Free fermions under adaptive quantum dynamics
We study free fermion systems under adaptive quantum dynamics consisting of unitary gates and projective measurements followed by corrective unitary operations. We further introduce a classical flag for each site, allowing for an active or inactive status which determines whether or not the unitary...
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| Format: | Article |
| Language: | English |
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Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften
2025-04-01
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| Series: | Quantum |
| Online Access: | https://quantum-journal.org/papers/q-2025-04-03-1685/pdf/ |
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| author | Vikram Ravindranath Zhi-Cheng Yang Xiao Chen |
| author_facet | Vikram Ravindranath Zhi-Cheng Yang Xiao Chen |
| author_sort | Vikram Ravindranath |
| collection | DOAJ |
| description | We study free fermion systems under adaptive quantum dynamics consisting of unitary gates and projective measurements followed by corrective unitary operations. We further introduce a classical flag for each site, allowing for an active or inactive status which determines whether or not the unitary gates are allowed to apply. In this dynamics, the individual quantum trajectories exhibit a measurement-induced entanglement transition from critical to area-law scaling above a critical measurement rate, similar to previously studied models of free fermions under continuous monitoring. Furthermore, we find that the corrective unitary operations can steer the system into a state characterized by charge-density-wave order. Consequently, an additional phase transition occurs, which can be observed at both the level of the quantum trajectory and the quantum channel. We establish that the entanglement transition and the steering transition are fundamentally distinct. The latter transition belongs to the parity-conserving (PC) universality class, arising from the interplay between the inherent fermionic parity and classical labelling. We demonstrate both the entanglement and the steering transitions via efficient numerical simulations of free fermion systems, which confirm the PC universality class of the latter. |
| format | Article |
| id | doaj-art-5c2a4682207449dab80f0d3a7d333d39 |
| institution | OA Journals |
| issn | 2521-327X |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften |
| record_format | Article |
| series | Quantum |
| spelling | doaj-art-5c2a4682207449dab80f0d3a7d333d392025-08-20T01:51:38ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2025-04-019168510.22331/q-2025-04-03-168510.22331/q-2025-04-03-1685Free fermions under adaptive quantum dynamicsVikram RavindranathZhi-Cheng YangXiao ChenWe study free fermion systems under adaptive quantum dynamics consisting of unitary gates and projective measurements followed by corrective unitary operations. We further introduce a classical flag for each site, allowing for an active or inactive status which determines whether or not the unitary gates are allowed to apply. In this dynamics, the individual quantum trajectories exhibit a measurement-induced entanglement transition from critical to area-law scaling above a critical measurement rate, similar to previously studied models of free fermions under continuous monitoring. Furthermore, we find that the corrective unitary operations can steer the system into a state characterized by charge-density-wave order. Consequently, an additional phase transition occurs, which can be observed at both the level of the quantum trajectory and the quantum channel. We establish that the entanglement transition and the steering transition are fundamentally distinct. The latter transition belongs to the parity-conserving (PC) universality class, arising from the interplay between the inherent fermionic parity and classical labelling. We demonstrate both the entanglement and the steering transitions via efficient numerical simulations of free fermion systems, which confirm the PC universality class of the latter.https://quantum-journal.org/papers/q-2025-04-03-1685/pdf/ |
| spellingShingle | Vikram Ravindranath Zhi-Cheng Yang Xiao Chen Free fermions under adaptive quantum dynamics Quantum |
| title | Free fermions under adaptive quantum dynamics |
| title_full | Free fermions under adaptive quantum dynamics |
| title_fullStr | Free fermions under adaptive quantum dynamics |
| title_full_unstemmed | Free fermions under adaptive quantum dynamics |
| title_short | Free fermions under adaptive quantum dynamics |
| title_sort | free fermions under adaptive quantum dynamics |
| url | https://quantum-journal.org/papers/q-2025-04-03-1685/pdf/ |
| work_keys_str_mv | AT vikramravindranath freefermionsunderadaptivequantumdynamics AT zhichengyang freefermionsunderadaptivequantumdynamics AT xiaochen freefermionsunderadaptivequantumdynamics |