scholarly journals Effects of symmetry breaking of the structurally-disordered Hamiltonian ensembles on the anisotropic decoherence

2021 ◽  
Author(s):  
Hong-Bin Chen
Keyword(s):  
Probability Distribution ◽  
Symmetry Breaking ◽  
Canonical Form ◽  
Open Quantum Systems ◽  
Dynamical Behavior ◽  
Structural Disorder ◽  
Quantum Systems ◽  
New Approach ◽  
Pure Dephasing ◽  
Different Types

Abstract It is commonly known that the dephasing in open quantum systems is due to the establishment of bipartite correlations with an environment. Recently, a new approach of average over disordered Hamiltonian ensemble is developed and shown to capable of describing both the incoherent dynamical behavior and the nonclassicality of dynamical processes. Here we further extend the approach of Hamiltonian ensemble in the canonical form to the realm of structural disorder. Under the separation of the probability distribution within the Hamiltonian ensemble, the geometrical structural is easily visualized and can be characterized according to the degree of symmetry. We demonstrate four degrees and investigate the effects of different types of symmetry breaking on the incoherent dynamics. With these effects, we obtain rather general master equations, going beyond the previous frameworks of pure dephasing or isotropic depolarization. The practicality of the Hamiltonian ensemble and the theory of process nonclassicality is significantly enhanced.

scholarly journals Emergence of PT-symmetry breaking in open quantum systems

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Julian Huber ◽  
Peter Kirton ◽  
Stefan Rotter ◽  
Peter Rabl
Keyword(s):  
Symmetry Breaking ◽  
Open Quantum Systems ◽  
Symmetry Transformation ◽  
Quantum Systems ◽  
Coupled Systems ◽  
Physical Systems ◽  
Open Quantum ◽  
Parity Symmetry ◽  
Classical Correspondence ◽  
Liouville Operators

The effect of \mathcal{PT}𝒫𝒯-symmetry breaking in coupled systems with balanced gain and loss has recently attracted considerable attention and has been demonstrated in various photonic, electrical and mechanical systems in the classical regime. However, it is still an unsolved problem how to generalize the concept of \mathcal{PT}𝒫𝒯 symmetry to the quantum domain, where the conventional definition in terms of non-Hermitian Hamiltonians is not applicable. Here we introduce a symmetry relation for Liouville operators that describe the dissipative evolution of arbitrary open quantum systems. Specifically, we show that the invariance of the Liouvillian under this symmetry transformation implies the existence of stationary states with preserved and broken parity symmetry. As the dimension of the Hilbert space grows, the transition between these two limiting phases becomes increasingly sharp and the classically expected \mathcal{PT}𝒫𝒯-symmetry breaking transition is recovered. This quantum-to-classical correspondence allows us to establish a common theoretical framework to identify and accurately describe \mathcal{PT}𝒫𝒯-symmetry breaking effects in a large variety of physical systems, operated both in the classical and quantum regimes.

scholarly journals Dynamical signatures of topological order in the driven-dissipative Kitaev chain

2019 ◽  
Vol 6 (2) ◽  
Author(s):  
Moos van Caspel ◽  
Sergio Enrique Tapias Arze ◽  
Isaac Pérez Castillo
Keyword(s):  
Steady State ◽  
Closed System ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Topological Phases ◽  
Topological Order ◽  
Superconducting Nanowires ◽  
Boundary Correspondence ◽  
Steady State Current ◽  
Different Types

We investigate the effects of dissipation and driving on topological order in superconducting nanowires. Rather than studying the non-equilibrium steady state, we propose a method to classify and detect dynamical signatures of topological order in open quantum systems. Bulk winding numbers for the Lindblad generator \hat{\mathcal{L}}ℒ̂ of the dissipative Kitaev chain are found to be linked to the presence of Majorana edge master modes – localized eigenmodes of \hat{\mathcal{L}}ℒ̂. Despite decaying in time, these modes provide dynamical fingerprints of the topological phases of the closed system, which are now separated by intermediate regions where winding numbers are ill-defined and the bulk-boundary correspondence breaks down. Combining these techniques with the Floquet formalism reveals higher winding numbers and different types of edge modes under periodic driving. Finally, we link the presence of edge modes to a steady state current.

scholarly journals Coherence Trapping in Open Two-Qubit Dynamics

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2445
Author(s):  
Mariam Algarni ◽  
Kamal Berrada ◽  
Sayed Abdel-Khalek ◽  
Hichem Eleuch
Keyword(s):  
Quantum Coherence ◽  
Open Quantum Systems ◽  
Dynamical Behavior ◽  
Quantum Systems ◽  
Completely Positive Maps ◽  
L1 Norm ◽  
Separable States ◽  
System Parameters ◽  
Quantum Dynamical ◽  
Qubit System

In this manuscript, we examine the dynamical behavior of the coherence in open quantum systems using the l1 norm. We consider a two-qubit system that evolves in the framework of Kossakowski-type quantum dynamical semigroups (KTQDSs) of completely positive maps (CPMs). We find that the quantum coherence can be asymptotically maintained with respect to the values of the system parameters. Moreover, we show that the quantum coherence can resist the effect of the environment and preserve even in the regime of long times. The obtained results also show that the initially separable states can provide a finite value of the coherence during the time evolution. Because of such properties, several states in this type of environments are good candidates for incorporating quantum information and optics (QIO) schemes. Finally, we compare the dynamical behavior of the coherence with the entire quantum correlation.

scholarly journals Symmetry Breaking and Error Correction in Open Quantum Systems

2020 ◽  
Vol 125 (24) ◽  
Author(s):  
Simon Lieu ◽  
Ron Belyansky ◽  
Jeremy T. Young ◽  
Rex Lundgren ◽  
Victor V. Albert ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Error Correction ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Open Quantum

scholarly journals DYNAMICS OF QUANTUM CORRELATIONS IN TWO-QUBIT SYSTEMS WITHIN NON-MARKOVIAN ENVIRONMENTS

2012 ◽  
Vol 27 (01n03) ◽  
pp. 1345053 ◽  
Author(s):  
ROSARIO LO FRANCO ◽  
BRUNO BELLOMO ◽  
SABRINA MANISCALCO ◽  
GIUSEPPE COMPAGNO
Keyword(s):  
Quantum Discord ◽  
Open Quantum Systems ◽  
Dynamical Behavior ◽  
Quantum Correlations ◽  
Quantum Systems ◽  
Primary Interest ◽  
Common Environment ◽  
Classical Counterpart ◽  
Qubit System ◽  
Dynamics Of Correlations

Knowledge of the dynamical behavior of correlations with no classical counterpart, like entanglement, nonlocal correlations and quantum discord, in open quantum systems is of primary interest because of the possibility to exploit these correlations for quantum information tasks. Here we review some of the most recent results on the dynamics of correlations in bipartite systems embedded in non-Markovian environments that, with their memory effects, influence in a relevant way the system dynamics and appear to be more fundamental than the Markovian ones for practical purposes. Firstly, we review the phenomenon of entanglement revivals in a two-qubit system for both independent environments and a common environment. We then consider the dynamics of quantum discord in non-Markovian dephasing channel and briefly discuss the occurrence of revivals of quantum correlations in classical environments.

scholarly journals Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

2021 ◽  
Author(s):  
Peizhi Wang ◽  
Jinshi Wang ◽  
Fengzhou Fang
Keyword(s):  
Surface Modification ◽  
Excited States ◽  
Linear Dependence ◽  
Material Removal ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Atomic Scale ◽  
New Approach ◽  
Von Neumann ◽  
Photon Irradiation

AbstractThis paper presents a new approach for material removal on silicon at atomic and close-to-atomic scale assisted by photons. The corresponding mechanisms are also investigated. The proposed approach consists of two sequential steps: surface modification and photon irradiation. The back bonds of silicon atoms are first weakened by the chemisorption of chlorine and then broken by photon energy, leading to the desorption of chlorinated silicon. The mechanisms of photon-induced desorption of chlorinated silicon, i.e., SiCl2 and SiCl, are explained by two models: the Menzel–Gomer–Redhead (MGR) and Antoniewicz models. The desorption probability associated with the two models is numerically calculated by solving the Liouville–von Neumann equations for open quantum systems. The calculation accuracy is verified by comparison with the results in literatures in the case of the NO/Pt (111) system. The calculation method is then applied to the cases of SiCl2/Si and SiCl/Si systems. The results show that the value of desorption probability first increases dramatically and then saturates to a stable value within hundreds of femtoseconds after excitation. The desorption probability shows a super-linear dependence on the lifetime of excited states.

scholarly journals Bulk–edge correspondence and stability of multiple edge states of a $\mathcal{PT}$-symmetric non-Hermitian system by using non-unitary quantum walks

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Makio Kawasaki ◽  
Ken Mochizuki ◽  
Norio Kawakami ◽  
Hideaki Obuse
Keyword(s):  
Symmetry Breaking ◽  
Open Quantum Systems ◽  
Quantum Walk ◽  
Quantum Systems ◽  
Quantum Walks ◽  
Multiple Edge ◽  
Exceptional Point ◽  
Topological Phase ◽  
Edge States ◽  
The Stability

Abstract Topological phases and the associated multiple edge states are studied for parity and time-reversal ($\mathcal{PT}$)-symmetric non-Hermitian open quantum systems by constructing a non-unitary three-step quantum walk retaining $\mathcal{PT}$ symmetry in one dimension. We show that the non-unitary quantum walk has large topological numbers of the $\mathbb{Z}$ topological phase and numerically confirm that multiple edge states appear as expected from the bulk–edge correspondence. Therefore, the bulk–edge correspondence is valid in this case. Moreover, we study the stability of the multiple edge states against a symmetry-breaking perturbation so that the topological phase is reduced to $\mathbb{Z}_2$ from $\mathbb{Z}$. In this case, we find that the number of edge states does not become one unless a pair of edge states coalesce at an exceptional point. Thereby, this is a new kind of breakdown of the bulk–edge correspondence in non-Hermitian systems. The mechanism of the prolongation of edge states against the symmetry-breaking perturbation is unique to non-Hermitian systems with multiple edge states and anti-linear symmetry. Toward experimental verifications, we propose a procedure to determine the number of multiple edge states from the time evolution of the probability distribution.

scholarly journals Continuous Dissipative Phase Transitions with or without Symmetry Breaking

2021 ◽  
Author(s):  
Fabrizio Minganti ◽  
Ievgen Arkhipov ◽  
Adam Miranowicz ◽  
Franco Nori
Keyword(s):  
Phase Transitions ◽  
Symmetry Breaking ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Second Order ◽  
Necessary Condition ◽  
Symmetric Model ◽  
Open Quantum ◽  
Modern Physics ◽  
Laser Model

Abstract The paradigm of second-order phase transitions (PTs) induced by spontaneous symmetry breaking (SSB) in thermal and quantum systems is a pillar of modern physics that has been fruitfully applied to out-of-equilibrium open quantum systems. Dissipative phase transitions (DPTs) of second order are often connected with SSB, in close analogy with well-known thermal second-order PTs in closed quantum and classical systems. That is, a second-order DPT should disappear by preventing the occurrence of SSB. Here, we prove this statement to be wrong, showing that, surprisingly, SSB is not a necessary condition for the occurrence of second-order DPTs in \textit{out-of-equilibrium open quantum systems}. We analytically prove this result using the Liouvillian theory of dissipative phase transitions, and demonstrate this anomalous transition in two exemplary models: a paradigmatic laser model, where we can arbitrarily remove SSB while retaining criticality, and a $Z_2$-symmetric model of a two-photon Kerr resonator.

scholarly journals Scattering–Like Control of the Cheshire Cat Effect in Open Quantum Systems

2019 ◽  
Vol 2 (1) ◽  
pp. 1-11
Author(s):  
Jerzy Dajka
Keyword(s):  
Open System ◽  
Control Strategy ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Open Loop ◽  
Weak Values ◽  
Open Loop Control ◽  
Loop Control ◽  
Open Quantum ◽  
Pure Dephasing

We study the Quantum Cheshire Cat effect in an open system coupled to a finite environment. We consider a very special type of coupling—pure dephasing—and show that there is a scattering-like mechanism which can be utilized to construct an open-loop control strategy for the weak values of the Cat and its grin.

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