Squeezing and entanglement in a Bose-Einstein condensate

Abstract

Entanglement, a key feature of quantum mechanics, is a resource that allows the improvement of precision measurements beyond the conventional bound reachable by classical means. This is known as the standard quantum limit, already defining the accuracy of the best available sensors for various quantities such as time or position. Many of these sensors are interferometers in which the standard quantum limit can be overcome by feeding their two input ports with quantum-entangled states, in particular spin squeezed states. For atomic interferometers, Bose-Einstein condensates of ultracold atoms are considered good candidates to provide such states involving a large number of particles. In this letter, we demonstrate their experimental realization by splitting a condensate in a few parts using a lattice potential. Site resolved detection of the atoms allows the measurement of the conjugated variables atom number difference and relative phase. The observed fluctuations imply entanglement between the particles, a resource that would allow a precision gain of 3.8 dB over the standard quantum limit for interferometric measurements.

References in corpus (2)

• Spin squeezing of atomic ensembles via nuclear-electronic spin entanglement
• Preparing and probing atomic number states with an atom interferometer

Cited by in corpus (9)

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• Spin squeezing in a generalized one-axis twisting model
• Optimizing number squeezing when splitting a mesoscopic condensate
• Beyond mean-field dynamics of small Bose-Hubbard systems based on the number-conserving phase space approach
• Dissipation induced coherence and stochastic resonance of an open two-mode Bose-Einstein condensate
• Fractional photon-assisted tunneling for Bose-Einstein condensates in a double well
• Stochastic optimization of a cold atom experiment using a genetic algorithm
• Generalized Purity and Quantum Phase Transition for Bose-Einstein condensates in a Symmetric Double Well
• Quantum noise thermometry for bosonic Josephson junctions in the mean field regime