# 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…

## 119 Citations

### Bell correlations between spatially separated pairs of atoms

- PhysicsNature Communications
- 2019

The authors generate spatially separated pairs of helium atoms by colliding Bose-Einstein condensates and show that they are entangled by observing nonlocal correlations, and observe a quantum mechanical witness of Bell correlations with 6σ significance.

### Two-mode entanglement in spin and spatial degrees of freedom

- Physics
- 2018

The predictions of quantum mechanics often differ from our everyday experiences. In the classical case, the state of a system can be predicted precisely, assuming the exact knowledge of all…

### Spatial entanglement patterns and Einstein-Podolsky-Rosen steering in Bose-Einstein condensates

- PhysicsScience
- 2018

High-resolution imaging is used to directly measure the spin correlations between spatially separated parts of a spin-squeezed Bose-Einstein condensate and observes entanglement that is strong enough for Einstein-Podolsky-Rosen steering: The authors can predict measurement outcomes for noncommuting observables in one spatial region on the basis of corresponding measurements in another region with an inferred uncertainty product below the Heisenberg uncertainty bound.

### Bell Inequality, Einstein-Podolsky-Rosen Steering, and Quantum Metrology with Spinor Bose-Einstein Condensates.

- PhysicsPhysical review letters
- 2018

It is shown how the degree of violation of the Bell inequality depends on the strengths of the two-body correlations and on the number of scattered pairs, and that the system can be used to demonstrate the Einstein-Podolsky-Rosen paradox.

### Fundamental Limit of Phase Coherence in Two-Component Bose-Einstein Condensates.

- PhysicsPhysical review letters
- 2020

We experimentally and theoretically study phase coherence in two-component Bose-Einstein condensates of ^{87}Rb atoms on an atom chip. Using Ramsey interferometry we determine the temporal decay of…

### Mesoscopic and macroscopic quantum correlations in photonic, atomic and optomechanical systems

- Physics
- 2021

This paper reviews the progress that has been made in our knowledge of quantum correlations at the mesoscopic and macroscopic level. We begin by summarizing the Einstein-Podolsky-Rosen (EPR) argument…

### Entanglement between two spatially separated atomic modes

- PhysicsScience
- 2018

The generation of entanglement between two spatially separated clouds is presented by splitting an ensemble of ultracold identical particles prepared in a twin Fock state: because the clouds can be addressed individually, the experiments open a path to exploit the available entangled states of indistinguishable particles for quantum information applications.

### Many-body Bell inequalities for bosonic qubits

- PhysicsSciPost Physics Core
- 2022

Since John Bell formulated his paramount inequality for a pair of spin-1/2 particles, quantum mechanics has been confronted with the postulates of local realism with various equivalent…

### Entanglement, nonlocality and multi-particle quantum correlations

- Physics
- 2018

This paper contributes to the proceedings of the Latin-American School of Physics (ELAF-2017) on Quantum Correlations, and is a brief review of quantum entanglement and nonlocality. In such a brief…

### Entanglement between more than two hundred macroscopic atomic ensembles in a solid

- PhysicsNature Communications
- 2017

This work creates a Dicke state in a solid by storing a single photon in a crystal that contains many large atomic ensembles with distinct resonance frequencies and derives a lower bound for the number of entangled ensemble based on the contrast of the interference and the single-photon character of the input.

## References

SHOWING 1-10 OF 34 REFERENCES

### Detecting nonlocality in many-body quantum states

- PhysicsScience
- 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

- PhysicsNature
- 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

- PhysicsScience
- 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

- PhysicsNature
- 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

- PhysicsNature
- 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.

- PhysicsPhysical 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…