Mixed-state entanglement from local randomized measurements

Citation:

Andreas Elben, Richard Kueng, Hsin-Yuan Huang, Rick Van Bijnen, Christian Kokail, Marcello Dalmonte, Pasquale Calabrese, Barbara Kraus, John Preskill, Peter Zoller, and Benoît Vermersch. 2020. “Mixed-state entanglement from local randomized measurements.” arXiv:2007.06305.

Abstract:

We propose a method for detecting bipartite entanglement in a many-body mixed state based on estimating moments of the partially transposed density matrix. The estimates are obtained by performing local random measurements on the state, followed by post-processing using the classical shadows framework. Our method can be applied to any quantum system with single-qubit control. We provide a detailed analysis of the required number of experimental runs, and demonstrate the protocol using existing experimental data [Brydges et al, Science 364, 260 (2019)].

Recent Publications

Critical drag as a mechanism for resistivity

Citation:

Dominic Else and T. Senthil. 6/29/2021. “Critical drag as a mechanism for resistivity”. arXiv

Abstract:

Critical drag is thus a mechanism for resistivity that, unlike conventional mechanisms, is unrelated to broken symmetries. We furthermore argue that an emergent symmetry that has the appropriate mixed anomaly with electric charge is in fact an inevitable consequence of compressibility in systems with lattice translation symmetry. Critical drag therefore seems to be the only way (other than through irrelevant perturbations breaking the emergent symmetry, that disappear at the renormalization group fixed point) to get nonzero resistivity in such systems. Finally, we present a very simple and concrete model -- the "Quantum Lifshitz Model" -- that illustrates the critical drag mechanism as well as the other considerations of the paper.

Last updated on 07/09/2021

Prediction of Toric Code Topological Order from Rydberg Blockade

Citation:

Ruben Verresen, Mikhail D. Lukin, and Ashvin Vishwanath. 2021. “Prediction of Toric Code Topological Order from Rydberg Blockade.” Phys. Rev. X. Publisher's Version

Last updated on 07/09/2021

Topology of superconductors beyond mean-field theory

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Matthew F Lapa. 2020. “Topology of superconductors beyond mean-field theory.” arXiv:2003.05948 (accepted for publication in Phys. Rev. Research). Physical Review Research

Abstract:

The study of topological superconductivity is largely based on the analysis of mean-field Hamiltonians that violate particle number conservation and have only short-range interactions. Although this approach has been very successful, it is not clear that it captures the topological properties of real superconductors, which are described by number-conserving Hamiltonians with long-range interactions. To address this issue, we study topological superconductivity directly in the number-conserving setting.

Last updated on 07/09/2021

Gapped domain walls between 2+1D topologically ordered states

Citation:

Tian Lan, Xueda Wen, Liang Kong, and Xiao-Gang Wen. 2020. “Gapped domain walls between 2+1D topologically ordered states.” Phys. Rev. Research, 2, Pp. 023331.

Emerging Two-Dimensional Gauge Theories in Rydberg Configurable Arrays

Citation:

Alessio Celi, Benoît Vermersch, Oscar Viyuela, Hannes Pichler, Mikhail D. Lukin, and Peter Zoller. 2020. “Emerging Two-Dimensional Gauge Theories in Rydberg Configurable Arrays.” Physical Review X, 10, Pp. 021057.

Abstract:

Solving strongly coupled gauge theories in two or three spatial dimensions is of fundamental importance in several areas of physics ranging from high-energy physics to condensed matter. On a lattice, gauge invariance and gauge invariant (plaquette) interactions involve (at least) four-body interactions that are challenging to realize. Here we show that Rydberg atoms in configurable arrays realized in current tweezer experiments are the natural platform to realize scalable simulators of the Rokhsar-Kivelson Hamiltonian –a 2D U(1) lattice gauge theory that describes quantum dimer and spin-ice dynamics. Using an electromagnetic duality, we implement the plaquette interactions as Rabi oscillations subject to Rydberg blockade. Remarkably, we show that by controlling the atom arrangement in the array we can engineer anisotropic interactions and generalized blockade conditions for spins built of atom pairs. We describe how to prepare the resonating valence bond and the crystal phases of the Rokhsar-Kivelson Hamiltonian adiabatically, and probe them and their quench dynamics by on-site measurements of their quantum correlations. We discuss the potential applications of our Rydberg simulator to lattice gauge theory and exotic spin models.

Quantum non-demolition measurement of a many-body Hamiltonian

Citation:

Dayou Yang, Andrey Grankin, Lukas M. Sieberer, Denis V. Vasilyev, and Peter Zoller. 2020. “Quantum non-demolition measurement of a many-body Hamiltonian.” Nature Communications, 11, Pp. 775.

Abstract:

In an ideal quantum measurement, the wave function of a quantum system collapses to an eigenstate of the measured observable, and the corresponding eigenvalue determines the measurement outcome. If the observable commutes with the system Hamiltonian, repeated measurements yield the same result and thus minimally disturb the system. Seminal quantum optics experiments have achieved such quantum non-demolition (QND) measurements of systems with few degrees of freedom. In contrast, here we describe how the QND measurement of a complex many-body observable, the Hamiltonian of an interacting many-body system, can be implemented in a trapped-ion analog quantum simulator. Through a single-shot measurement, the many-body system is prepared in a narrow band of (highly excited) energy eigenstates, and potentially even a single eigenstate. Our QND scheme, which can be carried over to other platforms of quantum simulation, provides a framework to investigate experimentally fundamental aspects of equilibrium and non-equilibrium statistical physics including the eigenstate thermalization hypothesis and quantum fluctuation relations.

Ultra-Quantum Matter

Recent developments demonstrate that in the right circumstances, quantum aspects can extend to macroscopic scale. This is UQM.

Mixed-state entanglement from local randomized measurements

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Abstract:

Recent Publications

Critical drag as a mechanism for resistivity

Citation:

Abstract:

Prediction of Toric Code Topological Order from Rydberg Blockade

Citation:

Topology of superconductors beyond mean-field theory

Citation:

Abstract:

Gapped domain walls between 2+1D topologically ordered states

Citation:

Emerging Two-Dimensional Gauge Theories in Rydberg Configurable Arrays

Citation:

Abstract:

Quantum non-demolition measurement of a many-body Hamiltonian

Citation:

Abstract: