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Alkaline earth atoms in tweezer arrays for quantum simulation, quantum optimization and quantum-enhanced metrology:
Recently, cold atoms in optical tweezer arrays have emerged as a versatile platform for quantum science experiments. Specifically, ''atom-by-atom assembly'' [1] now provides a fast and simple method for generating defect-free atomic arrays, which are used as qubit registers. Entanglement is generated in a highly controlled fashion via excitation to Rydberg states, which interact strongly at typical inter-atomic distances. Applications of such 'Rydberg Arrays' range from quantum simulation and quantum computing to quantum optimization tasks. While already reaching highly competitive results, these systems are still in their infancy. |
Our group uses alkaline earth atoms to improve upon existing limitations and to open new avenues in quantum metrology. Some of our recent highlights include:
1) A record in imaging-fidelity for neutral atoms and demonstration of narrow-line cooling in tweezers [2,3].
2) High-fidelity Rydberg excitation from a clock state, including a record in entanglement-fidelity for two neutral atoms [4].
3) Demonstration of an optical clock with single-atom detection in tweezer arrays [5].
Current efforts target high-fidelity operations and their verification in large-scale arrays and subsequent application to quantum simulation, quantum-enhanced metrology as well as quantum optimization.
[1] Endres et al., Science 354, 1024 (2016)
[2] Covey et. al, Phys. Rev. Lett. 122, 173201 (2019)
[3] Cooper et al., Phys. Rev. X 8, 041055 (2018)
[4] Madjarov*, Covey*, et al., Nature Physics (2020)
[5] Madjarov et al., Phys. Rev. X 9, 041052 (2019)
1) A record in imaging-fidelity for neutral atoms and demonstration of narrow-line cooling in tweezers [2,3].
2) High-fidelity Rydberg excitation from a clock state, including a record in entanglement-fidelity for two neutral atoms [4].
3) Demonstration of an optical clock with single-atom detection in tweezer arrays [5].
Current efforts target high-fidelity operations and their verification in large-scale arrays and subsequent application to quantum simulation, quantum-enhanced metrology as well as quantum optimization.
[1] Endres et al., Science 354, 1024 (2016)
[2] Covey et. al, Phys. Rev. Lett. 122, 173201 (2019)
[3] Cooper et al., Phys. Rev. X 8, 041055 (2018)
[4] Madjarov*, Covey*, et al., Nature Physics (2020)
[5] Madjarov et al., Phys. Rev. X 9, 041052 (2019)
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.
Verification and readout methods:
We are exploring new methods for readout of complex observables and for verification of large-scale quantum devices.
We are exploring new methods for readout of complex observables and for verification of large-scale quantum devices.
Examples of previous Research topics:
Alkaline-earth atoms for quantum communication
In collaboration with Oskar Painter's group at Caltech, we worked out 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 worked out a new idea for quantum communication based on individually controlled alkaline-earth atoms coupled to cavity systems in the telecom range.
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.
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.