Three-Dimensional Superconducting Resonators at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>T</mml:mi><mml:mo>&lt;</mml:mo><mml:mn>20</mml:mn></mml:math> mK with Photon Lifetimes up to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>τ</mml:mi><mml:mo>=</mml:mo><mml:mn>2</mml:mn></mml:math> s
Physical review applied