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Alkaline-earth atoms in tweezer arrays for quantum simulation, quantum computing and quantum-enhanced metrology:
Optical tweezer trapping experiments have developed into a major platform for quantum science applications, including quantum simulation and computing, as they provide inherent single atom control, fast experimental repetition rates and flexible geometric configurations. So far, however, these experiments have been restricted to alkali atoms, traditionally used in most cold atom setups due to their comparatively simple level structure. |
Extending tweezer techniques to alkaline earth atoms, which offer narrow and ultra-narrow optical transitions, would combine single atom control with the ability to apply precision spectroscopy tools, originally developed for optical lattice clocks, and more generally would open up a range of novel experimental opportunities -- from quantum science applications to fundamental experiments in atomic physics. These include entangling gates and quantum simulation based on unique Rydberg properties; novel approaches to quantum-enhanced metrology; molecular, Hubbard or Kondo model assembly; new approaches for cavity QED-type experiments and quantum communication; or optical trapping of ions through ionization in tweezers.
We are experimentally implementing tweezer trapping of alkaline earth-atoms with strontium. Our most recent results include demonstrating trapping, narrow-linewidth cooling and single-shot detection of an individual strontium atoms in tweezers an optical tweezer, and we have results for trapping and imaging in larger scale tweezer arrays. By exciting the atom on the 7kHz-wide, 689nm intercombination line, we uncovered a previously unexplored Sisyphus mechanism and demonstrated side-band cooling. We achieved single-shot single-atom-resolved imaging by detecting photons from the broad 461nm transition while suppressing trap loss with Sisyphus cooling. Side-band and Sisyphus cooling are, respectively, based on magic and non-magic tweezer trapping conditions, for which we showed precise tuning via the tweezer's ellipticity.
For the future, we are particularly excited about implementing a Rydberg excitation scheme -- unique to alkaline-earth atoms -- that promises a dramatic increase in coherence time compared to previous approaches, which could enable entanglement spreading over very large system volumes and highly improved entangling fidelities. At the same time, we will explore interrogation of the strontium clock transition on a single atom level and related quantum information, simulation and metrology schemes combing clock state control with strong and highly coherent Rydberg interactions.
See here for some first published results: https://arxiv.org/abs/1810.06537
Theory projects:
Quantum behavior and control of strongly interacting arrays:
We are exploring various new ideas for employing Rydberg arrays, and other long-range interacting spin systems, in quantum simulation, quantum information, entangled state engineering, and quantum metrology. Projects range from more abstract questions to realistic modeling of experimental scenarios, including open system dynamics.
We are exploring various new ideas for employing Rydberg arrays, and other long-range interacting spin systems, in quantum simulation, quantum information, entangled state engineering, and quantum metrology. Projects range from more abstract questions to realistic modeling of experimental scenarios, including open system dynamics.
Use of machine-learning techniques in quantum simulation experiments and many-body theory
We are investigating the use of machine-learning techniques applied to questions in quantum many body theory and experiments, specifically concerning quantum state reconstruction and numerical many-body methods in 2d.
We are investigating the use of machine-learning techniques applied to questions in quantum many body theory and experiments, specifically concerning quantum state reconstruction and numerical many-body methods in 2d.
Towards assembly of electronic matter:
In a collaboration with Chris Green's group at Purdue, we are theoretically exploring a new idea for coherent charge hopping between alkaline-earth ion cores trapped in optical tweezers. This could one day enable the assembly and dynamical control of electronic matter with optically trapped ionic cores that are individually controlled.
In a collaboration with Chris Green's group at Purdue, we are theoretically exploring a new idea for coherent charge hopping between alkaline-earth ion cores trapped in optical tweezers. This could one day enable the assembly and dynamical control of electronic matter with optically trapped ionic cores that are individually controlled.
Alkaline-earth atoms for quantum communication
In collaboration with Oskar Painter's group at Caltech, we have been working on a new idea for quantum communication based on individually controlled alkaline-earth atoms coupled to cavity systems in the telecom range.
In collaboration with Oskar Painter's group at Caltech, we have been working on a new idea for quantum communication based on individually controlled alkaline-earth atoms coupled to cavity systems in the telecom range.
Examples of previous Research topics:
Effects of dynamically changing Berry phases:
In a theory collaboration with Gil Refael, we are exploring effects of dynamically changing Berry phases in optical lattices.
In a theory collaboration with Gil Refael, we are exploring effects of dynamically changing Berry phases in optical lattices.
Rydberg array quantum simulation with alkali atoms:
In collaboration with Misha Lukin's group at Harvard, we have been developing new techniques for quantum simulations based on Rydberg atom arrays. These experiments are based on atom-by-atom assembly of defect-free atomic arrays with optical tweezer.
In collaboration with Misha Lukin's group at Harvard, we have been developing new techniques for quantum simulations based on Rydberg atom arrays. These experiments are based on atom-by-atom assembly of defect-free atomic arrays with optical tweezer.
Detection of dynamical correlation functions:
In collaboration with Michael Knap's group at TU Munich, we are exploring new techniques for measuring dynamical correlation functions, including out-of-time ordered functions.
In collaboration with Michael Knap's group at TU Munich, we are exploring new techniques for measuring dynamical correlation functions, including out-of-time ordered functions.
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Entanglement detection:
In collaboration with the Rosario Fazio's group, we theoretically proposed a method for spin-entanglement detection in optical lattices that was subsequently experimentally realized in a collaboration with the Bloch group. |
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Optical lattice version of strained graphene:
In collaboration with David Pekker's group, we proposed a method to generate relativistic Landau levels by straining an optical lattice |
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Coupling of atoms to nanophotonic structures:
In collaboration with Misha Lukin's group, we are coupling individual Rubidium atoms to one-dimensional photonic crystal structures enabling interactions between the atoms and single photons. Our main goal is to extend the scheme to multiple atoms for entanglement generation and photon-induced atom-atom interactions.
In collaboration with Misha Lukin's group, we are coupling individual Rubidium atoms to one-dimensional photonic crystal structures enabling interactions between the atoms and single photons. Our main goal is to extend the scheme to multiple atoms for entanglement generation and photon-induced atom-atom interactions.
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Wilson loops as probes for Bloch band topology:
In collaboration with the Bloch group, we are working on novel ways to probe the geometry of Bloch bands using Wilson loops and lines. |
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Development of a quantum microscope for optical lattices:
Development of a novel method for imaging and manipulating individual atoms in optical lattices. |
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Detection of a Higgs mode close to a 2d quantum phase transition:
We observed an amplitude ‘Higgs’ modes close to the 2d superfluid-Mott insulator transition by measuring the dynamical response to lattice modulation with single-atom-sensitivity. The observability of ‘Higgs’ modes close to 2d quantum phase transitions has been debated and our measurements helped to resolve the discussion. |
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Two-site and non-local correlation functions:
Using the quantum microscope, we detected correlation functions at the single particle level including a proof-of-principle that nonlocal observables are experimentally accessible. Such nonlocal quantities, taking into account detailed information of extended regions, are necessary for describing order in quantum phases that are beyond the standard Landau description (e.g., topological phases). |
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Out-of-equilibrium dynamics of correlations:
Experimental observation of light-cone spreading of two-site correlations after a quantum quench of 1d Mott insulators. |
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Quantum dynamics of individual spins and magnon bound states:
We prepared individual spin impurities using single atom addressing and watched their dynamics.
We prepared individual spin impurities using single atom addressing and watched their dynamics.
Theory for nonlocal correlations:
We worked out a theoretical extension of nonlocal order to 2d systems showing that area correlations correspond to spatial Wilson loops in a dual description. Further, we theoretically investigated the out-of-equilibrium dynamics of non-local correlations.
We worked out a theoretical extension of nonlocal order to 2d systems showing that area correlations correspond to spatial Wilson loops in a dual description. Further, we theoretically investigated the out-of-equilibrium dynamics of non-local correlations.