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We propose a scheme to probabilistically generate Greenberger-Horne-Zeilinger (GHZ) states encoded on the path degree of freedom of three photons. These photons are totally independent from each other, having no direct interaction during…

Quantum Physics · Physics 2018-11-27 Bertúlio de Lima Bernardo , M. Lencśes , S. Brito , Askery Canabarro

In recent years, there has been a significant progress in the development of digital quantum processors. The state-of-the-art quantum devices are imperfect, and fully-algorithmic fault-tolerant quantum computing is a matter of future. Until…

Quantum Physics · Physics 2020-05-28 D. V. Babukhin , A. A. Zhukov , W. V. Pogosov

Methods of processing quantum data become more important as quantum computing devices improve their quality towards fault tolerant universal quantum computers. These methods include discrimination and filtering of quantum states given as an…

Quantum Physics · Physics 2020-02-18 D. V. Babukhin , A. A. Zhukov , W. V. Pogosov

Projected squeezed (PS) states are multipartite entangled states generated by unitary spin squeezing, followed by a collective quantum measurement and post-selection. They can lead to an appreciable decrease in the state preparation time of…

Quantum Physics · Physics 2024-05-14 B. J. Alexander , J. J. Bollinger , M. S. Tame

Quantum Computing is believed to be the ultimate solution for quantum chemistry problems. Before the advent of large-scale, fully fault-tolerant quantum computers, the variational quantum eigensolver~(VQE) is a promising heuristic quantum…

Quantum Physics · Physics 2023-12-06 Chu Guo , Yi Fan , Zhiqian Xu , Honghui Shang

Hybrid classical-quantum algorithms aim at variationally solving optimisation problems, using a feedback loop between a classical computer and a quantum co-processor, while benefitting from quantum resources. Here we present experiments…

Non-Hermitian quantum systems have recently attracted considerable attention due to their exotic properties. Though many experimental realizations of non-Hermitian systems have been reported, the non-Hermiticity usually resorts to the…

Quantum Physics · Physics 2023-06-21 Hongfeng Liu , Xiaodong Yang , Kai Tang , Liangyu Che , Xinfang Nie , Tao Xin , Jun Li , Dawei Lu

Accurately characterizing multipartite entangled states is a critical challenge in quantum information processing. In this work, we focus on applying compressed sensing techniques to efficiently estimate the fidelity of…

Quantum Physics · Physics 2026-05-01 Farrokh Labib , David Nicholaeff , Vincent Russo , William J. Zeng

Multipartite entanglement is one of the core concepts in quantum information science with broad applications that span from condensed matter physics to quantum physics foundations tests. Although its most studied and tested forms encompass…

Quantum Physics · Physics 2022-02-25 Alba Cervera-Lierta , Mario Krenn , Alán Aspuru-Guzik , Alexey Galda

The ability to engineer parallel, programmable operations between desired qubits within a quantum processor is central for building scalable quantum information systems. In most state-of-the-art approaches, qubits interact locally,…

We propose a hybrid quantum-classical algorithm for approximating the ground state of two-dimensional quantum systems using an isometric tensor network ansatz, which maps naturally to quantum circuits. Inspired by the density matrix…

Variational quantum algorithms (VQAs) face an inherent trade-off between expressivity and trainability: deeper circuits can represent richer states but suffer from noise accumulation and barren plateaus, while shallow circuits remain…

Quantum Physics · Physics 2025-10-31 Shaojun Wu , Shan Jin , Abolfazl Bayat , Xiaoting Wang

An efficient algorithm is developed for quantum spin tubes in the context of the tensor network representations. It allows to efficiently compute the ground-state fidelity per lattice site, which in turn enables us to identify quantum…

Statistical Mechanics · Physics 2011-05-17 Ai-Min Chen , Qian-Qian Shi , Jin-Hua Liu , Huan-Qiang Zhou

Quantum systems have entered a competitive regime where classical computers must make approximations to represent highly entangled quantum states. However, in this beyond-classically-exact regime, fidelity comparisons between quantum and…

Utilizing quantum computer to investigate quantum chemistry is an important research field nowadays. In addition to the ground-state problems that have been widely studied, the determination of excited-states plays a crucial role in the…

We study continuous variable systems, in which quantum and classical degrees of freedom are combined and treated on the same footing. Thus all systems, including the inputs or outputs to a channel, may be quantum-classical hybrids. This…

Quantum Physics · Physics 2023-07-26 Lars Dammeier , Reinhard F. Werner

We present a study on preparing and manipulating path-like temporal-mode (TM) qubits based on third-order nonlinear interactions. Specifically, we consider the process of frequency conversion via difference frequency generation. To prepare…

Quantum Physics · Physics 2021-08-04 F. A. Domínguez-Serna , K. Garay-Palmett

John Bell has shown that the correlations entailed by quantum mechanics cannot be reproduced by a classical process involving non-communicating parties. But can they be simulated with the help of bounded communication? This problem has been…

Information Theory · Computer Science 2022-01-04 Gilles Brassard , Luc Devroye , Claude Gravel

We propose a complete architecture for deterministic generation of entangled multiphoton states. Our approach utilizes periodic driving of a quantum-dot emitter and an efficient light-matter interface enabled by a photonic crystal…

We propose a measurement-based quantum metrology protocol in a composite model, where the probe system (a spin ensemble) is coupled to an ancillary two-level system (qubit) with a general Heisenberg XXZ interaction. With an optimized and…

Quantum Physics · Physics 2026-01-23 Peng Chen , Jun Jing