%0 Journal Article %D 2019 %T Nondestructive cooling of an atomic quantum register via state-insensitive Rydberg interactions %A Ron Belyansky %A Jeremy T. Young %A Przemyslaw Bienias %A Zachary Eldredge %A Adam M. Kaufman %A Peter Zoller %A Alexey V. Gorshkov %X

We propose a protocol for sympathetically cooling neutral atoms without destroying the quantum information stored in their internal states. This is achieved by designing state-insensitive Rydberg interactions between the data-carrying atoms and cold auxiliary atoms. The resulting interactions give rise to an effective phonon coupling, which leads to the transfer of heat from the data atoms to the auxiliary atoms, where the latter can be cooled by conventional methods. This can be used to extend the lifetime of quantum storage based on neutral atoms and can have applications for long quantum computations. The protocol can also be modified to realize state-insensitive interactions between the data and the auxiliary atoms but tunable and non-trivial interactions among the data atoms, allowing one to simultaneously cool and simulate a quantum spin-model. 

%8 7/28/2019 %G eng %U https://arxiv.org/abs/1907.11156 %0 Journal Article %J Phys. Rev. Lett. %D 2018 %T Dark state optical lattice with sub-wavelength spatial structure %A Yang Wang %A Sarthak Subhankar %A Przemyslaw Bienias %A Mateusz Lacki %A Tsz-Chun Tsui %A Mikhail A. Baranov %A Alexey V. Gorshkov %A Peter Zoller %A James V. Porto %A Steven L. Rolston %X

We report on the experimental realization of a conservative optical lattice for cold atoms with a subwavelength spatial structure. The potential is based on the nonlinear optical response of three-level atoms in laser-dressed dark states, which is not constrained by the diffraction limit of the light generating the potential. The lattice consists of a one-dimensional array of ultranarrow barriers with widths less than 10 nm, well below the wavelength of the lattice light, physically realizing a Kronig-Penney potential. We study the band structure and dissipation of this lattice and find good agreement with theoretical predictions. Even on resonance, the observed lifetimes of atoms trapped in the lattice are as long as 44 ms, nearly 105times the excited state lifetime, and could be further improved with more laser intensity. The potential is readily generalizable to higher dimensions and different geometries, allowing, for example, nearly perfect box traps, narrow tunnel junctions for atomtronics applications, and dynamically generated lattices with subwavelength spacings.

%B Phys. Rev. Lett. %V 120 %P 083601 %8 2018/02/20 %G eng %U https://link.aps.org/doi/10.1103/PhysRevLett.120.083601 %R 10.1103/PhysRevLett.120.083601 %0 Journal Article %J Phys. Rev. X %D 2016 %T Measurement Protocol for the Entanglement Spectrum of Cold Atoms %A Hannes Pichler %A Guanyu Zhu %A Alireza Seif %A Peter Zoller %A Mohammad Hafezi %X

Entanglement, and, in particular the entanglement spectrum, plays a major role in characterizing many-body quantum systems. While there has been a surge of theoretical works on the subject, no experimental measurement has been performed to date because of the lack of an implementable measurement scheme. Here, we propose a measurement protocol to access the entanglement spectrum of many-body states in experiments with cold atoms in optical lattices. Our scheme effectively performs a Ramsey spectroscopy of the entanglement Hamiltonian and is based on the ability to produce several copies of the state under investigation together with the possibility to perform a global swap gate between two copies conditioned on the state of an auxiliary qubit. We show how the required conditional swap gate can be implemented with cold atoms, either by using Rydberg interactions or coupling the atoms to a cavity mode. We illustrate these ideas on a simple (extended) Bose-Hubbard model where such a measurement protocol reveals topological features of the Haldane phase. 

%B Phys. Rev. X %V 6(4) %8 2016/11/22 %G eng %U https://arxiv.org/abs/1605.08624 %N 041033 %R https://doi.org/10.1103/PhysRevX.6.041033 %0 Journal Article %J Nature Communications %D 2013 %T Topologically Protected Quantum State Transfer in a Chiral Spin Liquid %A Norman Y. Yao %A Chris R. Laumann %A Alexey V. Gorshkov %A Hendrik Weimer %A Liang Jiang %A J. Ignacio Cirac %A Peter Zoller %A Mikhail D. Lukin %X Topology plays a central role in ensuring the robustness of a wide variety of physical phenomena. Notable examples range from the robust current carrying edge states associated with the quantum Hall and the quantum spin Hall effects to proposals involving topologically protected quantum memory and quantum logic operations. Here, we propose and analyze a topologically protected channel for the transfer of quantum states between remote quantum nodes. In our approach, state transfer is mediated by the edge mode of a chiral spin liquid. We demonstrate that the proposed method is intrinsically robust to realistic imperfections associated with disorder and decoherence. Possible experimental implementations and applications to the detection and characterization of spin liquid phases are discussed. %B Nature Communications %V 4 %P 1585 %8 2013/3/12 %G eng %U http://arxiv.org/abs/1110.3788v1 %! Nat Comms %R 10.1038/ncomms2531 %0 Journal Article %J Physical Review Letters %D 2012 %T Topological Flat Bands from Dipolar Spin Systems %A Norman Y. Yao %A Chris R. Laumann %A Alexey V. Gorshkov %A Steven D. Bennett %A Eugene Demler %A Peter Zoller %A Mikhail D. Lukin %X We propose and analyze a physical system that naturally admits two-dimensional topological nearly flat bands. Our approach utilizes an array of three-level dipoles (effective S = 1 spins) driven by inhomogeneous electromagnetic fields. The dipolar interactions produce arbitrary uniform background gauge fields for an effective collection of conserved hardcore bosons, namely, the dressed spin-flips. These gauge fields result in topological band structures, whose bandgap can be larger than the corresponding bandwidth. Exact diagonalization of the full interacting Hamiltonian at half-filling reveals the existence of superfluid, crystalline, and supersolid phases. An experimental realization using either ultra-cold polar molecules or spins in the solid state is considered. %B Physical Review Letters %V 109 %8 2012/12/26 %G eng %U http://arxiv.org/abs/1207.4479v3 %N 26 %! Phys. Rev. Lett. %R 10.1103/PhysRevLett.109.266804 %0 Journal Article %J Physical Review Letters %D 2009 %T Alkaline-Earth-Metal Atoms as Few-Qubit Quantum Registers %A Alexey V. Gorshkov %A Ana Maria Rey %A Andrew J. Daley %A Martin M. Boyd %A Jun Ye %A Peter Zoller %A Mikhail D. Lukin %X We propose and analyze a novel approach to quantum information processing, in which multiple qubits can be encoded and manipulated using electronic and nuclear degrees of freedom associated with individual alkaline-earth atoms trapped in an optical lattice. Specifically, we describe how the qubits within each register can be individually manipulated and measured with sub-wavelength optical resolution. We also show how such few-qubit registers can be coupled to each other in optical superlattices via conditional tunneling to form a scalable quantum network. Finally, potential applications to quantum computation and precision measurements are discussed. %B Physical Review Letters %V 102 %8 2009/3/18 %G eng %U http://arxiv.org/abs/0812.3660v2 %N 11 %! Phys. Rev. Lett. %R 10.1103/PhysRevLett.102.110503 %0 Journal Article %J Nature Physics %D 2008 %T Anyonic interferometry and protected memories in atomic spin lattices %A Liang Jiang %A Gavin K. Brennen %A Alexey V. Gorshkov %A Klemens Hammerer %A Mohammad Hafezi %A Eugene Demler %A Mikhail D. Lukin %A Peter Zoller %X Strongly correlated quantum systems can exhibit exotic behavior called topological order which is characterized by non-local correlations that depend on the system topology. Such systems can exhibit remarkable phenomena such as quasi-particles with anyonic statistics and have been proposed as candidates for naturally fault-tolerant quantum computation. Despite these remarkable properties, anyons have never been observed in nature directly. Here we describe how to unambiguously detect and characterize such states in recently proposed spin lattice realizations using ultra-cold atoms or molecules trapped in an optical lattice. We propose an experimentally feasible technique to access non-local degrees of freedom by performing global operations on trapped spins mediated by an optical cavity mode. We show how to reliably read and write topologically protected quantum memory using an atomic or photonic qubit. Furthermore, our technique can be used to probe statistics and dynamics of anyonic excitations. %B Nature Physics %V 4 %P 482 - 488 %8 2008/4/20 %G eng %U http://arxiv.org/abs/0711.1365v1 %N 6 %! Nat Phys %R 10.1038/nphys943 %0 Journal Article %J Physical Review Letters %D 2008 %T Coherent Quantum Optical Control with Subwavelength Resolution %A Alexey V. Gorshkov %A Liang Jiang %A Markus Greiner %A Peter Zoller %A Mikhail D. Lukin %X We suggest a new method for quantum optical control with nanoscale resolution. Our method allows for coherent far-field manipulation of individual quantum systems with spatial selectivity that is not limited by the wavelength of radiation and can, in principle, approach a few nanometers. The selectivity is enabled by the nonlinear atomic response, under the conditions of Electromagnetically Induced Transparency, to a control beam with intensity vanishing at a certain location. Practical performance of this technique and its potential applications to quantum information science with cold atoms, ions, and solid-state qubits are discussed. %B Physical Review Letters %V 100 %8 2008/3/7 %G eng %U http://arxiv.org/abs/0706.3879v2 %N 9 %! Phys. Rev. Lett. %R 10.1103/PhysRevLett.100.093005