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

Physical Review A

Testing quantum mechanics against macroscopic realism using the output of χ(2) nonlinearity

Sergey A. Podoshvedov, Jaewan Kim

Published Sep 15, 2006• 15 citations
Publisher

Abstract

We suggest an all-optical scheme to generate entangled superposition of a single photon with macroscopic entangled states for testing macroscopic realism. The scheme consists of source of single photons, a Mach-Zehnder interferometer in routes of which a system of coupled-down converters with type-I phase matching is inserted, and a beam splitter for the other auxiliary modes of the scheme. We use quantization of the pumping modes, depletion of the coherent states passing through the system, and interference effect in the pumping modes in the process of erasing which-path information of the single-photon on exit from the Mach-Zehnder interferometer. We show the macroscopic fields of the output superposition are distinguishable states. This scheme generates macroscopic entangled state that violates Bell's inequality. Moreover, the detailed analysis concerning change of amplitudes of entangled superposition by means of repeating this process many times is accomplished. We show our scheme works without photon number resolving detection and it is robust to detector inefficiency.

DOI
10.1103/physreva.74.033810

Related papers

Generation of macroscopic entangled states by means of x(2) nonlinearity without photon number resolving detection

Sergey A. Podoshvedov

We generalize the scheme of conditional preparation of x (2) macroscopic entangled states [S.A. Podoshvedov, JETP 129 (2006)]. The studied system consists of a system of coupled down converters with type-I phase matching pumped simultaneously by powerful optical fields in coherent states with one auxiliary photon in the superposition state of two input modes and a projective measurement system. The projective measurement system involves two Hadamard gates introduced to generated output modes followed by photodetectors. Identification of macroscopic entangled states is produced by registration of one photon. No photon number resolving detection is required for the studied scheme.

Journal of Experimental and Theoretical Physics Letters•Jun 1, 2006•0 citations

Nonlinear χ(2) Mach-Zehnder interferometer: Conditional preparation of maximal microscopic entanglement

Sergey A. Podoshvedov, Jaewan Kim

A nonlinear ${\ensuremath{\chi}}^{(2)}$ Mach-Zehnder interferometer is proposed as a simple device for conditional preparation of a two-photon maximally entangled state. Successful generation is unambiguously heralded by detection of a single photon in one of the routes of the nonlinear ${\ensuremath{\chi}}^{(2)}$ Mach-Zehnder interferometer. The mechanism of the conditional preparation is based on interference of the pumping modes. The scheme works without photon-number-resolving detection with a high fidelity.

Physical Review A•Mar 29, 2007•5 citations

Generation of optical macroscopic quantum superposition states via state reduction with a Mach-Zehnder interferometer containing a Kerr medium

Christopher C. Gerry

A method for producing macroscopic quantum superposition states (generally known as Schr\"odinger cat) states for optical fields is presented. The proposed method involves two modes of the field interacting dispersively in a Kerr medium where one of the modes is an arm of a Mach-Zehnder interferometer and the other mode is external to it. If the external mode initially contains a macroscopic quantum state, such as a coherent state, and the vacuum and a single photon state are the inputs to the interferometer, the external field state becomes entangled with the number states associated with the two paths of the interferometer. Selective measurement at the output ports of the interferometer project the external mode into the desired cat states. It is pointed out that the method can also be used to generate cat states out of multimode states initially containing correlations.

Physical Review A•May 1, 1999•181 citations

Entangled coherent states

Barry C. Sanders

The nonlinear Mach-Zehnder interferometer is presented as a device whereby a pair of coherent states can be transformed into an entangled superposition of coherent states for which the notion of entanglement is generalized to include nonorthogonal, but distinct, component states. Each mode is directed to a homodyne detector. We show that there exist nonclassical intensity correlations at the output ports of the homodyne detectors which facilitate a test of local realism. In contradistinction to previous optical schemes which test local realism, the initial state used here possesses a positive Glauber-Sudarshan representation and is therefore a semiclassical state. The nonlinearity itself is responsible for generating the nonclassical state.

Physical Review A•May 1, 1992•485 citations

Modified nonclassical coherent state: Squeezing, antibunching, sub-Poissonian photon statistics, realization scheme with the χ(2)-nonlinearity, and generation of a macroscopic entangled state

Sergey A. Podoshvedov

The nonlinear χ (2) Mach-Zehnder interferometer is proposed as a device for conditional generation of a modified coherent nonclassical state. We show that the generated macroscopic state exhibits nonclassical effects, such as squeezing, photon antibunching, and sub-Poissonian statistics. The modified coherent state generates a macroscopic entangled state. The scheme works without the photon number resolving detection but requires high-efficiency photodetectors. We explain the mechanism of generation of the modified coherent non-classical state.

Journal of Experimental and Theoretical Physics•Apr 1, 2007•0 citations

A simple scheme with coupled down converters with type-I phase matching as resource for conditional preparation of macroscopic entangled states

Sergey A. Podoshvedov, Nguyen Ba An, Jaewan Kim

It is shown that macroscopic entangled states can be generated using an experimental arrangement consisting of coupled spontaneous parametric down-converters with type-I phase matching (SPDCI) pumped simultaneously by optical fields in coherent state and two beam splitters. Two beam splitters in auxiliary generated modes are used to conditionally prepare macroscopic entangled states in output pumping modes of the studied system. Identification of two macroscopic entangled states is produced by use of photon number resolving detection. In contrast to all previous schemes, our scheme does not need Kerr-type nonlinear interaction and is purely based on second-order susceptibility of the crystal which is stronger for the Kerr nonlinearity. We calculate concurrence of the states as a measure of the amount of entanglement stored in the states and present analysis concerning ‘separation’ between components forming studied entangled states.

Journal of Modern Optics•Jun 23, 2006•2 citations
We suggest an all-optical scheme to generate entangled superposition of a single photon with macroscopic entangled states for testing macroscopic realism. The scheme consists of source of single photons, a Mach-Zehnder interferometer in routes of which a system of coupled-down converters with type-I phase matching is inserted, and a beam splitter for the other auxiliary modes of the scheme. We use quantization of the pumping modes, depletion of the coherent states passing through the system, and interference effect in the pumping modes in the process of erasing which-path information of the single-photon on exit from the Mach-Zehnder interferometer. We show the macroscopic fields of the output superposition are distinguishable states. This scheme generates macroscopic entangled state that violates Bell's inequality. Moreover, the detailed analysis concerning change of amplitudes of entangled superposition by means of repeating this process many times is accomplished. We show our scheme works without photon number resolving detection and it is robust to detector inefficiency.
We generalize the scheme of conditional preparation of x (2) macroscopic entangled states [S.A. Podoshvedov, JETP 129 (2006)]. The studied system consists of a system of coupled down converters with type-I phase matching pumped simultaneously by powerful optical fields in coherent states with one auxiliary photon in the superposition state of two input modes and a projective measurement system. The projective measurement system involves two Hadamard gates introduced to generated output modes followed by photodetectors. Identification of macroscopic entangled states is produced by registration of one photon. No photon number resolving detection is required for the studied scheme.
A nonlinear ${\ensuremath{\chi}}^{(2)}$ Mach-Zehnder interferometer is proposed as a simple device for conditional preparation of a two-photon maximally entangled state. Successful generation is unambiguously heralded by detection of a single photon in one of the routes of the nonlinear ${\ensuremath{\chi}}^{(2)}$ Mach-Zehnder interferometer. The mechanism of the conditional preparation is based on interference of the pumping modes. The scheme works without photon-number-resolving detection with a high fidelity.
A method for producing macroscopic quantum superposition states (generally known as Schr\"odinger cat) states for optical fields is presented. The proposed method involves two modes of the field interacting dispersively in a Kerr medium where one of the modes is an arm of a Mach-Zehnder interferometer and the other mode is external to it. If the external mode initially contains a macroscopic quantum state, such as a coherent state, and the vacuum and a single photon state are the inputs to the interferometer, the external field state becomes entangled with the number states associated with the two paths of the interferometer. Selective measurement at the output ports of the interferometer project the external mode into the desired cat states. It is pointed out that the method can also be used to generate cat states out of multimode states initially containing correlations.
The nonlinear Mach-Zehnder interferometer is presented as a device whereby a pair of coherent states can be transformed into an entangled superposition of coherent states for which the notion of entanglement is generalized to include nonorthogonal, but distinct, component states. Each mode is directed to a homodyne detector. We show that there exist nonclassical intensity correlations at the output ports of the homodyne detectors which facilitate a test of local realism. In contradistinction to previous optical schemes which test local realism, the initial state used here possesses a positive Glauber-Sudarshan representation and is therefore a semiclassical state. The nonlinearity itself is responsible for generating the nonclassical state.
The nonlinear χ (2) Mach-Zehnder interferometer is proposed as a device for conditional generation of a modified coherent nonclassical state. We show that the generated macroscopic state exhibits nonclassical effects, such as squeezing, photon antibunching, and sub-Poissonian statistics. The modified coherent state generates a macroscopic entangled state. The scheme works without the photon number resolving detection but requires high-efficiency photodetectors. We explain the mechanism of generation of the modified coherent non-classical state.
It is shown that macroscopic entangled states can be generated using an experimental arrangement consisting of coupled spontaneous parametric down-converters with type-I phase matching (SPDCI) pumped simultaneously by optical fields in coherent state and two beam splitters. Two beam splitters in auxiliary generated modes are used to conditionally prepare macroscopic entangled states in output pumping modes of the studied system. Identification of two macroscopic entangled states is produced by use of photon number resolving detection. In contrast to all previous schemes, our scheme does not need Kerr-type nonlinear interaction and is purely based on second-order susceptibility of the crystal which is stronger for the Kerr nonlinearity. We calculate concurrence of the states as a measure of the amount of entanglement stored in the states and present analysis concerning ‘separation’ between components forming studied entangled states.