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Schemes of classical shadows have been developed to facilitate the read-out of digital quantum devices, but similar tools for analog quantum simulators are scarce and experimentally impractical. In this work, we provide a measurement scheme…

Quantum Physics · Physics 2024-12-18 Janek Denzler , Antonio Anna Mele , Ellen Derbyshire , Tommaso Guaita , Jens Eisert

We introduce the Green's functions technique as an alternative theory to the quantum regression theorem formalism for calculating the two-time correlation functions in open quantum systems. In particular, we investigate the potential of…

Quantum Physics · Physics 2015-02-03 Edgar A. Gomez , J. D. Hernandez-Rivero , Herbert Vinck-Posada

We present and benchmark quantum computing approaches for calculating real-time single-particle Green's functions and nonlinear susceptibilities of Hamiltonian systems. The approaches leverage adaptive variational quantum algorithms for…

Quantum Physics · Physics 2025-11-17 Martin Mootz , Thomas Iadecola , Yong-Xin Yao

The development of numerical methods capable of simulating realistic materials with strongly correlated electrons, with controllable errors, is a central challenge in quantum many-body physics. Here we describe how a hybrid between…

Strongly Correlated Electrons · Physics 2015-04-23 Alexei A. Kananenka , Emanuel Gull , Dominika Zgid

A central challenge in analog quantum simulation is to characterize desirable physical properties of quantum states produced in experiments. However, in conventional approaches, the extraction of arbitrary information requires performing…

Quantum Physics · Physics 2023-04-04 Minh C. Tran , Daniel K. Mark , Wen Wei Ho , Soonwon Choi

We develop a reliable parameter-free analytic continuation method for quantum many-body calculations. Our method is based on a kernel grid, a causal spline, a regularization using the second-derivative roughness penalty, and the L-curve…

Strongly Correlated Electrons · Physics 2023-01-03 Mancheon Han , Hyoung Joon Choi

Quantum simulations with ultra-cold atoms in optical lattices open up an exciting path towards understanding strongly interacting quantum systems. Atom gas microscopes are crucial for this as they offer single-site density resolution,…

Quantum Gases · Physics 2021-08-25 M. Gluza , J. Eisert

We introduce multi-pulse quantum noise spectroscopy protocols for spectral estimation of the noise affecting multiple qubits coupled to Gaussian dephasing environments including both classical and quantum sources. Our protocols are capable…

Quantum Physics · Physics 2017-03-01 Gerardo A. Paz-Silva , Leigh M. Norris , Lorenza Viola

In quantum metrology, entanglement represents a valuable resource that can be used to overcome the Standard Quantum Limit (SQL) that bounds the precision of sensors that operate with independent particles. Measurements beyond the SQL are…

We present a protocol for detecting multipartite entanglement in itinerant many-body electronic systems using single particle Green's functions. To achieve this, we first establish a connection between the quantum Fisher information (QFI)…

Quantum Physics · Physics 2024-10-11 Rajesh K. Malla , Andreas Weichselbaum , Tzu-Chieh Wei , Robert M. Konik

Nonequilibrium dynamics of quantum many-body systems is challenging for classical computing, providing opportunities for demonstrating practical quantum computational advantage with analogue quantum simulators. Owing to the intimate…

The problem of simulating the thermal behavior of quantum systems remains a central open challenge in quantum computing. Unlike well-established quantum algorithms for unitary dynamics, \emph{provably efficient} algorithms for preparing…

Quantum Physics · Physics 2026-05-14 Dominik Hahn , Ryan Sweke , Abhinav Deshpande , Oles Shtanko

We study in general the time-evolution of correlation functions in a extended quantum system after the quench of a parameter in the hamiltonian. We show that correlation functions in d dimensions can be extracted using methods of boundary…

Statistical Mechanics · Physics 2011-02-16 Pasquale Calabrese , John Cardy

Building on the many existing algorithms for calculating the DC transport properties of quantum tight-binding models, we develop a systematic approach that expresses finite frequency observables in terms of the stationary Green's function…

Mesoscale and Nanoscale Physics · Physics 2013-02-15 Oleksii Shevtsov , Xavier Waintal

Quantum simulators, in which well controlled quantum systems are used to reproduce the dynamics of less understood ones, have the potential to explore physics that is inaccessible to modeling with classical computers. However, checking the…

Quantum Physics · Physics 2015-06-18 C. Senko , J. Smith , P. Richerme , A. Lee , W. C. Campbell , C. Monroe

In quantum metrology, entangled states of many-particle systems are investigated to enhance measurement precision of the most precise clocks and field sensors. While single-parameter quantum metrology is well established, many metrological…

This study introduces a systematic approach for analyzing strongly correlated systems by adapting the conventional quantum cluster method to a quantum circuit model. We have developed a more concise formula for calculating the cluster's…

Quantum Physics · Physics 2025-12-24 Hengyue Li , Yusheng Yang , Pin Lv , Jinglong Qu , Zhe-Hui Wang , Jian Sun , Shenggang Ying

We show that the recently discovered quantum-enhanced measurement protocol of coherent averaging that is capable of achieving Heisenberg-limited sensitivity without using entanglement, has a classical analogue. The classical protocol uses N…

Quantum Physics · Physics 2013-05-07 Daniel Braun , Sandu Popescu

We consider measurement-based quantum computation using the state of a spin-lattice system in equilibrium with a thermal bath and free to evolve under its own Hamiltonian. Any single qubit measurements disturb the system from equilibrium…

Quantum Physics · Physics 2009-09-23 David Jennings , Andrzej Dragan , Sean D. Barrett , Stephen D. Bartlett , Terry Rudolph

Variational representations of quantum states abound and have successfully been used to guess ground-state properties of quantum many-body systems. Some are based on partial physical insight (Jastrow, Gutzwiller projected, and fractional…

Quantum Physics · Physics 2019-12-18 Douglas Hendry , Adrian E. Feiguin