@article {eldredge_entanglement_2020,
title = {Entanglement bounds on the performance of quantum computing architectures},
journal = {Phys. Rev. Res.},
volume = {2},
number = {3},
year = {2020},
note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article},
month = {aug},
abstract = {There are many possible architectures of qubit connectivity that designers of future quantum computers will need to choose between. However, the process of evaluating a particular connectivity graph{\textquoteright}s performance as a quantum architecture can be difficult. In this paper, we show that a quantity known as the isoperimetric number establishes a lower bound on the time required to create highly entangled states. This metric we propose counts resources based on the use of two-qubit unitary operations, while allowing for arbitrarily fast measurements and classical feedback. We use this metric to evaluate the hierarchical architecture proposed by A. Bapat et al. [Phys. Rev. A 98, 062328 (2018)] and find it to be a promising alternative to the conventional grid architecture. We also show that the lower bound that this metric places on the creation time of highly entangled states can be saturated with a constructive protocol, up to a factor logarithmic in the number of qubits.},
doi = {10.1103/PhysRevResearch.2.033316},
author = {Eldredge, Zachary and Zhou, Leo and Bapat, Aniruddha and Garrison, James R. and Deshpande, Abhinav and Chong, Frederic T. and Gorshkov, V, Alexey}
}
@article { ISI:000489036000001,
title = {Heisenberg-scaling measurement protocol for analytic functions with quantum sensor networks},
journal = {Phys. Rev. A},
volume = {100},
number = {4},
year = {2019},
month = {OCT 7},
pages = {042304},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {We generalize past work on quantum sensor networks to show that, for d input parameters, entanglement can yield a factor O(d) improvement in mean-squared error when estimating an analytic function of these parameters. We show that the protocol is optimal for qubit sensors, and we conjecture an optimal protocol for photons passing through interferometers. Our protocol is also applicable to continuous variable measurements, such as one quadrature of a field operator. We outline a few potential applications, including calibration of laser operations in trapped ion quantum computing.},
issn = {2469-9926},
doi = {10.1103/PhysRevA.100.042304},
author = {Qian, Kevin and Eldredge, Zachary and Ge, Wenchao and Pagano, Guido and Monroe, Christopher and Porto, V, J. and Gorshkov, V, Alexey}
}
@article {ISI:000474892400001,
title = {Locality and Digital Quantum Simulation of Power-Law Interactions},
journal = {Phys. Rev. X},
volume = {9},
number = {3},
year = {2019},
month = {JUL 10},
pages = {031006},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {The propagation of information in nonrelativistic quantum systems obeys a speed limit known as a Lieb-Robinson bound. We derive a new Lieb-Robinson bound for systems with interactions that decay with distance r as a power law, 1/r(alpha). The bound implies an effective light cone tighter than all previous bounds. Our approach is based on a technique for approximating the time evolution of a system, which was first introduced as part of a quantum simulation algorithm by Haah et al., FOCS{\textquoteright} 18. To bound the error of the approximation, we use a known Lieb-Robinson bound that is weaker than the bound we establish. This result brings the analysis full circle, suggesting a deep connection between Lieb-Robinson bounds and digital quantum simulation. In addition to the new Lieb-Robinson bound, our analysis also gives an error bound for the Haah et al. quantum simulation algorithm when used to simulate power-law decaying interactions. In particular, we show that the gate count of the algorithm scales with the system size better than existing algorithms when alpha > 3D (where D is the number of dimensions).},
issn = {2160-3308},
doi = {10.1103/PhysRevX.9.031006},
author = {Tran, Minh C. and Guo, Andrew Y. and Su, Yuan and Garrison, James R. and Eldredge, Zachary and Foss-Feig, Michael and Childs, Andrew M. and Gorshkov, Alexey V.}
}
@article { ISI:000498063400002,
title = {Nondestructive Cooling of an Atomic Quantum Register via State-Insensitive Rydberg Interactions},
journal = {Phys. Rev. Lett.},
volume = {123},
number = {21},
year = {2019},
month = {NOV 20},
pages = {213603},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {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 nontrivial interactions among the data atoms, allowing one to simultaneously cool and simulate a quantum spin model.},
issn = {0031-9007},
doi = {10.1103/PhysRevLett.123.213603},
author = {Belyansky, Ron and Young, Jeremy T. and Bienias, Przemyslaw and Eldredge, Zachary and Kaufman, Adam M. and Zoller, Peter and Gorshkov, V, Alexey}
}
@article {ISI:000462935500003,
title = {Scale-Invariant Continuous Entanglement Renormalization of a Chern Insulator},
journal = {Phys. Rev. Lett.},
volume = {122},
number = {12},
year = {2019},
month = {MAR 27},
pages = {120502},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {The multiscale entanglement renormalization ansatz (MERA) postulates the existence of quantum circuits that renormalize entanglement in real space at different length scales. Chem insulators, however, cannot have scale-invariant discrete MERA circuits with a finite bond dimension. In this Letter, we show that the continuous MERA (cMERA), a modified version of MERA adapted for field theories, possesses a fixed point wave function with a nonzero Chern number. Additionally, it is well known that reversed MERA circuits can be used to prepare quantum states efficiently in time that scales logarithmically with the size of the system. However, state preparation via MERA typically requires the advent of a full-fledged universal quantum computer. In this Letter, we demonstrate that our cMERA circuit can potentially be realized in existing analog quantum computers, i.e., an ultracold atomic Fermi gas in an optical lattice with light-induced spin-orbit coupling.},
issn = {0031-9007},
doi = {10.1103/PhysRevLett.122.120502},
author = {Chu, Su-Kuan and Zhu, Guanyu and Garrison, James R. and Eldredge, Zachary and Curiel, Ana Valdes and Bienias, Przemyslaw and Spielman, I. B. and Gorshkov, V, Alexey}
}
@article { ISI:000439744700003,
title = {Distributed Quantum Metrology with Linear Networks and Separable Inputs},
journal = {PHYSICAL REVIEW LETTERS},
volume = {121},
number = {4},
year = {2018},
month = {JUL 25},
pages = {043604},
issn = {0031-9007},
doi = {10.1103/PhysRevLett.121.043604},
author = {Ge, Wenchao and Jacobs, Kurt and Eldredge, Zachary and Gorshkov, V, Alexey and Foss-Feig, Michael}
}
@article {ISI:000430543700006,
title = {Optimal and secure measurement protocols for quantum sensor networks},
journal = {PHYSICAL REVIEW A},
volume = {97},
number = {4},
year = {2018},
month = {APR 23},
pages = {042337},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {Studies of quantum metrology have shown that the use of many-body entangled states can lead to an enhancement in sensitivity when compared with unentangled states. In this paper, we quantify the metrological advantage of entanglement in a setting where the measured quantity is a linear function of parameters individually coupled to each qubit. We first generalize the Heisenberg limit to the measurement of nonlocal observables in a quantum network, deriving a bound based on the multiparameter quantum Fisher information. We then propose measurement protocols that can make use of Greenberger-Horne-Zeilinger (GHZ) states or spin-squeezed states and show that in the case of GHZ states the protocol is optimal, i.e., it saturates our bound. We also identify nanoscale magnetic resonance imaging as a promising setting for this technology.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
issn = {2469-9926},
doi = {10.1103/PhysRevA.97.042337},
author = {Eldredge, Zachary and Foss-Feig, Michael and Gross, Jonathan A. and Rolston, S. L. and Gorshkov, Alexey V.}
}
@article { ISI:000454419500004,
title = {Unitary entanglement construction in hierarchical networks},
journal = {PHYSICAL REVIEW A},
volume = {98},
number = {6},
year = {2018},
month = {DEC 26},
pages = {062328},
abstract = {The construction of large-scale quantum computers will require modular architectures that allow physical resources to be localized in easy-to-manage packages. In this work we examine the impact of different graph structures on the preparation of entangled states. We begin by explaining a formal framework, the hierarchical product, in which modular graphs can be easily constructed. This framework naturally leads us to suggest a class of graphs, which we dub hierarchies. We argue that such graphs have favorable properties for quantum information processing, such as a small diameter and small total edge weight, and use the concept of Pareto efficiency to identify promising quantum graph architectures. We present numerical and analytical results on the speed at which large entangled states can be created on nearest-neighbor grids and hierarchy graphs. We also present a scheme for performing circuit placement-the translation from circuit diagrams to machine qubits-on quantum systems whose connectivity is described by hierarchies.},
issn = {2469-9926},
doi = {10.1103/PhysRevA.98.062328},
author = {Bapat, Aniruddha and Eldredge, Zachary and Garrison, James R. and Deshpande, Abhinav and Chong, Frederic T. and Gorshkov, Alexey V.}
}
@article { ISI:000413663300001,
title = {Fast Quantum State Transfer and Entanglement Renormalization Using Long-Range Interactions},
journal = {PHYSICAL REVIEW LETTERS},
volume = {119},
number = {17},
year = {2017},
month = {OCT 25},
issn = {0031-9007},
doi = {10.1103/PhysRevLett.119.170503},
author = {Eldredge, Zachary and Gong, Zhe-Xuan and Young, Jeremy T. and Moosavian, Ali Hamed and Foss-Feig, Michael and Gorshkov, Alexey V.}
}
@article {ISI:000388814500011,
title = {Self-organization of atoms coupled to a chiral reservoir},
journal = {PHYSICAL REVIEW A},
volume = {94},
number = {5},
year = {2016},
month = {NOV 29},
pages = {053855},
abstract = {Tightly confined modes of light, as in optical nanofibers or photonic crystal waveguides, can lead to large optical coupling in atomic systems, which mediates long-range interactions between atoms. These one-dimensional systems can naturally possess couplings that are asymmetric between modes propagating in different directions. Strong long-range interaction among atoms via these modes can drive them to a self-organized periodic distribution. In this paper, we examine the self-organizing behavior of atoms in one dimension coupled to a chiral reservoir. We determine the solution to the equations of motion in different parameter regimes, relative to both the detuning of the pump laser that initializes the atomic dipole-dipole interactions and the degree of reservoir chirality. In addition, we calculate possible experimental signatures such as reflectivity from self-organized atoms and motional sidebands.},
issn = {2469-9926},
doi = {10.1103/PhysRevA.94.053855},
author = {Eldredge, Zachary and Solano, Pablo and Chang, Darrick and Gorshkov, Alexey V.}
}