[seminar] @IoP: András Vukics - Friday 7th June 2023 at 13:00, 1st wing lecture hall

[Neven Šantić]

Seminar @Institute of Physics, Friday 7th June 2023 at 13:00, 1st wing lecture hall 


Photon-blockade breakdown as a first-order dissipative phase transition in zero dimension 



Dr. András Vukics 


Wigner Research Centre for Physics, Budapest, Hungary 



I present the relatively recent concept of first-order dissipative phase transitions that can occur in meso- and even microscopic quantum systems. One of the first examples of this phenomenology was the photon-blockade breakdown (PBB) effect, that occurs most simply in a coupled system of a bosonic mode and a qubit. For PBB, an abstract thermodynamic limit has been identified [1], where the coupling between the subsystems goes to infinity without affecting the system size, and this limit was studied in a finite-size scaling approach [2], with scaling exponents determined numerically. Upon discussing the microscopic mechanism and the fully quantum solution, I will assess the neo- and semiclassical models, and the connection with optical bistability. 




I describe the experimental studies: PBB was first observed in a circuit QED system [3], and the thermodynamic limit could also be modeled on this platform with a bespoke device [4]. The numerical modelling [5] of this latter set of experiments highlighted the role of the higher lying transmon levels and the phase noise. 




As an outlook, I describe a related phenomenology dubbed transmission-blockade breakdown, that was observed in the rubidium cold-atom – cavity QED lab of the Wigner Research Centre for Physics [6]. 




[1] H. J. Carmichael, Phys. Rev. X 5, 031028 (2015). 

[2] A. Vukics, A. Dombi, J. M. Fink, P. Domokos, Quantum 3, 150 (2019). 

[3] J. M. Fink, A. Dombi, A. Vukics, A. Wallraff, and P. Domokos, Phys. Rev. X 7, 011012 (2017). 

[4] R. Sett, F. Hassani, D. Phan, Sh. Barzanjeh, A. Vukics, and J. M. Fink, arXiv:2210.14182 (2022). 

[5] https://github.com/vukics/cppqed 

[6] B. Gábor, D. Nagy, A. Dombi, T. W. Clark, F. I. B. Williams, K. V. Adwaith, A. Vukics, P. Domokos, Phys. Rev. A 107, 023713 (2023) 






Seminar hosts : [ mailto:nsantic at ifs.hr | Neven Šantić ] i [ mailto:ddominko at ifs.hr | Damir Dominko ] 

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