Freiburg 2019 – scientific programme
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FM: Fall Meeting
FM 13: Open and Complex Quantum Systems I
FM 13.6: Talk
Monday, September 23, 2019, 15:30–15:45, 3042
Revealing hidden information by counting — •Björn Kubala1, Andrew D. Armour2, and Joachim Ankerhold1 — 1Institute for Complex Quantum Systems and IQST, Ulm University, Albert Einstein-Allee 11, 89069 Ulm, Germany — 2School of Physics and Astronomy and Centre for the Mathematics and Theoretical Physics of Quantum Non-Equilibrium Systems, University of Nottingham, Nottingham NG7 2RD, UK
The full counting statistic of emitted photons and the investigation of large deviations of the emission power are known to provide useful insights into the dynamics of driven, dissipative quantum-optical systems. In particular, the `rare' dynamics can reveal information about the system's behavior for a wide region of the parameter space; beyond the actual physically-realized driving and damping parameters.
Here, we employ these tools for a theoretical exploration of a Josephson-photonics device, where Cooper pairs tunneling across a voltage biased Josephson junction create photonic excitations in a microwave resonator, which is connected in series to the junction. By biasing at the corresponding excitation energy, such devices can realize a nonlinearly driven oscillator or (a nonlinear versions of) a parametric oscillator and have been shown to exhibit interesting dynamical critical points. When the state of the cavity is conditioned on measurements of the number of photons emitted one can reveal fragile features, such as cat states, which are lost within the usual unconditioned dynamics.