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Coherent states for equally spaced, homogeneous waveguide arrays are defined, in the infinite, semiinfinite and finite cases, and resolutions of the identity are constructed, using different methods. In the infinite case, which corresponds…

Quantum Physics · Physics 2021-12-06 Julio Guerrero , Héctor M. Moya-Cessa

Suppose you receive a sequence of qubits where each qubit is guaranteed to be in one of two pure states, but you do not know what those states are. Your task is to determine the states. This can be viewed as a kind of quantum state learning…

We develop an approach of quantifying entanglement in mixed quantum states by the optimal entanglement witness operator. We identify the convex set of mixed states for which a single witness provides the exact value of an entanglement…

Quantum Physics · Physics 2012-03-07 S. -S. B. Lee , H. -S. Sim

Coherent structures emerge from the dynamics of many kinds of dissipative, externally driven, nonlinear systems, and continue to provoke new questions that challenge our physical and mathematical understanding. In one specific sub-class of…

Pattern Formation and Solitons · Physics 2010-08-24 Jonathan Dawes

We demonstrate how large classes of discrete and continuous statistical distributions can be incorporated into coherent states, using the concept of a reproducing kernel Hilbert space. Each family of coherent states is shown to contain, in…

Mathematical Physics · Physics 2009-11-13 S. Twareque Ali , J. -P. Gazeau , B. Heller

Can one certify the preparation of a coherent, many-body quantum state by measurements with bounded accuracy in the presence of noise and decoherence? Here, we introduce a criterion to assess the fragility of large-scale quantum states…

Quantum Physics · Physics 2013-11-15 Florian Fröwis , Maarten van den Nest , Wolfgang Dür

We study the problem of witnessing entanglement among indistinguishable particles. For this purpose, we derive a set of equations which results in necessary and sufficient conditions for probing multipartite entanglement between arbitrary…

Quantum Physics · Physics 2015-04-22 A. Reusch , J. Sperling , W. Vogel

We present a class of entanglement identifiers which has the following experimentally friendly feature: once the expectation value of the identifier exceeds some definite limit, we can conclude the state is entangled, even if not all…

Quantum Physics · Physics 2013-08-22 Wieslaw Laskowski , Marcin Markiewicz , Tomasz Paterek , Ryszard Weinar

We consider multipartite quantum state discrimination and show that the minimum-error discrimination by separable measurements is closely related to the concept of entanglement witness. Based on the properties of entanglement witness, we…

Quantum Physics · Physics 2023-04-25 Donghoon Ha , Jeong San Kim

We show that some sets of quantum observables are unique up to an isometry and have a contextuality witness that attains the same value for any initial state. We prove that these two properties make it possible to certify any of these sets…

Quantum Physics · Physics 2024-04-09 Zhen-Peng Xu , Debashis Saha , Kishor Bharti , Adán Cabello

A typical concept in quantum state analysis is based on the idea that states in the vicinity of some pure entangled state share the same properties; implying that states with a high fidelity must be entangled. States whose entanglement can…

Quantum Physics · Physics 2021-04-12 Otfried Gühne , Yuanyuan Mao , Xiao-Dong Yu

The discrimination of non-orthogonal quantum states with reduced or without errors is a fundamental task in quantum measurement theory. In this work, we investigate a quantum measurement strategy capable of discriminating two coherent…

Quantum Physics · Physics 2010-10-12 Christoffer Wittmann , Ulrik L. Andersen , Gerd Leuchs

In the first half we show an interesting relation between coherent states and the Bell states in the case of spin 1/2, which was suggested by Fivel. In the latter half we treat generalized coherent states and try to generalize this relation…

Quantum Physics · Physics 2007-05-23 Kazuyuki Fujii

Generalized coherent states are developed for SU(n) systems for arbitrary $n$. This is done by first iteratively determining explicit representations for the SU(n) coherent states, and then determining parametric representations useful for…

Quantum Physics · Physics 2009-11-06 Kae Nemoto

Quantum coherence is the key resource in quantum technologies including faster computing, secure communication and advanced sensing. Its quantification and detection are, therefore, paramount within the context of quantum information…

Quantum Physics · Physics 2024-05-21 Mao-Sheng Li , Wen Xu , Shao-Ming Fei , Zhu-Jun Zheng , Yan-Ling Wang

Entanglement witnesses are invaluable for efficient quantum entanglement certification without the need for expensive quantum state tomography. Yet, standard entanglement witnessing requires multiple measurements and its bounds can be…

Quantum Physics · Physics 2017-03-22 Farid Shahandeh , Martin Ringbauer , Juan C. Loredo , Timothy C. Ralph

Quantum coherence is important in quantum mechanics, and its essence is from superposition principle. We study the coherence of any two pure states and that of their arbitrary superposition, and obtain the relationship between them. In the…

Quantum Physics · Physics 2016-05-25 Qiu-Ling Yue , Chao-Hua Yu , Feng Liu , Xiao-Li Wang , Fei Gao , Qiao-Yan Wen

We present entanglement witnesses for detecting genuine multi-qubit entanglement. Our constructions are robust against noise and require only two local measurement settings, independent of the number of qubits. Thus they allow to verify…

Quantum Physics · Physics 2007-05-23 Geza Toth , Otfried Guehne

The separability problem is formulated in terms of a characterization of a single entanglement witness. More specifically, we show that any (in general multipartite) state \varrho is separable if and only if a specially constructed…

Quantum Physics · Physics 2016-08-17 Piotr Badziąg , Paweł Horodecki , Ryszard Horodecki , Remigiusz Augusiak

From the very beginning, coherent state path integrals have always relied on a coherent state resolution of unity for their construction. By choosing an inadmissible fiducial vector, a set of ``coherent states'' spans the same space but…

Quantum Physics · Physics 2007-05-23 John R. Klauder