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Determining the energy levels of a quantum system is a significant task, for instance, to analyze reaction rates in drug discovery and catalysis or characterize the compatibility of materials. In this paper we exploit quantum metrology, the…

Determining the state of a system and measuring properties of its evolution are two of the most important tasks a physicist faces. For the first purpose one can use tomography, a method that after subjecting the system to a number of…

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

In measurement-based quantum computation, quantum algorithms are implemented via sequences of measurements. We describe a translationally invariant finite-range interaction on a one-dimensional qudit chain and prove that a single-shot…

Quantum Physics · Physics 2009-11-13 Dominik Janzing , Pawel Wocjan , Shengyu Zhang

The many-body state of carriers confined in a quantum dot is controlled by the balance between their kinetic energy and their Coulomb correlation. In coupled quantum dots, both can be tuned by varying the inter-dot tunneling and…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Massimo Rontani , Filippo Troiani , Ulrich Hohenester , Elisa Molinari

Quantum tomography makes it possible to obtain comprehensive information about certain logical elements of a quantum computer. In this regard, it is a promising tool for debugging quantum computers. The practical application of tomography,…

Quantum Physics · Physics 2020-12-23 B. I. Bantysh , Yu. I. Bogdanov

Quantum dots are an important model system for thermoelectric phenomena, and may be used to enhance the thermal-to-electric energy conversion efficiency in functional materials. It is therefore important to obtain a detailed understanding…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 S. Fahlvik Svensson , A. I. Persson , E. A. Hoffmann , N. Nakpathomkun , H. A. Nilsson , H. Q. Xu , L. Samuelson , H. Linke

We demonstrate tunneling spectroscopy of synthetic quantum matter in superconducting circuit lattices. We measure site-resolved excitation spectra by coupling the lattice to engineered driven-dissipative particle baths that serve as local…

Quantum Gases · Physics 2025-05-20 Botao Du , Qihao Guo , Santiago López , Ruichao Ma

In an ideal quantum measurement, the wave function of a quantum system collapses to an eigenstate of the measured observable, and the corresponding eigenvalue determines the measurement outcome. If the observable commutes with the system…

Quantum Physics · Physics 2020-02-13 Dayou Yang , Andrey Grankin , Lukas M. Sieberer , Denis V. Vasilyev , Peter Zoller

We suggest and demonstrate experimentally a strategy to obtain relevant information about a composite system by only performing measurements on a small and easily accessible part of it, which we call quantum probe. We show in particular how…

Quantum Physics · Physics 2013-07-15 Andrea Smirne , Simone Cialdi , Giorgio Anelli , Matteo G. A. Paris , Bassano Vacchini

Quantum computation has been growing rapidly in both theory and experiments. In particular, quantum computing devices with a large number of qubits have been developed by IBM, Google, IonQ, and others. The current quantum computing devices…

Quantum Physics · Physics 2021-02-10 Rishabh Gupta , Rongxin Xia , Raphael D. Levine , Sabre Kais

We demonstrate that the task of determining an unknown quantum state can be accomplished efficiently by making a sequential measurement of two observables $\hat{A}$ and $\hat{B}$, provided that the two observables are chosen in such a way…

Quantum Physics · Physics 2013-10-22 Antonio Di Lorenzo

Quantum state tomography is a key process in most quantum experiments. In this work, we employ quantum machine learning for state tomography. Given an unknown quantum state, it can be learned by maximizing the fidelity between the output of…

Practical quantum state tomography is usually performed by carrying out repeated measurements on many copies of a given state. The accuracy of the reconstruction depends strongly on the dimensionality of the system and the number of copies…

Quantum Physics · Physics 2008-07-08 Alex Ling , Antia Lamas-Linares , Christian Kurtsiefer

Low-capacitance Josephson junction systems as well as coupled quantum dots, in a parameter range where single charges can be controlled, provide physical realizations of quantum bits, discussed in connection with quantum computing. The…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Alexander Shnirman , Gerd Schoen

We propose an efficient quantum state tomography method inspired by compressed sensing and threshold quantum state tomography that can drastically reduce the number of measurement settings to reconstruct the density matrix of an $N$-qudit…

Quantum Physics · Physics 2025-04-01 Giovanni Garberoglio , Maurizio Dapor , Diego Maragnano , Marco Liscidini , Daniele Binosi

It is not a general opinion that that a quantum system could be purified into a target eigenstate via repeated measurements on a coupled qubit rather than direct transitions in the Hamiltonian. The projective measurement on the ancillary…

Quantum Physics · Physics 2023-10-30 Jia-shun Yan , Jun Jing

Quantum many-body scar (QMBS) in kinetically constrained quantum systems challenges the conventional eigenstate thermalization hypothesis (ETH). We develop an effective open-system description for constrained dynamics and introduce the…

Quantum Physics · Physics 2026-03-09 Jia-wei Wang , Xiang-Fa Zhou , Guang-Can Guo , Zheng-Wei Zhou

Quantum state tomography (QST) is a universal tool for the design and optimization of entangled-photon sources. It typically requires single-photon detectors and coincidence measurements. Recently, it was suggested that the information…

The comprehension of quantum phase transitions (QPTs) is considered as a critical foothold in the field of many-body physics. Developing protocols to effectively identify and understand QPTs thus represents a key but challenging task for…

Quantum Physics · Physics 2025-04-03 Xiangbei Li , Yaoming Chu , Shaoliang Zhang , Jianming Cai