Abstract
We investigate the transport properties of neutral, fermionic atoms passing through a one-dimensional quantum wire containing a mesoscopic lattice. The lattice is realized by projecting individually controlled, thin optical barriers on top of a ballistic conductor. Building an increasingly longer lattice, one site after another, we observe and characterize the emergence of a band insulating phase, demonstrating control over quantum-coherent transport. We explore the influence of atom-atom interactions and show that the insulating state persists as contact interactions are tuned from moderately to strongly attractive. Using bosonization and classical Monte-Carlo simulations we analyze such a model of interacting fermions and find good qualitative agreement with the data. The robustness of the insulating state supports the existence of a Luther-Emery liquid in the one-dimensional wire. Our work realizes a tunable, site-controlled lattice Fermi gas strongly coupled to reservoirs, which is an ideal test bed for non-equilibrium many-body physics.
Highlights
Quantum effects are the cornerstone of most of the properties encountered in electronic materials and devices
We demonstrate local control of the potential landscape in a quantum wire to study the transport properties of a one-dimensional fermionic insulator created by a mesoscopic lattice, in the presence of attractive interactions
By mapping out conductance against chemical potential, lattice height, and temperature, we confirm that our observations are in agreement with the physics of a band insulator and confront our system with the traditional definition of an insulating phase
Summary
Quantum effects are the cornerstone of most of the properties encountered in electronic materials and devices. Periodic lattice and the correct commensurability, i.e., one pair per site, leads to the opening of a gap in the charge sector This turns the system into a correlated insulator, even for arbitrarily strong attractive interactions. Interaction would address this challenge and at the same time serve as a probe for the existence of the LutherEmery liquid and its properties This is the task that we undertake in the present paper, using and expanding the toolbox of cold-atom experiments [5,6,7,8] to investigate transport in mesoscopic lattices [9,10]. The persistence of the insulating behavior even for resonant interactions and superfluid reservoirs is a strong indication of the existence of a Luther-Emery liquid pinned on the weak periodic potential [Fig. 1(c)]. This is similar in spirit to techniques pioneered with scanning tunneling microscopes on solid-state surfaces [17,18], yet going beyond noninteracting situations
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