MDPI - Publisher of Open Access Journals

16 pages, 8172 KiB

Open AccessArticle

A Comparative Analysis of a Nonlinear Phase Space Evolution of SU(2) and SU(1,1) Coherent States

by Rodrigo D. Aceves, Miguel Baltazar, Iván F. Valtierra and Andrei B. Klimov

Quantum Rep. 2025, 7(3), 31; https://doi.org/10.3390/quantum7030031 - 5 Jul 2025

Viewed by 256

We carried out a comparative study of the phase space evolution of SU(2) and SU(1,1) coherent states generated by the same nonlinear two-mode Hamiltonian. We analyze the dynamics of the Wigner functions in the respective phase spaces and discuss the principal associated physical effects: the squeezing of the appropriate observables and the Schrödinger’s cat state generation characteristic of both the considered symmetry groups. Full article

(This article belongs to the Special Issue Exclusive Feature Papers of Quantum Reports in 2024–2025)

► Show Figures

Figure 1

18 pages, 1359 KiB

Open AccessArticle

Transfer of Quantum States and Stationary Quantum Correlations in a Hybrid Optomechanical Network

by Hugo Molinares, Bing He and Vitalie Eremeev

Mathematics 2023, 11(13), 2790; https://doi.org/10.3390/math11132790 - 21 Jun 2023

Cited by 2 | Viewed by 1991

Abstract

We present a systematic study on the effects of dynamical transfer and steady-state synchronization of quantum states in a hybrid optomechanical network consisting of two cavities, which carry atoms inside and interact via a common moving mirror such as the mechanical oscillator. It is found that a high fidelity transfer of Schrödinger’s cat and squeezed states between two cavities modes is possible. On the other hand, we demonstrate the synchronization effect of the cavity modes in a steady squeezed state with its high fidelity realized by the mechanical oscillator that intermediates the generation, transfer and stabilization of the squeezing. In this framework, we also study the generation and evolution of bipartite and tripartite entanglement and find its connection to the effects of quantum state transfer and synchronization. Particularly, when the transfer occurs at the maximal fidelity, any entanglement is almost zero, so the different cavity modes are disentangled. However, these modes become entangled when the two bosonic modes are synchronized in a stationary squeezed state. The results provided by the current study may find applications in quantum information technologies, in addition to the setups for metrology, where squeezed states are essential. Full article

(This article belongs to the Special Issue Advances in Quantum Optics and Quantum Information)

► Show Figures

Figure 1

17 pages, 923 KiB

Open AccessArticle

Theory of Photon Subtraction for Two-Mode Entangled Light Beams

by Oscar Rosas-Ortiz and Kevin Zelaya

Quantum Rep. 2021, 3(3), 500-516; https://doi.org/10.3390/quantum3030033 - 3 Sep 2021

Cited by 2 | Viewed by 3595

Abstract

Photon subtraction is useful to produce nonclassical states of light addressed to applications in photonic quantum technologies. After a very accelerated development, this technique makes possible obtaining either single photons or optical cats on demand. However, it lacks theoretical formulation enabling precise predictions [...] Read more.

S U (2)

coherent states, we introduce a model of entangled light beams leading to the subtraction of photons in one of the modes, conditioned to the detection of any photon in the other mode. We show that photon subtraction does not produce nonclassical fields from classical fields. It is also derived a compact expression for the output field from which the calculation of conditional probabilities is straightforward for any input state. Examples include the analysis of squeezed-vacuum and odd-squeezed states. We also show that injecting optical cats into a beam splitter gives rise to entangled states in the Bell representation. Full article

► Show Figures

Figure 1

9 pages, 1034 KiB

Open AccessEditor’s ChoiceArticle

Testing Quantum Coherence in Stochastic Electrodynamics with Squeezed Schrödinger Cat States

by Wayne Cheng-Wei Huang and Herman Batelaan

Atoms 2019, 7(2), 42; https://doi.org/10.3390/atoms7020042 - 5 Apr 2019

Cited by 11 | Viewed by 4433

Abstract

The interference pattern in electron double-slit diffraction is a hallmark of quantum mechanics. A long-standing question for stochastic electrodynamics (SED) is whether or not it is capable of reproducing such effects, as interference is a manifestation of quantum coherence. In this study, we used excited harmonic oscillators to directly test this quantum feature in SED. We used two counter-propagating dichromatic laser pulses to promote a ground-state harmonic oscillator to a squeezed Schrödinger cat state. Upon recombination of the two well-separated wavepackets, an interference pattern emerges in the quantum probability distribution but is absent in the SED probability distribution. We thus give a counterexample that rejects SED as a valid alternative to quantum mechanics. Full article

► Show Figures

Figure 1

10 pages, 2826 KiB

Open AccessArticle

Implementation of Traveling Odd Schrödinger Cat States in Circuit-QED

by Jaewoo Joo, Su-Yong Lee and Jaewan Kim

Photonics 2016, 3(4), 57; https://doi.org/10.3390/photonics3040057 - 31 Oct 2016

Cited by 5 | Viewed by 5842

Abstract

We propose a realistic scheme of generating a traveling odd Schrödinger cat state and a generalized entangled coherent state in circuit quantum electrodynamics (circuit-QED). A squeezed vacuum state is used as the initial resource of nonclassical states, which can be created through a Josephson traveling-wave parametric amplifier, and travels through a transmission line. Because a single-photon subtraction from the squeezed vacuum gives an odd Schrödinger cat state with very high fidelity, we consider a specific circuit-QED setup consisting of the Josephson amplifier creating the traveling resource in a line, a beam-splitter coupling two transmission lines, and a single photon detector located at the end of the other line. When a single microwave photon is detected by measuring the excited state of a superconducting qubit in the detector, a heralded cat state is generated with high fidelity in the opposite line. For example, we show that the high fidelity of the outcome with the ideal cat state can be achieved with appropriate squeezing parameters theoretically. As its extended setup, we suggest that generalized entangled coherent states can be also built probabilistically and that they are useful for microwave quantum information processing for error-correctable qudits in circuit-QED. Full article

(This article belongs to the Special Issue Quantum Photonics Circuits)

► Show Figures

Figure 1

Search Results (5)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI

Saved Queries

Search Filter Reset All

Years

Feature Papers

Subjects

Journals

Article Types

Countries / Regions

Search Results (5)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI