# 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}
}
• Published 21 April 2016
• Physics
• Science
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

• Physics
Science
• 2014
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

• Physics
• 2009
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

• Physics
Nature
• 2009
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

• Physics
Science
• 2012
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

• Physics
Nature
• 2010
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

• Physics
• 2008
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

• Physics
Nature
• 2010
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.

• Physics
Physical review. A, Atomic, molecular, and optical physics
• 1994
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

• Physics
• 2012
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

• Physics
• 2013
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