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We give an explicit expression for the geometric measure of entanglement for three qubit states that are linear combinations of four orthogonal product states. It turns out that the geometric measure for these states has three different…

Quantum Physics · Physics 2008-09-03 Levon Tamaryan , DaeKil Park , Jin-Woo Son , Sayatnova Tamaryan

We propose and experimentally verify a scheme to engineer arbitrary states of traveling light field up to the two-photon level. The desired state is remotely prepared in the signal channel of spontaneous parametric down-conversion by means…

Quantum Physics · Physics 2015-05-14 Erwan Bimbard , Nitin Jain , Andrew MacRae , A. I. Lvovsky

We consider the mixed three-qubit bound entangled state defined as the normalized projector on the subspace that is complementary to an Unextendible Product Basis [C. H. Bennett et. al., Phys. Rev. Lett. 82, 5385 (1999)]. Using the fact…

Quantum Physics · Physics 2010-07-28 Cyril Branciard , Huangjun Zhu , Lin Chen , Valerio Scarani

Quantum computers have the potential to solve certain interesting problems significantly faster than classical computers. To exploit the power of a quantum computation it is necessary to perform inter-qubit operations and generate entangled…

Mesoscale and Nanoscale Physics · Physics 2013-04-09 Michael D. Shulman , Oliver E. Dial , Shannon P. Harvey , Hendrik Bluhm , Vladimir Umansky , Amir Yacoby

We consider a device which can be programmed using coherent states of light to approximate a given projective measurement on an input coherent state. We provide and discuss three practical implementations of this programmable projective…

Quantum Physics · Physics 2022-07-26 Niraj Kumar , Ulysse Chabaud , Elham Kashefi , Damian Markham , Eleni Diamanti

Entanglement is a key ingredient for quantum technologies and a fundamental signature of quantumness in a broad range of phenomena encompassing many-body physics, thermodynamics, cosmology, and life sciences. For arbitrary multiparticle…

Quantum Physics · Physics 2016-10-24 Marco Cianciaruso , Thomas R. Bromley , Gerardo Adesso

We introduce a new measure for the genuinely N-partite (all-party) entanglement of N-qubit states using the trace distance metric, and find an algebraic formula for the GHZ-diagonal states. We then use this formula to show how the all-party…

Quantum Physics · Physics 2014-01-06 S. M. Hashemi Rafsanjani , C. J. Broadbent , J. H. Eberly

We construct a linear optics measurement process to determine the entanglement measure, named \emph{I-concurrence}, of a set of $4 \times 4$ dimensional two-photon entangled pure states produced in the optical parametric down conversion…

Quantum Physics · Physics 2007-11-20 F. W. Sun , J. M. Cai , J. S. Xu , G. Chen , B. H. Liu , C. F. Li , Z. W. Zhou , G. C. Guo

Despite an apparent progress in implementing individual solid-state qubits, there have been no experimental reports so far on multi-bit gates required for building a real quantum computer. Here we report a new circuit comprising two coupled…

Mesoscale and Nanoscale Physics · Physics 2010-04-20 Yu. A. Pashkin , T. Yamamoto , O. Astafiev , Y. Nakamura , D. V. Averin , J. S. Tsai

Self-testing is a powerful device-independent technique that enables one to deduce the forms of both the quantum state and the measurements involved in a physical experiment based solely on observed correlations. Although numerous schemes…

Quantum Physics · Physics 2025-08-22 Arturo Konderak , Wojciech Bruzda , Remigiusz Augusiak

We describe a protocol capable of preparing an arbitrary state of two photons in several spatial modes using pairs of photons generated by spontaneous parametric down-conversion, linear optical elements and single-photon detectors or…

Quantum Physics · Physics 2009-11-13 Karel Lemr , Jaromir Fiurasek

The experimental realization of many-body entangled states is one of the main goals of quantum technology as these states are a key resource for quantum computation and quantum sensing. However, increasing the number of photons in an…

Quantum Physics · Physics 2017-02-08 Y. Pilnyak , N. Aharon , D. Istrati , E. Megidish , A. Retzker , H. S. Eisenberg

The act of measuring optical emissions from two remote qubits can entangle them. By demanding that a photon from each qubit reaches the detectors, one can ensure than no photon was lost. But the failure rate then rises quadratically with…

Quantum Physics · Physics 2009-06-09 Earl T. Campbell , Simon C. Benjamin

A new method is developed to derive an algebraic equations for the geometric measure of entanglement of three qubit pure states. The equations are derived explicitly and solved in cases of most interest. These equations allow oneself to…

Quantum Physics · Physics 2008-03-01 Levon Tamaryan , DaeKil Park , Sayatnova Tamaryan

Entangled measurement is a crucial tool in quantum technology. We propose a new entanglement measure of multi-mode detection, which estimates the amount of entanglement that can be created in a measurement. To illustrate the proposed…

We propose an entanglement purification scheme based on material qubits and ancillary coherent multiphoton states. We consider a typical QED scenario where material qubits implemented by two-level atoms fly sequentially through a cavity and…

Quantum Physics · Physics 2016-03-14 József Zsolt Bernád , Juan Mauricio Torres , Ludwig Kunz , Gernot Alber

In this paper, I will discuss the geometrical structures of multipartite quantum systems based on complex projective schemes. In particular, I will explicitly construct multi-qubit states in terms of these schemes and also discuss…

Quantum Physics · Physics 2015-05-13 Hoshang Heydari

We propose an experimental method to measure the entanglement of coupled spins, each in a separate quantum dot, by means of multiphoton interference patterns generated through the scattering of two laser beams off the quantum dots. We…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Michael N. Leuenberger , Michael E. Flatte , D. D. Awschalom

We propose a scalable approach to building cluster states of matter qubits using coherent states of light. Recent work on the subject relies on the use of single photonic qubits in the measurement process. These schemes have a low initial…

Quantum Physics · Physics 2009-11-13 Sebastien G. R. Louis , Kae Nemoto , W. J. Munro , T. P. Spiller

We propose a method to prepare entangled states and implement quantum computation with atoms in optical cavities. The internal state of the atoms are entangled by a measurement of the phase of light transmitted through the cavity. By…

Quantum Physics · Physics 2009-11-10 Anders S. Sorensen , Klaus Molmer