Optimal Purification of a Spin Ensemble by Quantum-Algorithmic Feedback
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Authors
Zaporski, L
Bodey, JH
Shofer, N
Hugues, M
Le Gall, C
Publication Date
2022Journal Title
Physical Review X
ISSN
2160-3308
Publisher
American Physical Society (APS)
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Jackson, D., Haeusler, U., Zaporski, L., Bodey, J., Shofer, N., Clarke, E., Hugues, M., et al. (2022). Optimal Purification of a Spin Ensemble by Quantum-Algorithmic Feedback. Physical Review X https://doi.org/10.1103/PhysRevX.12.031014
Abstract
Purifying a high-temperature ensemble of quantum particles towards a known
state is a key requirement to exploit quantum many-body effects. An alternative
to passive cooling, which brings a system to its ground state, is based on
feedback to stabilise the system actively around a target state. This
alternative, if realised, offers additional control capabilities for the design
of quantum states. Here we present a quantum feedback algorithm capable of
stabilising the collective state of an ensemble from an infinite-temperature
state to the limit of single quanta. We implement this on ~50,000 nuclei in a
semiconductor quantum dot, and show that the nuclear-spin fluctuations are
reduced 83-fold down to 10 spin macrostates. While our algorithm can purify a
single macrostate, system-specific inhomogeneities prevent reaching this limit.
Our feedback algorithm further engineers classically correlated ensemble states
via macrostate tuning, weighted bimodality, and latticed multistability,
constituting a pre-cursor towards quantum-correlated macrostates.
Keywords
quant-ph, quant-ph, cond-mat.mes-hall
Sponsorship
European Research Council (617985)
Engineering and Physical Sciences Research Council (EP/M013243/1)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (861097)
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (862035)
Identifiers
External DOI: https://doi.org/10.1103/PhysRevX.12.031014
This record's URL: https://www.repository.cam.ac.uk/handle/1810/340169
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