Amplifying hybrid entangled states and superpositions of coherent states

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Hauptverfasser: Jeon, InU, Cho, Sungjoo, Jeong, Hyunseok
Format: Preprint
Veröffentlicht: 2024
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author Jeon, InU
Cho, Sungjoo
Jeong, Hyunseok
author_facet Jeon, InU
Cho, Sungjoo
Jeong, Hyunseok
contents We compare two amplification schemes, photon addition and then subtraction ($\hat{a}\hat{a}^\dagger$) and successive photon addition ($\hat{a}^\dagger{}^2$), applied to hybrid entangled states (HESs) and superpositions of coherent states (SCSs). We show that the amplification schemes' fidelity and gain for HESs are the same as those of coherent states. On the other hand, SCSs show quite nontrivial behaviors by the amplification schemes, depending on the amplitudes of coherent states, number of coherent-state components, and relative phases between the components. This implies that appropriate amplification schemes for SCSs should be chosen depending on the tasks and specific forms of the states. To investigate the quality of amplified states, we calculate the quantum Fisher information, a measure of quantum phase estimation. In terms of the quantum Fisher information, the $\hat{a}\hat{a}^\dagger$ scheme tends to show better performance for relatively small amplitudes while the $\hat{a}^\dagger{}^2$ scheme is better in larger amplitude regime. The performance of the two schemes becomes indistinguishable as the amplitude grows sufficiently large.
format Preprint
id arxiv_https___arxiv_org_abs_2409_16562
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Amplifying hybrid entangled states and superpositions of coherent states
Jeon, InU
Cho, Sungjoo
Jeong, Hyunseok
Quantum Physics
Optics
We compare two amplification schemes, photon addition and then subtraction ($\hat{a}\hat{a}^\dagger$) and successive photon addition ($\hat{a}^\dagger{}^2$), applied to hybrid entangled states (HESs) and superpositions of coherent states (SCSs). We show that the amplification schemes' fidelity and gain for HESs are the same as those of coherent states. On the other hand, SCSs show quite nontrivial behaviors by the amplification schemes, depending on the amplitudes of coherent states, number of coherent-state components, and relative phases between the components. This implies that appropriate amplification schemes for SCSs should be chosen depending on the tasks and specific forms of the states. To investigate the quality of amplified states, we calculate the quantum Fisher information, a measure of quantum phase estimation. In terms of the quantum Fisher information, the $\hat{a}\hat{a}^\dagger$ scheme tends to show better performance for relatively small amplitudes while the $\hat{a}^\dagger{}^2$ scheme is better in larger amplitude regime. The performance of the two schemes becomes indistinguishable as the amplitude grows sufficiently large.
title Amplifying hybrid entangled states and superpositions of coherent states
topic Quantum Physics
Optics
url https://arxiv.org/abs/2409.16562