Spikes in quantum trajectories

Antoine Tilloy (1) , Michel Bauer (2) , Denis Bernard (1)

1 LPTENS - Laboratoire de Physique Théorique de l'ENS [École Normale Supérieure]
2 IPHT - Institut de Physique Théorique - UMR CNRS 3681

A quantum system subjected to a strong continuous monitoring undergoes quantum jumps. This very well known fact hides a neglected subtlety: sharp scale-invariant fluctuations invariably decorate the jump process even in the limit where the measurement rate is very large. This article is devoted to the quantitative study of these remaining fluctuations, which we call spikes, and to a discussion of their physical status. We start by introducing a classical model where the origin of these fluctuations is more intuitive and then jump to the quantum realm where their existence is less intuitive. We compute the exact distribution of the spikes for a continuously monitored qubit. We conclude by discussing their physical and operational relevance.

Domains: Quantum Physics [quant-ph]; Mathematical Physics [math-ph]

Antoine Tilloy, Michel Bauer, Denis Bernard. Spikes in quantum trajectories. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2015, 92, pp.052111. ⟨10.1103/PhysRevA.92.052111⟩. ⟨cea-01626336⟩