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Identification of nonorthogonal quantum states without error is crucial for various applications in quantum information technology, as well as the foundations of quantum physics. Theoretical studies have proposed measurements that maximize…

Quantum Physics · Physics 2026-03-11 Kang-Min Hu , Min Namkung , Myung-Hyun Sohn , Hyang-Tag Lim

We consider a device which can be programmed using coherent states of light to approximate a given projective measurement on an input coherent state. We provide and discuss three practical implementations of this programmable projective…

Quantum Physics · Physics 2022-07-26 Niraj Kumar , Ulysse Chabaud , Elham Kashefi , Damian Markham , Eleni Diamanti

In quantum information transformation and quantum computation, the most critical issues are security and accuracy. These features, therefore, stimulate research on quantum state characterization. A characterization tool, Quantum state…

Quantum Physics · Physics 2023-06-01 Xudan Chai , Teng Ma , Qihao Guo , Zhangqi Yin , Hao Wu , Qing Zhao

We present a scheme to conditionally engineer an optical quantum system via continuous-variable measurements. This scheme yields high-fidelity squeezed single photon and superposition of coherent states, from input single and two photon…

The temporal evolution of a quantum system can be characterized by quantum process tomography, a complex task that consumes a number of physical resources scaling exponentially with the number of subsystems. An alternative approach to the…

Robust and reliable method for reconstructing quasi-distributions of integrated intensities of twin beams generated in spontaneous parametric down-conversion and entangled in photon numbers is suggested. It utilizes the first and second…

Quantum Physics · Physics 2015-06-12 Jan Perina , Ondrej Haderka , Vaclav Michalek , Martin Hamar

In this work, we report on a novel quantum state reconstruction process based on the disentanglement algorithm. Using variational quantum circuits, we disentangle the quantum state to a product of computational zero states. Inverse…

Quantum Physics · Physics 2024-11-08 Juan Yao

Multimode multiphoton states are at the center of many photonic quantum technologies, from photonic quantum computing to quantum sensing. In this work, we derive a procedure to generate exactly, and with a predictable number of steps, any…

Characterizing quantum systems is a fundamental task that enables the development of quantum technologies. Various approaches, ranging from full tomography to instances of classical shadows, have been proposed to this end. However, quantum…

Quantum Physics · Physics 2025-06-16 Franz J. Schreiber , Jens Eisert , Johannes Jakob Meyer

So far, various multi-photon entangled states have been observed experimentally by using different experimental set-ups. Here, we present a scheme to realize many SLOCC-inequivalent states of three and four qubits via projective…

Quantum Physics · Physics 2009-02-17 Witlef Wieczorek , Nikolai Kiesel , Christian Schmid , Harald Weinfurter

In standard optical tomographic methods, the off-diagonal elements of a density matrix $\rho$ are measured indirectly. Thus, the reconstruction of $\rho$, even if it is based on linear inversion, typically magnifies small errors in the…

Quantum Physics · Physics 2016-07-19 Karol Bartkiewicz , Antonín Černoch , Karel Lemr , Adam Miranowicz

We experimentally demonstrate the reconstruction of a photon number conditioned state without using a photon number discriminating detector. By using only phase randomized homodyne measurements, we reconstruct up to the three photon…

Quantum Physics · Physics 2021-07-28 H. M. Chrzanowski , S. M. Assad , Julien Bernu , Boris Hage , A. P. Lund , T. C. Ralph , P. K. Lam , T. Symul

We introduce the concept of quantum field tomography, the efficient and reliable reconstruction of unknown quantum fields based on data of correlation functions. At the basis of the analysis is the concept of continuous matrix product…

Quantum Physics · Physics 2015-06-22 A. Steffens , C. A. Riofrío , R. Hübener , J. Eisert

Quantum tomography is crucial for characterizing the quantum states of multipartite systems, but its practicality is often limited by the exponentially large dimension of the Hilbert space. Most existing approaches, such as compressed…

Quantum Physics · Physics 2025-03-04 Yat Wong , Ming Yuan , Kevin He , Srivatsan Chakram , Alireza Seif , David I. Schuster , Liang Jiang

We consider how the conventional spectroscopic and interferometric schemes can be rearranged to serve for reconstructing quantum states of physical systems possessing SU(2) symmetry. The discussed systems include a collection of two-level…

Quantum Physics · Physics 2009-10-31 C. Brif , A. Mann

Quantum state and process tomography are typically analyzed under the assumption that devices emit independent and identically distributed (i.i.d.) states or channels. In realistic experiments, however, noise, drift, feedback, or…

Quantum Physics · Physics 2026-02-26 Leonardo Zambrano

In this work we propose a simple optical architecture, based on phase-only programmable spatial light modulators, in order to characterize general processes on photonic spatial quantum systems in a $d>2$ Hilbert space. We demonstrate the…

Quantum Physics · Physics 2023-01-27 Juan José Miguel Varga , Lorena Rebón , Quimey Pears Stefano , Claudio Iemmi

Quantum state tomography (QST) is a fundamental task in quantum information science that aims to reconstruct unknown quantum states from measurement data. However, the exponential growth of Hilbert-space dimension with system size makes…

Quantum Physics · Physics 2026-05-27 Zhen Qin , Michael B. Wakin , Zhihui Zhu

In the framework of quantum information geometry, we derive, from quantum relative Tsallis entropy, a family of quantum metrics on the space of full rank, N level quantum states, by means of a suitably defined coordinate free differential…

Quantum Physics · Physics 2017-07-24 Vladimir I. Man'ko , Giuseppe Marmo , Franco Ventriglia , Patrizia Vitale

We implement a compressive quantum state tomography capable of reconstructing any arbitrary low-rank spectral-temporal optical signal with extremely few measurement settings and without any \emph{ad hoc} assumptions about the initially…

Quantum Physics · Physics 2021-05-27 J. Gil-Lopez , Y. S. Teo , S. De , B. Brecht , H. Jeong , C. Silberhorn , L. L. Sanchez-Soto