Metrology, metastability and dynamical phase transitions in open quantum systems
In this thesis we explore aspects of dynamics of open quantum systems related to coherence and quantum correlations - necessary resources for enhanced quantum metrology and quantum computation. We first discuss limits to the precision of parameter estimation when using a quantum system in the pres...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English |
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2017
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| Online Access: | https://eprints.nottingham.ac.uk/39811/ |
| _version_ | 1848795918530248704 |
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| author | Macieszczak, Katarzyna |
| author_facet | Macieszczak, Katarzyna |
| author_sort | Macieszczak, Katarzyna |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | In this thesis we explore aspects of dynamics of open quantum systems related to coherence and quantum correlations - necessary resources for enhanced quantum metrology and quantum computation.
We first discuss limits to the precision of parameter estimation when using a quantum system in the presence of noise. To this end we introduce a variational principle for the quantum Fisher information (QFI) bounding the estimation errors of any measurement, which motivates an efficient iterative algorithm for finding optimal system preparations for noisy estimation experiments. Furthermore, we investigate influence of noise correlations on the precision in phase and frequency estimation, by delivering bounds for both spatially and temporarily correlated (non-Markovian) dephasing noise. This allows us to prove the Zeno limit in frequency estimation, conjectured in Phys. Rev. A 84, 012103 (2011) and Phys. Rev. Lett. 109, 233601 (2012). The enhanced estimation precision in quantum metrology can be, however, achieved only using highly entangled states. We propose a scheme of generating such highly correlated states as outputs of Markovian open quantum systems near first-order dynamical phase transitions. We show that the quadratic scaling of the QFI with time is present for experiments within the correlation time of the dynamics and describe a theoretical scheme for quantum enhanced estimation of an optical phase-shift using the photons being emitted from an intermittent quantum system. Finally, we establish the basis for a theory of metastability in Markovian open quantum systems, by extending methods from classical stochastic dynamics. We argue that the partial relaxation into long-lived metastable states - distinct from the asymptotic stationary state - may preserve initial coherences within decoherence-free subspaces or noiseless subsystems, thus allowing for quantum computation during the metastable regime. |
| first_indexed | 2025-11-14T19:39:43Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-39811 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T19:39:43Z |
| publishDate | 2017 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-398112017-10-13T17:01:30Z https://eprints.nottingham.ac.uk/39811/ Metrology, metastability and dynamical phase transitions in open quantum systems Macieszczak, Katarzyna In this thesis we explore aspects of dynamics of open quantum systems related to coherence and quantum correlations - necessary resources for enhanced quantum metrology and quantum computation. We first discuss limits to the precision of parameter estimation when using a quantum system in the presence of noise. To this end we introduce a variational principle for the quantum Fisher information (QFI) bounding the estimation errors of any measurement, which motivates an efficient iterative algorithm for finding optimal system preparations for noisy estimation experiments. Furthermore, we investigate influence of noise correlations on the precision in phase and frequency estimation, by delivering bounds for both spatially and temporarily correlated (non-Markovian) dephasing noise. This allows us to prove the Zeno limit in frequency estimation, conjectured in Phys. Rev. A 84, 012103 (2011) and Phys. Rev. Lett. 109, 233601 (2012). The enhanced estimation precision in quantum metrology can be, however, achieved only using highly entangled states. We propose a scheme of generating such highly correlated states as outputs of Markovian open quantum systems near first-order dynamical phase transitions. We show that the quadratic scaling of the QFI with time is present for experiments within the correlation time of the dynamics and describe a theoretical scheme for quantum enhanced estimation of an optical phase-shift using the photons being emitted from an intermittent quantum system. Finally, we establish the basis for a theory of metastability in Markovian open quantum systems, by extending methods from classical stochastic dynamics. We argue that the partial relaxation into long-lived metastable states - distinct from the asymptotic stationary state - may preserve initial coherences within decoherence-free subspaces or noiseless subsystems, thus allowing for quantum computation during the metastable regime. 2017-07-12 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en cc_by_nc_nd https://eprints.nottingham.ac.uk/39811/1/KMacieszczakThesis.pdf Macieszczak, Katarzyna (2017) Metrology, metastability and dynamical phase transitions in open quantum systems. PhD thesis, University of Nottingham. quantum metrology dynamical phase transition quantum metastability open quantum system Markovian noise non-Markovian noise quantum Fisher information Heisenberg scaling Zeno scaling matrix product state coherence |
| spellingShingle | quantum metrology dynamical phase transition quantum metastability open quantum system Markovian noise non-Markovian noise quantum Fisher information Heisenberg scaling Zeno scaling matrix product state coherence Macieszczak, Katarzyna Metrology, metastability and dynamical phase transitions in open quantum systems |
| title | Metrology, metastability and dynamical phase transitions in open quantum systems |
| title_full | Metrology, metastability and dynamical phase transitions in open quantum systems |
| title_fullStr | Metrology, metastability and dynamical phase transitions in open quantum systems |
| title_full_unstemmed | Metrology, metastability and dynamical phase transitions in open quantum systems |
| title_short | Metrology, metastability and dynamical phase transitions in open quantum systems |
| title_sort | metrology, metastability and dynamical phase transitions in open quantum systems |
| topic | quantum metrology dynamical phase transition quantum metastability open quantum system Markovian noise non-Markovian noise quantum Fisher information Heisenberg scaling Zeno scaling matrix product state coherence |
| url | https://eprints.nottingham.ac.uk/39811/ |