Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:quant-ph/9910029 · Optics Communications

Measuring quantum state overlaps of traveling optical fields

J. Clausen, Mohammed Dakna, L. Knöll, D.‐G. Welsch

Published May 1, 2000• 13 citations
arXivHTMLPDF
DOI
10.1016/s0030-4018(99)00537-4

Related papers

Simple optical measurement of the overlap and fidelity of quantum states

Martin Hendrych, Miloslav Dušek, Radim Filip +1 more

arXiv:quant-ph/0208091•Physics Letters A•Apr 1, 2003•35 citations

Measurement and manipulation of quantum states of travelling light fields

Brian J. Smith

•Jan 1, 2014•0 citations

Conditional quantum state engineering at beam splitter arrays

Clausen, J., Mohammed Dakna, L. Knoell +1 more

The generation of arbitrary single-mode quantum states from the vacuum by alternate coherent displacement and photon adding as well as the measurement of the overlap of a signal with an arbitrarily chosen quantum state are studied. With regard to implementations, the transformation of the quantum state of a traveling optical field at an array of beam splitters is considered, using conditional measurement. Allowing for arbitrary quantum states of both the input reference modes and the output reference modes on which the measurements are performed, the setup is described within the concept of two-port non-unitary transformation, and the overall non-unitary transformation operator is derived. It is shown to be a product of operators, where each operator is assigned to one of the beam splitters and can be expressed in terms of an s-ordered operator product, with s being determined by the beam splitter transmittance or reflectance. As an example we discuss the generation of and overlap measurement with Schroedinger-cat-like states.

arXiv:quant-ph/9905085•May 25, 1999•3 citations

Time-delayed quantum feedback for traveling optical fields

M. Yanagisawa

Quantum nonlinear feedback control is developed for traveling optical fields. We first describe the discretization of the traveling optical fields. The discrete-time formulation is used to describe the stochastic master equation subject to homodyne measurement. Nonlinear feedback is formulated by directly feeding the measurement outcomes back to the traveling field through a multiplicative action. Since the measurement outcomes have a correlation with the system, the multiplicative feedback control can create nonlinear effects in the traveling field. In this formulation, a time delay is naturally introduced in the feedback loop. This is essentially different from instantaneous feedback in a continuous-time setting. As an example of the feedback scheme, a quantum nondemolition sum gate is considered. Numerical results show that quantum superposition state can be created by applying the feedback to a squeezed state.

Physical Review A•Sep 20, 2010•2 citations

Measuring the classical and quantum states and ultrafast correlations of optical fields

D. F. McAlister

•Jan 1, 1999•1 citation

Generation of arbitrary quantum states of traveling fields

Mohammed Dakna, J. Clausen, L. Knöll +1 more

We show that any single-mode quantum state can be generated from the vacuum by alternate application of the coherent displacement operator and the creation operator. We propose an experimental implementation of the scheme for traveling optical fields, which is based on field mixings and conditional measurements in a beam-splitter array, and calculate the probability of state generation.

arXiv:quant-ph/9807089•Physical Review A•Feb 1, 1999•175 citations
The generation of arbitrary single-mode quantum states from the vacuum by alternate coherent displacement and photon adding as well as the measurement of the overlap of a signal with an arbitrarily chosen quantum state are studied. With regard to implementations, the transformation of the quantum state of a traveling optical field at an array of beam splitters is considered, using conditional measurement. Allowing for arbitrary quantum states of both the input reference modes and the output reference modes on which the measurements are performed, the setup is described within the concept of two-port non-unitary transformation, and the overall non-unitary transformation operator is derived. It is shown to be a product of operators, where each operator is assigned to one of the beam splitters and can be expressed in terms of an s-ordered operator product, with s being determined by the beam splitter transmittance or reflectance. As an example we discuss the generation of and overlap measurement with Schroedinger-cat-like states.
Quantum nonlinear feedback control is developed for traveling optical fields. We first describe the discretization of the traveling optical fields. The discrete-time formulation is used to describe the stochastic master equation subject to homodyne measurement. Nonlinear feedback is formulated by directly feeding the measurement outcomes back to the traveling field through a multiplicative action. Since the measurement outcomes have a correlation with the system, the multiplicative feedback control can create nonlinear effects in the traveling field. In this formulation, a time delay is naturally introduced in the feedback loop. This is essentially different from instantaneous feedback in a continuous-time setting. As an example of the feedback scheme, a quantum nondemolition sum gate is considered. Numerical results show that quantum superposition state can be created by applying the feedback to a squeezed state.