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arXiv:2601.01519 · Annalen der Physik

Entropy and Variance Squeezing of V-type Atom in Dissipative Cavity

Zijin Liang, Qiying Pan, Hong-Mei Zou, Chenrui Bi

quant-phSubmitted Jan 4, 2026• Announced Jan 6, 2026• 0 citations• Revised Sep 30, 2026 (v4)

v1 · Jan 4, 2026 v2 · Aug 4, 2026 v3 · Aug 5, 2026 v4 · Sep 30, 2026

Abstract

Based on Ref.\cite{Riccardi A}, we investigate the entropy and variance squeezing of a V-type atom in a dissipative cavity, and discuss the influences of parameters including the spontaneously generated interference (SGI) ($θ$), the cavity-environment coupling ($γ_0/κ$) and the atom-cavity detuning ($Δ$) on the atomic squeezing by using different initial states. The results show that no squeezing of $S_y$ occurs under any condition and that variance squeezing of $S_x$ appears only when $Δ>0$. Entropy squeezing quantifies quantum fluctuations more precisely than variance squeezing. Moreover, the atomic squeezing of $S_x$ clearly depends on $θ$, $γ_0/κ$, $Δ$ and the initial state. These findings are meaningful for quantum information processing as an ultra-low-noise resource.

Journal reference: Annalen der Physik 538(10), 70294 (2026)
DOI: 10.1002/andp.70294
Comments: Withdrawal due to errors: (1) entropy squeezing calculated with wrong information entropy, inconsistent with cited entropic uncertainty relation Eq. (25); (2) basis inconsistency between spin operators and reduced density matrix

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Based on Ref.\cite{Riccardi A}, we investigate the entropy and variance squeezing of a V-type atom in a dissipative cavity, and discuss the influences of parameters including the spontaneously generated interference (SGI) (

θ

), the cavity-environment coupling (

γ_0/κ

) and the atom-cavity detuning (

Δ

) on the atomic squeezing by using different initial states. The results show that no squeezing of

S_y

occurs under any condition and that variance squeezing of

S_x

appears only when

Δ>0

. Entropy squeezing quantifies quantum fluctuations more precisely than variance squeezing. Moreover, the atomic squeezing of

S_x

clearly depends on

Δ>0

,

γ_0/κ

,

Δ

and the initial state. These findings are meaningful for quantum information processing as an ultra-low-noise resource.

Variance squeezing of a V-type atom interacting with a dissipative cavity is investigated. First, the influence of atomic initial state parameters on the variance squeezing is explored. The results show that the atomic variance squeezing switches alternately between Sx and Sy as the initial state parameter alpha sweeps from -pi to pi. The two squeezing intervals are symmetric about alpha = pi/4, each with a width of pi/2. For alpha = pi/14, only the Sx component can generate variance squeezing and will eventually disappear with time evolution due to unavoidable environmental noise. Then, the influence of system parameters on the variance squeezing is also studied. It is found that, the optical variance squeezing depth of Sx is determined solely by the atomic initial parameters and is independent of the system parameters. Both weak cavity-environment coupling and atom-cavity detuning can significantly enhance the robustness of the Sx variance squeezing. The SGI parameter has an extremely weak influence on variance squeezing. These results are beneficial for high-precision quantum communication applications.

The entropy squeezing of a V-type three-level atom interacting with a single-mode field and passing through the amplitude damping channel is investigated in detail. Our results show that when coupled to the single-mode field, the atom in appropriate initial states can not only generate obvious entropy squeezing but also keep in the optimal squeezing state, while passing through the amplitude damping channel, the atom can generate entropy squeezing under the control of the weak measurement. Besides, it is proved again that as a measurement method for atomic squeezing, the entropy squeezing is precise and effective. Therefore our work is instructive for experiments in preparing three-level system information resource with ultra-low quantum noise.

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The position- and momentum-entopic squeezing properties of the optical field in the system of a nearly degenerate three-level atom interacting with a single-mode field are investigated. Calculation results indicate that when the field is initially in the vacuum state, it may lead to squeezing of the position entropy or the momentum entropy of the field if the atom is prepared properly. The effects of initial atomic state and the splitting of the excited levels of the atom on field entropies are discussed in this case. When the initial field is in a coherent state, we find that position-entropy squeezing of the field is present even if the atom is prepared in the ground state. By comparing the variance squeezing and entropy squeezing of the field we confirm that entropy is more sensitive than variance in measuring quantum fluctuations.

In this work, an interactive system composed of a V-type atom and a dissipative single-mode cavity is considered and the atomic quantum coherences are investigated under parameters including spontaneously generated interference (SGI), cavity-environment coupling, weak measurement and its reversal, and detuning between the atom and the cavity. The results indicate that strong coupling can induce coherence sudden death (CSD) and coherence sudden birth (CSB), while the non-zero SGI parameter only induces CSB. Detuning, however, may avoid both CSD and CSB. Moreover, detuning and weak measurement reversal can very effectively protect quantum coherence, while the SGI parameter, weak measurement, and strong coupling can accelerate its attenuation. The SGI parameter, detuning, weak measurement reversal, and strong coupling all promote the generation of coherence, whereas weak measurement alone can suppress it. In particular, the maximal coherent state can be very effectively protected and the coherent state can be prepared if all parameters are selected appropriately. Physical interpretations are also provided for these results.