Search results for "optical lattice"

Free fermion antibunching in a degenerate atomic Fermi gas released from an optical lattice

2006

Noise in a quantum system is fundamentally governed by the statistics and the many-body state of the underlying particles. Whereas for bosonic particles the correlated noise observed for e.g. photons or bosonic neutral atoms can still be explained within a classical field description with fluctuating phases, the anticorrelations in the detection of fermionic particles have no classical analogue. The observation of such fermionic antibunching is so far scarce and has been confined to electrons and neutrons. Here we report on the first direct observation of antibunching of neutral fermionic atoms. Through an analysis of the atomic shot noise in a set of standard absorption images, of a gas of…

Shaking the entropy out of a lattice:atomic filtering by vibrational excitations

2012

We present a simple and efficient scheme to reduce atom-number fluctuations in optical lattices. The interaction-energy difference for atoms in different vibrational states is used to remove excess atomic occupation. The remaining vacant sites are then filled with atoms by merging adjacent wells, for which we implement a protocol that circumvents the constraints of unitarity. The preparation of large regions with precisely one atom per lattice site is discussed for both bosons and fermions. The resulting low-entropy Mott-insulating states may serve as high-fidelity register states for quantum computing and as a starting point for investigations of many-body physics.

Engineering NonBinary Rydberg Interactions via Phonons in an Optical Lattice

2019

Coupling electronic and vibrational degrees of freedom of Rydberg atoms held in optical tweezer arrays offers a flexible mechanism for creating and controlling atom-atom interactions. We find that the state-dependent coupling between Rydberg atoms and local oscillator modes gives rise to two- and three-body interactions which are controllable through the strength of the local confinement. This approach even permits the cancellation of two-body terms such that three-body interactions become dominant. We analyze the structure of these interactions on two-dimensional bipartite lattice geometries and explore the impact of three-body interactions on system ground state on a square lattice. Focus…

Transport of Strongly Correlated Bosons in an Optical Lattice

2019

Can entanglement be extracted from many body systems?

2007

Some thermodynamical properties of solids, such as heat capacity and magnetic susceptibility, have recently been shown to be linked to the amount of entanglement in a solid. Until now, however, it was not clear whether this entanglement can be used as a resource in quantum information theory. Here we show that this entanglement is physical, demonstrating the principles of its extraction from a typical spin chain by scattering two particles off the system. Moreover, we show how to simulate this process using present-day optical lattice technology. © 2007 World Scientific Publishing Company.

Dipolar bosons on an optical lattice ring

2011

We consider an ultra-small system of polarized bosons on an optical lattice with a ring topology interacting via long range dipole-dipole interactions. Dipoles polarized perpendicular to the plane of the ring reveal sharp transitions between different density wave phases. As the strength of the dipolar interactions is varied the behavior of the transitions is first-order like. For dipoles polarized in the plane of the ring the transitions between possible phases show pronounced sensitivity to the lattice depth. The abundance of possible configurations may be useful for quantum information applications.

Phase-stable free-space optical lattices for trapped ions

2015

We demonstrate control of the absolute phase of an optical lattice with respect to a single trapped ion. The lattice is generated by off-resonant free-space laser beams, we actively stabilize its phase by measuring its ac-Stark shift on a trapped ion. The ion is localized within the standing wave to better than 2\% of its period. The locked lattice allows us to apply displacement operations via resonant optical forces with a controlled direction in phase space. Moreover, we observe the lattice-induced phase evolution of spin superposition states in order to analyze the relevant decoherence mechanisms. Finally, we employ lattice-induced phase shifts for inferring the variation of the ion pos…

Tensor Network Annealing Algorithm for Two-Dimensional Thermal States

2019

Tensor network methods have become a powerful class of tools to capture strongly correlated matter, but methods to capture the experimentally ubiquitous family of models at finite temperature beyond one spatial dimension are largely lacking. We introduce a tensor network algorithm able to simulate thermal states of two-dimensional quantum lattice systems in the thermodynamic limit. The method develops instances of projected entangled pair states and projected entangled pair operators for this purpose. It is the key feature of this algorithm to resemble the cooling down of the system from an infinite temperature state until it reaches the desired finite-temperature regime. As a benchmark we …

Precision measurement of spin-dependent interaction strengths for spin-1 and spin-2 87Rb atoms

2006

We report on precision measurements of spin-dependent interaction-strengths in the 87Rb spin-1 and spin-2 hyperfine ground states. Our method is based on the recent observation of coherence in the collisionally driven spin-dynamics of ultracold atom pairs trapped in optical lattices. Analysis of the Rabi-type oscillations between two spin states of an atom pair allows a direct determination of the coupling parameters in the interaction hamiltonian. We deduce differences in scattering lengths from our data that can directly be compared to theoretical predictions in order to test interatomic potentials. Our measurements agree with the predictions within 20%. The knowledge of these coupling pa…

Quantum transport of non-interacting Fermi gas in an optical lattice combined with harmonic trapping

2004

We consider a non-interacting Fermi gas in a combined harmonic and periodic potential. We calculate the energy spectrum and simulate the motion of the gas after sudden replacement of the trap center. For different parameter regimes, the system presents dipole oscillations, damped oscillations around the replaced center, and localization. The behaviour is explained by the change of the energy spectrum from linear to quadratic.