The development of highly sensitive methods for the detection of minute fields lies at the heart of quantum metrology and has, over the history of science, led to many discoveries. This motivates the continuous drive towards the development of ever more sensitive metrology methods. Of particular interest in this context are atoms and ions that are trapped in ultra-high vacuum as they can be isolated to a remarkable degree from environmental influences. Still noise will impose limitations and needs to be addressed.
We demonstrate a novel method for sensing magnetic fields and demonstrate that it can achieve the best sensitivity ever realized for a single trapped atomic particle and it can do so over a broad range of frequencies. State-of-the-art magnetometers reach their best sensitivity in a limited frequency-band or do not work at all (for all practical purposes) outside a certain frequency range. The type of magnetometer introduced here could be used to detect fields from direct-current to the gigahertz regime – an unprecedented range of frequencies – using an atom confined to a nanometer-sized region in space. Moreover, the magnetometer is essentially immune against magnetic disturbances and reaches a sensitivity close to the standard quantum limit.
Updated: June 2016