Quantum entanglement with Freedman's inequality

Brody, Jed; Selton, Charlotte

doi:10.1119/1.5036619

Cited by 6 publications

(16 citation statements)

References 21 publications

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“…Beyond the standard CHSH Bell test which requires 16 measurements, the so-called Freedman's inequality [79] , [80] requires only 3 coincidence measurements with very simpler mathematical calculations and experiment, more understandable from the philosophical aspects and simpler physical interpretation, notably for undergraduate students in quantum optics Laboratories.…”

Section: Resultsmentioning

confidence: 99%

“…Freedman's inequality can be quantified by Freedman parameter F which is defined as (to see full details of derivation of Freedman's inequality, see Refs. [79,80])…”

Section: Freedman's Testmentioning

confidence: 99%

“…Let us consider Bell state | (−) Bell ⟩ in Eq. (1), it can be easily shown that the coincidence count can be obtained as [2,12,77,79,80]…”

Section: Freedman's Testmentioning

confidence: 99%

“…As theory predicted for entangled state for Φ = 22.5 • and 67.5 • , Freedman parameter becomes positive which shows a strong violation. It should be mentioned that to calculate the error in Freedman parameter, we have used relation [80] Bell ⟩. To reconstruct the physical nonnegative density operator, we follow the generalized method of qubit measurement in Ref.…”

Section: Freedman's Testmentioning

confidence: 99%

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Nonlocal realism tests and quantum state tomography in Sagnac-based type-II polarization-entanglement SPDC-source

Motazedifard

Madani

Dashkasan

et al. 2021

Heliyon

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We have experimentally created a robust, ultrabright and phase-stable polarization-entangled state close to maximally entangled Bell-state with %98-fidelity using the type-II spontaneous parametric down-conversion (SPDC) process in periodically-poled KTiOPO 4 (PPKTP) collinear crystal inside a Sagnac interferometer (SI). Bell inequality measurement, Freedman's test, as the different versions of CHSH inequality, and also visibility test which all can be seen as the nonlocal realism tests, imply that our created entangled state shows a strong violation from the classical physics or any hidden-variable theory. We have obtained very reliable and very strong Bell violation as = 2.78 ± 0.01 with high brightness  HV = %(99.969 ± 0.003) and  DA = %(96.751 ± 0.002) and very strong violation due to Freedman test as F = 0.01715 ± 0.00001. Furthermore, using the tomographic reconstruction of quantum states together a maximum-likelihood-technique (MLT) as the numerical optimization, we obtain the physical non-negative definite density operator which shows the nonseparability and entanglement of our prepared state. By having the maximum likelihood density operator, we calculate some important entanglement-measures and entanglement entropies. The Sagnac configuration provides bidirectional crystal pumping yields to high-rate entanglement source which is very applicable in quantum communication, sensing and metrology as well as quantum information protocols, and has potential to be used in quantum illuminationbased LIDAR and free-space quantum key distribution (QKD).

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Section: Resultsmentioning

confidence: 99%

“…Freedman's inequality can be quantified by Freedman parameter F which is defined as (to see full details of derivation of Freedman's inequality, see Refs. [79,80])…”

Section: Freedman's Testmentioning

confidence: 99%

“…Let us consider Bell state | (−) Bell ⟩ in Eq. (1), it can be easily shown that the coincidence count can be obtained as [2,12,77,79,80]…”

Section: Freedman's Testmentioning

confidence: 99%

Section: Freedman's Testmentioning

confidence: 99%

See 2 more Smart Citations

Nonlocal realism tests and quantum state tomography in Sagnac-based type-II polarization-entanglement SPDC-source

Motazedifard

Madani

Dashkasan

et al. 2021

Heliyon

View full text Add to dashboard Cite

show abstract

“…On the other hand, the Field-Programmable Gated Arrays (FPGAs) [16] are not common in the practical activities of the laboratories for physics teaching and a few papers were found in our search [17,18]. The main reason may be the challenge of introducing a new component in the experimental activities of these laboratories.…”

Section: Related Workmentioning

confidence: 99%

Introducing programmable logic devices in physics laboratories: a practical guide for the implementation of experiments

Runge

Cerqueira

Arnold

2020

Rev. Bras. Ensino Fís.

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Modern electronic instrumentation techniques are being introduced in the programs of the Physics and Physical Engineering courses and, in this context, the programmable logic devices play an important role. We present the fundamental steps for the design, development, and validation of systems based on programmable logic devices. Two digital filters have been implemented for illustrating the guide procedures. The results show that the function-response complies with the common requirements of generic filter performance. This work is targeted at students and lectures and aims stimulate and challenge them to develop electronic instrumentation using programmable logic devices in teaching activities.

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Quantum no-cloning theorem and entanglement

Kuzyk

2019

American Journal of Physics

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The article by Ortigoso [1] describes the history of the quantum no-cloning theorem, [2,3] arguing that Jim Park discovered it 12 years prior to 1982. [4] Given that AJP is dedicated to pedagogy, I am writing to recast the state vectors given by Ortigoso in a form that reflects the required statistics of indistinguishable particles, which might be less confusing to students. This more precise form also applies to entanglement, which I believe is often described in a way that implies that identical particles may sometimes be excused from spin statistics. Here I describe both.Cloning means making an exact copy, where two identical systems result; the original and the copy. Consider a single particle in state |φ that is cloned, leaving the two-particle state |φ |φ . This state is nonsensical for a fermion, which forbids two particles from occupying the same state.The resolution is to start with a particle here whose state we wish to duplicate there. Rather than expressing the initial state of the two identical particles as |φ |0 , where the state |φ is to be copied according to the operation T |φ |0 → |φ |φ , the initial two-particle state |φ h , 0 t with exchange symmetry is given bywhere the subscripts h and t refer to here and there and the ± signs designate bosons/fermions. The first ket represents Particle #1 and the second ket Particle #2. Note that we use the convention that |φ h |0 t represents a direct product while |φ h , 0 t is the symmetrized form as given by Eq.(1). The two occupied states can be identical for bosons, such as |φ, φ = |φ |φ , but will generally be different. Eq.(1) implicitly assumes that states here are orthogonal to states there, or φ h | φ t = 0. If here and there represent two spatial regions separated by an infinite barrier, then the two locations span a space that is orthogonal to the internal states, so |φ h can be separated into a direct product of the form |φ h = |φ |h . Then, Eq. (1) can be expressed aswhere the subscripts 1 and 2 remind us that the direct product within parentheses reefers to Particle #1 and #2, respectively; and where we have regrouped the terms on the last line.When cloning yields two particles in the same "internal" state but at two different locations, the definition of the cloning operation must beEqs. (1) and (3) define the action of the cloning operation to bewhich does not imply that T |φ h |0 t → |φ h |φ t . If this were so,which clearly is not a clone. As such, the cloning operator cannot act on just a single direct product of state vectors but must operate on the symmetrized state vector. The cloned state in Eq.(3), written in the form given by Eq. (2), separates into the productEq. (6) illustrates how the form |φ |φ generally used by researchers refers to the internal part of the state vector and the exchange symmetry is contained in the second term, which is not explicitly stated but implicitly assumed. However, the initial state vector prior to cloning given by Eq.(2) cannot be separated into an internal and external part, so |φ |0 is nonsensical...

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Quantum entanglement with Freedman's inequality

Cited by 6 publications

References 21 publications

Nonlocal realism tests and quantum state tomography in Sagnac-based type-II polarization-entanglement SPDC-source

Nonlocal realism tests and quantum state tomography in Sagnac-based type-II polarization-entanglement SPDC-source

Introducing programmable logic devices in physics laboratories: a practical guide for the implementation of experiments

Quantum no-cloning theorem and entanglement

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