The quantum picture of a detector

Zavatta, Alessandro; Bellini, M.

doi:10.1038/nphoton.2012.120

Cited by 5 publications

(4 citation statements)

References 6 publications

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“…Exploiting critical coupling, the cavity reflectance can be rewritten without further approximations as in Eqs. ( 1) and (2).…”

Section: Derivation Of the Cavity Reflectancementioning

confidence: 99%

“…This technique of superimposing electromagnetic waves is an important method with applications across all the natural sciences [1]. But standard detectors for optical or higher-frequency fields are sensitive to the field intensity only, masking the phase required for many applications [2]. In x-ray science, prominent examples are crystallography [3] and coherent imaging [4].…”

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confidence: 99%

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Interferometric phase detection at x-ray energies via Fano resonance control

et al. 2015

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Modern x-ray light sources promise access to structure and dynamics of matter in largely unexplored spectral regions. However, the desired information is encoded in the light intensity and phase, whereas detectors register only the intensity. This phase problem is ubiquitous in crystallography and imaging and impedes the exploration of quantum effects at x-ray energies. Here, we demonstrate phase-sensitive measurements characterizing the quantum state of a nuclear two-level system at hard x-ray energies. The nuclei are initially prepared in a superposition state. Subsequently, the relative phase of this superposition is interferometrically reconstructed from the emitted x rays. Our results form a first step towards x-ray quantum state tomography and provide new avenues for structure determination and precision metrology via x-ray Fano interference.

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“…Exploiting critical coupling, the cavity reflectance can be rewritten without further approximations as in Eqs. ( 1) and (2).…”

Section: Derivation Of the Cavity Reflectancementioning

confidence: 99%

mentioning

confidence: 99%

Interferometric phase detection at x-ray energies via Fano resonance control

et al. 2015

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“…Unfortunately, the quantum measurement description of von Neumann is not valid for measurement schemes that employ real detectors, which are normally affected by several imperfections. Zavatta and Bellini, 2012 [156] Complementing the preceding discussion of concrete measurement arrangements, we now discuss a conceptually important class of discrete quantum measures and the associated measurements. We call a discrete quantum measure projective if the P k satisfy the orthogonality relations…”

Section: Projective Measurementsmentioning

confidence: 98%

Quantum mechanics via quantum tomography

Neumaier¹

2021

Preprint

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Starting from first principles inspired by quantum tomography rather than from Born's rule, this paper gives a new, elementary, and self-contained deductive approach to quantum mechanics. A suggestive notion for what constitutes a quantum detector and for the behavior of its responses leads to a logically impeccable definition of measurement. Applications to measurement schemes for optical states, position measurements and particle tracks demonstrate that this definition is applicable to complex realistic experiments without any idealization.The various forms of quantum tomography for quantum states, quantum detectors, quantum processes, and quantum instruments are discussed. The traditional dynamical and spectral properties of quantum mechanics are derived from a continuum limit of quantum processes. In particular, the Schrödinger equation for the state vector of a pure, nonmixing quantum system and the Lindblad equation for the density operator of a mixing quantum system are shown to be consequences of the new approach. A slight idealization of the measurement process leads to the notion of quantum fields, whose smeared quantum expectations emerge as reproducible properties of regions of space accessible to measurements.For the discussion of questions related to this paper, please use the discussion forum https://www.physicsoverflow.org.

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“…Unfortunately, the quantum measurement description of von Neumann is not valid for measurement schemes that employ real detectors, which are normally affected by several imperfections. Zavatta and Bellini, 2012 [89] Complementing the preceding discussion of concrete measurement arrangements, we now discuss the traditional idealized view of quantum measurements that goes back to Born, Dirac, and von Neumann.…”

Section: Projective Measurementsmentioning

confidence: 99%

Born's rule and measurement

Neumaier¹

2019

Preprint

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Born's rule in its conventional textbook form applies to the small class of projective measurements only. It is well-known that a generalization of Born's rule to realistic experiments must be phrased in terms of positive operator valued measures (POVMs). This generalization accounts for things like losses, imperfect measurements, limited detection accuracy, dark detector counts, and the simultaneous measurement of position and momentum.Starting from first principles, this paper gives a self-contained, deductive introduction to quantum measurement and Born's rule, in its generalized form that applies to the results of measurements described by POVMs. It is based on a suggestive definition of what constitutes a detector, assuming an intuitive informal notion of response.The formal exposition is embedded into the context of a variaety of quotes from the literature illuminating historical aspects of the subject. The material presented suggests a new approach to introductory courses on quantum mechanics.For the discussion of questions related to this paper, please use the discussion forum https://www.physicsoverflow.org.

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The quantum picture of a detector

Cited by 5 publications

References 6 publications

Interferometric phase detection at x-ray energies via Fano resonance control

Interferometric phase detection at x-ray energies via Fano resonance control

Quantum mechanics via quantum tomography

Born's rule and measurement

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