Anatomy of fluorescence: quantum trajectory statistics from continuously measuring spontaneous emission

Andrew N Jordan (1) , Areeya N Chantasri (1) , Pierre Rouchon (2, 3) , Benjamin N Huard (2, 4)

1 Department of Physics and Astronomy [Rochester]
2 QUANTIC - QUANTum Information Circuits
3 CAS - Centre Automatique et Systèmes
4 LPA - Laboratoire Pierre Aigrain

We investigate the continuous quantum measurement of a superconducting qubit undergoing fluorescence. The fluorescence of the qubit is detected via a phase preserving heterodyne measurement, giving the fluorescence quadrature signals as two continuous qubit readout results. Using the stochastic path integral approach to the measurement physics, we derive most likely paths between boundary conditions on the state, and compute approximate time correlation functions between all stochastic variables via diagrammatic perturbation theory. We focus on paths that increase in energy during the continuous measurement. Our results are compared to Monte Carlo numerical simulation of the trajectories, and we find close agreement between direct simulation and theory. We generalize this analysis to arbitrary diffusive quantum systems that are continuously monitored.

Mots clés: Quantum trajectories; Quantum measurement; Spontaneous emission; Heterodyne measurement; Stochastic path integral

Domaines: Physique Quantique [quant-ph]; Automatique / Robotique

Andrew N Jordan, Areeya N Chantasri, Pierre Rouchon, Benjamin N Huard. Anatomy of fluorescence: quantum trajectory statistics from continuously measuring spontaneous emission. Quantum Studies: Mathematics and Foundations, 2016, 3, pp.237 - 263. ⟨10.1007/s40509-016-0075-9⟩. ⟨hal-01403635⟩