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

Mysteries, Puzzles, and Paradoxes in Quantum Mechanics

A new class of all-optical Parametric Schroedinger-cats

S. Branca, F. De Martini, F. Mariani, Giovanni Di Giuseppe

Published Jan 1, 1999• 0 citations
Publisher

Abstract

The process of quantum-injection into an amplifier operating in a novel entangled configuration is adopted to “amplify” into a large dimensionality spin-12 Hilbert space the superposition properties of the entangled photon-couples generated by parametric down-conversion. The process is applied to the cases of mode-degenerate and mode non-degenerate Parametric Amplification. The quantum structure of the Wigner function and of the field correlation functions shows in both cases that the Schroedinger-cat behavior of the emitted field is largely detectable against the squeezed-vacuum noise. The absence of decoherence is explained in terms of a basic property of nonlinear complex systems.

DOI
10.1063/1.57853

Related papers

Amplification of Quantum Entanglement

F. De Martini

The new process of quantum injection into an optical parametric amplifier operating in entangled configuration is adopted to ``amplify'' into a large dimensionality spin- $\frac{1}{2}$ Hilbert space the quantum entanglement and superposition properties of the photon couples generated by parametric down-conversion. The structure of the Wigner function and of the field's correlation functions shows a decoherence-free multiphoton Schroedinger-cat behavior of the emitted field which is largely detectable against the squeezed-vacuum noise.

Physical Review Letters•Oct 5, 1998•96 citations

Quantum Superposition of Parametrically Amplified Multiphoton Pure States whitin a Decoherence-Free Schroedinger-Cat Structure

Fabio Antonio Bovino, F. De Martini, Valentina Mussi

The new process of quantum-injection into an optical parametric amplifier operating in entangled configuration is adopted to amplify into a large dimensionality spin 1/2 Hilbert space the quantum entanglement and superposition properties of the photon-couples generated by parametric down-conversion. The structure of the Wigner function and of the field's correlation functions shows a decoherence-free, multiphoton Schroedinger-cat behaviour of the emitted field which is largely detectable against the squeezed-vacuum noise. Furthermore, owing to its entanglement character, the system is found to exhibit multi-particle quantum nonseparability and Bell-type nonlocality properties. These relevant quantum features are analyzed for several travelling-wave optical configurations implying different input quantum-injection schemes

arXiv:quant-ph/9905048•May 14, 1999•0 citations

Universal Quantum Cloning and Macroscopic Superposition in Parametric Amplification

F. De Martini, Valentina Mussi

The new process of quantum-injection into an optical parametric amplifier operating in entangled configuration is adopted to amplify into a large dimensionality spin-½ Hilbert space the quantum entanglement and superposition properties of the photon-couples generated by parametric down-conversion. The invariance properties of the OPA interaction hamiltonian show that, under certain conditions, the device may act as a Universal Quantum Cloning Machine (UQCM) of the input qubits. Preliminary results here reported show the first experimental realization of such a device. The structure of the Wigner function and of the field's correlation functions shows a multiphoton Schrödinger-cat behaviour of the emitted field which is largely detectable against the squeezed-vacuum noise.

Fortschritte der Physik•May 1, 2000•7 citations

Amplification of Schrödinger-cat state in a degenerate optical parametric amplifier

Radim Filip

Amplification of the Schrödinger-cat state (even coherent-state superposition) can be accompanied by its non-exponential decoherence and strong squeezing effect in the degenerate optical parametric amplifier. In the classical pump approximation and small thermal noise limit, the Wigner function behaviour illustrates that this non-exponential effect is induced by the phase-selective character of amplification. The non-exponential decoherence is much slower, in contrast with phase-unselective amplification exhibiting faster exponential decay. Thus, if one is able to produce the Schrödinger-cat state with at least a small amplitude, then it can be partially amplified with only a weak decoherence effect.

Journal of Optics B Quantum and Semiclassical Optics•Jan 25, 2001•16 citations

Enhancement of photonic entanglement and antibunching of the emitted waves from a non-degenerate parametric amplifier

R. Usefi, Mohammad Kazem Tavassoly

Our purpose in this paper is to investigate the response of a well-known nonlinear quantum optical medium, i.e. non-degenerate parametric amplifier (NDPA), to the pair coherent and two-mode squeezed states, distinctly, both analytically and numerically. To achieve the aim, we start from the NDPA quantum Hamiltonian in the rotating wave approximation (RWA) and via solving the Heisenberg equations of motion of signal and idler modes of the dynamical system is derived, by which we can achieve the time evolution of the NDPA response to the above-mentioned input field states. Accordingly, we are able to evaluate two important nonclassical properties, i.e. photonic entanglement and photon statistics (second-order correlation function and antibunching effect) after the interaction with NDPA for the output emitted fields, and compare the results with the associated quantities for the input field states. Summing up, our numerical simulations show that the amplification (and in some cases the appearance) of the considered nonclassical properties of the radiation field in the output states is clearly confirmed. The results can be beneficial for various quantum science and technology protocols, i.e. quantum communication, quantum metrology, quantum teleportation and quantum computing.

Modern Physics Letters A•Aug 7, 2025•2 citations

Entanglement, Einstein Podolsky Rosen correlations and Schrodinger cat state generation by quantum-injected optical parametric amplification

F. De Martini, Fabio Sciarrino

We investigate the multi-photon quantum superposition state generated by the quantum-injected high-gain optical parametric amplification of a single photon. The physical configurations based on the optimal universal and on the phase-covariant quantum cloning have been adopted. The theoretical results are supported by a set of experiments leading to the generation of an average number of clones in excess of 103.

Journal of Physics A Mathematical and Theoretical•Mar 7, 2007•4 citations
The process of quantum-injection into an amplifier operating in a novel entangled configuration is adopted to “amplify” into a large dimensionality spin-12 Hilbert space the superposition properties of the entangled photon-couples generated by parametric down-conversion. The process is applied to the cases of mode-degenerate and mode non-degenerate Parametric Amplification. The quantum structure of the Wigner function and of the field correlation functions shows in both cases that the Schroedinger-cat behavior of the emitted field is largely detectable against the squeezed-vacuum noise. The absence of decoherence is explained in terms of a basic property of nonlinear complex systems.
The new process of quantum injection into an optical parametric amplifier operating in entangled configuration is adopted to ``amplify'' into a large dimensionality spin- 12\frac{1}{2}21​ Hilbert space the quantum entanglement and superposition properties of the photon couples generated by parametric down-conversion. The structure of the Wigner function and of the field's correlation functions shows a decoherence-free multiphoton Schroedinger-cat behavior of the emitted field which is largely detectable against the squeezed-vacuum noise.
The new process of quantum-injection into an optical parametric amplifier operating in entangled configuration is adopted to amplify into a large dimensionality spin 1/2 Hilbert space the quantum entanglement and superposition properties of the photon-couples generated by parametric down-conversion. The structure of the Wigner function and of the field's correlation functions shows a decoherence-free, multiphoton Schroedinger-cat behaviour of the emitted field which is largely detectable against the squeezed-vacuum noise. Furthermore, owing to its entanglement character, the system is found to exhibit multi-particle quantum nonseparability and Bell-type nonlocality properties. These relevant quantum features are analyzed for several travelling-wave optical configurations implying different input quantum-injection schemes
The new process of quantum-injection into an optical parametric amplifier operating in entangled configuration is adopted to amplify into a large dimensionality spin-½ Hilbert space the quantum entanglement and superposition properties of the photon-couples generated by parametric down-conversion. The invariance properties of the OPA interaction hamiltonian show that, under certain conditions, the device may act as a Universal Quantum Cloning Machine (UQCM) of the input qubits. Preliminary results here reported show the first experimental realization of such a device. The structure of the Wigner function and of the field's correlation functions shows a multiphoton Schrödinger-cat behaviour of the emitted field which is largely detectable against the squeezed-vacuum noise.
Amplification of the Schrödinger-cat state (even coherent-state superposition) can be accompanied by its non-exponential decoherence and strong squeezing effect in the degenerate optical parametric amplifier. In the classical pump approximation and small thermal noise limit, the Wigner function behaviour illustrates that this non-exponential effect is induced by the phase-selective character of amplification. The non-exponential decoherence is much slower, in contrast with phase-unselective amplification exhibiting faster exponential decay. Thus, if one is able to produce the Schrödinger-cat state with at least a small amplitude, then it can be partially amplified with only a weak decoherence effect.
Our purpose in this paper is to investigate the response of a well-known nonlinear quantum optical medium, i.e. non-degenerate parametric amplifier (NDPA), to the pair coherent and two-mode squeezed states, distinctly, both analytically and numerically. To achieve the aim, we start from the NDPA quantum Hamiltonian in the rotating wave approximation (RWA) and via solving the Heisenberg equations of motion of signal and idler modes of the dynamical system is derived, by which we can achieve the time evolution of the NDPA response to the above-mentioned input field states. Accordingly, we are able to evaluate two important nonclassical properties, i.e. photonic entanglement and photon statistics (second-order correlation function and antibunching effect) after the interaction with NDPA for the output emitted fields, and compare the results with the associated quantities for the input field states. Summing up, our numerical simulations show that the amplification (and in some cases the appearance) of the considered nonclassical properties of the radiation field in the output states is clearly confirmed. The results can be beneficial for various quantum science and technology protocols, i.e. quantum communication, quantum metrology, quantum teleportation and quantum computing.