Homodyne monitoring of post-selected decay
| Autor: | Tan, D., Foroozani, N., Naghiloo, M., Kiilerich, A. H., Mølmer, K., Murch, K. W. |
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| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | Phys. Rev. A 96, 022104 (2017) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevA.96.022104 |
| Popis: | We use homodyne detection to monitor the radiative decay of a superconducting qubit. According to the classical theory of conditional probabilities, the excited state population differs from an exponential decay law if it is conditioned upon a later projective qubit measurement. Quantum trajectory theory accounts for the expectation values of general observables, and we use experimental data to show how a homodyne detection signal is conditioned upon both the initial state and the finally projected state of a decaying qubit. We observe, in particular, how anomalous weak values occur in continuous weak measurement for certain pre- and post-selected states. Subject to homodyne detection, the density matrix evolves in a stochastic manner, but it is restricted to a specific surface in the Bloch sphere. We show that a similar restriction applies to the information associated with the post-selection, and thus bounds the predictions of the theory. Comment: 11 pages, 8 figures |
| Databáze: | arXiv |
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