npj Quantum Information, Published online: 11 November 2024; doi:10.1038/s41534-024-00913-x
The Kirkwood-Dirac quasiprobability distribution, intimately connected with the quantum correlation function of two observables measured at distinct times, is becoming increasingly relevant for fundamental physics and quantum technologies.
This quasiprobability distribution can take non-positive values, and its experimental reconstruction becomes challenging when expectation values of incompatible observables are involved.
In this paper, researchers have used an interferometric scheme aided by an auxiliary system to reconstruct the Kirkwood-Dirac quasiprobability distribution. They experimentally demonstrated this scheme in an electron-nuclear spin system associated with a nitrogen-vacancy center in diamond.
By measuring the characteristic function, they have reconstructed the quasiprobability distribution of work and analyze the behavior of its first and second moments.
These results clarify the physical meaning of the work quasiprobability distribution in the context of quantum thermodynamics.
Finally, they have studied the uncertainty of measuring the Hamiltonian of the system at two times, via the Robertson-Schrödinger uncertainty relation, for different initial states.
