Experimental and numerical study of the microwave field distribution in a compact magnetron-type microwave cavity

The homogeneity of the microwave magnetic field distribution inside a microwave cavity resonator is of crucial importance for the performance of high-stability vapor-cell atomic clocks, in particular when operating in the pulsed regime. Here we report on measurements and numerical simulations of the microwave field distribution inside a highly compact magnetron-type microwave cavity. A microwave field imaging technique is used to measure the microwave field distribution over the cavity volume occupied by the Rb vapor cell. Over the measured volume, we find a variation in the microwave field's z-component (relevant for the clock performance) of 20%, with good agreement between experiments and simulations. The presented results are relevant for assessing clock performance limitations arising from the cavity studied, and give design guidelines for future improved cavities of similar type.

[1]  Philipp Treutlein,et al.  Simple microwave field imaging technique using hot atomic vapor cells , 2012, 1207.4964.

[2]  H.W. Hellwig,et al.  Atomic frequency standards: A survey , 1974, Proceedings of the IEEE.

[3]  F. Levi,et al.  Metrological characterization of the pulsed Rb clock with optical detection , 2011, 1111.3450.

[4]  F. Levi,et al.  Pulsed optically pumpedRb87vapor cell frequency standard: A multilevel approach , 2009 .

[5]  F. Gruet,et al.  Pulsed optically pumped rubidium clock with high frequency-stability performance , 2012, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[6]  Philipp Treutlein,et al.  Imaging of microwave fields using ultracold atoms , 2010, 1009.4651.

[7]  Filippo Levi,et al.  Microwave cavities for vapor cell frequency standards. , 2011, The Review of scientific instruments.

[8]  Gaetano Mileti,et al.  Imaging of Relaxation Times and Microwave Field Strength in a Microfabricated Vapor Cell , 2013, 1306.1387.

[9]  James Camparo,et al.  The rubidium atomic clock and basic research , 2007 .

[10]  J. Vanier,et al.  The quantum physics of atomic frequency standards , 1989 .

[11]  J. Hyde,et al.  The loop-gap resonator: a new microwave lumped circuit ESR sample structure , 1982 .

[12]  J. Hyde,et al.  Cavities with axially uniform fields for use in electron paramagnetic resonance. II. Free space generalization , 2002 .

[13]  J. Vanier,et al.  The passive optically pumped Rb frequency standard: the laser approach , 2007, 2007 IEEE International Frequency Control Symposium Joint with the 21st European Frequency and Time Forum.

[14]  Gaetano Mileti,et al.  Pulsed optical pumping in a Rb vapor cell using a compact magnetron-type microwave cavity , 2014, 2014 European Frequency and Time Forum (EFTF).

[15]  Gaetano Mileti,et al.  Compact microwave cavity for high performance rubidium frequency standards. , 2012, The Review of scientific instruments.