From quantum storage to amplification: the effect of unwanted couplings and an additional level in cavity-based ensemble quantum memories
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arXiv
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| Auteurs principaux: | , |
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| Format: | Preprint |
| Publié: |
2026
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| _version_ | 1866913080241291264 |
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| author | Ji, Jia-Wei Simon, Christoph |
| author_facet | Ji, Jia-Wei Simon, Christoph |
| contents | Quantum-memory models often reduce complex level structures to an idealized $Λ$ system, potentially missing nearby levels and unwanted couplings that can qualitatively alter the predicted performance. Here, we study an extension of a cavity-based $Λ$-type ensemble memory, a four-level model with unwanted couplings from both the control field and signal, using a fully quantum treatment. We derive explicit expressions for the single-photon storage efficiency, retrieval efficiency, and fidelity, and on this basis identify three distinct dynamical regimes: stable, threshold, and unstable. Within the stable regime, we additionally discriminate between two qualitatively different sub-regimes. Applying the theory to warm-vapor-inspired parameters, we determine the conditions under which the system can still operate as a high-quality quantum memory. More generally, our results provide a practical framework for distinguishing genuine memory operation from amplification and for optimizing realistic quantum memories beyond idealized models. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_00446 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | From quantum storage to amplification: the effect of unwanted couplings and an additional level in cavity-based ensemble quantum memories Ji, Jia-Wei Simon, Christoph Quantum Physics Quantum-memory models often reduce complex level structures to an idealized $Λ$ system, potentially missing nearby levels and unwanted couplings that can qualitatively alter the predicted performance. Here, we study an extension of a cavity-based $Λ$-type ensemble memory, a four-level model with unwanted couplings from both the control field and signal, using a fully quantum treatment. We derive explicit expressions for the single-photon storage efficiency, retrieval efficiency, and fidelity, and on this basis identify three distinct dynamical regimes: stable, threshold, and unstable. Within the stable regime, we additionally discriminate between two qualitatively different sub-regimes. Applying the theory to warm-vapor-inspired parameters, we determine the conditions under which the system can still operate as a high-quality quantum memory. More generally, our results provide a practical framework for distinguishing genuine memory operation from amplification and for optimizing realistic quantum memories beyond idealized models. |
| title | From quantum storage to amplification: the effect of unwanted couplings and an additional level in cavity-based ensemble quantum memories |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2605.00446 |