Comparing the quantum switch and its simulations with energetically constrained operations
Quantum mechanics allows processes to be superposed, leading to a genuinely quantum lack of causal structure. For example, the process known as the quantum switch applies two operations A and B in a superposition of the two possible orders, A before B and B before A. Experimental implementations of...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2023-05-01
|
| Series: | Physical Review Research |
| Online Access: | http://doi.org/10.1103/PhysRevResearch.5.023111 |
| _version_ | 1797210428902735872 |
|---|---|
| author | Marco Fellous-Asiani Raphaël Mothe Léa Bresque Hippolyte Dourdent Patrice A. Camati Alastair A. Abbott Alexia Auffèves Cyril Branciard |
| author_facet | Marco Fellous-Asiani Raphaël Mothe Léa Bresque Hippolyte Dourdent Patrice A. Camati Alastair A. Abbott Alexia Auffèves Cyril Branciard |
| author_sort | Marco Fellous-Asiani |
| collection | DOAJ |
| description | Quantum mechanics allows processes to be superposed, leading to a genuinely quantum lack of causal structure. For example, the process known as the quantum switch applies two operations A and B in a superposition of the two possible orders, A before B and B before A. Experimental implementations of the quantum switch have been challenged by some on the grounds that the operations A and B were implemented more than once, thereby simulating indefinite causal order rather than actually implementing it. Motivated by this debate, we consider a situation in which the quantum operations are physically described by a light-matter interaction model. While for our model the two processes are indistinguishable in the infinite-energy regime, restricting the energy available for the implementation of the operations introduces imperfections, which allow one to distinguish processes using different numbers of operations. We consider such an energetically constrained scenario and compare the quantum switch to one of its natural simulations, where each operation is implemented twice. Considering a commuting-versus-anticommuting unitary discrimination task, we find that within our model the quantum switch performs better, for some fixed amount of energy, than its simulation. In addition to the known computational or communication advantages of causal superpositions, our work raises questions about their potential energetic advantages. |
| first_indexed | 2024-04-24T10:10:27Z |
| format | Article |
| id | doaj.art-2ea840a9e6624d01b021fa431b283bf5 |
| institution | Directory Open Access Journal |
| issn | 2643-1564 |
| language | English |
| last_indexed | 2024-04-24T10:10:27Z |
| publishDate | 2023-05-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Research |
| spelling | doaj.art-2ea840a9e6624d01b021fa431b283bf52024-04-12T17:31:04ZengAmerican Physical SocietyPhysical Review Research2643-15642023-05-015202311110.1103/PhysRevResearch.5.023111Comparing the quantum switch and its simulations with energetically constrained operationsMarco Fellous-AsianiRaphaël MotheLéa BresqueHippolyte DourdentPatrice A. CamatiAlastair A. AbbottAlexia AuffèvesCyril BranciardQuantum mechanics allows processes to be superposed, leading to a genuinely quantum lack of causal structure. For example, the process known as the quantum switch applies two operations A and B in a superposition of the two possible orders, A before B and B before A. Experimental implementations of the quantum switch have been challenged by some on the grounds that the operations A and B were implemented more than once, thereby simulating indefinite causal order rather than actually implementing it. Motivated by this debate, we consider a situation in which the quantum operations are physically described by a light-matter interaction model. While for our model the two processes are indistinguishable in the infinite-energy regime, restricting the energy available for the implementation of the operations introduces imperfections, which allow one to distinguish processes using different numbers of operations. We consider such an energetically constrained scenario and compare the quantum switch to one of its natural simulations, where each operation is implemented twice. Considering a commuting-versus-anticommuting unitary discrimination task, we find that within our model the quantum switch performs better, for some fixed amount of energy, than its simulation. In addition to the known computational or communication advantages of causal superpositions, our work raises questions about their potential energetic advantages.http://doi.org/10.1103/PhysRevResearch.5.023111 |
| spellingShingle | Marco Fellous-Asiani Raphaël Mothe Léa Bresque Hippolyte Dourdent Patrice A. Camati Alastair A. Abbott Alexia Auffèves Cyril Branciard Comparing the quantum switch and its simulations with energetically constrained operations Physical Review Research |
| title | Comparing the quantum switch and its simulations with energetically constrained operations |
| title_full | Comparing the quantum switch and its simulations with energetically constrained operations |
| title_fullStr | Comparing the quantum switch and its simulations with energetically constrained operations |
| title_full_unstemmed | Comparing the quantum switch and its simulations with energetically constrained operations |
| title_short | Comparing the quantum switch and its simulations with energetically constrained operations |
| title_sort | comparing the quantum switch and its simulations with energetically constrained operations |
| url | http://doi.org/10.1103/PhysRevResearch.5.023111 |
| work_keys_str_mv | AT marcofellousasiani comparingthequantumswitchanditssimulationswithenergeticallyconstrainedoperations AT raphaelmothe comparingthequantumswitchanditssimulationswithenergeticallyconstrainedoperations AT leabresque comparingthequantumswitchanditssimulationswithenergeticallyconstrainedoperations AT hippolytedourdent comparingthequantumswitchanditssimulationswithenergeticallyconstrainedoperations AT patriceacamati comparingthequantumswitchanditssimulationswithenergeticallyconstrainedoperations AT alastairaabbott comparingthequantumswitchanditssimulationswithenergeticallyconstrainedoperations AT alexiaauffeves comparingthequantumswitchanditssimulationswithenergeticallyconstrainedoperations AT cyrilbranciard comparingthequantumswitchanditssimulationswithenergeticallyconstrainedoperations |