Rubidium Lab


Postdocs


Former Group Members

Alex Lukin

Graduate Student (2012-2018)

Matthew Rispoli

Graduate Student (2013-2019)

Eric Tai

Graduate Student (2009-2017)

Adam Kaufman

Postdoc (2015-2017)

Tim Menke

Graduate Student (2016-2017)

Philipp Preiss

Graduate Student (2010-2015)

Rajibul Islam

Postdoc (2012-2015)

Ruichao Ma

Graduate Student (2009-2014)

Philip Zupancic

Visiting Student (2012-2013)

Jonathan Simon

Postdoc (2010-2012)

Waseem Bakr

Graduate Student (2006-2011)

Johannes Brachmann

Diploma/Master’s Student

Peter Unterwaditzer

Diploma/Master’s Student

Simon Fölling

Postdoc (200x-2010)

Amy Peng

Graduate Student (200x-2010)

Jonathon Gillen

Graduate Student (200x-2009)

Ultracold atomic systems can be used as quantum simulators to study a range of phenomena in strongly-correlated materials ranging from high-Tc superconductors to quantum magnets. The micron-scale spacing of atoms in these systems provides an opportunity to optically image fluctuations and correlations in strongly correlated systems in a way not possible in condensed matter. Our quantum gas microscopy (QGM) allows, for the first time, for optical imaging and manipulation of strongly-interacting quantum gases containing thousands of atoms at the single atom level. The ideas introduced in QGM are quite general and can be applied to a range of other systems including fermionic (See our Fermi Gas Microscope experiment) and dipolar gases (See our planned Erbium QGM). In addition, it provides a path to quantum computation in a system with a scalable architecture.

Quantum critical behaviour at the many-body localization transition
12/2018
Nature 573, 385-389 (2019) arXiv:1812.06959
Phase transitions are driven by collective fluctuations of a system’s constituents that emerge at a critical point. This mechanism has been extensively explored for classical and quantum systems in equilibrium, whose critical behavior is described by a general theory of phase transitions. Recently, however, fundamentally distinct phase transitions have been discovered for out-of-equilibrium quantum systems, which can exhibit critical behavior that defies this description and is not well understood. A paradigmatic example is the many-body-localization (MBL) transition, which marks the breakdown of quantum thermalization. Characterizing quantum critical behavior in an MBL system requires the measurement of its entanglement properties over space and time, which has proven experimentally challenging due to stringent requirements on quantum state preparation and system isolation. Here, we observe quantum critical behavior at the MBL transition in a disordered Bose-Hubbard system and characterize its entanglement properties via its quantum correlations. We observe strong correlations, whose emergence is accompanied by the onset of anomalous diffusive transport throughout the system, and verify their critical nature by measuring their system-size dependence. The correlations extend to high orders in the quantum critical regime and appear to form via a sparse network of many-body resonances that spans the entire system. Our results unify the system’s microscopic structure with its macroscopic quantum critical behavior, and they provide an essential step towards understanding criticality and universality in non-equilibrium systems.
Probing entanglement in a many-body-localized system
07/2018
Science 364, 256-260 (2019) arXiv:1805.09819
An interacting quantum system that is subject to disorder may cease to thermalize due to localization of its constituents, thereby marking the breakdown of thermodynamics. The key to our understanding of this phenomenon lies in the system’s entanglement, which is experimentally challenging to measure. We realize such a many-body-localized system in a disordered Bose-Hubbard chain and characterize its entanglement properties through particle fluctuations and correlations. We observe that the particles become localized, suppressing transport and preventing the thermalization of subsystems. Notably, we measure the development of non-local correlations, whose evolution is consistent with a logarithmic growth of entanglement entropy - the hallmark of many-body localization. Our work experimentally establishes many-body localization as a qualitatively distinct phenomenon from localization in non-interacting, disordered systems.
Microscopy of the interacting Harper-Hofstadter model in the two-body limit
06/2017
Nature 546, 519-523 (2017) arXiv:1612.05631v1
The interplay between magnetic fields and interacting particles can lead to exotic phases of matter that exhibit topological order and high degrees of spatial entanglement. Although these phases were discovered in a solid-state setting, recent innovations in systems of ultracold neutral atoms - uncharged atoms that do not naturally experience a Lorentz force - allow the synthesis of artificial magnetic, or gauge, fields. This experimental platform holds promise for exploring exotic physics in fractional quantum Hall systems, owing to the microscopic control and precision that is achievable in cold-atom systems. However, so far these experiments have mostly explored the regime of weak interactions, which precludes access to correlated many-body states. Here, through microscopic atomic control and detection, we demonstrate the controlled incorporation of strong interactions into a two-body system with a chiral band structure.