title: Parametric Symmetry Breaking in a Nonlinear Resonator.
abstract: Much of the physical world around us can be described in terms of harmonic oscillators in thermodynamic equilibrium. At the same time, the far-from-equilibrium behavior of oscillators is important in many aspects of modern physics. Here, we investigate a resonating system subject to a fundamental interplay between intrinsic nonlinearities and a combination of several driving forces. We have constructed a controllable and robust realization of such a system using a macroscopic doubly clamped string. We experimentally observe a hitherto unseen double hysteresis in both the amplitude and the phase of the resonator's response function and present a theoretical model that is in excellent agreement with the experiment. Our work unveils that the double hysteresis is a manifestation of an out-of-equilibrium symmetry breaking between parametric phase states. Such a fundamental phenomenon, in the most ubiquitous building block of nature, paves the way for the investigation of new dynamical phases of matter in parametrically driven many-body systems and motivates applications ranging from ultrasensitive force detection to low-energy computing memory units.
authors.affiliation: Institute for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Anina
authors.initials: A
authors.lastname: Leuch
authors.affiliation: Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Luca
authors.initials: L
authors.lastname: Papariello
authors.affiliation: Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Oded
authors.initials: O
authors.lastname: Zilberberg
authors.affiliation: Institute for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Christian L
authors.initials: CL
authors.lastname: Degen
authors.affiliation: Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Chitra
authors.affiliation: Institute for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Alexander
authors.initials: A
authors.lastname: Eichler