50 research outputs found
Subthreshold phonon generation in an optomechanical system with an exceptional point
A phonon laser based on an optomechanical system consisting of two optical
modes interacting with each other via a phononic mode is considered. An
external wave exciting one of the optical modes plays a role of the pumping. It
is shown that at some amplitude of the external wave an exceptional point
exists. When the external wave amplitude is less than one corresponding to the
exceptional point, the splitting of the eigenfrequencies takes place. It is
demonstrated that in this case, the periodic modulation of the external wave
amplitude can result in simultaneous generation of photons and phonons even
below the threshold of optomechanical instability
Spontaneous symmetry emergence as a source of new class of phase transitions
Spontaneous symmetry breaking in systems with symmetry is core-stone
phenomenon accompanying second-order phase transitions. Here, we predict an
opposite phenomenon, namely, spontaneous symmetry emergence in a system without
symmetry. On the example of two coupled oscillators interacting
non-symmetrically with a set of oscillators whose frequencies uniformly fill a
finite frequency range, we demonstrate that the system state can acquire
symmetry, which is not inherent to the system Hamiltonian. The symmetry
emergence manifests in the change of the system dynamics, which can be
interpreted as a new class of phase transitions