Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2512.07632 · Physical Review A

Mesoscopic superfluid to superconductor transition

Yehoshua Winsten, Doron Cohen

cond-mat.mes-hallquant-phSubmitted Dec 8, 2025• Announced Dec 9, 2025• 0 citations
v1 · Dec 8, 2025v2 · Mar 31, 2026
arXivHTMLPDF

Abstract

Spectrum tomography for the energy ($E$) of a ring-shaped Bose-Hubbard circuit is illustrated. There is an inter-particle interaction $U$ that controls superfluidity (SF) and the transition to the Mott Insulator (MI) regime. The circuit is coupled to an electromagnetic cavity mode of frequency $ω_0$, and the coupling is characterized by a generalized fine-structure-constant $α$ that controls the emergence of superconductivity (SC). The ${(U,α,ω_0,E)}$ diagram features SF and SC regions, a vast region of fragmented possibly chaotic states, and an MI regime for large $U$. The mesoscopic version of the Meissner effect and the Anderson-Higgs mechanism are discussed.

Journal reference
Phys. Rev. A 113, 032221 (2026)
DOI
10.1103/tssc-m89q
Comments
15 pages, 8 figures

Related papers

Quantum tomography of the superfluid-insulator transition for a mesoscopic atomtronic ring

Yehoshua Winsten, Doron Cohen

We provide a phase-space perspective for the analysis of the superfluid-insulator transition for finite-size Bose-Hubbard circuits. We explore how the eigenstates parametrically evolve as the inter-particle interaction is varied, paying attention to the fingerprints of chaos at the quantum phase-transition. Consequently, we demonstrate that the tomographic spectrum reflects the existence of mixed-regions of chaos and quasi-regular motion in phase-space. This tomographic semiclassical approach is much more efficient and informative compared to the traditional "level statistics" inspection. Of particular interest is the characterization of the fluctuations that are exhibited by the many-body eigenstates. In this context, we associate with each eigenstate a Higgs measure for the identification of amplitude modes of the order-parameter. Finally we focus on the formation of the lowest Goldstone and Higgs bands.

arXiv:2504.14505•Physical Review A•Jun 26, 2025•2 citations

Sitewise manipulations and Mott insulator-superfluid transition of interacting photons using superconducting circuit simulators

Xiu–Hao Deng, Chunjing Jia, Chih-Chun Chien

The Bose-Hubbard model (BHM) of interacting bosons in a lattice has been a paradigm in many-body physics, and it exhibits a Mott insulator-superfluid (MI-SF) transition at integer filling. Here a quantum simulator of the BHM using a superconducting circuit is proposed. Specifically, a superconducting transmission line resonator supporting microwave photons is coupled to a charge qubit to form one site of the BHM, and adjacent sites are connected by a tunable coupler. To obtain a mapping from the superconducting circuit to the BHM, we focus on the dispersive regime where the excitations remain photonlike. Standard perturbation theory is implemented to locate the parameter range where the MI-SF transition may be simulated. This simulator allows single-site manipulations, and we illustrate this feature by considering two scenarios where a single-site manipulation can drive a MI-SF transition. The transition can be analyzed by mean-field analyses, and the exact diagonalization was implemented to provide accurate results. The variance of the photon density and the fidelity metric clearly show signatures of the transition. Experimental realizations and other possible applications of this simulator are also discussed.

arXiv:1410.8458•Physical Review B•Feb 23, 2015•12 citations

Entanglement Entropy across the Superfluid-Insulator Transition: A Signature of Bosonic Criticality

Irénée Frérot, Tommaso Roscilde

We study the entanglement entropy and entanglement spectrum of the paradigmatic Bose-Hubbard model, describing strongly correlated bosons on a lattice. The use of a controlled approximation-the slave-boson approach-allows us to study entanglement in all regimes of the model (and, most importantly, across its superfluid-Mott-insulator transition) at a minimal cost. We find that the area-law scaling of entanglement-verified in all the phases-exhibits a sharp singularity at the transition. The singularity is greatly enhanced when the transition is crossed at fixed, integer filling, due to a richer entanglement spectrum containing an additional gapless mode, which descends from the amplitude (Higgs) mode of the global excitation spectrum-while this mode remains gapped at the generic (commensurate-incommensurate) transition with variable filling. Hence, the entanglement properties contain a unique signature of the two different forms of bosonic criticality exhibited by the Bose-Hubbard model.

arXiv:1512.00805•Physical Review Letters•May 11, 2016•70 citations

Triangular Bose-Hubbard trimer as a minimal model for a superfluid circuit

Geva Arwas, Amichay Vardi, Doron Cohen

The triangular Bose-Hubbard trimer is topologically the minimal model for a BEC superfluid circuit. As a dynamical system of two coupled freedoms it has mixed phase space with chaotic dynamics. We employ a semiclassical perspective to study triangular trimer physics beyond the conventional picture of the superfluid-to-insulator transition. From the analysis of the Peierls-Nabarro energy landscape, we deduce the various regimes in the $(\ensuremath{\Omega},u)$ parameter space, where $u$ is the interaction and $\ensuremath{\Omega}$ is the superfluid rotation-velocity. We thus characterize the superfluid stability and chaoticity of the many-body eigenstates throughout the Hilbert space.

arXiv:1308.5860•Physical Review A•Jan 6, 2014•30 citations

Superfluid-to-Mott transition in a Bose-Hubbard ring: Persistent currents and defect formation

Lucas Kohn, Pietro Silvi, Matthias Gerster +4 more

We revisit here the Kibble-Zurek mechanism for superfluid bosons slowly driven across the transition toward the Mott-insulating phase. By means of a combination of the time-dependent variational principle and a tree-tensor network, we characterize the current flowing during annealing in a ring-shaped one-dimensional Bose-Hubbard model with artificial classical gauge field on up to 32 lattice sites. We find that the superfluid current shows, after an initial decrease, persistent oscillations which survive even when the system is well inside the Mott insulating phase. We demonstrate that the amplitude of such oscillations is connected to the residual energy, characterizing the creation of defects while crossing the quantum critical point, while their frequency matches the spectral gap in the Mott insulating phase. Our predictions can be verified in future atomtronics experiments with neutral atoms in ring-shaped traps. We believe that the proposed setup provides an interesting but simple platform to study the nonequilibrium quantum dynamics of persistent currents experimentally.

arXiv:1907.00009•Physical Review A•Feb 24, 2020•23 citations

Phase diagram of the Bose-Hubbard model with T3 symmetry

Matteo Rizzi, V. Cataudella, Rosario Fazio

We study the quantum phase transition between the insulating and the globally coherent superfluid phases in the Bose-Hubbard model with ${\mathcal{T}}_{3}$ structure, the ``dice lattice.'' Even in the absence of any frustration the superfluid phase is characterized by modulation of the order parameter on the different sublattices of the ${\mathcal{T}}_{3}$ structure. The zero-temperature critical point as a function of magnetic field shows the characteristic ``butterfly'' form. At full frustration the superfluid region is strongly suppressed. In addition, due to the existence of the Aharonov-Bohm cages at $f=1∕2$, we find some evidence for the existence of an intermediate insulating phase characterized by a zero superfluid stiffness but finite compressibility. In this intermediate phase bosons are localized due to the external frustration and the topology of the ${\mathcal{T}}_{3}$ lattice. We name this new phase the Aharonov-Bohm insulator. In the presence of charge frustration the phase diagram acquires the typical lobe structure. The form and hierarchy of the Mott insulating states with fractional fillings are dictated by the particular topology of the ${\mathcal{T}}_{3}$ lattice. The results presented were obtained by a variety of analytical methods: mean-field and variational techniques to approach the phase boundary from the superconducting side and a strongly coupled expansion appropriate for the Mott insulating region. In addition we performed quantum Monte Carlo simulations of the corresponding $(2+1)$-dimensional $XY$ model to corroborate the analytical calculations with a more accurate quantitative analysis. We finally discuss experimental realization of the ${\mathcal{T}}_{3}$ lattice both with optical lattices and with Josephson junction arrays.

arXiv:cond-mat/0510341•Physical Review B•Apr 14, 2006•90 citations
Spectrum tomography for the energy (EEE) of a ring-shaped Bose-Hubbard circuit is illustrated. There is an inter-particle interaction UUU that controls superfluidity (SF) and the transition to the Mott Insulator (MI) regime. The circuit is coupled to an electromagnetic cavity mode of frequency ω0ω_0ω0​, and the coupling is characterized by a generalized fine-structure-constant ααα that controls the emergence of superconductivity (SC). The (U,α,ω0,E){(U,α,ω_0,E)}(U,α,ω0​,E) diagram features SF and SC regions, a vast region of fragmented possibly chaotic states, and an MI regime for large UUU. The mesoscopic version of the Meissner effect and the Anderson-Higgs mechanism are discussed.
We provide a phase-space perspective for the analysis of the superfluid-insulator transition for finite-size Bose-Hubbard circuits. We explore how the eigenstates parametrically evolve as the inter-particle interaction is varied, paying attention to the fingerprints of chaos at the quantum phase-transition. Consequently, we demonstrate that the tomographic spectrum reflects the existence of mixed-regions of chaos and quasi-regular motion in phase-space. This tomographic semiclassical approach is much more efficient and informative compared to the traditional "level statistics" inspection. Of particular interest is the characterization of the fluctuations that are exhibited by the many-body eigenstates. In this context, we associate with each eigenstate a Higgs measure for the identification of amplitude modes of the order-parameter. Finally we focus on the formation of the lowest Goldstone and Higgs bands.
The Bose-Hubbard model (BHM) of interacting bosons in a lattice has been a paradigm in many-body physics, and it exhibits a Mott insulator-superfluid (MI-SF) transition at integer filling. Here a quantum simulator of the BHM using a superconducting circuit is proposed. Specifically, a superconducting transmission line resonator supporting microwave photons is coupled to a charge qubit to form one site of the BHM, and adjacent sites are connected by a tunable coupler. To obtain a mapping from the superconducting circuit to the BHM, we focus on the dispersive regime where the excitations remain photonlike. Standard perturbation theory is implemented to locate the parameter range where the MI-SF transition may be simulated. This simulator allows single-site manipulations, and we illustrate this feature by considering two scenarios where a single-site manipulation can drive a MI-SF transition. The transition can be analyzed by mean-field analyses, and the exact diagonalization was implemented to provide accurate results. The variance of the photon density and the fidelity metric clearly show signatures of the transition. Experimental realizations and other possible applications of this simulator are also discussed.
We study the entanglement entropy and entanglement spectrum of the paradigmatic Bose-Hubbard model, describing strongly correlated bosons on a lattice. The use of a controlled approximation-the slave-boson approach-allows us to study entanglement in all regimes of the model (and, most importantly, across its superfluid-Mott-insulator transition) at a minimal cost. We find that the area-law scaling of entanglement-verified in all the phases-exhibits a sharp singularity at the transition. The singularity is greatly enhanced when the transition is crossed at fixed, integer filling, due to a richer entanglement spectrum containing an additional gapless mode, which descends from the amplitude (Higgs) mode of the global excitation spectrum-while this mode remains gapped at the generic (commensurate-incommensurate) transition with variable filling. Hence, the entanglement properties contain a unique signature of the two different forms of bosonic criticality exhibited by the Bose-Hubbard model.
The triangular Bose-Hubbard trimer is topologically the minimal model for a BEC superfluid circuit. As a dynamical system of two coupled freedoms it has mixed phase space with chaotic dynamics. We employ a semiclassical perspective to study triangular trimer physics beyond the conventional picture of the superfluid-to-insulator transition. From the analysis of the Peierls-Nabarro energy landscape, we deduce the various regimes in the $(\ensuremath{\Omega},u)$ parameter space, where uuu is the interaction and $\ensuremath{\Omega}$ is the superfluid rotation-velocity. We thus characterize the superfluid stability and chaoticity of the many-body eigenstates throughout the Hilbert space.
We revisit here the Kibble-Zurek mechanism for superfluid bosons slowly driven across the transition toward the Mott-insulating phase. By means of a combination of the time-dependent variational principle and a tree-tensor network, we characterize the current flowing during annealing in a ring-shaped one-dimensional Bose-Hubbard model with artificial classical gauge field on up to 32 lattice sites. We find that the superfluid current shows, after an initial decrease, persistent oscillations which survive even when the system is well inside the Mott insulating phase. We demonstrate that the amplitude of such oscillations is connected to the residual energy, characterizing the creation of defects while crossing the quantum critical point, while their frequency matches the spectral gap in the Mott insulating phase. Our predictions can be verified in future atomtronics experiments with neutral atoms in ring-shaped traps. We believe that the proposed setup provides an interesting but simple platform to study the nonequilibrium quantum dynamics of persistent currents experimentally.
We study the quantum phase transition between the insulating and the globally coherent superfluid phases in the Bose-Hubbard model with T3{\mathcal{T}}_{3}T3​ structure, the ``dice lattice.'' Even in the absence of any frustration the superfluid phase is characterized by modulation of the order parameter on the different sublattices of the T3{\mathcal{T}}_{3}T3​ structure. The zero-temperature critical point as a function of magnetic field shows the characteristic ``butterfly'' form. At full frustration the superfluid region is strongly suppressed. In addition, due to the existence of the Aharonov-Bohm cages at f=1∕2f=1∕2f=1∕2, we find some evidence for the existence of an intermediate insulating phase characterized by a zero superfluid stiffness but finite compressibility. In this intermediate phase bosons are localized due to the external frustration and the topology of the T3{\mathcal{T}}_{3}T3​ lattice. We name this new phase the Aharonov-Bohm insulator. In the presence of charge frustration the phase diagram acquires the typical lobe structure. The form and hierarchy of the Mott insulating states with fractional fillings are dictated by the particular topology of the T3{\mathcal{T}}_{3}T3​ lattice. The results presented were obtained by a variety of analytical methods: mean-field and variational techniques to approach the phase boundary from the superconducting side and a strongly coupled expansion appropriate for the Mott insulating region. In addition we performed quantum Monte Carlo simulations of the corresponding (2+1)(2+1)(2+1)-dimensional XYXYXY model to corroborate the analytical calculations with a more accurate quantitative analysis. We finally discuss experimental realization of the T3{\mathcal{T}}_{3}T3​ lattice both with optical lattices and with Josephson junction arrays.