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Superconducting qubits have been used in the most advanced demonstrations of quantum information processing, and they can be manufactured at-scale using proven semiconductor techniques. This makes them one of the leading technologies in the…

The quantum speed limit time for quantum system under squeezed environment is studied. We consider two typical models, the damped Jaynes-Cummings model and the dephasing model. For the damped Jaynes-Cummings model under squeezed…

Quantum Physics · Physics 2021-10-08 Kang-ying Du , Ya-jie Ma , Shao-xiong Wu , Chang-shui Yu

Quantum state tomography (QST) is a fundamental technique for estimating the state of a quantum system from measured data and plays a crucial role in evaluating the performance of quantum devices. However, standard estimation methods become…

Quantum Physics · Physics 2026-01-27 Shakir Showkat Sofi , Charlotte Vermeylen , Lieven De Lathauwer

The speed of evolution between perfectly distinguishable states is thoroughly analyzed in a closed three-level (qutrit) quantum system. Considering an evolution under an arbitrary time-independent Hamiltonian, we fully characterize the…

Quantum Physics · Physics 2025-10-10 Jesica Espino-González , Francisco J. Sevilla , Andrea Valdés-Hernández

We study the quantum speed limit for open quantum systems described by the Lindblad master equation. The obtained inequality shows a trade-off relation between the operation time and the physical quantities such as the energy fluctuation…

Quantum Physics · Physics 2019-01-14 Ken Funo , Naoto Shiraishi , Keiji Saito

Quantum state verification (QSV) is the task of relying on local measurements only to verify that a given quantum device does produce the desired target state. Up to now, certain types of entangled states can be verified efficiently or even…

Quantum Physics · Physics 2023-06-16 Ye-Chao Liu , Yinfei Li , Jiangwei Shang , Xiangdong Zhang

What is the minimal time until a quantum system can exhibit genuine quantum features? To answer this question we derive quantum speed limits for two-time correlation functions arising from statistics of measurements. Generally, these…

Quantum Physics · Physics 2025-05-27 Sagar Silva Pratapsi , Sebastian Deffner , Stefano Gherardini

Quantum machine learning (QML) is emerging as an application of quantum computing with the potential to deliver quantum advantage, but its realisation for practical applications remains impeded by challenges. Amongst those, a key barrier is…

Quantum State Tomography (QST) is a fundamental technique in Quantum Information Processing (QIP) for reconstructing unknown quantum states. However, the conventional QST methods are limited by the number of measurements required, which…

The quantum speed limit sets a fundamental restriction on the evolution time of quantum systems. We explore the relationship between quantum imaginarity and the quantum speed limit by utilizing measures such as relative entropy, trace…

Quantum Physics · Physics 2025-11-11 Dong-Ping Xuan , Zhong-Xi Shen , Wen Zhou , Shao-Ming Fei , Zhi-Xi Wang

Quantum metrology is a promising practical use case for quantum technologies, where physical quantities can be measured with unprecedented precision. In lieu of quantum error correction procedures, near term quantum devices are expected to…

Quantum Physics · Physics 2021-12-03 Yingkai Ouyang , Nathan Shettell , Damian Markham

We prove that the time required for sustained information scrambling in any Hamiltonian quantum system is universally at least logarithmic in the entanglement entropy of scrambled states. This addresses two foundational problems in…

Quantum Physics · Physics 2024-04-25 Amit Vikram , Laura Shou , Victor Galitski

Robust, accurate and efficient quantum tomography is key for future quantum technologies. Traditional methods are impractical for even medium sized systems and are not robust against noise and errors. Here we report on an experimental…

Quantum Physics · Physics 2016-07-27 Robert J. Chapman , Christopher Ferrie , Alberto Peruzzo

Quantum linear system algorithms (QLSAs) for gate-based quantum computing can provide exponential speedups for solving linear systems but face challenges when applied to finite element problems due to the growth of the condition number with…

Quantum Physics · Physics 2023-10-20 Osama Muhammad Raisuddin , Suvranu De

We initiate the systematic study of experimental quantum physics from the perspective of computational complexity. To this end, we define the framework of quantum algorithmic measurements (QUALMs), a hybrid of black box quantum algorithms…

Quantum Physics · Physics 2022-03-09 Dorit Aharonov , Jordan Cotler , Xiao-Liang Qi

Decoherence represents a major obstacle towards realizing reliable quantum technologies. Identifying states that can be uphold against decoherence by purely coherent means, i.e., {\it stabilizable states}, for which the dissipation-induced…

Quantum Physics · Physics 2023-04-26 Tomasz Linowski , Łukasz Rudnicki , Clemens Gneiting

Driven by exploring the power of quantum computation with a limited number of qubits, we present a novel complete characterization for space-bounded quantum computation, which encompasses settings with one-sided error (unitary coRQL) and…

Quantum Physics · Physics 2024-05-24 François Le Gall , Yupan Liu , Qisheng Wang

We study the problem of robust performance of quantum systems under structured uncertainties. A specific feature of closed (Hamiltonian) quantum systems is that their poles lie on the imaginary axis and that neither a coherent controller…

Quantum Physics · Physics 2021-10-12 S G Schirmer , F C Langbein , C A Weidner , E A Jonckheere

This paper considers a class of uncertain linear quantum systems subject to uncertain perturbations in the system Hamiltonian. We present a method to design a coherent robust H-infinity controller so that the closed loop system is robustly…

Systems and Control · Computer Science 2015-09-10 Chengdi Xiang , Ian R. Petersen , Daoyi Dong

Quantum speed limits are relations yielding lower bounds on the evolution time of quantum systems. These results have been generalized in some ways, in particular by including evolutions to non-orthogonal states. However, there was a gap in…

Quantum Physics · Physics 2014-07-17 M. M. Taddei