QTF Annual Discovery Prize 2019: Sergey Danilin

The QTF Annual Discovery Prize 2019 was awarded to Sergey Danilin for his work on Quantum-enhanced magnetometry by phase estimation algorithms with a single artificial atom, published in NPJ Quantum Information 4, 29 (2018).

The work is a prime example of Quantum Technology: In the words of the paper, “The idea of the experiment is to combine the extreme magnetic-field sensitivity of superconducting quantum interference devices (SQUIDs) with an enhanced performance brought about by exploiting quantum coherence.” The work first starts by showing how in standard classical measurements the obtained variable is shot-noise limited, whereas the fundamental limit is given by quantum mechanics. Then it goes on showing how utilizing a quantum two-level system in a transmon qubit can improve the accuracy of magnetometry if measured with certain types of quantum metrological algorithms. Two distinct algorithms are considered and explained in detail in this work. These algorithms are then demonstrated experimentally, and their scaling vs. the total sensing time goes as expected. Due to the non-ideal quality of the employed transmon qubit, the flux measurement sensitivity is not yet better than in other types of realizations, but the potential of the quantum metrology has been beautifully demonstrated. As discussed in the conclusions of the work, this has the potential of improving the characteristics of magnetometry over other approaches, based on SQUIDs, atomic magnetometers, and NV centers in diamond.