Welcome

Welcome to the website of our group at Harvard. Our research focuses on studying ultracold gases loaded into artificial crystals of light known as optical lattices. Recent experiments on such systems have opened the door to an emerging field at the interface of atomic physics, condensed matter physics and quantum information. The behavior of ultracold atoms in optical lattices is similar to that of electrons in solids. Because of that, ultracold atoms can provide clean realizations of models from condensed matter which can be studied in a highly controlled environment.

"Probing the superfluid to Mott insulator transition at the single atom level" wins the 2011 AAAS Newcomb Cleveland Prize!

Paper Press release

Markus is now a Professor of Physics!

Orbital Excitation Blockade and Algorithmic Cooling in Quantum Gases

Nature DOI: 10.1038/nature10668

Paper Press release Nature News and Views ScienceBlog review

Markus wins a MacArthur Fellowship!

MacArthur Foundation Press Release MacArthur Foundation Profile Harvard Gazette Article boston.com Article

Quantum simulation of antiferromagnetic spin chains in an optical lattice

Nature DOI: 10.1038/nature09994

Paper Press release Harvard Gazette Article Theoretical Proposal Nature News and Views

Quantum Magnetism in an Optical lattice. (a) Two spin chains, one paramagnetically ordered (back), and one antiferromagnetically ordered (front). The background is a single-shot image from the quantum gas microscope, demonstrating the scalability of this approach. (b) Strong magnetic interactions and fast dynamics are realized by mapping the position degree of freedom of each atom onto the state of a single spin 1/2 particle. By adiabatically tuning the tilt (E/U) of the lattice, we drive a phase transition from a paramagnetically ordered (Mott) state, to an antiferromagnetically ordered state with density-wave (DW) ordering. Because the DW ordered state is contains sites with occupations of only n=2,0, it appears dark (podd~0), while the Mott state appears bright (podd~1). This first demonstration of quantum magnetism in a lattice should open new perspectives for studies of criticality, and high temperature superconductivity, with cold atoms. The work uses a theoretical proposal by Prof. Subir Sachdev and collaborators, PRB 66, 075128 (2002).

Probing the superfluid to Mott insulator transition at the single atom level

Science DOI: 10.1126/science.1192368

Paper Press release Physics Today review Science perspective ScienceBlog review

News: Single atom imaging of Mott insulator selected as a top breakthrough of this year by Science

Mott insulator (MI) in a Quantum Gas Microscope. (a) Sketch of Quantum Gas Microscope, enabling high fidelity single lattice site imaging. (b) Mott insulator shell structure with n=1 MI (bright ring), surrounding a n=2 MI core (dark). (c) near perfect n=1 Mott insulator.

Experimentally observed Mott shells (averaged) for increasing atom number.

The Quantum Gas Microscope enables high fidelity detection of single atoms in a Hubbard-regime optical lattice, bringing ultracold atom research to a new, microscopic level. We investigate the Bose-Hubbard model using space- and time-resolved characterization of the number statistics across the superfluid - Mott insulator quantum phase transition. Site-resolved probing of fluctuations provides us with a sensitive local thermometer, allows us to identify microscopic heterostructures of low entropy Mott domains, and enables us to measure local quantum dynamics, revealing surprisingly fast transition timescales. Our results may serve as a benchmark for theoretical studies of quantum dynamics, and open new possibilities for realizing and probing quantum magnetism.

Next generation Fermi gas microscope!

We are one of the two labs in Markus Greiner's group. Our long term goal is to do experiments with Degenerate Fermi Gases in an Optical Lattice. Our experiment is a dual species, Bosonic Sodium (Na) and Fermionic Lithium (Li), BEC experiment.