New quantum detector measures the tiniest energies in superconducting circuits

Measuring the energy of quantum states requires detecting energy changes so exceptionally small they are hard to pick out from background fluctuations, like using only a thermometer to try and work out if someone has blown out a candle in the room you’re in.

Researchers at at Aalto University and Lund University presents sensitive quantum thermometry hitting the bounds that nature allows. The paper is published in Nature Communications.

The team had to make a thermometer able to measure very small changes without interfering with any of the quantum states they plan to measure. The device is a calorimeter, which measures the heat in a system. It uses a strip of copper about one thousand times thinner than a human hair. (Aalto University)

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