Bell correlations in a Bose-Einstein condensate

@article{Schmied2016BellCI,
  title={Bell correlations in a Bose-Einstein condensate},
  author={Roman Schmied and Jean-Daniel Bancal and Baptiste Allard and Matteo Fadel and Valerio Scarani and Philipp Treutlein and Nicolas Sangouard},
  journal={Science},
  year={2016},
  volume={352},
  pages={441 - 444}
}
Correlating an atomic condensate Parts of a quantum system can be more “correlated” than what is allowed in the everyday classical world: A measurement on one part of the system can immediately affect a spatially distant component. The strongest of such correlations, Bell correlations, have been detected in small systems containing two to a handful of particles. Schmied et al. used collective measurements to detect Bell correlations among the spins of 480 Rb atoms cooled to a condensed state… 

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References

SHOWING 1-10 OF 34 REFERENCES

Detecting nonlocality in many-body quantum states

TLDR
A simplified, experimentally accessible form of Bell inequalities is derived and can be tested by measuring total spin components, opening the way to the experimental detection of many-body nonlocality, for instance with atomic ensembles.

Coherent manipulation of Bose–Einstein condensates with state-dependent microwave potentials on an atom chip

Entanglement-based technologies, such as quantum information processing, quantum simulations and quantum-enhanced metrology, have the potential to revolutionize our way of computing and measuring,

Violation of Bell's inequality in Josephson phase qubits

TLDR
This experiment uses a pair of Josephson phase qubits acting as spin-1/2 particles, and shows that the qubits can be entangled and measured so as to violate the Clauser–Horne–Shimony–Holt (CHSH) version of the Bell inequality.

Heralded Entanglement Between Widely Separated Atoms

TLDR
The creation and analysis of heralded entanglement between spins of two single rubidium-87 atoms trapped independently 20 meters apart is reported on, illustrating the viability of an integral resource for quantum information science, as well as for fundamental tests of quantum mechanics.

Atom-chip-based generation of entanglement for quantum metrology

TLDR
The experimental generation of multi-particle entanglement on an atom chip is reported by controlling elastic collisional interactions with a state-dependent potential to generate spin-squeezed states of a two-component Bose–Einstein condensate; such states are a useful resource for quantum metrology.

Entanglement in many-body systems

Recent interest in aspects common to quantum information and condensed matter has prompted a flurry of activity at the border of these disciplines that were far distant until a few years ago.

Nonlinear atom interferometer surpasses classical precision limit

TLDR
It is shown experimentally that the classical precision limit can be surpassed using nonlinear atom interferometry with a Bose–Einstein condensate and the results provide information on the many-particle quantum state, and imply the entanglement of 170 atoms.

Squeezed atomic states and projection noise in spectroscopy.

TLDR
If the particles are first prepared in particular quantum-mechanically correlated states, it is found that the signal-to-noise ratio can be improved over the case of initially uncorrelated particles, and a squeezing parameter is introduced which quantifies the sensitivity of an angular-momentum state to rotation.

Entanglement and extreme spin squeezing for a fluctuating number of indistinguishable particles

We extend the criteria for $k$-particle entanglement from the spin squeezing parameter presented in [A.S. S{\o}rensen and K. M{\o}lmer, Phys. Rev. Lett. {\bf 86}, 4431 (2001)] to systems with a

Detecting non-locality in multipartite quantum systems with two-body correlation functions

Bell inequalities define experimentally observable quantities to detect non-locality. In general, they involve correlation functions of all the parties. Unfortunately, these measurements are hard to