Interacton-driven phenomena and Wigner transition in two-dimensional systems

Konrad Singer, William Richard Smith

Pavel E. Dolgirev, Ilya Esterlis, Alexander Zibrov +3 more

We propose local electromagnetic noise spectroscopy as a versatile and noninvasive tool to study Wigner crystal phases of strongly interacting two-dimensional electronic systems. In-plane imaging of the local noise is predicted to enable single-site resolution of the electron crystal when the sample-probe distance is less than the interelectron separation. At larger sample-probe distances, noise spectroscopy encodes information about the low-energy Wigner crystal phonons, including the dispersion of the transverse shear mode, the pinning resonance due to disorder, and optical modes emerging, for instance, in bilayer crystals. We discuss the potential utility of local noise probes in analyzing the rich set of phenomena expected to occur in the vicinity of the melting transition.

W. P. Schleich, Joachim Dahl, Sándor Varró

Xingyu Zhao, Qian Bin, Waner Hou +5 more

Symmetry is crucial for gaining insights into the fundamental properties of physical systems, bringing possibilities in studying exotic phenomena such as quantum phase transitions and ground-state entanglement. Here, we experimentally simulate a highly controllable extended quantum Rabi model, capable of tuning into the ultrastrong or deep coupling regime, in a spin-motion-coupled trapped ion. We observe that the phonon driven by such a model with Z_{2} symmetry preserved (broken) would experience double (single) excitation in the ultrastrong coupling regime. Quantum phenomena such as strong ground-state entanglement and quantum superposition in systems occur with parity symmetry, and these phenomena disappear following the symmetry breaking. We also find sensitive responses for the two-level system entropy and phonon Wigner function in the deep coupling regime, depending on the parameter across the symmetry transition point. This Letter offers the prospect of exploring symmetry-controlled quantum phenomena and their applications in high-precision quantum technologies.

Pei‐Rong Han, Tian-Le Yang, Wen Ning +4 more

Abstract Exceptional points in non-Hermitian quantum systems give rise to genuine quantum phenomena. Recent explorations of exceptional-point-induced phase transitions have extended from discrete-variable to continuous-variable-encoded quantum systems. However, phase transitions driven by Liouvillian exceptional points (LEPs) in continuous-variable platforms remain largely unexplored. Here, we construct and investigate a Liouvillian exceptional structure based on a driven-dissipative Kerr-cat qubit. Through numerical simulations, we numerically reveal a non-Hermitian phase transition occurring at the LEP characterized by a sudden change in dynamical behavior from underdamped oscillations to overdamped relaxations as visualized via Wigner functions and Bloch sphere trajectories. The dynamical pattern of Wigner interference fringes provides a phase-space signature of the LEP-induced phase transition, while Wigner negativity certifies the genuine quantum nonclassicality of the system. Our results establish the Kerr-cat qubit as a continuous-variable setting for exploring dissipative quantum criticality and intrinsic non-Hermitian physics.

Senz, Volkmar