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For the precise estimation of the unknown quantum state, the independent samples should be prepared. Can we reduce the error of the estimation by the measurement using the quantum correlation between every sample? In this paper, this…

Quantum Physics · Physics 2007-05-23 Masahito Hayashi

In this paper, we investigate the problem of estimating the phase of a coherent state in the presence of unavoidable noisy quantum states. These unwarranted quantum states are represented by outlier quantum states in this study. We first…

Quantum Physics · Physics 2020-08-06 Yukito Mototake , Jun Suzuki

The performance of the quantum approximate optimization algorithm is evaluated by using three different measures: the probability of finding the ground state, the energy expectation value, and a ratio closely related to the approximation…

Quantum Physics · Physics 2020-06-08 Madita Willsch , Dennis Willsch , Fengping Jin , Hans De Raedt , Kristel Michielsen

We develop a potentially practical proposal for robust quantum state transfer (QST) between two superconducting qubits coupled by a coplanar waveguide (CPW) resonator. We show that the partial measurement could drastically enhance the…

Quantum Physics · Physics 2022-09-14 Yan-Ling Li , Yao Yao , Xing Xiao

As one of the most intriguing intrinsic properties of quantum world, quantum superposition provokes great interests in its own generation. Oszmaniec [Phys. Rev. Lett. 116, 110403 (2016)] have proven that though a universal quantum machine…

Establishing a notion of the quantum state that applies consistently across space and time could be a crucial step toward formulating a relativistic quantum theory. We give an operational meaning to multipartite quantum states over…

Quantum Physics · Physics 2026-04-14 Seok Hyung Lie , Hyukjoon Kwon

The design and benchmarking of quantum computer architectures traditionally rely on practical hardware restrictions, such as gate fidelities, control, and cooling. At the theoretical and software levels, numerous approaches have been…

Superconducting quantum computing technology has ushered in a new era of computational possibilities. While a considerable research effort has been geared toward improving the quantum technology and building the software stack to…

Quantum Physics · Physics 2021-02-03 Tirthak Patel , Devesh Tiwari

Detecting and quantifying quantum entanglement remain significant challenges in the noisy intermediate-scale quantum (NISQ) era. This study presents the implementation of quantum support vector machines (QSVMs) on IBM quantum devices to…

Quantum Physics · Physics 2025-04-10 M. Mahdian , Z. Mousavi

In the noisy intermediate-scale quantum (NISQ) era, quantum error mitigation (QEM) is essential for producing reliable outputs from quantum circuits. We present a statistical signal processing approach to QEM that estimates the most likely…

Quantum state discrimination is a fundamental concept in quantum information theory, which refers to a class of techniques to identify a specific quantum state through a positive operator-valued measure. In this work, we investigate how…

Quantum Physics · Physics 2025-07-09 Hyunho Cha , Jungwoo Lee

Higher-dimensional quantum systems (qudits) offer advantages in information encoding, error resilience, and compact gate implementations, and naturally arise in platforms such as superconducting and solid-state systems. However, realistic…

Quantum Physics · Physics 2025-06-17 Yule Mayevsky , Akram Youssry , Ritik Sareen , Gerardo A. Paz-Silva , Alberto Peruzzo

We propose a quantum-state-certification protocol for stabilizer states, motivated by application in in-situ testing of NISQ-era quantum computer systems: The number of qubits is bounded, and in terms of cost of running the protocol,…

Quantum Physics · Physics 2025-07-21 Dirk Oliver Theis

We study the fundamental design automation problem of equivalence checking in the NISQ (Noisy Intermediate-Scale Quantum) computing realm where quantum noise is present inevitably. The notion of approximate equivalence of (possibly noisy)…

Quantum Physics · Physics 2021-06-04 Xin Hong , Mingsheng Ying , Yuan Feng , Xiangzhen Zhou , Sanjiang Li

Quantum algorithms on the noisy intermediate-scale quantum (NISQ) devices are expected to simulate quantum systems that are classically intractable to demonstrate quantum advantages. However, the non-negligible gate error on the NISQ…

Quantum Physics · Physics 2021-12-06 Joseph C. Aulicino , Trevor Keen , Bo Peng

Quantum State Tomography (QST) has been the traditional method for characterization of an unknown state. Recently, many direct measurement methods have been implemented to reconstruct the state in a resource efficient way. In this letter,…

Quantum Physics · Physics 2020-09-23 Surya Narayan Sahoo , Sanchari Chakraborti , Arun K. Pati , Urbasi Sinha

Quantum computers can accurately compute ground state energies using phase estimation, but this requires a guiding state that has significant overlap with the true ground state. For large molecules and extended materials, it becomes…

Experimental determination of an unknown quantum state usually requires several incompatible measurements. However, it is also possible to determine the full quantum state from a single, repeated measurement. For this purpose, the quantum…

Quantum Physics · Physics 2008-03-25 Xinhua Peng , Jiangfeng Du , Dieter Suter

One of the key steps in quantum algorithms is to prepare an initial quantum superposition state with different kinds of features. These so-called state preparation algorithms are essential to the behavior of quantum algorithms, and…

Quantum Physics · Physics 2026-02-24 Liyi Li , Anshu Sharma , Zoukarneini Difaizi Tagba , Sean Frett , Alex Potanin

We propose a quantum device that can approximate any projective measurement on a qubit. The desired measurement basis is selected by the quantum state of a "program register". The device is optimized with respect to maximal average fidelity…

Quantum Physics · Physics 2009-11-07 Jaromir Fiurasek , Miloslav Dusek , Radim Filip