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Understanding mixed-state quantum phases is a central challenge in the era of quantum simulation, where many existing studies focus on renormalization fixed points. In this work, we move beyond the renormalization fixed-point paradigm by…

Quantum Physics · Physics 2026-05-07 Yuhan Liu

Coherent superposition is a key feature of quantum mechanics that underlies the advantage of quantum technologies over their classical counterparts. Recently, coherence has been recast as a resource theory in an attempt to identify and…

The high-precision interferometric measurement of an unknown phase is the basis for metrology in many areas of science and technology. Quantum entanglement provides an increase in sensitivity, but present techniques have only surpassed the…

Quantum Physics · Physics 2011-01-25 G. Y. Xiang , B. L. Higgins , D. W. Berry , H. M. Wiseman , G. J. Pryde

We present a method to reconstruct pure spatial qudits of arbitrary dimension $d$, which is based on a point diffraction interferometer. In the proposed scheme, the quantum states are codified in the discretized transverse position of a…

Quantum Physics · Physics 2023-01-27 Quimey Pears Stefano , Lorena Rebón , Claudio Iemmi

A necessary condition for reversibility (sufficiency) of a quantum channel with respect to complete families of states with bounded rank is obtained. A full description (up to isometrical equivalence) of all quantum channels reversible with…

Quantum Physics · Physics 2015-06-04 M. E. Shirokov

Consider a scenario in which an unknown signal is transformed by a known linear operator, and then the pointwise absolute value of the unknown output function is reported. This scenario appears in several applications, and the goal is to…

Information Theory · Computer Science 2014-03-10 Dustin G. Mixon

The one-dimensional phase retrieval problem consists in the recovery of a complex-valued signal from its Fourier intensity. Due to the well-known ambiguousness of this problem, the determination of the original signal within the extensive…

Numerical Analysis · Mathematics 2021-03-19 Robert Beinert

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

We find a large class of pure and mixed input states with which the phase estimation precision saturates the Cramer-Rao bound under the compound measurements of parity and particle number. We further propose a quantum-phase-estimation…

Quantum Physics · Physics 2019-04-23 Haijun Xing , Libin Fu , Su Yi

Quantum interferometers offer phase measurement capabilities that surpass the standard quantum limit (SQL), with phase sensitivity and quantum enhancement factor serving as key performance metrics. However, practical implementations face…

Quantum Physics · Physics 2026-01-27 Jie Zhao , Zeliang Wu , Haoran Liu , Yueya Liu , Xin Chen , Xinyun Liang , Wenfeng Huang , Chun-Hua Yuan , L. Q. Chen

By exploiting a generalization of recent results on environment-assisted channel correction, we show that, whenever a quantum system undergoes a channel realized as an interaction with a probe, the more efficiently the information about the…

Quantum Physics · Physics 2007-10-29 Francesco Buscemi

Phase retrieval problems in antenna measurements arise when a reference phase cannot be provided to all measurement locations. Phase retrieval algorithms require sufficiently many independent measurement samples of the radiated fields to be…

Signal Processing · Electrical Eng. & Systems 2022-06-24 Josef Knapp , Alexander Paulus , Jonas Kornprobst , Uwe Siart , Thomas F. Eibert

Phase retrieval consists in the recovery of a complex-valued signal from intensity-only measurements. As it pervades a broad variety of applications, many researchers have striven to develop phase-retrieval algorithms. Classical approaches…

We characterize operationally meaningful quantum gains in a paradigmatic model of lossless multiple-phase interferometry and stress insufficiency of the analysis based solely on the concept of quantum Fisher information. We show that the…

Quantum Physics · Physics 2022-01-28 Wojciech Gorecki , Rafal Demkowicz-Dobrzanski

The sensitivity in optical interferometry is strongly affected by losses during the signal propagation or at the detection stage. The optimal quantum states of the probing signals in the presence of loss were recently found. However, in…

In this paper, we will introduce the notion of {\it conjugate phase retrieval}, which is a relaxed definition of phase retrieval allowing recovery of signals up to conjugacy as well as a global phase factor. It is known that frames of real…

Functional Analysis · Mathematics 2019-05-21 Luke Evans , Chun-Kit Lai

We present an alternative framework for quantifying the coherence of quantum channels, which contains three conditions: the faithfulness, nonincreasing under sets of all the incoherent superchannels and the additivity. Based on the…

Quantum Physics · Physics 2022-04-20 Shi-Yun Kong , Ya-Juan Wu , Qiao-Qiao Lv , Zhi-Xi Wang , Shao-Ming Fei

A new method for phase recovery from a single two-beam interferogram is presented. Conventional approaches, relying on trigonometric inversion followed by phase unfolding and unwrapping, are hindered by discontinuities typically addressed…

Optics · Physics 2025-09-24 V. Berejnov , B. Y. Rubinstein

Open system quantum dynamics can generate a variety of long-range entangled mixed states, yet it has been unclear in what sense they constitute phases of matter. To establish that two mixed states are in the same phase, as defined by their…

Quantum Physics · Physics 2026-02-27 Shengqi Sang , Yijian Zou , Timothy H. Hsieh

We present strategies how to reconstruct (estimate) properties of a quantum channel described by the map E based on incomplete measurements. In a particular case of a qubit channel a complete reconstruction of the map E can be performed via…

Quantum Physics · Physics 2016-10-18 Mario Ziman , Martin Plesch , Vladimir Buzek