Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userStable States with Non-Zero Entropy under Broken $mathcal{PT}$-Symmetry
120
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The $mathcal{PT}$-symmetric non-Hermitian systems have been widely studied and explored both in theory and in experiment these years due to various interesting features. In this work, we focus on the dynamical features of a triple-qubit system, one of which evolves under local $mathcal{PT}$-symmetric Hamiltonian. A new kind of abnormal dynamic pattern in the entropy evolution process is identified, which presents a parameter-dependent stable state, determined by the non-Hermiticity of Hamiltonian in the broken phase of $mathcal{PT}$-symmetry. The entanglement and mutual information of a two-body subsystem can increase beyond the initial values, which do not exist in the Hermitian and two-qubit $mathcal{PT}$-symmetric systems. Moreover, an experimental demonstration of the stable states in non-Hermitian system with non-zero entropy and entanglement is realized on a four-qubit quantum simulator with nuclear spins. Our work reveals the distinctive dynamic features in the triple-qubit $mathcal{PT}$-symmetric system and paves the way for practical quantum simulation of multi-party non-Hermitian system on quantum computers.
rate research
Read More
We theoretically study the dynamics of typical optomechanical systems, consisting of a passive optical mode and an active mechanical mode, in the $mathcal{PT}$- and broken-$mathcal{PT}$-symmetric regimes. By fully analytical treatments for the dynamics of the average displacement and particle numbers, we reveal the phase diagram under different conditions and the various regimes of both $mathcal{PT}$-symmetry and stability of the system. We find that by appropriately tuning either mechanical gain or optomechanical coupling, both phase transitions of the $mathcal{PT}$-symmetry and stability of the system can be flexibly controlled. As a result, the dynamical behaviors of the average displacement, photons, and phonons are radically changed in different regimes. Our study shows that $mathcal{PT}$-symmetric optomechanical devices can serve as a powerful tool for the manipulation of mechanical motion, photons, and phonons.
Due to the boundary coupling in a finite system, the zero modes of a standard Su-Schrieffer-Heeger (SSH) model may deviate from exact-zero energy. A recent experiment has shown that by increasing the system size or altering gain or loss strength of the SSH model with parity-time ($mathcal{PT}$) symmetry, the real parts of the energies of the edge modes can be recovered to exact-zero value [Song emph{et al.} Phys. Rev. Lett. textbf{123}, 165701 (2019)]. To clarify the effects of $mathcal{PT}$-symmetric potentials on the recovery of the nontrivial zero modes, we study the SSH model with $mathcal{PT}$-symmetric potentials of different forms in both infinite and finite systems. Our results indicate that the energies of the edge modes in the infinite size case decide whether or not the success of the recovery of the zero modes by tuning the strength of $mathcal{PT}$-symmetric potential in a finite system. If the energies of the edge modes amount to zero in the thermodynamic limit under an open boundary condition (OBC), the recovery of the zero modes will break down by increasing the gain or loss strength for a finite system. Our results can be easily examined in different experimental platforms and inspire more insightful understanding on nontrivial edge modes in topologically non-Hermitian systems.
We generalize the recently proposed $mathcal{PT}$-symmetric axion haloscope to a larger array with more $mathcal{PT}$-symmetric structures. The optimized signal-to-noise ratio (SNR) has a greater enhancement, as well as the signal power. Furthermore, we show that the robustness of the detector towards the variations of the array coupling is the strongest when a binary tree structure is introduced which contains a largely enhanced $mathcal{PT}$ symmetry. The multiple allowed probing sensors can further increase the SNR by a factor of sensors number due to the correlation of the signals. This type of array can strongly boost the search for axion compared to single mode resonant detection. The enhancement to the SNR becomes the most manifest when applied to the newly proposed detection using superconducting radiofrequency caivty with AC magnetic field where most of the parameter space of the QCD axion above kHz can be probed.
Non-Hermitian systems with parity-time reversal ($mathcal{PT}$) or anti-$mathcal{PT}$ symmetry have attracted a wide range of interest owing to their unique characteristics and counterintuitive phenomena. One of the most extraordinary features is the presence of an exception point (EP), across which a phase transition with spontaneously broken $mathcal{PT}$ symmetry takes place. We implement a Floquet Hamiltonian of a single qubit with anti-$mathcal{PT}$ symmetry by periodically driving a dissipative quantum system of a single trapped ion. With stroboscopic emission and quantum state tomography, we obtain the time evolution of density matrix for an arbitrary initial state, and directly demonstrate information retrieval, eigenstates coalescence, and topological energy spectra as unique features of non-Hermitian systems.
We analyze the problem of how different ground states associated to the same set of the Hamiltonian parameters evolve after a sudden quench. To realize our analysis we define a quantitative approach to the local distinguishability between different ground states of a magnetically ordered phase in terms of the trace distance between the reduced density matrices obtained projecting two ground states in the same subset. Before the quench, regardless the particular choice of the subset, any system in a magnetically ordered phase is characterized by ground states that are locally distinguishable. On the other hand, after the quench, the maximum of the distinguishability shows an exponential decay in time. Hence, in the limit of very large time, all the informations about the particular initial ground state are lost even if the systems are integrable. We prove our claims in the framework of the magnetically ordered phases that characterize both the $XY$ model and $N$-cluster Ising models. The fact that we find similar behavior in models within different classes of symmetry makes us confident about the generality of our results.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
