Skip to content
Free planNo credit card requiredStart writing
AI for Research home
AI for Research home
Dashboard
Sign inGet started

Search 250 million research papers

Read the abstract, see who wrote it and who cites it, and get the citation in APA, MLA, Chicago or Harvard.

About 10,000 papers for “Open quantum system”

Open Quantum System Engineering

Creston David Herold, Creston David Herold · 2014

Exquisite experimental control of quantum systems has led to sharp growth of basic quantum research in recent years. Controlling dissipation has been crucial in producing ultracold, trapped atomic samples. Recent theoretical work has suggested dissipation can be a useful tool for quantum state preparation. Controlling not only how a system interacts with a reservoir, but the ability to engineer the reservoir itself would be a powerful platform for open quantum system research. Toward this end, we have constructed an apparatus to study ultracold mixtures of rubidium (Rb) and ytterbium (Yb). We have developed a Rb-blind optical lattice at zero = 423:018(7) nm, which will enable us to immerse a lattice of Yb atoms (the system) into a Rb BEC (superfluid reservoir). We have produced Bose-Einstein condensates of 170Yb and 174Yb, two of the five bosonic isotopes of Yb, which also has two fermionic isotopes. Flexible optical trapping of Rb and Yb was achieved with a two-color dipole trap of 532 and 1064 nm, and we observed thermalization in ultracold mixtures of Rb and Yb. Using the Rb-blind optical lattice, we measured very small light shifts of 87Rb BECs near the zero wavelengths adjacent the 6p electronic states, through a coherent series of lattice pulses. The positions of the zero wavelengths are sensitive to the electric dipole matrix elements between the 5s and 6p states, and we made the first experimental measurement of their strength. By measuring a light shift, we were not sensitive to excited state branching ratios, and we achieved a precision better than 0.3%. Ultracold Mixtures of Rubidium and Ytterbium for

Cited by 0

Open-System Quantum Error Correction

Len, Yink Loong, Ng, Hui Khoon · arXiv (Cornell University) · 2018

We study the performance of quantum error correction (QEC) on a system undergoing open-system (OS) dynamics. The noise on the system originates from a joint quantum channel on the system-bath composite, a framework that includes and interpolates between the commonly used system-only quantum noise channel model and the system-bath Hamiltonian noise model. We derive the perfect OSQEC conditions, with QEC recovery only on the system and not the inaccessible bath. When the noise is only approximately correctable, the generic case of interest, we quantify the performance of OSQEC using worst-case fidelity. We find that the leading deviation from unit fidelity after recovery is quadratic in the uncorrectable part, a result reminiscent of past work on approximate QEC for system-only noise, although the approach here requires the use of different techniques than in past work.

Cited by 0Open access

A cosmological open quantum system

Shandera, Sarah, Agarwal, Nishant, Kamal, Archana · arXiv (Cornell University) · 2017

We derive the evolution equation for the density matrix of a UV- and IR- limited band of comoving momentum modes of the canonically normalized scalar degree of freedom in two examples of nearly de Sitter universes. Including the effects of a cubic interaction term from the gravitational action and tracing out a set of longer wavelength modes, we find that the evolution of the system is non-Hamiltonian and non-Markovian. We find linear dissipation terms for a few modes with wavelength near the boundary between system and bath and nonlinear dissipation terms for all modes. The non-Hamiltonian terms persist to late times when the scalar field dynamics is such that the curvature perturbation continues to evolve on super-Hubble scales.

Cited by 0Open access

Complexity for Open Quantum System

Arpan Bhattacharyya, T. Hanif, S. Shajidul Haque et al. · arXiv (Cornell University) · 2021

We study the complexity for an open quantum system. Our system is a harmonic oscillator coupled to a one-dimensional massless scalar field, which acts as the bath. Specifically, we consider the reduced density matrix by tracing out the bath degrees of freedom for both regular and inverted oscillators and compute the complexity of purification (COP) and complexity by using the operator-state mapping. We find that when the oscillator is regular, the COP saturates quickly for both underdamped and overdamped oscillators. Interestingly, when the oscillator is underdamped, we discover a kink-like behavior for the saturation value of the COP with a varying damping coefficient. For the inverted oscillator, we find a linear growth of the COP with time for all values of the bath-system interaction. However, when the interaction is increased the slope of the linear growth decreases, implying that the unstable nature of the system can be regulated by the bath.

Cited by 0Open access

An Open–quantum–system Formulation . . .

Reinhold A. Bertlmann, Walter Grimus, Beatrix C. Hiesmayr · 2006

We consider an open quantum system which contains unstable states. The time evolution of the system can be described by an effective non-hermitian Hamiltonian Heff, in accord with the Wigner–Weisskopf approximation, and an additional term of the Lindblad form, the socalled dissipator. We show that, after enlarging the original Hilbert space by states which represent the decay products of the unstable states, the non-hermitian part of Heff —the “particle decay” — can be incorporated into the dissipator of the enlarged space via a specific Lindblad operator. Thus the new formulation of the time evolution on the enlarged space has a hermitian Hamiltonian and is probability conserving. The equivalence of the new formulation with the original one demonstrates that the time evolution which is governed by a non-hermitian Hamiltonian and a dissipator of the Lindblad form is nevertheless completely positive, just as systems with hermitian Hamiltonians.

Cited by 0

Open-system quantum error correction

Yink Loong Len, Hui Khoon Ng · Physical review. A/Physical review, A · 2018

We study the performance of quantum error correction (QEC) on a system undergoing open-system (OS) dynamics. The noise on the system originates from a joint quantum channel on the system-bath composite, a framework that includes and interpolates between the commonly used system-only quantum noise channel model and the system-bath Hamiltonian noise model. We derive the perfect OSQEC conditions, with QEC recovery only on the system and not the inaccessible bath. When the noise is only approximately correctable, the generic case of interest, we quantify the performance of OSQEC using worst-case fidelity. We find that the leading deviation from unit fidelity after recovery is quadratic in the uncorrectable part, a result reminiscent of past work on approximate QEC for system-only noise, although the approach here requires the use of different techniques than in past work.

Cited by 6Open access

Modeling Open Quantum System Dynamics.

Chatterjee, Avi · OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2019

Abstract not provided.

Cited by 0Open access

Minisuperspace as a Quantum Open System

B. L. Hu, Juan Pablo Paz, S. Sinha · Cambridge University Press eBooks · 1993

We trace the development of ideas on dissipative processes in chaotic cosmology and on minisuperspace quantum cosmology from the time Misner proposed them to current research. We show

Cited by 36

Optimization Via Open System Quantum Annealing

Sergio Boixo, Robert F. Lucas, Daniel A. Lidar et al. · 2016

Abstract : Many computationally challenging problems can be reduced to Quadratic Unconstrained Binary Optimization (QUBO), which can be solved by a quantum evolution from a strong transverse field to a spin glass Hamiltonian (also known as quantum annealing or QA). We have examined open system QA, using theoretical and experimental techniques to deepen our understanding of open system QA by situating it in the context of related, well studied classical and quantum problems. We have explored and elucidated the significance of tunneling in QA with Path Integral Monte Carlo. We have also provided signatures of quantum behavior of QA against closely related simulated annealing implementations, analytically, numerically, and experimentally. We have carried out a comprehensive comparison of geometrically-local open-system QA and classical solvers for computationally hard problems such as MAX-2-SAT. We have exploited and further developed a graph-theoretical mapping between the Ising spin glass partition function and circuit model decision problems, discovered in a previous ARO Quantum Algorithms funded project. We have made significant progress on error correction techniques for QA, both theoretically and experimentally, and in demonstration of quantum speedup.

Cited by 0

Quantum Open System Theory: Bipartite Aspects

Ting Yu, J. H. Eberly · Physical Review Letters · 2006

We demonstrate in straightforward calculations that even under ideally weak noise the relaxation of bipartite open quantum systems contains elements not previously encountered in quantum noise physics. While additivity of decay rates is known to be generic for decoherence of a single system, we demonstrate that it breaks down for bipartite coherence of even the simplest composite systems.

Cited by 623Open access

Complexity for an open quantum system

Arpan Bhattacharyya, T. Hanif, S. Shajidul Haque et al. · Physical review. D/Physical review. D. · 2022

We study the complexity for an open quantum system. Our system is a harmonic oscillator coupled to a one-dimensional massless scalar field, which acts as the bath. Specifically, we consider the reduced density matrix by tracing out the bath degrees of freedom for both regular and inverted oscillators and compute the complexity of purification (COP) and complexity by using the operator-state mapping. We find that when the oscillator is regular, the COP saturates quickly for both underdamped and overdamped oscillators. Interestingly, when the oscillator is underdamped, we discover a kink-like behavior for the saturation value of the COP with a varying damping coefficient. For the inverted oscillator, we find a linear growth of the COP with time for all values of the bath-system interaction. However, when the interaction is increased the slope of the linear growth decreases, implying that the unstable nature of the system can be regulated by the bath.

Cited by 23Open access

Quantum Open System Theory: Bipartite Aspects

Yu, Ting, Eberly, J. H. · arXiv (Cornell University) · 2006

We demonstrate in straightforward calculations that even under ideally weak noise the relaxation of bipartite open quantum systems contains elements not previously encountered in quantum noise physics. While additivity of decay rates is known to be generic for decoherence of a single system, we demonstrate that it breaks down for bipartite coherence of even the simplest composite systems.

Cited by 0Open access

Topological lattice as open quantum system

Wang, Danqi · DR-NTU (Nanyang Technological University) · 2024

Topological Insulators are novel materials with unique properties, such as topologically protected boundary states. However, current research is more focused on topological insulators as closed systems, and little is known about their properties as open quantum system. In this project, I aim to study the properties of a bosonic Hofstadter lattice connected to thermal baths of different temperatures at its boundaries, including intriguing features such as (1) Thermal Erasure Effect, (2) Topological Thermal Currents, (3) Edge Nonequilibrium Crosscurrent.
\nIn this report, I have reviewed the beginning of topological condensed mater physics from the discovery of Quantum Hall Effect, with its robust topologically protected edge states which inspired the prediction of existence of 2D Topological Insulator with similarly topologically protected robust edge states but without the need to break Time-Reversal Symmetry (TRS). I then reviewed the boundary driven open quantum system, in which an open quantum system is connected to the environment at its boundaries and allowed to equilibrate, reaching a Non-Equilibrium Steady States (NESS). This justified the use of local GLSK quantum master equation under weak coupling to the environment. [1]
\nI then briefly described our project which aimed to use QuTiP to simulate the Topological Heat Transport of bosonic topological lattices connected to thermal baths. I aimed to reproduce the results of the paper by Rivas.[2] As a warmup, I have used QuTiP to simulate the NESS of simple systems such as the Heisenberg ladders and Bosonic ladders, using Local GLSK equation. I then moved on to study topological bosonic Hofstadter lattice as Thermal Hall Insulators including observing the nonequilibrium thermal currents carried by edge states, as well as how varying driving bias as well as the strength of the gauge field can affect the magnitude of the edge currents.
\nMy results can be realized in bosonic systems such as ultracold atoms simulations as well as photonic chips. These results can be applicable to nano-engineering of topological insulators under non- equilibrium conditions to account for the thermal hall effect. Other potential uses of topological insulators as thermal hall insulators as well as rectifier can be similarly explored in future studies.

Cited by 0

Aspects of Open Quantum System Dynamics

Walter T. Strunz · Kluwer Academic Publishers eBooks · 2005

The interaction of a quantum system with a many degree of freedom environment entails damping and the loss of quantum coherence. In these two lectures we focus on two aspects of open quantum system dynamics. First, we present decoherence as a dynamical phenomenon and determine the corresponding time scales, discuss an experiment and the nature of robust states, and mention universal properties of short-time decoherence of macroscopic superpositions. Secondly, in analogy to the classical description of open systems in terms of Langevin equations, we present a stochastic approach to open quantum system dynamics in terms of a stochastic Schrödinger equation. We give a microscopic derivation that allows us to generalize the stochastic approach to non-Markovian situations. We discuss a convolutionless formulation of our theory and finally, we focus on the quantised version of Brownian motion as an often-employed example.

Cited by 0

Coherence in an open quantum system

Nikolay Gromov, I. V. Kostyakov, В. В. Куратов · Proceedings of the Komi Science Centre of the Ural Division of the Russian Academy of Sciences · 2020

Cited by 0Open access