; Vanier & Tomescu, 2015). Apart from having charge, the valence electron and atomic nucleus of all alkali atoms possess spin angular momentum, therefore creating a magnetic moment (Shah & Kitchin, 2010).
When it comes to the underlying physics for the operation of atomic clocks, it is vital to note that electrons moving about an atomic nucleus are confined to the occupation of a limited amount of well-defined states that possess well-defined energies. It is significant to note that this discovery is among the inventions that resulted in the establishment of quantum mechanics (Quantum Flagship, n.d.). When it comes to the simple Bohr model, it can be imaged that the movement of electrons is limited to a small amount of trajectories about the nucleus, which is contrary to the planets within the solar system that, in principle, can accomplish their rotation around the core star at any space or distance (Quantum Flagship, n.d.). In relation to the atomic clock, it can be noted that electromagnetic radiation or light of a given frequency is illuminated on an atom or a cooling cluster of atoms. In a situation where the light frequency is appropriate or energy associated with its photons is equal to the difference of energy between two states, a photon is absorbed by the atom, thereby changing into an excited state (Quantum Flagship, n.d; Vanier & Tomescu, 2015). This process often occurs repeatedly in atomic clocks. The efficiency associated with exciting the atom is continuously monitored and the light frequency is constantly rectified to generate the highest efficiency (Quantum Flagship, n.d.). As such, the atoms continuously watch over the light source frequency, which in turn can be enumerated or counted and employed in measuring the duration associated with an event (Quantum Flagship, n.d.).
According to Quantum Flagship (n.d.), the difference of energy between the excited state and the ground state is only constantly individual atoms that are completely isolated. Nonetheless, external factors or influences like electromagnetic fields can affect the levels of energy associated with the states, thereby influencing the transition frequency (Quantum Flagship, n.d.; Vanier & Tomescu, 2015). Therefore, it can be noted that atomic clocks are shielded at great cost, and special electrical configurations’ pairs are chosen that are largely insensitive to external influence or interferences. In general, the principle underlying the operation of atomic clocks is that all atoms belonging to a given element are identical and when such atoms release or absorb energy, they generate radiation of precisely the same or equal frequency, which in turn makes the atoms ideal timepieces.
Historical Context of the Discovery of Atomic Clocks
Predecessors of the atomic clock were the pendulum and quartz clock. Even though the pendulum clock existed, its significant limitation was lower timing resolution (Physics World, 2018). Therefore, as technology progressed, there was a need for timing of higher-resolution (Physics World, 2018). As a result, the pendulum clock was gradually replaced by quartz clocks. According to Physics World (2018), Joseph Horton and Warren Marrison built the first quartz in 1927 at the then Bell Telephone Laboratories within the US. The frequency of quartz clocks was established to be less sensitive or responsive to environmental interferences relative to the older devices for timekeeping such as the pendulum clock, which in turn make them more precise (Physics World, 2018).
In quartz clocks, an electric current triggers the resonation of a quartz crystal at a given frequency that is many times higher than the oscillations of a pendulum. Nonetheless, the quartz clock had a limitation of relying on a mechanical pulsation whose frequency relied on the crystal’s temperature, shape, and size (Physics World, 2018). Since two crystals cannot be exactly the same, their calibration has to be done against a different reference, which was taken as the Earth’s rotation period with the definition of a second being a 1/86,400th associated with the mean solar day (Physics World, 2018). Nevertheless, this definition was established to have problems considering that the advancement in time unit measurement led to the establishment that the Earth’s rotation period is not constant. This period varies with tidal friction and season and fluctuates in irregular ways (Physics World, 2018).
In 1949, the National Institute of Standards and Technology (NIST) established the first atomic beam watch, which was founded on an ammonia-regulated quartz crystal oscillator (Ost, 2014). This watch was associated with a precision of approximately one part within 20 million (Ost, 2104). In 1955, the first sensible caesium atomic frequency standard was produced by Jack Parry and Louis Essen (Physics World, 2018). This gadget was not essential clock considering that it did not run constantly, and was merely employed in calibrating an external quartz clock’s frequency at a few days’ interval. In 1967, the second was redefined by the General Conference on Weights and Measures as “the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom” (Physics World, 2018, par. 17).
Social or Cultural Impacts of Atomic clocks
Atomic clocks are associated with two physical values including stability and accuracy over a given period. These features have resulted in many applications of these clocks that have greatly impacted society. Atomic clocks have greatly improved timekeeping by enhancing the reliability and stability of timing events. Besides, these clocks have significantly improved communication and electricity distribution. According to Thales Group (2014), telecommunication is an everyday activity that depends on atomic clocks. Information sent by individuals across networks often travels through various operators, without the senders knowing the identity and number of operators handling their information (Thales Group, 2014). The sending of this information occurs in a packet after which it is packaged together once it reaches its ultimate destination. In situations where networks are not operating at equal speed, issues such as congestion of data highways and loss of information can occur (Thales Group, 2014). To prevent this, the International Telecommunication Union (ITU) outlines a standard for operators that restrict the speed difference between two networks (Thales Group, 2014). Atomic clocks are effective in meeting these accuracy standards. The requirement of network synchronization does not only apply to 4G networks or high-speed mobile networks, but also to networks of electricity distribution, which must connect sources of energy with synchronized phases and identical frequencies (Thales Group, 2014). With the presence of atomic clocks, the establishment of smart grid has been accomplished with ease as they rely on extremely accurate clocks for their operations.
Atomic clocks have also enhanced the operations of financial institutions by ensuring the quick processing of high-frequency transactions. According to Thales Group (2014), banks require extremely precise clocks to guarantee the date and time stamps of high-frequency operations with microsecond accuracy. These systems generally employ clocks relying on special Global Positioning Systems (GPS) receivers developed to determine the date and time of transactions and the arrangement in which such transactions can be executed (Thales Group, 2014). With the presence of atomic clocks, these operations can be executed efficiently and effectively.
In conclusion, this paper has effectively discussed atomic clocks by focusing on the historical context that led to their discovery, their impact on the society, and the underlying physics associated with their operations. Indeed, atomic clocks are among the significant inventions in the modern society.
Ost, L. (2018). A New Era for Atomic Clocks. Retrieved March 19, 2022, from: https://phys.org/news/2014-02-era-atomic-clocks.html
Physics World. (2018). A Brief History of Timekeeping. Retrieved March 19, 2022, from: https://physicsworld.com/a/a-brief-history-of-timekeeping/
Shah, V., & Kitching, J. (2010). Advances in coherent population trapping for atomic clocks. In Advances in atomic, molecular, and optical physics (Vol. 59, pp. 21-74). Academic Press.
Thames Group. (2014). Atomic Clocks and The Importance of Being on Time. Retrieved March 20, 2022, from: https://www.thalesgroup.com/en/worldwide/news/atomic-clocks-and-importance-being-time
Quantum Flagship (n.d.). Atomic Clocks. Retrieved March 19, 2022, from: https://qt.eu/discover-quantum/underlying-principles/atomic-clocks/
Vanier, J., & Tomescu, C. (2015). The quantum physics of atomic frequency standards: recent developments.