- 标题
- 摘要
- 关键词
- 实验方案
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Entanglement generation between distant parties via disordered spin chains
摘要： We study the emergence of bipartite entanglement between a pair of spins weakly connected to the ends of a linear disordered X Y spin-1/2 channel. We analyze how their concurrence responds to structural and on-site fluctuations embodied by long-range spatially-correlated sequences. We show that the end-to-end entanglement is very robust against disorder and asymmetries in the channel provided that the degree of correlations are strong enough and both entangling parties are tuned accordingly. Our results offer further alternatives in the design of stable quantum communication protocols via imperfect spin channels.
关键词： Quantum entanglement,Quantum state transfer,Anderson localization
更新于2025-09-23 15:23:52
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The Quantum Dense Coding in a Two Atomic System Under the Non-Markovian Environment
摘要： The quantum dense coding in a two atomic system under the non-Markovian environment is investigated in detail. We mainly concentrate on the effects about the environment parameter (cid:2)(or γ ) and the purity r of the initial state on the dense coding capacity χ . It is found that the dense coding capacity χ is initially decreased and gradually trends to be a constant nonzero value with evolution of time for different environment parameter (cid:2)(or γ ). This constant value is determined the initial state and independent to the environment. In other word, environment noise only affects the process of quantum dense coding, but not affects the final result of dense coding capacity. The purity r of the initial state has a strong influence on the initial value of the χ . Besides, for one value r, dense coding capacity χ is decreased firstly, and then reaches a stable value for a long time, whatever the values of other parameters are, but when the purity r of the initial state increased, the initial value of dense coding capacity increased.
关键词： Quantum entanglement,The non-Markovian environment,Quantum dense encoding,Two atomic system
更新于2025-09-23 15:21:21
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Resource state structure for controlled quantum key distribution
摘要： Quantum entanglement plays a pivotal role in many communication protocols, like secret sharing and quantum cryptography. We consider a scenario where more than two parties are involved in a protocol and share a multipartite entangled state. In particular, we considered the protocol of Controlled Quantum Key Distribution (CoQKD), introduced in the reference H. Chao, X. Peng, and G. G-Can, Chin. Phys. Lett. 20, 183 (2003), where, two parties, Alice and Bob establish a key with the cooperation of other parties. Other parties control/supervise whether Alice and Bob can establish the key, its security and key rate. We discuss the case of three parties in detail and find suitable resource states. We discuss the controlling power of the third party, Charlie. We also examine the usefulness of the new resource states for generating conference key and for cooperative teleportation. We find that recently introduced Bell inequalities can be useful to establish the security of the conference key. We also generalize the scenario to more than three parties.
关键词： conference key,cooperative teleportation,Bell inequalities,CoQKD,Quantum entanglement,Controlled Quantum Key Distribution
更新于2025-09-23 15:21:01
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Entanglement teleportation with photons from quantum dots: towards a solid-state based quantum network
摘要： Semiconductor quantum dots are currently emerging as one of the most promising sources of non-classical light on which to base future quantum networks. They can generate single photons as well as pairs of entangled photons with unprecedented brightness, indistinguishability, and degree of entanglement. These features have very recently opened up the possibility to perform advanced quantum optics protocols that were previously inaccessible to single quantum emitters. In this work, we report on two experiments that use the non-local properties of entanglement to teleport quantum states: three-photon state teleportation and four-photon entanglement teleportation. We discuss all the experimental results in light of a theoretical model that we develop to account for the non-idealities of the quantum source. The excellent agreement between theory and experiment enables a deep understanding of how each parameter of the source affects the teleportation fidelities and it pinpoints the requirements needed to overcome the classical limits. Finally, our model suggests how to further improve quantum-dot entangled-photon sources for practical quantum networks.
关键词： quantum teleportation,entanglement swapping,quantum optics,semiconductor physics,quantum entanglement,quantum dot
更新于2025-09-23 15:19:57
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Experimental demonstration of one-sided device-independent self-testing of any pure two-qubit entangled state
摘要： We demonstrate one-sided device-independent self-testing of any pure two-qubit entangled state based on a fine-grained steering inequality. The maximum violation of a fine-grained steering inequality can be used to witness certain steerable correlations, which certify all pure two-qubit entangled states. Our experimental results identify which particular pure two-qubit entangled state has been self-tested and which measurement operators are used on the untrusted side. Furthermore, we analytically derive the robustness bound of our protocol, enabling our subsequent experimental verification of robustness through state tomography. Finally, we ensure that the requisite no-signaling constraints are maintained in the experiment.
关键词： device-independent,two-qubit state,self-testing,steering inequality,quantum entanglement
更新于2025-09-23 15:19:57
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Quantum information capsule and information delocalization by entanglement in multiple-qubit systems
摘要： Where do entangled multiple-qubit systems store information? For information injected into a qubit, this question is nontrivial and interesting since the entanglement delocalizes the information. So far, a common picture is that of a qubit and its purification partner sharing the information quantum mechanically. Here, we introduce a new picture of a single qubit in the correlation space, referred to as quantum information capsule (QIC), confining the information perfectly. This picture is applicable for the entangled multiple-qubit system in an arbitrary state. Unlike the partner picture, in the QIC picture, by swapping the single-body state, leaving other subsystems untouched, the whole information can be retrieved out of the system. After the swapping process, no information remains in the system.
关键词： Quantum information,Quantum memory,Black hole information loss problem,Quantum entanglement
更新于2025-09-19 17:15:36
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Operational symmetries of entangled states
摘要： Quantum entanglement obscures the notion of local operations; there exist quantum states for which all local actions on one subsystem can be equivalently realized by actions on another. We characterize the states for which this fundamental property of entanglement does and does not hold, including multipartite and mixed states. Our results lead to a method for quantifying entanglement based on operational symmetries and has connections to quantum steering, envariance, the Reeh–Schlieder theorem, and classical entanglement.
关键词： entanglement manipulation,entanglement in field theory,quantum entanglement,entanglement measures,quantum nonlocality
更新于2025-09-19 17:13:59
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Interaction between Microwave and Mesoscopic Circuits in Cavity-circuit Quantum Electrodynamics
摘要： Mesoscopic electric circuits can exhibit a large number of effects relevant to quantum mechanics, quantum electrodynamics and quantum statistics. The topic presented here can be identified as an analog of conventional cavity quantum electrodynamics, where the quantum objects are multilevel atoms and quantized optical fields (photons), namely, a theoretical subject called “cavity-circuit quantum electrodynamics”, where the atoms are replaced with quantum mesoscopic circuits, will be developed. We will study the quantum characteristics of the interaction between the quantum mesoscopic circuits and the quantized electromagnetic field at microwave frequencies. These issues include quantum entangled eigenstates of two coupled mesoscopic circuits, time evolution of the circuit energy quanta (governed by the time-dependent Schr?dinger equation) and entanglement transfer between external photons and mesoscopic circuit energy quanta. Since there is inevitable electromagnetic interaction such as mutual capacitance and inductance coupling between two neighboring circuits, the quantum effects resulting from the aforementioned quantized circuit coupling would unavoidably affect the relevant processes in quantum computing devices and hence they deserve consideration in some issues of quantum information.
关键词： Quantum computing,Microwave photons,Quantum entanglement,Mesoscopic circuits,Quantum electrodynamics
更新于2025-09-19 17:13:59
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Quantum collapse as reduction from a continuum of conditional amplitudes in an entangled state to a single actualized amplitude in the collapsed state
摘要： According to the Copenhagen interpretation of quantum mechanics a measurement leads to the collapse of a quantum system. A uni?ed description of a quantum system before and after measurement of the position ra1 and the spin sa1 of one of its electrons is proposed based on the conditional amplitude and its density. Quantum collapse is described as reduction from continuum of the conditional amplitudes {(cid:2)(x2, . . . , xN |rh1 )} in an initial quantum state to the single actualized amplitude (cid:2)(x2, . . . , xN |ra1 ) in a collapsed state. The latter state contains the information about quantum entanglement, the extraction of which with fragment entanglement measure is demonstrated for the realistic valence bond models of the dissociating dihydrogen and ethylene molecules.
关键词： ethylene molecules,quantum collapse,dihydrogen,conditional amplitude,quantum entanglement,valence bond models
更新于2025-09-19 17:13:59
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Error correction of polarization entanglement in hyper-entangled state
摘要： We present two schemes for error-correction of polarization entanglement with time-bin entanglement and frequency entanglement in hyper-entangled state. In these two protocols, by performing the polarization parity-check operation, the bit-flip and phase-flip errors on the polarization part can be corrected and eliminated in one step. The parties in quantum communication can obtain a maximally hyper-entangled states in two degrees of freedom in a deterministic way. Our protocols for purification are useful in practical applications for long-distance quantum communication.
关键词： quantum communication,hyper-entangled state,error correction,polarization parity-check operation,quantum entanglement
更新于2025-09-19 17:13:59