Reply to “Comment on ‘Protecting bipartite entanglement by quantum interferences' ”

2018 ◽  
Vol 97 (3) ◽  
Author(s):  
Sumanta Das ◽  
G. S. Agarwal
Keyword(s):  
Bipartite Entanglement

SPIN-PARITY EFFECT IN VIOLATION OF BELL'S INEQUALITIES

2013 ◽  
Vol 28 (01) ◽  
pp. 1450004 ◽  
Author(s):  
ZHIGANG SONG ◽  
J.-Q. LIANG ◽  
L.-F. WEI
Keyword(s):  
Berry Phase ◽  
Quantum Probability ◽  
Quantum Nonlocality ◽  
Entangled State ◽  
Bell’S Inequalities ◽  
Bipartite Entanglement ◽  
Spin Parity ◽  
Parity Effect ◽  
Bell's Inequalities ◽  
Spin Parity Effect

Analytic formulas of Bell correlations are derived in terms of quantum probability statistics under the assumption of measuring outcome-independence and the Bell's inequalities (BIs) are extended to general bipartite-entanglement macroscopic quantum-states (MQS) of arbitrary spins. For a spin-½ entangled state we find analytically that the violations of BIs really resulted from the quantum nonlocal correlations. However, the BIs are always satisfied for the spin-1 entangled MQS. More generally the quantum nonlocality does not lead to the violation for the integer spins since the nonlocal interference effects cancel each other by the quantum statistical-average. Such a cancellation no longer exists for the half-integer spins due to the nontrivial Berry phase, and thus the violation of BIs is understood remarkably as an effect of geometric phase. Specifically, our generic observation of the spin-parity effect can be experimentally tested with the entangled photon-pairs.

Dependence of Bipartite Entanglement on Qubit-basis in the Amplitude-damping Environment

2020 ◽  
Vol 49 (10) ◽  
pp. 1027002-1027002
Author(s):  
汪新文 Xin-wen WANG ◽  
张慧敏 Hui-min ZHANG ◽  
刘珂 Ke LIU ◽  
刘延 Yan LIU
Keyword(s):  
Bipartite Entanglement ◽  
Amplitude Damping

scholarly journals Entanglement cost of generalised measurements

2003 ◽  
Vol 3 (5) ◽  
pp. 405-422
Author(s):  
R. Jozsa ◽  
M. Koashi ◽  
N. Linden ◽  
S. Popescu ◽  
S. Presnell ◽  
...  
Keyword(s):  
Quantum Measurements ◽  
Great Circle ◽  
Bloch Sphere ◽  
Numerical Techniques ◽  
Bipartite Entanglement ◽  
Von Neumann ◽  
Tensor Product Space ◽  
Large N ◽  
Dimension 2 ◽  
The Cost

Bipartite entanglement is one of the fundamental quantifiable resources of quantum information theory. We propose a new application of this resource to the theory of quantum measurements. According to Naimark's theorem any rank 1 generalised measurement (POVM) M may be represented as a von Neumann measurement in an extended (tensor product) space of the system plus ancilla. By considering a suitable average of the entanglements of these measurement directions and minimising over all Naimark extensions, we define a notion of entanglement cost E_{\min}(M) of M. We give a constructive means of characterising all Naimark extensions of a given POVM. We identify various classes of POVMs with zero and non-zero cost and explicitly characterise all POVMs in 2 dimensions having zero cost. We prove a constant upper bound on the entanglement cost of any POVM in any dimension. Hence the asymptotic entanglement cost (i.e. the large n limit of the cost of n applications of M, divided by n) is zero for all POVMs. The trine measurement is defined by three rank 1 elements, with directions symmetrically placed around a great circle on the Bloch sphere. We give an analytic expression for its entanglement cost. Defining a normalised cost of any $d$-dimensional POVM by E_{\min} (M)/\log_2 d, we show (using a combination of analytic and numerical techniques) that the trine measurement is more costly than any other POVM with d>2, or with d=2 and ancilla dimension 2. This strongly suggests that the trine measurement is the most costly of all POVMs.

TRANSMITTING BIPARTITE AND MULTIPARTITE CORRELATIONS VIA SPIN CHAINS UNDER PHASE DECOHERENCE

2012 ◽  
Vol 10 (06) ◽  
pp. 1250073
Author(s):  
JIAN-FENG AI ◽  
JIAN-SONG ZHANG ◽  
AI-XI CHEN
Keyword(s):  
Steady State ◽  
Anisotropy Parameter ◽  
Quantum Correlations ◽  
Spin Chains ◽  
The Other ◽  
Bipartite Entanglement ◽  
Other Hand ◽  
Long Time ◽  
Phase Decoherence ◽  
The One

We investigate the transfer of bipartite (measured by cocurrence) and multipartite (measured by global discord) quantum correlations though spin chains under phase decoherence. The influence of phase decoherence and anisotropy parameter upon quantum correlations transfer is investigated. On the one hand, in the case of no phase decoherence, there is no steady state quantum correlations between spins. On the other hand, if the phase decoherence is larger than zero, the bipartite quantum correlations can be transferred through a Heisenberg XXX chain for a long time and there is steady state bipartite entanglement. For a Heisenberg XX chain, bipartite entanglement between two spins is destroyed completely after a long time. Multipartite quantum correlations of all spins are more robust than bipartite quantum correlations. Thus, one can store multipartite quantum correlations in spin chains for a long time under phase decoherence.

scholarly journals The Entanglement Generation in P T -Symmetric Optical Quadrimer System

Symmetry ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1110 ◽  
Author(s):  
Joanna K. Kalaga
Keyword(s):  
Phase Transition ◽  
Transition Point ◽  
Single Mode ◽  
Phase Transition Point ◽  
Bipartite Entanglement ◽  
Entanglement Generation ◽  
Linear Interaction ◽  
Gain And Loss ◽  
A Chain

We discuss a model consisting of four single-mode cavities with gain and loss energy in the first and last modes. The cavities are coupled to each other by linear interaction and form a chain. Such a system is described by a non-Hermitian Hamiltonian which, under some conditions, becomes P T -symmetric. We identify the phase-transition point and study the possibility of generation bipartite entanglement (entanglement between all pairs of cavities) in the system.

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