Comparison of Gravitational and Light Frequency Shifts in Rubidium Atomic Clock

• Published in: Universe
• Main Authors: Alexey Baranov, Sergey Ermak, Roman Lozov, Vladimir Semenov
• Format: Article
• Language: English
• Published: MDPI AG 2020-12-01
• Subjects: rubidium atomic clocks; light shift; navigation satellites
• Online Access: https://www.mdpi.com/2218-1997/7/1/3
• ISSN: 2218-1997

The article presents the results of an experimental study of the external magnetic field orientation and magnitude influence on the rubidium atomic clock, simulating the influence of the geomagnetic field on the onboard rubidium atomic clock of navigation satellites. The tensor component value of the atomic clock frequency light shift on the rubidium cell was obtained, and this value was <inline-formula><math display="inline"><semantics><mo>~</mo></semantics></math></inline-formula>2 Hz. The comparability of the relative light shift <inline-formula><math display="inline"><semantics><mrow><mrow><mo>(</mo><mrow><mo>~</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>9</mn></mrow></msup></mrow><mo>)</mo></mrow></mrow></semantics></math></inline-formula> and the regular gravitational correction <inline-formula><math display="inline"><semantics><mrow><mrow><mo>(</mo><mrow><mn>4</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>10</mn></mrow></msup></mrow><mo>)</mo></mrow></mrow></semantics></math></inline-formula> to the frequency of the rubidium atomic clock was shown. The experimental results to determine the orientational shift influence on the rubidium atomic clock frequency were presented. A significant effect on the relative frequency instability of a rubidium atomic clock at a level of <inline-formula><math display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>12</mn></mrow></msup></mrow></semantics></math></inline-formula><inline-formula><math display="inline"><semantics><mrow><mrow><mo>(</mo><mrow><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>13</mn></mrow></msup></mrow><mo>)</mo></mrow></mrow></semantics></math></inline-formula> for rotating external magnetic field amplitudes of 1.5 A/m and 3 A/m was demonstrated. This magnitude corresponds to the geomagnetic field in the orbit of navigation satellites. The necessity of taking into account various factors (satellite orbit parameters and atomic clock characteristics) is substantiated for correct comparison of corrections to the rubidium onboard atomic clock frequency associated with the Earth’s gravitational field action and the satellite orientation in the geomagnetic field.