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We introduce a procedure based on quantum expectation values of measurement observables to characterize quantum coherence. Our measure allows one to quantify coherence without having to perform tomography of the quantum state, and can be…

Variational quantum algorithms are considered one of the most promising methods for obtaining near-term quantum advantages; however, most of these algorithms are only expressed in the conventional quantum circuit scheme. The roadblock to…

Quantum Physics · Physics 2024-07-30 Zheng Qin , Xiufan Li , Yang Zhou , Shikun Zhang , Rui Li , Chunxiao Du , Zhisong Xiao

We develop a quantum learning scheme for binary discrimination of coherent states of light. This is a problem of technological relevance for the reading of information stored in a digital memory. In our setting, a coherent light source is…

Quantum Physics · Physics 2015-07-09 Gael Sentís , Madalin Guta , Gerardo Adesso

It is well known that a quantum correlated probe can yield better precision in estimating an unknown parameter than classically possible. However, how such a quantum probe should be measured remains somewhat elusive. We examine the role of…

Quantum Physics · Physics 2015-02-20 K. Micadei , D. A. Rowlands , F. A. Pollock , L. C. Céleri , R. M. Serra , K. Modi

We report an algorithm, based on quantum optics formulation, where a coherent state is used as the elementary quantum resource for the image representation. We provide an architecture with constituent optical elements in linear order with…

Quantum Physics · Physics 2024-10-01 Vivek Mehta , Sonali Jana , Utpal Roy

Extracting classical information from quantum systems is of fundamental importance, and classical shadows allow us to extract a large amount of information using relatively few measurements. Conventional shadow estimators are unbiased and…

Quantum Physics · Physics 2025-04-03 Zhenyu Cai , Adrian Chapman , Hamza Jnane , Bálint Koczor

Measuring the state of a quantum system is a fundamental process in quantum mechanics and plays an essential role in quantum information and quantum technologies. One method to measure a quantum observable is to sort the system in different…

Quantum Physics · Physics 2016-05-05 Radu Ionicioiu

The challenge of imbalanced learning lies not only in class imbalance problem, but also in the class overlapping problem which is complex. However, most of the existing algorithms mainly focus on the former. The limitation prevents the…

Machine Learning · Computer Science 2022-12-07 Fan Li , Bo Wang , Pin Wang , Yongming Li

Quantum chemistry calculations of large, strongly correlated systems are typically limited by the computation cost that scales exponentially with the size of the system. Quantum algorithms, designed specifically for quantum computers, can…

The accurate and efficient energy estimation of quantum Hamiltonians consisting of Pauli observables is an essential task in modern quantum computing. We introduce a Resource-Optimized Grouping Shadow (ROGS) algorithm, which optimally…

Quantum Physics · Physics 2025-04-09 Min Li , Mao Lin , Matthew J. S. Beach

We study an influence of the continuous measurement in a composite quantum system C on the evolution of the states of its parts. It is shown that the character of the evolution (decoherence or recoherence) depends on the type of the…

Quantum Physics · Physics 2009-11-11 E. D. Vol

Quantum coherence is the key resource for quantum technology, with applications in quantum optics, information processing, metrology and cryptography. Yet, there is no universally efficient method for quantifying coherence either in…

Quantum Physics · Physics 2014-10-24 Davide Girolami

Shadow estimation is an efficient method for predicting many observables of a quantum state with a statistical guarantee. In the multi-shot scenario, one performs projective measurement on the sequentially prepared state for $K$ times after…

Quantum Physics · Physics 2023-07-05 You Zhou , Qing Liu

Quantum tomography is a fundamental technique for characterizing, benchmarking, and verifying quantum states and devices. It plays a crucial role in advancing quantum technologies and deepening our understanding of quantum mechanics.…

Relevant metrological scenarios involve the simultaneous estimation of multiple parameters. The fundamental ingredient to achieve quantum-enhanced performances is based on the use of appropriately tailored quantum probes. However, reaching…

We introduce a projected complex Langevin (CL) numerical sampling method -- a fictitious Langevin dynamics scheme that uses numerical projection to sample a constrained stationary distribution with highly oscillatory character. Despite the…

Quantum Gases · Physics 2025-03-04 Ethan C. McGarrigle , Hector D. Ceniceros , Glenn H. Fredrickson

Owing to the computational complexity of electronic structure algorithms running on classical digital computers, the range of molecular systems amenable to simulation remains tightly circumscribed even after many decades of work. Quantum…

Quantum Physics · Physics 2022-05-18 Alexis Ralli , Michael I. Williams , Peter V. Coveney

Simulating large quantum circuits on hardware with limited qubit counts is often attempted through methods like circuit knitting, which typically incur sample costs that grow exponentially with the number of connections cut. In this work,…

Quantum Physics · Physics 2026-03-11 Junxiang Huang , Yunxin Tang , Xiao Yuan

Gradient estimation is a central challenge in training parameterized quantum circuits (PQCs) for hybrid quantum-classical optimization and learning problems. This difficulty arises from several factors, including the exponential…

Quantum Physics · Physics 2026-05-25 Mohsen Heidari , Masih Mozakka , Wojciech Szpankowski

Recent development in quantum information sciences and technologies, especially building programmable quantum computers, provide us new opportunities to study fundamental aspects of quantum mechanics. We propose qubit models to emulate the…

Quantum Physics · Physics 2022-06-29 Meng-Jun Hu , Yanbei Chen , Yiqiu Ma , Xiang Li , Yubao Liu , Yong-Sheng Zhang , Haixing Miao