Entanglement swapping between photons that have never coexisted.

  title={Entanglement swapping between photons that have never coexisted.},
  author={Eli Megidish and A. Halevy and Tomer Shacham and Tom Dvir and L. Dovrat and H S Eisenberg},
  journal={Physical review letters},
  volume={110 21},
The role of the timing and order of quantum measurements is not just a fundamental question of quantum mechanics, but also a puzzling one. Any part of a quantum system that has finished evolving can be measured immediately or saved for later, without affecting the final results, regardless of the continued evolution of the rest of the system. In addition, the nonlocality of quantum mechanics, as manifested by entanglement, does not apply only to particles with spacelike separation, but also to… 

Figures from this paper

Dissipative entanglement swapping in the presence of detuning and Kerr medium: Bell state measurement method
Abstract.In this paper, we investigate the possibility of entanglement swapping between two independent nonperfect cavities consisting of an atom with finite lifetime of atomic levels (as two
Quantum entanglement: Bell's inequality trivially violated also classically
Quantum entanglement manifests in the perfect correlation between particles or photons separated by space and time beyond causal interference. However, classical covariance between vectorial
Entanglement swapping with autonomous polarization-entangled photon pairs from a warm atomic ensemble.
This work experimentally demonstrate entanglement swapping between two independent polarization-entangled photon-pair sources obtained via spontaneous four-wave mixing in a Doppler-broadened atomic ensemble of 87Rb atoms.
Entanglement Swapping with Semiconductor-Generated Photons Violates Bell's Inequality.
This work shows for the first time swapping of entangled states between two pairs of photons emitted by a single dot, and heralds the successful generation of the Bell state Ψ^{+}, yielding a fidelity of 0.81±0.04.
A Loss Resilient Entanglement Swapping Protocol using Non-Classical States of Light
This thesis presents two possible entanglement swapping protocols, and shows that these protocols are resilient to small levels of photonic losses, and proposes the use of these protocols in quantum communication schemes that require shared entangled qubits, in the form of a Bell state.
Generalized quantum interference of correlated photon pairs
The experimental demonstrations of the generalized two-photon interferometry with both the interferometric properties of the Hong-Ou-Mandel effect and the fully unfolded version of the path-entangled photon number state using photon-pair sources, which are independently generated by spontaneous parametric down-conversion.
Taking tomographic measurements for photonic qubits 88 ns before they are created
We experimentally demonstrate that tomographic measurements can be performed for states of qubits before they are prepared. A variant of the quantum teleportation protocol is used as a channel


Entangling independent photons by time measurement
Entanglement is at the heart of quantum physics, both for its conceptual foundations and for applications in quantum communication. Remarkably, entanglement can be ‘swapped’: if we prepare two
Experimental Entanglement Swapping: Entangling Photons That Never Interacted
We experimentally entangle freely propagating particles that never physically interacted with one another or which have never been dynamically coupled by any other means. This demonstrates that
Multistage entanglement swapping.
By successful realizations of two cascaded photonic entanglement swapping processes,Entanglement is generated and distributed between two photons, that originate from independent sources and do not share any common past.
Extraction of timelike entanglement from the quantum vacuum
An intriguing property of the massless quantum vacuum state is that it contains entanglement between both spacelike and timelike separated regions of space-time. The implications of timelike
Measurement of qubits
We describe in detail the theory underpinning the measurement of density matrices of a pair of quantum two-level systems ~‘‘qubits’’ !. Our particular emphasis is on qubits realized by the two
Quantum entanglement of a large number of photons.
A bipartite multiphoton entangled state is created through stimulated parametric down-conversion of strong laser pulses in a nonlinear crystal. It is shown how detectors that do not resolve the
Resource efficient source of multiphoton polarization entanglement.
This work presents a new approach that generates quantum entanglement between many photons, using only a single source of entangled photon pairs, solving the scalability problem caused by the previous need for extra resources.
Entanglement of Formation of an Arbitrary State of Two Qubits
The entanglement of a pure state of a pair of quantum systems is defined as the entropy of either member of the pair. The entanglement of formation of a mixed state is defined as the minimum average
Quantum correlations with no causal order
It is shown that in a classical limit causal order always arises, which suggests that space-time may emerge from a more fundamental structure in a quantum-to-classical transition.
Experimental realization of a photonic Bell-state analyzer
Efficient teleportation is a crucial step for quantum computation and quantum networking. In the case of qubits, four different entangled Bell states have to be distinguished. We have realized a