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:1607.06223 · Physical Review A

Negative differential conductivity and quantum statistical effects in a three-site Bose-Hubbard model

M. K. Olsen, Joel Frederick Corney

Published Sep 6, 2016• 11 citations
arXivHTMLPDF

Abstract

The use of an electron beam to remove ultracold atoms from selected sites in an optical lattice has opened up new opportunities to study transport in quantum systems [R. Labouvie et al., Phys. Rev. Lett. 115, 050601 (2015)]. Inspired by this experimental result, we examine the effects of number difference, dephasing, and initial quantum statistics on the filling of an initially depleted middle well in the three-well inline Bose-Hubbard model. We find that the well-known phenomenon of macroscopic self-trapping is the main contributor to oscillatory negative differential conductivity in our model, with phase diffusion being a secondary effect. However, we find that phase diffusion is required for the production of direct atomic current, with the coherent process showing damped oscillatory currents. We also find that our results are highly dependent on the initial quantum states of the atoms in the system.

DOI
10.1103/physreva.94.033605

Related papers

Nonequilibrium Transport in a Superfluid Josephson Junction Chain: Is There Negative Differential Conductivity?

Samuel E. Begg, Matthew J. Davis, Matthew T. Reeves

We consider the far-from-equilibrium quantum transport dynamics in a 1D Josephson junction chain of multimode Bose-Einstein condensates. We develop a theoretical model to examine the experiment of Labouvie et al. [Phys. Rev. Lett. 115, 050601 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.050601], wherein the phenomenon of negative differential conductivity (NDC) was reported in the refilling dynamics of an initially depleted site within the chain. We demonstrate that a unitary c-field description can quantitatively reproduce the experimental results over the full range of tunnel couplings, and requires no fitted parameters. With a view toward atomtronic implementations, we further demonstrate that the filling is strongly dependent on spatial phase variations stemming from quantum fluctuations. Our findings suggest that the interpretation of the device in terms of NDC is invalid outside of the weak coupling regime. Within this restricted regime, the device exhibits a hybrid behavior of NDC and the ac Josephson effect. A simplified circuit model of the device will require an approach tailored to atomtronics that incorporates quantum fluctuations.

arXiv:2307.14590•Physical Review Letters•Mar 7, 2024•3 citations

Negative Differential Conductivity in an Interacting Quantum Gas

Ralf Labouvie, Bodhaditya Santra, Simon Heun +2 more

We report on the observation of negative differential conductivity (NDC) in a quantum transport device for neutral atoms employing a multimode tunneling junction. The system is realized with a Bose-Einstein condensate loaded in a one-dimensional optical lattice with high site occupancy. We induce an initial difference in chemical potential at one site by local atom removal. The ensuing transport dynamics are governed by the interplay between the tunneling coupling, the interaction energy, and intrinsic collisions, which turn the coherent coupling into a hopping process. The resulting current-voltage characteristics exhibit NDC, for which we identify atom number-dependent tunneling as a new microscopic mechanism. Our study opens new ways for the future implementation and control of complex neutral atom quantum circuits.

arXiv:1411.5632•Physical Review Letters•Jul 27, 2015•111 citations

Comment on "Negative Differential Conductivity in an Interacting Quantum Gas."

M. K. Olsen, Joel Frederick Corney

Labouvie \etal (\prl {\bf 115}, 050601, (20015)) recently demonstrated negative differential conductivity (NDC) in a multi-well Bose-Einstein condensate. They stated "we demonstrate that NDC originates from a nonlinear, atom number dependent tunneling coupling in combination with fast collisional decoherence." We show theoretically how the essential feature of NDC, a reduction in atomic current caused by an increase in chemical potential, is present in unitary dynamics through the well-known mechanism of macroscopic self-trapping (MST), and that the collisional decoherence merely serves as a quantitative modification of this.

arXiv:1605.06559•May 20, 2016•0 citations

Decoherence and entanglement in a bosonic Josephson junction: Bose-enhanced quantum Zeno control of phase diffusion

Yuri Khodorkovsky, Gershon Kurizki, Amichay Vardi

We study the effect of decoherence on dynamical phase diffusion in the two-site Bose-Hubbard model. Starting with an odd parity excited coherent state, the initial loss of single-particle coherence varies from small bound oscillations in the Rabi regime, through hyperbolic depletion in the Josephson regime, to a Gaussian decay in the Fock regime. The inclusion of local-site noise, measuring the relative number difference between the modes, is shown to enhance phase diffusion. In comparison, site-indiscriminate noise measuring the population imbalance between the two quasimomentum modes slows down the loss of single-particle coherence. Decoherence thus either enhances or suppresses phase diffusion, depending on the details of system-bath coupling and the overlap of decoherence pointer states with collisional-entanglement pointer states. The deceleration of phase diffusion due to the coupling with the environment may be viewed as a many-body quantum Zeno effect. The extended effective decay times in the presence of projective measurement are further enhanced with increasing number of particles $N$ by a bosonic factor of $\sqrt{N}$ in the Fock regime and $N/\text{log}\text{ }N$ in the Josephson regime.

arXiv:0905.1004•Physical Review A•Aug 17, 2009•40 citations

Towards an Atomtronic Diode

Andrew J. Daley

We report on the observation of negative differential conductivity (NDC) in a quantum transport device for neutral atoms employing a multimode tunneling junction.The system is realized with a Bose-Einstein condensate loaded in a one-dimensional optical lattice with high site occupancy.We induce an initial difference in chemical potential at one site by local atom removal.The ensuing transport dynamics are governed by the interplay between the tunneling coupling, the interaction energy, and intrinsic collisions, which turn the coherent coupling into a hopping process.The resulting current-voltage characteristics exhibit NDC, for which we identify atom number-dependent tunneling as a new microscopic mechanism.Our study opens new ways for the future implementation and control of complex neutral atom quantum circuits.

Physics•Jul 27, 2015•4 citations

Conductivity in the Bose-Hubbard model at high temperatures

Ivana Vasić, J. Vučičević

Quantum simulations are quickly becoming an indispensable tool for studying particle transport in correlated lattice models. One of the central topics in the study of transport is bad-metal behavior, characterized by the direct-current resistivity linear in temperature. In the fermionic Hubbard model, optical conductivity has been studied extensively, and a recent optical lattice experiment demonstrated bad-metal behavior in qualitative agreement with theory. Far less is known about transport in the bosonic Hubbard model. We investigate the conductivity in the Bose-Hubbard model and focus on the regime of strong interactions and high temperatures. We use numerically exact calculations for small lattice sizes. At weak tunneling, we find multiple peaks in the optical conductivity that stem from the Hubbard bands present in the many-body spectrum. This feature slowly washes out as the tunneling rate gets stronger. At high temperature, we identify a regime of $T$-linear resistivity, as expected. When the interactions are very strong, the leading inverse-temperature coefficient in conductivity is proportional to the tunneling amplitude. As the tunneling becomes stronger, this dependence takes quadratic form. At very strong coupling and half filling, we identify a separate linear resistivity regime at lower temperature, corresponding to the hard-core boson regime. Additionally, we unexpectedly observe that at half filling, in a big part of the phase diagram, conductivity is an increasing function of the coupling constant before it saturates at the hard-core-boson result. We explain this feature based on the analysis of the many-body energy spectrum and the contributions to conductivity of individual eigenstates of the system.

arXiv:2404.16559•Physical review. B./Physical review. B•Aug 1, 2024•3 citations
The use of an electron beam to remove ultracold atoms from selected sites in an optical lattice has opened up new opportunities to study transport in quantum systems [R. Labouvie et al., Phys. Rev. Lett. 115, 050601 (2015)]. Inspired by this experimental result, we examine the effects of number difference, dephasing, and initial quantum statistics on the filling of an initially depleted middle well in the three-well inline Bose-Hubbard model. We find that the well-known phenomenon of macroscopic self-trapping is the main contributor to oscillatory negative differential conductivity in our model, with phase diffusion being a secondary effect. However, we find that phase diffusion is required for the production of direct atomic current, with the coherent process showing damped oscillatory currents. We also find that our results are highly dependent on the initial quantum states of the atoms in the system.
We consider the far-from-equilibrium quantum transport dynamics in a 1D Josephson junction chain of multimode Bose-Einstein condensates. We develop a theoretical model to examine the experiment of Labouvie et al. [Phys. Rev. Lett. 115, 050601 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.050601], wherein the phenomenon of negative differential conductivity (NDC) was reported in the refilling dynamics of an initially depleted site within the chain. We demonstrate that a unitary c-field description can quantitatively reproduce the experimental results over the full range of tunnel couplings, and requires no fitted parameters. With a view toward atomtronic implementations, we further demonstrate that the filling is strongly dependent on spatial phase variations stemming from quantum fluctuations. Our findings suggest that the interpretation of the device in terms of NDC is invalid outside of the weak coupling regime. Within this restricted regime, the device exhibits a hybrid behavior of NDC and the ac Josephson effect. A simplified circuit model of the device will require an approach tailored to atomtronics that incorporates quantum fluctuations.
We report on the observation of negative differential conductivity (NDC) in a quantum transport device for neutral atoms employing a multimode tunneling junction. The system is realized with a Bose-Einstein condensate loaded in a one-dimensional optical lattice with high site occupancy. We induce an initial difference in chemical potential at one site by local atom removal. The ensuing transport dynamics are governed by the interplay between the tunneling coupling, the interaction energy, and intrinsic collisions, which turn the coherent coupling into a hopping process. The resulting current-voltage characteristics exhibit NDC, for which we identify atom number-dependent tunneling as a new microscopic mechanism. Our study opens new ways for the future implementation and control of complex neutral atom quantum circuits.
Labouvie \etal (\prl {\bf 115}, 050601, (20015)) recently demonstrated negative differential conductivity (NDC) in a multi-well Bose-Einstein condensate. They stated "we demonstrate that NDC originates from a nonlinear, atom number dependent tunneling coupling in combination with fast collisional decoherence." We show theoretically how the essential feature of NDC, a reduction in atomic current caused by an increase in chemical potential, is present in unitary dynamics through the well-known mechanism of macroscopic self-trapping (MST), and that the collisional decoherence merely serves as a quantitative modification of this.
We study the effect of decoherence on dynamical phase diffusion in the two-site Bose-Hubbard model. Starting with an odd parity excited coherent state, the initial loss of single-particle coherence varies from small bound oscillations in the Rabi regime, through hyperbolic depletion in the Josephson regime, to a Gaussian decay in the Fock regime. The inclusion of local-site noise, measuring the relative number difference between the modes, is shown to enhance phase diffusion. In comparison, site-indiscriminate noise measuring the population imbalance between the two quasimomentum modes slows down the loss of single-particle coherence. Decoherence thus either enhances or suppresses phase diffusion, depending on the details of system-bath coupling and the overlap of decoherence pointer states with collisional-entanglement pointer states. The deceleration of phase diffusion due to the coupling with the environment may be viewed as a many-body quantum Zeno effect. The extended effective decay times in the presence of projective measurement are further enhanced with increasing number of particles NNN by a bosonic factor of N\sqrt{N}N​ in the Fock regime and N/log NN/\text{log}\text{ }NN/log N in the Josephson regime.
We report on the observation of negative differential conductivity (NDC) in a quantum transport device for neutral atoms employing a multimode tunneling junction.The system is realized with a Bose-Einstein condensate loaded in a one-dimensional optical lattice with high site occupancy.We induce an initial difference in chemical potential at one site by local atom removal.The ensuing transport dynamics are governed by the interplay between the tunneling coupling, the interaction energy, and intrinsic collisions, which turn the coherent coupling into a hopping process.The resulting current-voltage characteristics exhibit NDC, for which we identify atom number-dependent tunneling as a new microscopic mechanism.Our study opens new ways for the future implementation and control of complex neutral atom quantum circuits.
Quantum simulations are quickly becoming an indispensable tool for studying particle transport in correlated lattice models. One of the central topics in the study of transport is bad-metal behavior, characterized by the direct-current resistivity linear in temperature. In the fermionic Hubbard model, optical conductivity has been studied extensively, and a recent optical lattice experiment demonstrated bad-metal behavior in qualitative agreement with theory. Far less is known about transport in the bosonic Hubbard model. We investigate the conductivity in the Bose-Hubbard model and focus on the regime of strong interactions and high temperatures. We use numerically exact calculations for small lattice sizes. At weak tunneling, we find multiple peaks in the optical conductivity that stem from the Hubbard bands present in the many-body spectrum. This feature slowly washes out as the tunneling rate gets stronger. At high temperature, we identify a regime of TTT-linear resistivity, as expected. When the interactions are very strong, the leading inverse-temperature coefficient in conductivity is proportional to the tunneling amplitude. As the tunneling becomes stronger, this dependence takes quadratic form. At very strong coupling and half filling, we identify a separate linear resistivity regime at lower temperature, corresponding to the hard-core boson regime. Additionally, we unexpectedly observe that at half filling, in a big part of the phase diagram, conductivity is an increasing function of the coupling constant before it saturates at the hard-core-boson result. We explain this feature based on the analysis of the many-body energy spectrum and the contributions to conductivity of individual eigenstates of the system.