Abstract
We show that a hybrid atom-optomechanical quantum many-body system with two internal atom states undergoes both first- and second-order nonequilibrium quantum phase transitions (NQPTs). A nanomembrane is placed in a pumped optical cavity, whose outcoupled light forms a lattice for an ultracold Bose gas. By changing the pump strength, the effective membrane-atom coupling can be tuned. Above a critical intensity, a symmetry-broken phase emerges which is characterized by a sizeable occupation of the high-energy internal states and a displaced membrane. The order of this NQPT can be changed by tuning the transition frequency. For a symmetric coupling, the transition is continuous below a certain transition frequency and discontinuous above. For an asymmetric coupling, a first-order phase transition occurs.
Highlights
Using the concept of phase transitions, a great variety of different physical systems can be classified in terms of their emergent collective behaviour [1,2,3]
We show that a hybrid atom-optomechanical quantum many-body system with two internal atom states undergoes both first- and second-order nonequilibrium quantum phase transitions
The order of this nonequilibrium quantum phase transition can be changed by tuning the transition frequency
Summary
Using the concept of phase transitions, a great variety of different physical systems can be classified in terms of their emergent collective behaviour [1,2,3]. We show that the internal state coupling scheme allows for a NQPT, whose order can be readily tuned by changing the atomic transition frequency. Both a first- and a second-order NQPT can be realized in the same physical set-up by only changing a directly accessible control parameter. We show this for the membrane-in-the-middle-setup [23], where the adiabatic elimination of the light field yields an effective coupling between the membrane and the transition between two states in the atom gas, see Fig. 1.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
