scholarly journals Sudden death and revival of Gaussian Einstein–Podolsky–Rosen steering in noisy channels

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Xiaowei Deng ◽  
Yang Liu ◽  
Meihong Wang ◽  
Xiaolong Su ◽  
Kunchi Peng
Keyword(s):  
Quantum Information ◽  
Sudden Death ◽  
Quantum Information Processing ◽  
Excess Noise ◽  
Quantum Channels ◽  
Noisy Environment ◽  
Noisy Channels ◽  
Asymmetric Quantum ◽  
Einstein Podolsky Rosen ◽  
Epr Steering

AbstractEinstein–Podolsky–Rosen (EPR) steering is a useful resource for secure quantum information tasks. It is crucial to investigate the effect of inevitable loss and noise in quantum channels on EPR steering. We analyze and experimentally demonstrate the influence of purity of quantum states and excess noise on Gaussian EPR steering by distributing a two-mode squeezed state through lossy and noisy channels, respectively. We show that the impurity of state never leads to sudden death of Gaussian EPR steering, but the noise in quantum channel can. Then we revive the disappeared Gaussian EPR steering by establishing a correlated noisy channel. Different from entanglement, the sudden death and revival of Gaussian EPR steering are directional. Our result confirms that EPR steering criteria proposed by Reid and I. Kogias et al. are equivalent in our case. The presented results pave way for asymmetric quantum information processing exploiting Gaussian EPR steering in noisy environment.

scholarly journals Device-independent verification of Einstein-Podolsky-Rosen steering

2021 ◽  
Author(s):  
Yuan-Yuan Zhao ◽  
Chao Zhang ◽  
Shuming Cheng ◽  
Xinhui Li ◽  
Yu Guo ◽  
...  
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Entangled States ◽  
Independent Verification ◽  
Self Testing ◽  
Experimental Implementation ◽  
Einstein Podolsky Rosen ◽  
Complete Framework ◽  
Epr Steering

Abstract If the presence of entanglement could be certified in a device-independent (DI) way, it is likely to provide various quantum information processing tasks with unconditional security. Recently, it was shown that a DI protocol, combining measurement-device-independent techniques with self-testing, is able to verify all entangled states, however, it imposes demanding requirements on its experimental implementation. In this work, we propose a much less-demanding protocol based on Einstein-Podolsky-Rosen (EPR) steering to certify entanglement. We establish a complete framework for DI verification of EPR steering in which all steerable states could be verified. We then analyze its robustness towards noise and imperfections of self-testing by considering the measurement scenario with three settings at each side. Finally, a four-photon experiment is implemented to demonstrate that even Bell local states can be device-independently verified. Our work may pave the way for realistic applications of secure quantum information tasks.

scholarly journals Construction of genuinely entangled subspacesand the associated bounds on entanglement measures for mixed states

2021 ◽  
Author(s):  
Konstantin Antipin
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Lower Bounds ◽  
Quantum Information Processing ◽  
Multipartite Entanglement ◽  
Quantum Channels ◽  
Valuable Resource ◽  
Mixed States ◽  
Entanglement Measures ◽  
Pure States

Abstract Genuine entanglement is the strongest form of multipartite entanglement. Genuinely entangled pure states contain entanglement in every bipartition and as such can be regarded as a valuable resource in the protocols of quantum information processing. A recent direction of research is the construction of genuinely entangled subspaces — the class of subspaces consisting entirely of genuinely entangled pure states. In this paper we present methods of construction of such subspaces including those of maximal possible dimension. The approach is based on the composition of bipartite entangled subspaces and quantum channels of certain types. The examples include maximal subspaces for systems of three qubits, four qubits, three qutrits. We also provide lower bounds on two entanglement measures for mixed states, the concurrence and the convex-roof extended negativity, which are directly connected with the projection on genuinely entangled subspaces.

A NOTE ON "SPLITTING FOUR ENSEMBLES OF TWO-QUBIT QUANTUM INFORMATION VIA THREE EINSTEIN–PODOLSKY–ROSEN PAIRS"

2010 ◽  
Vol 08 (03) ◽  
pp. 529-533
Author(s):  
YI-MIN LIU ◽  
MING-LING LI ◽  
HUA-MIN GAO ◽  
XIAN-SONG LIU ◽  
ZHAN-JUN ZHANG
Keyword(s):  
Quantum Information ◽  
Recent Literature ◽  
Qubit State ◽  
The Novel ◽  
Quantum Channels ◽  
Einstein Podolsky Rosen

Enlightened by the novel idea in recent literature, we improve the tripartite quantum scheme to be a more economical and efficient one for splitting any two-qubit state in the four specific ensembles with only two Einstein–Podolsky–Rosen pairs as quantum channels.

ON THE SECURITY OF DECOHERENCE-FREE SUBSPACES AND SUBSYSTEMS FOR CLASSICAL INFORMATION CONVEYING THROUGH QUANTUM CHANNELS

2013 ◽  
Vol 11 (02) ◽  
pp. 1350022
Author(s):  
ELLOÁ B. GUEDES ◽  
FRANCISCO M. DE ASSIS
Keyword(s):  
Quantum Information ◽  
Communication Systems ◽  
Quantum Communication ◽  
Quantum Information Processing ◽  
Information Leakage ◽  
Practical Implementation ◽  
Quantum Channels ◽  
Quantum Properties ◽  
Message Exchange ◽  
Decoherence Free Subspaces

Decoherence is one of the main obstacles in quantum information processing. In cryptographic scenarios, in particular, decoherence is not only responsible for the loss of the quantum properties but also for information leakage out to a wiretapper. Given that decoherence must be fought in real-world quantum communication systems, we present a scheme, using decoherence-free subspaces and subsystems, to perform secure classical communications through noisy quantum channels. Using quantum information and wiretap theories, we establish a proof of unconditional security of our scheme. We illustrate our proposal with a non-trivial example and discuss some of its impacts on already existing quantum secure message exchange protocols. Furthermore, we present some up-to-date technologies that can be used for practical implementation of the scheme proposed.

scholarly journals Environmental Effects on Nonlocal Correlations

Quanta ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 57-67
Author(s):  
Tamal Guha ◽  
Bihalan Bhattacharya ◽  
Debarshi Das ◽  
Some Sankar Bhattacharya ◽  
Amit Mukherjee ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Classical Mechanics ◽  
Complete Loss ◽  
Quantum Channels ◽  
Output State ◽  
Environmental Interactions ◽  
Nonlocal Correlations

Environmental interactions are ubiquitous in practical instances of any quantum information processing protocol. The interaction results in depletion of various quantum resources and even complete loss in numerous situations. Nonlocality, which is one particular quantum resource marking a significant departure of quantum mechanics from classical mechanics, meets the same fate. In the present work we study the decay in nonlocality to the extent of the output state admitting a local hidden state model. Using some fundamental quantum channels we also demonstrate the complete decay in the resources in the purview of the Bell–Clauser–Horne–Shimony–Holt inequality and a three-settings steering inequality. We also obtain bounds on the parameter of the depolarizing map for which it becomes steerability breaking pertaining to a general class of two qubit states.Quanta 2019; 8: 57–67.

BIPARTITE AND MULTIPARTITE CORRELATIONS OF COUPLED QUBITS IN A NON-MARKOVIAN ENVIRONMENT: HIERARCHY EQUATION METHOD

2013 ◽  
Vol 11 (06) ◽  
pp. 1350058 ◽  
Author(s):  
JIAN-SONG ZHANG ◽  
ZHI-YUAN HUANG ◽  
AI-XI CHEN
Keyword(s):  
Quantum Information ◽  
Sudden Death ◽  
Quantum Information Processing ◽  
Quantum Correlations ◽  
Spin Squeezing ◽  
Equation Method ◽  
Entanglement Sudden Death ◽  
Markovian Approximations ◽  
Rotating Wave ◽  
Coupled Qubits

We study bipartite and multipartite correlations of several coupled qubits within a common non-Markovian bath using the hierarchy equation method. This method does not use the rotating-wave and Born–Markovian approximations. The interaction between the qubits and their coupling strength with the bath have remarkable influence on the dynamics of quantum correlations. The entanglement sudden death (ESD) phenomenon, the amount of stationary state concurrence and spin squeezing can be controled by the non-Markovianity of the environment and interactions between qubits. These properties may be useful for purposes of quantum information processing with multiqubit system in non-Markovian environments.

scholarly journals Generation and sudden death of entanglement in qubit–qutrit systems with depolarising noise

2013 ◽  
Vol 23 (6) ◽  
pp. 1220-1233 ◽  
Author(s):  
SALMAN KHAN
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Sudden Death ◽  
Critical Point ◽  
Quantum Information Processing ◽  
Local Environment ◽  
Global Environment

In this paper we study the dynamics of entanglement in some hybrid qubit–qutrit systems under the influence of global, collective, local and multilocal depolarising noise. We show that depolarising noise can be used to induce entanglement. A critical point exists under every coupling of the system with the environment at which all the states are equally entangled. Furthermore, we show that no ESD occurs when either only the qubit is coupled to its local environment or the system is coupled to a multilocal or global environment. This is an important result for various quantum information processing tasks and thus merits further investigation.

FOUR PHOTON POLARIZATION ENTANGLEMENT TESTS AND APPLICATIONS

2004 ◽  
Vol 02 (01) ◽  
pp. 133-147 ◽  
Author(s):  
M. BOURENNANE ◽  
M. EIBL ◽  
S. GAERTNER ◽  
C. KURTSIEFER ◽  
H. WEINFURTER ◽  
...  
Keyword(s):  
Quantum Information ◽  
Quantum Information Processing ◽  
Quantum Channels ◽  
Photon Polarization ◽  
Entanglement Witness ◽  
Photon State ◽  
Parametric Down Conversion ◽  
Local Polarization ◽  
Down Conversion ◽  
Decoherence Free Subspace

Multipartite entangled states are key elements for quantum information processing. Here we experimentally investigate the particular properties of a polarization-entangled four-photon state, which can be generated directly by second order parametric down-conversion. The perfect correlations and the invariance under local transformations enable one to encode one qubit of quantum information in a decoherence-free subspace and thus to communicate it safely over noisy quantum channels. Furthermore, we present an experimental method to detect genuine fourpartite entanglement using entanglement witness operators. The implementation of such operators requires only of few local polarization measurements but uniquely proves the genuine multipartite entanglement.

scholarly journals NOTES ON THE FIDELITY OF SYMPLECTIC QUANTUM ERROR-CORRECTING CODES

2003 ◽  
Vol 01 (04) ◽  
pp. 443-463 ◽  
Author(s):  
MITSURU HAMADA
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Exponential Convergence ◽  
Error Correcting Codes ◽  
Quantum Channels ◽  
General Quantum ◽  
Quantum Capacity ◽  
Stabilizer Code ◽  
Quantum Error

Two observations are given on the fidelity of schemes for quantum information processing. In the first one, we show that the fidelity of a symplectic (stabilizer) code, if properly defined, exactly equals the "probability" of the correctable errors for general quantum channels. The second observation states that for any coding rate below the quantum capacity, exponential convergence of the fidelity of some codes to unity is possible.

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