The Budapest Quantum Optics Group

Ultracold atoms in optical resonators

Research objectives

  • simulation of artificial, long-range interactions
  • supersolidity
  • quantum phase transitions in non-equilibrium systems

Schematic plot of a Bose-Einstein condensate (BEC) interacting with a single mode optical cavity. The cavity mode is described by a cos(kx) function along the cavity axis while it has a Gaussian envelope in the transverse direction. The BEC wave function evolves dynamically in time due to the interaction with the radiation field. The figure illustrates self-organization. A quasi homogeneous BEC (which has a shape of an elongated ellipsoid with its semi major axis well exceeding the optical wavelength) is illuminated by a pumping laser perpendicular to the cavity axis. When the intensity of the pump laser is below a threshold value (left panel) the BEC wave function remains homogeneous and incapable of scattering a classical field into the resonator. However, above threshold intensity (right panel) the BEC self-organizes into a one-wavelength pattern that scatters photons constructively into the resonator and thus stabilizes the optical potential supporting the Bragg lattice.



Peter Domokos
(group leader)


Dávid Nagy


Gergely Szirmai


András Vukics


Gábor Kónya
(PhD student)



  • D. Nagy, G. Szirmai, and P. Domokos: Critical exponent of a quantum-noise-driven phase transition: The open-system Dicke model, Phys. Rev. A 84, 043637 (2011)
  • D. Nagy, G. Konya, G. Szirmai, and P. Domokos: Dicke-Model Phase Transition in the Quantum Motion of a Bose-Einstein Condensate in an Optical Cavity, Phys. Rev. Lett. 104, 130401 (2010)