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We show how a quantum computer may efficiently simulate a disordered Hamiltonian, by incorporating a pseudo-random number generator directly into the time evolution circuit. This technique is applied to quantum simulation of few-body…

Disordered Systems and Neural Networks · Physics 2020-03-25 Andrei Alexandru , Paulo F. Bedaque , Scott Lawrence

One of the most promising applications of noisy intermediate-scale quantum computers is the simulation of molecular Hamiltonians using the variational quantum eigensolver. We show that encoding symmetries of the simulated Hamiltonian in the…

Efficiently characterizing large quantum states and processes is a central yet notoriously challenging task in quantum information science, as conventional tomography methods typically require resources that grow exponentially with system…

Quantum Physics · Physics 2026-03-03 Chenyang Li , Shengxin Zhuang , Yukun Zhang , Jingbo B. Wang , Xiao Yuan , Yusen Wu , Chuan Wang

Characterizing and understanding noise affecting quantum states has immense benefits in spectroscopy as well as in realizing quantum devices. Transverse relaxation times under a set of dynamical decoupling (DD) sequences with varying…

Quantum Physics · Physics 2017-01-11 Deepak Khurana , Govind Unnikrishnan , T. S. Mahesh

We study the problem of learning the parameters for the Hamiltonian of a quantum many-body system, given limited access to the system. In this work, we build upon recent approaches to Hamiltonian learning via derivative estimation. We…

Quantum Physics · Physics 2024-01-10 Andi Gu , Lukasz Cincio , Patrick J. Coles

We consider how to characterize the dynamics of a quantum system from a restricted set of initial states and measurements using Bayesian analysis. Previous work has shown that Hamiltonian systems can be well estimated from analysis of noisy…

Quantum Physics · Physics 2014-03-04 S. G. Schirmer , D. K. L. Oi

The identification of parameters in the Hamiltonian that describes complex many-body quantum systems is generally a very hard task. Recent attention has focused on such problems of Hamiltonian tomography for networks constructed with…

Quantum Physics · Physics 2012-07-13 Koji Maruyama , Daniel Burgarth , Akihito Ishizaki , K. Birgitta Whaley , Takeji Takui

Based on recently introduced efficient quantum state tomography schemes, we propose a scalable method for the tomography of unitary processes and the reconstruction of one-dimensional local Hamiltonians. As opposed to the exponential…

Quantum Physics · Physics 2015-04-30 M. Holzäpfel , T. Baumgratz , M. Cramer , M. B. Plenio

We consider the use of quantum noise to characterize many-body states of spin systems realized with ultracold atomic systems. These systems offer a wealth of experimental techniques for realizing strongly interacting many-body states in a…

Strongly Correlated Electrons · Physics 2009-11-11 R. W. Cherng , Eugene Demler

Quantum simulation uses a well-known quantum system to predict the behavior of another quantum system. Certain limitations in this technique arise, however, when applied to specific problems, as we demonstrate with a theoretical and…

Quantum Physics · Physics 2009-11-13 Kenneth R. Brown , Robert J. Clark , Isaac L. Chuang

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

The numerical emulation of quantum physics and quantum chemistry often involves an intractable number of degrees of freedom and admits no known approximation in general form. In practice, representing quantum-mechanical states using…

With the fast development of quantum technology, the sizes of both digital and analog quantum systems increase drastically. In order to have better control and understanding of the quantum hardware, an important task is to characterize the…

Quantum Physics · Physics 2023-07-05 Wenjun Yu , Jinzhao Sun , Zeyao Han , Xiao Yuan

Noise that exhibits significant temporal and spatial correlations across multiple qubits can be especially harmful to both fault-tolerant quantum computation and quantum-enhanced metrology. However, a complete spectral characterization of…

We present a benchmarking protocol for universal quantum computers, achieved through the simulation of random dynamical quantum maps. This protocol provides a holistic assessment of system-wide error rates, encapsulating both gate…

Quantum Physics · Physics 2024-04-30 Daniel Volya , Prabhat Mishra

Quantum pseudorandomness, also known as unitary designs, comprise a powerful resource for quantum computation and quantum engineering. While it is known in theory that pseudorandom unitary operators can be constructed efficiently, realizing…

Quantum Physics · Physics 2019-07-24 Jun Li , Zhihuang Luo , Tao Xin , Hengyan Wang , David Kribs , Dawei Lu , Bei Zeng , Raymond Laflamme

Scalable characterization of quantum processors is crucial for mitigating noise and imperfections. While randomized measurement protocols enable efficient access to local observables, inferring a globally consistent description of…

Quantum Physics · Physics 2026-03-10 Zidu Liu , Dominik S. Wild

Hamiltonian learning is an important procedure in quantum system identification, calibration, and successful operation of quantum computers. Through queries to the quantum system, this procedure seeks to obtain the parameters of a given…

Quantum Physics · Physics 2023-08-25 Arkopal Dutt , Edwin Pednault , Chai Wah Wu , Sarah Sheldon , John Smolin , Lev Bishop , Isaac L. Chuang

We study the regimes in which Hamiltonian simulation benefits from randomization. We introduce a sparse-QSVT construction based on composite stochastic decompositions, where dominant terms are treated deterministically and smaller…

Quantum Physics · Physics 2026-04-10 Francesco Paganelli , Michele Grossi , Andrea Giachero , Thomas E. O'Brien , Oriel Kiss

We investigate the Ising and Heisenberg models using the Block Renormalization Group Method (BRGM), focusing on its behavior across different system sizes. The BRGM reduces the number of spins by a factor of 1/2 (1/3) for the Ising…