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We propose a method for reconstruction of the density matrix from measurable time-dependent (probability) distributions of physical quantities. The applicability of the method based on least-squares inversion is - compared with other…

Quantum Physics · Physics 2016-09-08 T. Opatrny , D. -G. Welsch , W. Vogel

Continuous phase spaces have become a powerful tool for describing, analyzing, and tomographically reconstructing quantum states in quantum optics and beyond. A plethora of these phase-space techniques are known, however a thorough…

Quantum Physics · Physics 2020-02-24 Bálint Koczor , Robert Zeier , Steffen J. Glaser

It has been recently shown that a state generated by a one-dimensional noisy quantum computer is well approximated by a matrix product operator with a finite bond dimension independent of the number of qubits. We show that full quantum…

Quantum Physics · Physics 2022-07-14 Alexander Lidiak , Casey Jameson , Zhen Qin , Gongguo Tang , Michael B. Wakin , Zhihui Zhu , Zhexuan Gong

We discuss the tomography of $N$-qubit states using collective measurements. The method is exact for symmetric states, whereas for not completely symmetric states the information accessible can be arranged as a mixture of irreducible SU(2)…

Quantum Physics · Physics 2018-09-17 A. Muñoz , A. B. Klimov , M. Grassl , L. L. Sanchez-Soto

To quantify the effect of decoherence in quantum measurements, it is desirable to measure not merely the square modulus of the spatial wavefunction, but the entire density matrix, whose phases carry information about momentum and how pure…

Quantum Physics · Physics 2009-10-30 Max Tegmark

We study the possibility of performing quantum state tomography via equidistant states. This class of states allows us to propose a non-symmetric informationally complete POVM based tomographic scheme. The scheme is defined for odd…

Quantum Physics · Physics 2015-05-14 C. Paiva-Sánchez , E. Burgos-Inostroza , O. Jiménez , A. Delgado

A general framework in the setting of $C^*$-algebras for the tomographical description of states, that includes, among other tomographical schemes, the classical Radon transform, quantum state tomography and group quantum tomography, is…

Quantum Physics · Physics 2024-01-19 Alberto Ibort , Alberto López-Yela

The field of quantum information has been growing fast over the past decade. Optical quantum computation, based on the concepts of KLM and cluster states, has witnessed experimental realizations of larger and more complex systems in terms…

Quantum Physics · Physics 2014-11-11 Dikla Oren , Yoav Shechtman , Maor Mutzafi , Yonina C. Eldar , Mordechai Segev

A review is given on phase-sensitive measurements, such as homodyne detection, for radiation fields and material systems. Methods of quantum-state reconstruction are considered for radiation fields, including multimode and pulsed radiation.…

Quantum Physics · Physics 2009-07-10 Dirk-Gunnar Welsch , Werner Vogel , Tomas Opatrny

Pure entangled states of two spatial qudits have been produced by using the momentum transverse correlation of the parametric down-converted photons [Phys. Rev. Lett. \textbf{94} 100501]. Here we show a generalization of this process to…

Quantum Physics · Physics 2009-11-13 G. Lima , F. A. Torres-Ruiz , L. Neves , A. Delgado , C. Saavedra , S. Pádua

Quantum state tomography is the standard technique for reconstructing a quantum state from experimental data. In the regime of finite statistics, experimental data cannot give perfect information about the quantum state. A common way to…

Quantum Physics · Physics 2024-07-03 Carlos de Gois , Matthias Kleinmann

Classical and quantum perturbations can be described in terms of marginal distribution functions in the framework of tomographic cosmology. In particular, the so called Radon transformation and the mode-parametric quantum oscillator…

General Relativity and Quantum Cosmology · Physics 2015-05-13 S. Capozziello , V. I. Man'ko , G. Marmo , C. Stornaiolo

We describe and demonstrate a quantum state tomography for measuring the complex temporal waveform of narrowband biphotons. Through six sets of two-photon interference measurements projected in different polarization subspaces, we can…

Quantum Physics · Physics 2015-01-14 Peng Chen , Chi Shu , Xianxin Guo , M. M. T. Loy , Shengwang Du

We revisit the problem of quantum state reconstruction of light beams from the photocurrent quantum noise. As is well-known, but often overlooked, two longitudinal field modes contribute to each spectral component of the photocurrent…

Feasible tomography schemes for large particle numbers must possess, besides an appropriate data acquisition protocol, also an efficient way to reconstruct the density operator from the observed finite data set. Since state reconstruction…

Complete characterization of states and processes that occur within quantum devices is crucial for understanding and testing their potential to outperform classical technologies for communications and computing. However, solving this task…

Quantum Physics · Physics 2020-05-07 E. S. Tiunov , V. V. Tiunova , A. E. Ulanov , A. I. Lvovsky , A. K. Fedorov

Quantum information has been drawing a wealth of research in recent years, shedding light on questions at the heart of quantum mechanics, as well as advancing fields such as complexity theory, cryptography, key distribution, and chemistry.…

Quantum Physics · Physics 2017-04-25 Dikla Oren , Maor Mutzafi , Yonina C. Eldar , Mordechai Segev

We introduce a method of quantum tomography for a continuous variable system in position and momentum space. We consider a single two-level probe interacting with a quantum harmonic oscillator by means of a class of Hamiltonians, linear in…

Quantum Physics · Physics 2015-03-19 J. Casanova , C. E. Lopez , J. J. Garcia-Ripoll , C. F. Roos , E. Solano

The quantum state of a light beam can be represented as an infinite dimensional density matrix or equivalently as a density on the plane called the Wigner function. We describe quantum tomography as an inverse statistical problem in which…

Statistics Theory · Mathematics 2007-06-13 L. M. Artiles , R. D. Gill , M. I. Guta

Quantum phase is not a direct observable and is usually determined by interferometric methods. We present a method to map complete electron wave functions, including internal quantum phase information, from measured single-state probability…

Mesoscale and Nanoscale Physics · Physics 2008-03-19 Christopher R. Moon , Laila S. Mattos , Brian K. Foster , Gabriel Zeltzer , Wonhee Ko , Hari C. Manoharan