CORRELATION OF SUPERCURRENTS IN TWO DISTANT MESOSCOPIC SQUID RINGS IN THE PRESENCE OF TWO-MODE NONCLASSICAL FIELD

In this paper we consider two distant mesoscopic superconducting quantum interference device (SQUID) rings A and B in the presence of two-mode squeezed vacuum state field, and aim to see the effect of the field on the correlation of supercurrents in the two rings. We know the degree of entanglement of the two-mode squeezed vacuum state increases with the squeezing parameter r. In this paper we find that the correlation of the supercurrents increases with the parameter r too, meaning that the correlation of the supercurrents increases with the degree of entanglement of the field.

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NON-LINEAR DYNAMICS, ENTANGLEMENT AND THE QUANTUM-CLASSICAL CROSSOVER OF TWO COUPLED SQUID RINGS

International Journal of Modern Physics B ◽

10.1142/s0217979209063468 ◽

2009 ◽

Vol 23 (20n21) ◽

pp. 4311-4319

Author(s):

M. J. EVERITT

Keyword(s):

Classical Limit ◽

Quantum Interference ◽

Superconducting Quantum Interference Device ◽

Similar System ◽

Linear Dynamics ◽

Superconducting Quantum Interference ◽

Non Linear ◽

Two Systems ◽

Coupled Duffing Oscillators ◽

Squid Rings

We explore the quantum-classical crossover of two coupled, identical, superconducting quantum interference device (SQUID) rings. We note that the motivation for this work is based on a study of a similar system comprising two coupled Duffing oscillators. In that work we showed that the entanglement characteristics of chaotic and periodic (entrained) solutions differed significantly and that in the classical limit entanglement was preserved only in the chaotic-like solutions. However, Duffing oscillators are a highly idealised toy model. Motivated by a wish to explore more experimentally realisable systems we now extend our work to an analysis of two coupled SQUID rings. We observe some differences in behaviour between the system that is based on SQUID rings rather than on Duffing oscillators. However, we show that the two systems share a common feature. That is, even when the SQUID ring's trajectories appear to follow (semi) classical orbits entanglement persists.

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IMPLEMENTING AN n-QUBIT FREDKIN GATE WITH SUPERCONDUCTING QUANTUM-INTERFERENCE DEVICES IN CAVITY QED

International Journal of Modern Physics B ◽

10.1142/s0217979211100874 ◽

2011 ◽

Vol 25 (21) ◽

pp. 2915-2924 ◽

Cited By ~ 1

Author(s):

ANSHOU ZHENG ◽

YONGJIN CHENG ◽

JIBIN LIU ◽

XICHENG WANG ◽

YUAN ZHENG

Keyword(s):

Quantum Interference ◽

Cavity Qed ◽

Vacuum State ◽

Superconducting Quantum Interference Device ◽

Alternative Scheme ◽

Superconducting Quantum Interference Devices ◽

Superconducting Quantum Interference ◽

Fredkin Gate ◽

Logical Gate

An alternative scheme is proposed in this paper to realize an n-qubit Fredkin gate with superconducting quantum-interference device (SQUID) in cavity QED. The multiqubit logical gate is essentially accomplished by a sequence of operations on only two SQUIDs in a large-detuned cavity. In the scheme, the two logical states of a qubit are presented by the two lowest states of a SQUID and the cavity is always in vacuum state so that the limit on the cavity is not serious.

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Quantum entanglement and teleportation in superposition of multiple-photon-added two-mode squeezed vacuum state

International Journal of Modern Physics B ◽

10.1142/s0217979220502239 ◽

2020 ◽

Vol 34 (25) ◽

pp. 2050223

Author(s):

T. M. Duc ◽

T. Q. Dat ◽

H. S. Chuong

Keyword(s):

Quantum Entanglement ◽

Single Photon ◽

Vacuum State ◽

Addition Formula ◽

Squeezed Vacuum State ◽

Squeezed Vacuum ◽

Einstein Podolsky Rosen ◽

Quantum Steering ◽

Degree Of Entanglement ◽

Photon Addition

In this paper, a new state called superposition of multiple-photon-added two-mode squeezed vacuum state (SMPA-TMSVS) is introduced by adding the multiple photons to both modes of a two-mode squeezed vacuum state (TMSVS). We explicitly investigate the degree of quantum entanglement, the Einstein–Podolsky–Rosen (EPR) correlation and the quantum steering in the SMPA-TMSVS. The results show in the SMPA-TMSVS that the degree of entanglement and the EPR correlation can be enhanced by nonlocal adding photons to a TMSVS. The quantum steering appears in the SMPA-TMSVS in case the superposition of single-photon addition [Formula: see text], in which mode [Formula: see text] can steer mode [Formula: see text]. By using the SMPA-TMSVS as an entangled resource, the quantum teleportation process is studied in detail based on the Vaidman–Braunstein–Kimble (VBK) protocol.

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