Original title: Fock-state Filtering of Squeezed States: Enhanced Nonclassicality and Effects of a Thermal Bath
João Pedro González de Oliveira, A. Vidiella-Barranco · September 2026
Scientists want to shape the quantum properties of light, but controlling the exact number of light particles, called photons, is difficult. In this study, researchers looked at squeezed coherent statesQuantum states of light with reduced noise in one quadrature at the expense of increased noise in the other., which are special quantum light beams. They tested what happens when you filter out states with exactly m=0 and m=1 photons. By selectively removing these specific photon components, they discovered they could enhance the sub-PoissonianA property where the photon number distribution is narrower than that of coherent light, indicating less randomness. nature of the light, making its photon stream more regular. This effect depends on the light's coherent amplitude. The team also placed these engineered beams into a warm thermal environment. While the states eventually degrade into thermal light, the signatures of the filtering last for a significant part of the process.
Imagine you have a bag of marbles with a mix of colors. You carefully remove all the red and blue marbles to make the bag more uniform. That works well in a still room. But if someone keeps adding random marbles from a mixed bag, the uniformity quickly disappears. In this paper, the marbles are photons, and removing specific ones (like the zero-photon and one-photon components) makes the light's statistics more uniform, but a warm environment (thermal bath) adds random photons and destroys that uniformity.
Nonclassical light is essential for quantum technologies like computing and sensing, but it is fragile. This work shows that by selectively removing specific photon numbers from squeezed light, we can make it even more nonclassical—but only if we control thermal noise. It highlights both the potential and the practical limits of engineering light for real-world quantum applications.
The work only considers filtering of the m=0 and m=1 Fock components, and the enhancement of sub-Poissonian character depends on the coherent amplitude. Moreover, in a thermal bath, purity degrades rapidly, and the nonclassical signatures eventually vanish. The results are limited to the specific model of a thermal bath and do not address other decoherence mechanisms.
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Fock-state Filtering of Squeezed States: Enhanced Nonclassicality and Effects of a Thermal Bath — João Pedro González de Oliveira, A. Vidiella-Barranco — Brazilian Journal of Physics — doi:10.1007/s13538-026-02146-z
Abstract licence: CC BY
Explanation generated by Synthesis from the abstract — it is not the original paper.