Nonclassicality of open circuit QED systems in the deep-strong coupling regime
<p dir="ltr">We investigate theoretically how the ground state of a qubit–resonator (Q–R) system in the deep-strong coupling (DSC) regime is affected by the coupling to an environment. We employ as a variational ansatz for the ground state of the Q–R–environment system a superpositio...
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2021
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| _version_ | 1864513516774359040 |
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| author | Tomohiro Shitara (18508206) |
| author2 | Motoaki Bamba (14221603) Fumiki Yoshihara (15347847) Tomoko Fuse (18508209) Sahel Ashhab (8708694) Kouichi Semba (18508212) Kazuki Koshino (14414181) |
| author2_role | author author author author author author |
| author_facet | Tomohiro Shitara (18508206) Motoaki Bamba (14221603) Fumiki Yoshihara (15347847) Tomoko Fuse (18508209) Sahel Ashhab (8708694) Kouichi Semba (18508212) Kazuki Koshino (14414181) |
| author_role | author |
| dc.creator.none.fl_str_mv | Tomohiro Shitara (18508206) Motoaki Bamba (14221603) Fumiki Yoshihara (15347847) Tomoko Fuse (18508209) Sahel Ashhab (8708694) Kouichi Semba (18508212) Kazuki Koshino (14414181) |
| dc.date.none.fl_str_mv | 2021-10-08T03:00:00Z |
| dc.identifier.none.fl_str_mv | 10.1088/1367-2630/ac2850 |
| dc.relation.none.fl_str_mv | https://figshare.com/articles/journal_contribution/Nonclassicality_of_open_circuit_QED_systems_in_the_deep-strong_coupling_regime/25756464 |
| dc.rights.none.fl_str_mv | CC BY 4.0 info:eu-repo/semantics/openAccess |
| dc.subject.none.fl_str_mv | Information and computing sciences Applied computing circuit QED nonclassicality deep strong coupling metrological power |
| dc.title.none.fl_str_mv | Nonclassicality of open circuit QED systems in the deep-strong coupling regime |
| dc.type.none.fl_str_mv | Text Journal contribution info:eu-repo/semantics/publishedVersion text contribution to journal |
| description | <p dir="ltr">We investigate theoretically how the ground state of a qubit–resonator (Q–R) system in the deep-strong coupling (DSC) regime is affected by the coupling to an environment. We employ as a variational ansatz for the ground state of the Q–R–environment system a superposition of coherent states displaced in qubit-state-dependent directions. We show that the reduced density matrix of the Q–R system strongly depends on how the system is coupled to the environment, i.e. capacitive or inductive, because of the broken rotational symmetry of the eigenstates of the DSC system in the resonator phase space. When the resonator couples to the qubit and the environment in different ways (for instance, one is inductive and the other is capacitive), the system is almost unaffected by the resonator–waveguide (R–W) coupling. In contrast, when the two couplings are of the same type (for instance, both are inductive), by increasing the R–W coupling strength, the average number of virtual photons increases and the quantum superposition realized in the Q–R entangled ground state is partially degraded. Since the superposition becomes more fragile with increasing the Q–R coupling, there exists an optimal coupling strength to maximize the nonclassicality of the Q–R system.</p><h2>Other Information</h2><p dir="ltr">Published in: New Journal of Physics<br>License: <a href="https://creativecommons.org/licenses/by/4.0/" target="_blank">https://creativecommons.org/licenses/by/4.0/</a><br>See article on publisher's website: <a href="https://dx.doi.org/10.1088/1367-2630/ac2850" target="_blank">https://dx.doi.org/10.1088/1367-2630/ac2850</a></p> |
| eu_rights_str_mv | openAccess |
| id | Manara2_4f3fb55b2ea241485393e8b8a88b6e7b |
| identifier_str_mv | 10.1088/1367-2630/ac2850 |
| network_acronym_str | Manara2 |
| network_name_str | Manara2 |
| oai_identifier_str | oai:figshare.com:article/25756464 |
| publishDate | 2021 |
| repository.mail.fl_str_mv | |
| repository.name.fl_str_mv | |
| repository_id_str | |
| rights_invalid_str_mv | CC BY 4.0 |
| spelling | Nonclassicality of open circuit QED systems in the deep-strong coupling regimeTomohiro Shitara (18508206)Motoaki Bamba (14221603)Fumiki Yoshihara (15347847)Tomoko Fuse (18508209)Sahel Ashhab (8708694)Kouichi Semba (18508212)Kazuki Koshino (14414181)Information and computing sciencesApplied computingcircuit QEDnonclassicalitydeep strong couplingmetrological power<p dir="ltr">We investigate theoretically how the ground state of a qubit–resonator (Q–R) system in the deep-strong coupling (DSC) regime is affected by the coupling to an environment. We employ as a variational ansatz for the ground state of the Q–R–environment system a superposition of coherent states displaced in qubit-state-dependent directions. We show that the reduced density matrix of the Q–R system strongly depends on how the system is coupled to the environment, i.e. capacitive or inductive, because of the broken rotational symmetry of the eigenstates of the DSC system in the resonator phase space. When the resonator couples to the qubit and the environment in different ways (for instance, one is inductive and the other is capacitive), the system is almost unaffected by the resonator–waveguide (R–W) coupling. In contrast, when the two couplings are of the same type (for instance, both are inductive), by increasing the R–W coupling strength, the average number of virtual photons increases and the quantum superposition realized in the Q–R entangled ground state is partially degraded. Since the superposition becomes more fragile with increasing the Q–R coupling, there exists an optimal coupling strength to maximize the nonclassicality of the Q–R system.</p><h2>Other Information</h2><p dir="ltr">Published in: New Journal of Physics<br>License: <a href="https://creativecommons.org/licenses/by/4.0/" target="_blank">https://creativecommons.org/licenses/by/4.0/</a><br>See article on publisher's website: <a href="https://dx.doi.org/10.1088/1367-2630/ac2850" target="_blank">https://dx.doi.org/10.1088/1367-2630/ac2850</a></p>2021-10-08T03:00:00ZTextJournal contributioninfo:eu-repo/semantics/publishedVersiontextcontribution to journal10.1088/1367-2630/ac2850https://figshare.com/articles/journal_contribution/Nonclassicality_of_open_circuit_QED_systems_in_the_deep-strong_coupling_regime/25756464CC BY 4.0info:eu-repo/semantics/openAccessoai:figshare.com:article/257564642021-10-08T03:00:00Z |
| spellingShingle | Nonclassicality of open circuit QED systems in the deep-strong coupling regime Tomohiro Shitara (18508206) Information and computing sciences Applied computing circuit QED nonclassicality deep strong coupling metrological power |
| status_str | publishedVersion |
| title | Nonclassicality of open circuit QED systems in the deep-strong coupling regime |
| title_full | Nonclassicality of open circuit QED systems in the deep-strong coupling regime |
| title_fullStr | Nonclassicality of open circuit QED systems in the deep-strong coupling regime |
| title_full_unstemmed | Nonclassicality of open circuit QED systems in the deep-strong coupling regime |
| title_short | Nonclassicality of open circuit QED systems in the deep-strong coupling regime |
| title_sort | Nonclassicality of open circuit QED systems in the deep-strong coupling regime |
| topic | Information and computing sciences Applied computing circuit QED nonclassicality deep strong coupling metrological power |