Effect of chaos on information gain in quantum tomography

• URL: http://arxiv.org/abs/2203.07692v2
• Date: Sat, 27 Aug 2022 06:57:44 GMT
• Title: Effect of chaos on information gain in quantum tomography
• Authors: Abinash Sahu, Sreeram PG, and Vaibhav Madhok
• Abstract summary: We consider continuous measurement tomography in which the measurement record is obtained as a sequence of expectation values of a Hermitian observable evolving. As the chaos in the dynamics increases, the reconstruction fidelity of spin coherent states decreases. This contrasts with the previous results connecting information gain in tomography of random states with the degree of chaos in the dynamics that drives the system.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Does chaos in the dynamics enable information gain in quantum tomography or impede it? We address this question by considering continuous measurement tomography in which the measurement record is obtained as a sequence of expectation values of a Hermitian observable evolving under the repeated application of the Floquet map of the quantum kicked top. For a given dynamics and Hermitian observables, we observe completely opposite behavior in the tomography of well-localized spin coherent states compared to random states. As the chaos in the dynamics increases, the reconstruction fidelity of spin coherent states decreases. This contrasts with the previous results connecting information gain in tomography of random states with the degree of chaos in the dynamics that drives the system. The rate of information gain and hence the fidelity obtained in tomography depends not only on the degree of chaos in the dynamics and to what extent it causes the initial observable to spread in various directions of the operator space but, more importantly, how well these directions are aligned with the density matrix to be estimated. Our study also gives an operational interpretation for operator spreading in terms of fidelity gain in an actual quantum information tomography protocol.

Related papers

• Information Gain, Operator Spreading, and Sensitivity to Perturbations as Quantifiers of Chaos in Quantum Systems [0.0]
  We generate the measurement record as a series of expectation values of an observable evolving under the desired dynamics. We find that the rate of information gain depends on the degree of chaos in the dynamics. The amount of operator spreading in the Krylov subspace, as quantified by the fidelity in quantum tomography, increases with the degree of chaos in the system.
  arXiv  Detail & Related papers  (2024-04-15T05:15:29Z)
• Dynamical signatures of non-Markovianity in a dissipative-driven qubit [0.0]
  We investigate signatures of non-Markovianity in the dynamics of a periodically-driven qubit coupled to a bosonic environment. Non-Markovian features are quantified by comparing on an equal footing the predictions from diverse and complementary approaches to quantum dissipation.
  arXiv  Detail & Related papers  (2024-01-17T15:58:50Z)
• Quantifying operator spreading and chaos in Krylov subspaces with quantum state reconstruction [0.0]
  We study operator spreading in many-body quantum systems by its potential to generate an informationally complete measurement record. We generate the measurement record as a series of expectation values of an observable evolving under the desired dynamics. We find that the amount of operator spreading, as quantified by the fidelity in quantum tomography, increases with the degree of chaos in the system.
  arXiv  Detail & Related papers  (2023-08-16T17:10:00Z)
• Evolution of many-body systems under ancilla quantum measurements [58.720142291102135]
  We study the concept of implementing quantum measurements by coupling a many-body lattice system to an ancillary degree of freedom. We find evidence of a disentangling-entangling measurement-induced transition as was previously observed in more abstract models.
  arXiv  Detail & Related papers  (2023-03-13T13:06:40Z)
• Full counting statistics as probe of measurement-induced transitions in the quantum Ising chain [62.997667081978825]
  We show that local projective measurements induce a modification of the out-of-equilibrium probability distribution function of the local magnetization. In particular we describe how the probability distribution of the former shows different behaviour in the area-law and volume-law regimes.
  arXiv  Detail & Related papers  (2022-12-19T12:34:37Z)
• Information scrambling and the growth of errors in noisy tomography -- a quantum signature of chaos [0.0]
  We use continuous measurement quantum tomography as a paradigm to study quantum chaos. We define a quantity to capture the scrambling of errors, an out-of-time-ordered correlator (OTOC) between two operators under perturbed and unperturbed system dynamics. Our results demonstrate not only a fundamental link between Loschmidt echo and scrambling of errors, as captured by OTOCs, but that such a link can have operational consequences in quantum information processing.
  arXiv  Detail & Related papers  (2022-11-21T07:32:53Z)
• Reminiscence of classical chaos in driven transmons [117.851325578242]
  We show that even off-resonant drives can cause strong modifications to the structure of the transmon spectrum rendering a large part of it chaotic. Results lead to a photon number threshold characterizing the appearance of chaos-induced quantum demolition effects.
  arXiv  Detail & Related papers  (2022-07-19T16:04:46Z)
• Monitored Open Fermion Dynamics: Exploring the Interplay of Measurement, Decoherence, and Free Hamiltonian Evolution [0.0]
  We investigate the impact of dephasing and the inevitable evolution into a non-Gaussian, mixed state, on the dynamics of monitored fermions. For weak dephasing, constant monitoring preserves a weakly mixed state, which displays a robust measurement-induced phase transition. We interpret this as a signature of gapless, classical diffusion, which is stabilized by the balanced interplay of Hamiltonian dynamics, measurements, and decoherence.
  arXiv  Detail & Related papers  (2022-02-28T19:00:13Z)
• Continuous-time dynamics and error scaling of noisy highly-entangling quantum circuits [58.720142291102135]
  We simulate a noisy quantum Fourier transform processor with up to 21 qubits. We take into account microscopic dissipative processes rather than relying on digital error models. We show that depending on the dissipative mechanisms at play, the choice of input state has a strong impact on the performance of the quantum algorithm.
  arXiv  Detail & Related papers  (2021-02-08T14:55:44Z)
• Process tomography of Robust Dynamical Decoupling in Superconducting Qubits [91.3755431537592]
  The Rigetti quantum computing platform was used to test different dynamical decoupling sequences. The performance of the sequences was characterized by Quantum Process Tomography and analyzed using the quantum channels formalism.
  arXiv  Detail & Related papers  (2020-06-18T14:48:18Z)
• Quantum Zeno effect appears in stages [64.41511459132334]
  In the quantum Zeno effect, quantum measurements can block the coherent oscillation of a two level system by freezing its state to one of the measurement eigenstates. We show that the onset of the Zeno regime is marked by a $textitcascade of transitions$ in the system dynamics as the measurement strength is increased.
  arXiv  Detail & Related papers  (2020-03-23T18:17:36Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.