Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms

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Main Authors: Greiner, Markus, Mandel, Olaf, Esslinger, Tilman, Hänsch, Theodor W, Bloch, Immanuel
Format: Preprint
Published: 2025
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author Greiner, Markus
Mandel, Olaf
Esslinger, Tilman
Hänsch, Theodor W
Bloch, Immanuel
author_facet Greiner, Markus
Mandel, Olaf
Esslinger, Tilman
Hänsch, Theodor W
Bloch, Immanuel
contents For a system at a temperature of absolute zero, all thermal fluctuations are frozen out, while quantum fluctuations prevail. These microscopic quantum fluctuations can induce a macroscopic phase transition in the ground state of a many-body system when the relative strength of two competing energy terms is varied across a critical value. Here we observe such a quantum phase transition in a Bose-Einstein condensate with repulsive interactions, held in a three-dimensional optical lattice potential. As the potential depth of the lattice is increased, a transition is observed from a superfluid to a Mott insulator phase. In the superfluid phase, each atom is spread out over the entire lattice, with long-range phase coherence. But in the insulating phase, exact numbers of atoms are localized at individual lattice sites, with no phase coherence across the lattice; this phase is characterized by a gap in the excitation spectrum. We can induce reversible changes between the two ground states of the system.
format Preprint
id arxiv_https___arxiv_org_abs_2506_21303
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
Greiner, Markus
Mandel, Olaf
Esslinger, Tilman
Hänsch, Theodor W
Bloch, Immanuel
Quantum Gases
For a system at a temperature of absolute zero, all thermal fluctuations are frozen out, while quantum fluctuations prevail. These microscopic quantum fluctuations can induce a macroscopic phase transition in the ground state of a many-body system when the relative strength of two competing energy terms is varied across a critical value. Here we observe such a quantum phase transition in a Bose-Einstein condensate with repulsive interactions, held in a three-dimensional optical lattice potential. As the potential depth of the lattice is increased, a transition is observed from a superfluid to a Mott insulator phase. In the superfluid phase, each atom is spread out over the entire lattice, with long-range phase coherence. But in the insulating phase, exact numbers of atoms are localized at individual lattice sites, with no phase coherence across the lattice; this phase is characterized by a gap in the excitation spectrum. We can induce reversible changes between the two ground states of the system.
title Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
topic Quantum Gases
url https://arxiv.org/abs/2506.21303