Observation of the photon blockade breakdown phase transition Journal Article

Author(s): Fink, Johannes; Dombi, András; Vukics, András; Wallraff, Andreas; Domokos, Peter
Article Title: Observation of the photon blockade breakdown phase transition
Affiliation IST Austria
Abstract: Nonequilibrium phase transitions exist in damped-driven open quantum systems when the continuous tuning of an external parameter leads to a transition between two robust steady states. In second-order transitions this change is abrupt at a critical point, whereas in first-order transitions the two phases can coexist in a critical hysteresis domain. Here, we report the observation of a first-order dissipative quantum phase transition in a driven circuit quantum electrodynamics system. It takes place when the photon blockade of the driven cavity-atom system is broken by increasing the drive power. The observed experimental signature is a bimodal phase space distribution with varying weights controlled by the drive strength. Our measurements show an improved stabilization of the classical attractors up to the millisecond range when the size of the quantum system is increased from one to three artificial atoms. The formation of such robust pointer states could be used for new quantum measurement schemes or to investigate multiphoton phases of finite-size, nonlinear, open quantum systems.
Keywords: Condensed matter physics, quantum physics, superconductivity
Journal Title: Physical Review X
Volume: 7
Issue 1
ISSN: 2160-3308
Publisher: American Physical Society  
Date Published: 2017-01-31
Start Page: Article number: 011012
Copyright Statement: CC BY 4.0
DOI: 10.1103/PhysRevX.7.011012
Notes: We thank A. Blais for comments on the manuscript. This work was supported by ETH Zurich, IST Austria, the Hungarian Academy of Sciences (Lendület Program, LP2011-016), and the National Research, Development and Innovation Office (K115624). A. V. acknowledges support from the János Bolyai Research Scholarship of the Hungarian Academy of Sciences. We acknowledge NIIF for awarding us access to the computational resource based in Hungary at Debrecen.
Open access: yes (OA journal)