We analyze low-energy photon detectors based on Josephson junctions. The initial quantum state of the Josephson junction is described as a metastable state of a phase particle in one of the local minima of a washboard potential. When the photon is absorbed, the phase particle is excited and the photon is detected if this gets into the running state. The excited particle may get into the running state either directly or indirectly (by tunneling or thermal fluctuations), depending whether the excitation energy is above or below the potential barrier, respectively. We provide a full quantum description of the process by including into the model both, the Josephson junction and the antenna. The quantum state of the system is described by the phase particle in a 3D potential landscape. In the initial state, the quantum particle may be in a metastable state in one of the local minima or the 3D potential, from where it may get excited by the photon.

Prezentarea este parte din cadrul fazei „Studiul efectelor de dimensiune finita in sisteme nanoscopice si al jonctiunilor Josephson in regim cuantic" in cadrul PN 23 21 01 01 / 2023 „Cercetari fundamentale de fizica teoretica, prin modele cuantice moderne si metode matematice avansate pentru investigarea structurii materiei si a dinamicii sistemelor condensate, nucleare si subnucleare”.