Circularly polarized fields

Generation of circularly polarized fields

How can we create circularly polarized fields?

Using two orthogonal coils to which we apply two radiofrequency (RF) signals phase shifted by 90°.

To this purpose, quadrature coils are used.

Reference: Mariusz Mrózek, et al. “Circularly Polarized Microwaves for Magnetic Resonance Study in the GHz Range: Application to Nitrogen-Vacancy in Diamonds.” Applied Physics Letters, vol. 107, no. 1, 6 July 2015, https://doi.org/10.1063/1.4923252. (PDF)

Advantages of circular over linear polarization

Advantages of circular over linear polarization include the following:

1) elimination of the Bloch-Siegert shift, 

2) increase of effective strength, 

3) improvement of homogeneity,

4) possibility of addressing a specific spin state e.g. in the field of quantum information.

Reference: Mariusz Mrózek, et al. “Circularly Polarized Microwaves for Magnetic Resonance Study in the GHz Range: Application to Nitrogen-Vacancy in Diamonds.” Applied Physics Letters, vol. 107, no. 1, 6 July 2015, https://doi.org/10.1063/1.4923252. (PDF)