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We report on the usage of a linear optics phase gate for distinguishing all four Bell states simultaneously in a quantum teleportation and entanglement swapping protocol. This is demonstrated by full state tomography of the one and two…

The Bell theorem stands as an insuperable roadblock in the path to a very desired intuitive solution of the EPR paradox and, hence, it lies at the core of the current lack of a clear interpretation of the quantum formalism. The theorem…

Quantum Physics · Physics 2022-02-22 David H. Oaknin

A recent experiment presented, for photons, the first violation of a Bell inequality closing the fair-sampling loophole, i.e., without having to assume that the sample of measured photons fairly represents the entire ensemble. In this note,…

Quantum Physics · Physics 2013-07-25 Johannes Kofler , Sven Ramelow , Marissa Giustina , Anton Zeilinger

We find that Bell's inequality can be significantly violated (up to Tsirelson's bound) with two-mode entangled coherent states using only homodyne measurements. This requires Kerr nonlinear interactions for local operations on the entangled…

Quantum Physics · Physics 2007-06-13 Magdalena Stobińska , Hyunseok Jeong , Timothy C. Ralph

We use hyper-entanglement to experimentally realize deterministic entanglement swapping based on quantum Elegant Joint Measurements. These are joint projections of two qubits onto highly symmetric, iso-entangled, bases. We report…

Bell inequalities and nonlocality have been widely studied in one-dimensional quantum systems. As a kind of quantum correlation, it is expected that bipartite nonlocaity should be present in quantum systems, just as bipartite entanglement…

Quantum Physics · Physics 2015-06-16 Zhao-Yu Sun , Yu-Ying Wu , Hai-Lin Huang , Bo-Jun Chen , Bo Wang

In recent decades, quantum technologies have made significant strides toward achieving quantum utility. However, practical applications are hindered by challenges related to scaling the number of qubits and the depth of circuits. In this…

Quantum Physics · Physics 2025-10-01 Pingal Pratyush Nath , Aninda Sinha , Urbasi Sinha

For a system composed of two particles Bell's theorem asserts that averages of physical quantities determined from local variables must conform to a family of inequalities. In this work we show that a classical model containing a local…

Quantum Physics · Physics 2008-06-22 A. Matzkin

The implementation of quantum gates with fidelities that exceed the threshold for reliable quantum computing requires robust gates whose performance is not limited by the precision of the available control fields. The performance of these…

Quantum Physics · Physics 2015-12-30 Alexandre M. Souza , Roberto S. Sarthour , Ivan S. Oliveira , Dieter Suter

Universal quantum computation will require qubit technology based on a scalable platform, together with quantum error correction protocols that place strict limits on the maximum infidelities for one- and two-qubit gate operations. While a…

We present new bell inequalities for arbitrary dimensional bipartite quantum systems. The maximal violation of the inequalities is computed. The Bell inequality is capable of detecting quantum entanglement of both pure and mixed quantum…

Quantum Physics · Physics 2015-05-27 Ming Li , Shao-Ming Fei , Xianqing Li-Jost

Using the concept of non-degenerate Bell inequality, we show that quantum entanglement, the critical resource for various quantum information processing tasks, can be quantified for any unknown quantum states in a semi-device-independent…

In the present article, based on the formalism introduced in [Loubenets, J. Math. Phys. 53, 022201 (2012)], we derive for a pure bipartite quantum state a new upper bound on its maximal violation of general Bell inequalities. This new bound…

Quantum Physics · Physics 2021-10-19 Elena R. Loubenets , Min Namkung

We demonstrate high fidelity two-qubit Rydberg blockade and entanglement in a two-dimensional qubit array. The qubit array is defined by a grid of blue detuned lines of light with 121 sites for trapping atomic qubits. Improved experimental…

Quantum Physics · Physics 2019-12-11 T. M. Graham , M. Kwon , B. Grinkemeyer , Z. Marra , X. Jiang , M. T. Lichtman , Y. Sun , M. Ebert , M. Saffman

In this paper we obtain violations of general bipartite Bell inequalities of order $\frac{\sqrt{n}}{\log n}$ with $n$ inputs, $n$ outputs and $n$-dimensional Hilbert spaces. Moreover, we construct explicitly, up to a random choice of signs,…

Quantum Physics · Physics 2011-08-30 Marius Junge , Carlos Palazuelos

High-dimensional quantum entanglement is drawing attention because it enables us to perform quantum information tasks that are robust against noises. To test the nonlocality of entangled qudits, the Collins-Gisin-Linden-Massar-Popescu…

Quantum Physics · Physics 2016-02-05 Takuya Ikuta , Hiroki Takesue

For a special stochastic realistic model in certain spin-correlation experiments and without imposing the locality condition, an inequality is found. Then, it is shown that quantum theory is able (is possible) to violate this inequality.…

Quantum Physics · Physics 2007-05-23 Habibollah Razmi

Certification of quantum nonlocality plays a central role in practical applications like device-independent quantum cryptography and random number generation protocols. These applications entail the challenging problem of certifying quantum…

Quantum Physics · Physics 2021-07-21 S. Gómez , D. Uzcategui , I. Machuca , E. S. Gómez , S. P. Walborn , G. Lima , D. Goyeneche

For a multipartite quantum state, the maximal violation of all Bell inequalities constitutes a measure of its nonlocality [Loubenets, J. Math. Phys. 53, 022201 (2012)]. In the present article, for the maximal violation of Bell inequalities…

Quantum Physics · Physics 2022-07-06 Elena R. Loubenets , Min Namkung

Quantum steering can be detected via the violation of steering inequalities, which provide sufficient conditions for the steerability of quantum states. Here we discuss the converse problem, namely ensuring that a state is unsteerable, and…

Quantum Physics · Physics 2016-03-21 Joseph Bowles , Flavien Hirsch , Marco Túlio Quintino , Nicolas Brunner