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Quantum Simulation in Cold Atomic Matter

Dipolar fractional chern insulator and surrounding phases

Dipolar fractional chern insulator and surrounding phases

The development of ultra-cold atomic and molecular gases has raised the possibility of studying topological phases in out-of-equilibrium spin systems. Unlike traditional condensed matter systems, one cannot simply “cool” into a desired topological ground state by decreasing the temperature of a surrounding bath. Rather, preparation must proceed coherently, e.g. by exploiting the quantum adiabatic theorem. This necessitates a detailed knowledge of the phase transitions separating topological states from their short-range-entangled neighbors and requires understanding the interplay between topology, lattice symmetries and out-of-equilibrium dynamics.

Conformal cooling quenches in the AKLT phase

Conformal cooling quenches in the AKLT phase

One particular context where lattice and topology meet is in the notion offractional Chern insulators (FCI) --- exotic phases, which arise when strongly interacting particles inhabit a flat topological bandstructure. Particles injected into these exotic states of matter fractionalize into multiple independently propagating pieces, each of which carries a fraction of the original particle's quantum numbers. While similar effects underpin the fractional quantum Hall effect observed in continuum two dimensional electron gases, fractional Chern insulators, by contrast, are lattice dominated. They have an extremely high density of correlated particles whose collective excitations can transform non-trivially under lattice symmetries.  Since the FCI state generally competes with superfluid and crystalline orders, the resulting phase diagram exhibits both conventional and topological phases. Our group is interested in the quantum simulation of fractional Chern insulators and quantum spin liquids in long-range dipolar systems. To diagnose the intrinsic topological features of such phases, we are also exploring new methods to measure single-particle and many-body topological invariants in AMO systems.


Recent Publications

  1. Preparation of Low Entropy Correlated Many-body States via Conformal Cooling Quenches. Michael P. Zaletel, Dan M. Stamper-Kurn and Norman Y. Yao, arXiv:1611.04591.

  2. Observing Topological Invariants Using Quantum Walk in Superconducting Circuits. Emmanuel Flurin, Vinay V. Ramasesh, Shay Hacohen-Gourgy, Leigh S. Martin, Norman Y. Yao and Irfan Siddiqi, arXiv:1610.03069.

  3. Direct Probe of Topological Invariants Using Bloch Oscillating Quantum Walks. Vinay V. Ramasesh, Emmanuel Flurin, Mark S. Rudner, Irfan Siddiqi and Norman Y. Yao, arXiv:1609.09504.

  4. Interferometric Measurements of Many-body Topological Invariants using Mobile Impurities. Fabian Grusdt, Norman Y. Yao, Dmitry A. Abanin, Michael Fleischhauer and Eugene A. Demler, Nature Communications 7, 11994 (2016).

  5. A Quantum Dipolar Spin Liquid. Norman Y. Yao, Michael P. Zaletel, Dan M. Stamper-Kurn and Ashvin Vishwanath, arXiv:1510.06403.

  6. Continuous Preparation of a Fractional Chern Insulator. Maissam Barkeshli, Norman Y. Yao and Chris R. Laumann, Phys. Rev. Lett. 115, 026802 (2015).

  7. Bilayer fractional quantum Hall states with ultracold dysprosium. Norman Y. Yao, Steven D. Bennett, Chris R. Laumann, Benjamin L. Lev and Alexey V. Gorshkov, Phys. Rev. A 92, 033609 (2015).

  8. Realizing Fractional Chern Insulators with Dipolar Spins. Norman Y. Yao, Alexey V. Gorshkov, Chris R. Laumann, Andreas M. Läuchli, Jun Ye and Mikhail D. Lukin, Phys. Rev. Lett. 110, 185302 (2013).